Injector Discussion

I have seen quite a few posts recently about preventively replacing injectors in hopes to head off possible cylinder wall scoring. Now I am no longer a mechanic by profession, but I used to be and I have built several engines over the last 20 years. None of those engines were Porsche flat sixes, but one of them was a 928 S4 32v V8. So I have seen what a damaged engine looks like and I have seen what causes failures. Which leads me to this discussion and I just want to talk about injectors. Specifically the value of replacing them at a certain age. In all my years working on cars I have never seen "leaky" injectors that wash out a cylinder. I have seen temp sensors cause a car to go rich and wash down cylinders. I have seen fuel pumps and regulators go crazy and increase pressure and wash down cylinders, but I have never seen a leaky injector wash down a cylinder to the point where it causes wall scoring. Not that it can't happen and I am some super expert on it, but I personally not seen that kind of failure. So some of my observations about injectors. Injector failure is random, so if we were seeing injectors fail they would cause random cylinders to fail. Not the same 2 cylinders on every car. The data would be all over the place. When you have injectors reconditioned they are pressure tested to hold a specific PSI. If they fail that test they are junk. If an injector was to leak down fuel over time it would only be bleeding off excess pressure at a very slow rate. Probably at a rate in which the fuel would evaporate before it pools. Assuming there even is enough to pool. So again not enough to wash out a cylinder. If gas was leaking into the cylinder in enough volume to "wash" the cylinder out there would be gas in the oil. That gas in the oil would be very very easy to smell and would cause the oil lever to increase over time. In a 9+ quart system it would take a fair amount of gas to dilute the oil to the point it was no longer effective. Cylinder scoring from my experience is caused by ring problems, detonation or expansion issues of the metals. (mostly from the rings or detonation). As soon as the engine cranks oil is splashed back up to the bottom of the cylinder and lubricated, it would take a lot of starts to score a cylinder from washed out liner. Not saying it can't happen, just saying it is unlikely. So lubrication issues not related to oil starvation typically don't cause scoring. Those are my thoughts and I am trying to think through this injector replacement thing logically before everyone puts injectors on their 100K tune up list. Recently I had a 1997 BMW M3 with 250,000+ miles on the original Bosch injectors. Car ran perfect, had great compression and when the head was off there was zero scoring. I have had several VW turbo engines go past 200K miles and never an injector problem. If injectors failed around 100K miles we would see this on other cars because they all use the same injectors from the same supplier. Discuss away and maybe some logic will come from this thread. :-)

^^ Good points/questions - maybe Jake Raby will chime in as he seems to be a big proponent of this injector theory. *Even though the injectors may be the same, it's possible that the idiosyncrasies of the M96 are causing them to fail earlier than with other platforms.

Jake never said it was THE cause, he said it was ONE of the causes. There are other reasons why it affects one bank over the other.

As I was thinking about this more why have we not seen this on the Mezger engines? I realize this new block setup is very unique and was a first for Porsche, but why are the 2.5/2.7s in the Boxster not affected as much and it carried over to the 987 Caymans/Boxsters and 997s even as different parts and components of the injection systems changed over. Mostly this is just rambling at this point, but I am not seeing a need to replace injectors at some interval unless I know there is actually a problem with them. For instance if there is a specific failure which is what we suspect to be contributed to by a leaky injector I would like to see what parameters of that injector fell out of spec. Meaning you can put the injector on a bench and measure spray, response, resistance, pressure and leak down. It is a pretty definitive way of proving this theory.

Different animals.. The Mezger, along with all aircooled engines use Nikisil plated cylinders. Nikisil will streak and consume oil when too much fuel is present, but they will not score. Often once the over- fueling issue is corrected, the issues go away. The only thing that will touch the surface of a Nikisil bore is a diamond, or a tungsten- carbide cutter. remember, Nikisil is a composition of Nickel, Silicon, and Carbide. That said, I have collected enough conclusive data to support this that I don't need to substantiate my feelings. I know what keeps my engines alive, and that's what I do. Its not like I sell fuel injectors, or any other part.. I have no benefit from sharing this with you.. In fact, the best thing I could do is not share anything, let the effects occur, and watch my line att he door for engines get longer and longer....all while no one has figured out the things that create the equation of failure. Do as you wish :-) On a bench you don't have a real world scenario. You don't have warm fuel, you don't have engine vibration, you don't have a hot engine that stays hot, and even gets a little hotter just after being shut down. Further, you don't have all these elements working in unison with the engine in a car, using unknown fuel. You don't have all of this happening, then requiring the injectors to hold fuel pressure without leaking down. You can't test this scenario in a lab.

The Mezger engines are not the same as the M96 and M97, so they really don't compare. The M96 & M97 3.6 and 3.8 suffer the most from bore scoring (as compared to the smaller M96s) because they have the most contributing factors. As I said before, fuel injectors are not THE cause, but one contributing factor. But it is one that all of the M96/M97 engines, and many other engine designs, have. Leaking fuel injectors cause issues with LOTS of different engine designs, not just Porsche M96s. Those issues can be bore-scoring, hydro-lock, failed cats. etc. Oops, Jake posted while I was typing my post. Jake has the most experience with these engines, so I don't expect him to explain his findings unless he feels like sharing. If he says a X causes Y in these engines, then I'll except that as an experienced statement.

Jake: Did you get to putting that video together on how to modify the .2 injectors for the .1 3.4's? We would love to see it! Thanks!

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Another good thing you could do for your business is allow quality to reduce (by outsourcing some of the work) so you could increase productivity. But that's not your business style, thankfully!

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FIrst thanks Jake for chiming in and thanks for the answer on the Mezgar engine, that makes sense. As an engineer and working with many different OE manufactures I can assure you there is a way to test this. However feasibility of setting up the lab and cost may be prohibitive, but I highly suspect Bosch, Denso, or another injector OEM has the proper simulations and tests for this exact case. It's not like this is new technology either, injectors have been around in this form since the 80s. I am not trying to stir the pot and get emotional, instead I really want to understand what is happening and what the proper course of action is. In my garage is both a 3.2 and 3.4 M96 of the correct vintage and mileage for this type of failure, but neither car is at the moment exhibiting any symptoms and I would prefer to keep it that way. Both cars however were southern cars and very well maintained prior to my ownership, but most Porsches are very well maintained. That being said pandora's box has been opened about suspect injector behavior and I would like to understand it better because my personal experience leads me to believe this shouldn't be an issue. If it is an issue there should be a protocol developed to reduce risk. As a business owner and innovator I understand your apprehension in sharing too much information and possible negative effects to your bottom line. On the other hand this is a community which does try to help each other out as best we can without regard to profit. So any additional insight you could share would be greatly appreciated.

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If I didn't want to help, I would have never brought this up. Yes, you can test this. It is tested in the car, using the vehicle as the lab. When things that are designed in labs don't work, this is how people like me solve problems. Nothing trumps practical application testing, and development. Someone can learn all they need to about this with their own vehicle that is showing symptoms. I just used a 32.00 bore scope from Amazon to assist me in a couple of the bore scoring videos we shot this week. A fuel pressure gauge, a bore scope, and some common sense and someone can figure this out. There's a difference in sharing, and arguing. Most people that want to argue have no personal direct experience with the problem, nor the solution. I don't argue with people that haven't experienced it themselves.

Thank you Jake, I think I got it. So, lets pretend it is the dead of winter and I have a car I was planning to do plugs, plug tubes and some other maintenance to anyway. When I take the plugs out what I could theoretically do is turn the car on to pressurize the fuel pump and bore scope each cylinder looking for scoring and any fuel leaking or pooling in the cylinder. Additionally if I put a pressure gauge on the fuel rail after you shut off the car it should hold pressure for a specific time period. I don’t have the factory 911 manuals so I don’t know what the exact pressure and leak down specifications are, but I am sure I can dig them up somewhere. If the car passes both those tests it is probably fine, but if there is some leakdown detected the suspect injector should probably be replace. Theoretically..... This is where I was hoping this thread would go.

"On a bench you don't have a real world scenario. You don't have warm fuel, you don't have engine vibration, you don't have a hot engine that stays hot, and even gets a little hotter just after being shut down. Further, you don't have all these elements working in unison with the engine in a car, using unknown fuel. You don't have all of this happening, then requiring the injectors to hold fuel pressure without leaking down. You can't test this scenario in a lab." ^^This is exactly what I meant when I said this: "*Even though the injectors may be the same, it's possible that the idiosyncrasies of the M96 are causing them to fail earlier than with other platforms."

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Not without the engine being hot.. When l first started finding this l had to keep the engine hot, and test 1 cylinder at a time, removing one plug and coil pack at a time.. Then wear welding gloves, and a kevlar sleeve on my forearm to do the work. Insert the scope and start watching. The scope can�t stay in place long, due to the heat. The caveat to this method is the intake valves on the cylinder you are testing has to be open. Doing it this way is tough. You can also use a test set of upper intake plenums that allow for an expansion plug to be fitted to the runners. When the engine is shut down remove these and start looking at the intake ports with the scope as soon as possible. This is much easier on my engine dyno, which is coinsidered a lab, as long as we can limit the variables. Doing this test with a cold engine isn�t going to net a result unless you have a really bad injector, and that usually means that its bad enough to misfire.

Back to my pressure gauge thought, if the system is pressurized it should hold that pressure for a certain amount of time. Does the 996 system have a check valve to prevent back flow to the pump? So if you take a known good set of injectors and get the car hot and then turn off the key the fuel pressure will back down in a specific amount of time. It will be pretty consistent at the same temp. When I designed my own injection for my 2.2 engine back in the day I was having problems when the engine was hot not having enough pressure in the system. What I found was the tank return line was swirling the gas and adding air to the system causing the gas to have bubbles in it when hot. The solution was to put a check valve/restrictor on the return line to slow the rate of return to the tank. (also keeping the tank above the 1/4 level) Later tanks didn't have this problem since the return line was in a different position. I diagnosed this by watching the pressure gauge over several days to see how it acted at different operating temps. Porsche figured this out in 72 and mine was an early 71 LOL Anyway if an injector is bleeding pressure off the system it should be pretty easy to detect by watching a gauge and the behavior from control good to bad. Once diagnosed bad then you just need to figure out which injector, but at that point they all have to come out anyway so you can just replace them all at that point. Am I crazy here? Might be easier than bore scoping a hot engine or trying to get access to the intake runners.....which was my first thought BTW. It may not be as straightforward as just putting a gauge on the rail, but I think it could be done in this manner. You diagnose boost leaks on a turbo car in this manner and a variation to diagnose vacuum leaks on a 928 S4 in the absence of a smoke tester. Again just thinking out loud here.

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This won�t work without a twist.. Why? Because the fuel pump will allow bleed down. How you make this work is with an aeroquip valve in the fuel line. Install the pressure gauge in the system between the fuel rail feed, and the cut off valve, with the cut off valve as close to the fuel rail as possible. With the engine hot, shut it down, and then immediately close the valve. Watch the pressure gauge. Now, this is more difficult with cars 01 and earlier, as they have a return line and fuel pressure regulator. This means two valves are needed and both must be shut off simultaneously after engine shut down. Been here, done this. Now, that said... As you can see all of this is hard work. At the end of the day the fuel injectors in the newest 996 are 15 years old. For more than half that period of time they have been exposed to crappy fuel. They are tired and should be replaced simply due to time in service. Thats my philosophy based on tests as l describe above, and direct experience. Fuel is the life blood of combustion, make no compromises.

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From the perspective if the engine is out and apart anyway I totally agree here. Every motor I have built got new injectors regardless, but for cars still in service it may not be feasible from an economic/effort perspective to do this at let's say 100K miles. That being said I am all behind developing some kind of test to see if they should be replaced or investigated further that is relatively easy to do without pulling the motor. You have provided way more insight on this than I was hoping for so thank you for that again. I am going to ponder this a bit more and maybe let the community digest some of the thoughts floating around here. For sure I understand this way better than I did at the beginning of yesterday. Thanks again!

To add to Jake's point about replacing tired injectors as preventative maintenance, I have decided to replace the injectors on my 3.6 FSI engine, which was a 3.4L originally. I think that something that scares off a lot of MK1 owners from replacing injectors is how expensive the specific 3.4L injectors are.....somewhere around $1.5K to $1.8K for a set. This leads one to look for alternatives to replacing (i.e cleaning, refurbishment etc). However the MK2 (3.6L) injectors can be had new for less than $40 each and it is my understanding that they will work on the 3.4L engine with a minor mod to them. Jake tells me they will be fine on my 3.6 FSI engine so I am going to put on new as they are relatively affordable (although the labour is the same) and will give great peace of mind! I am looking at this as preventative maintenance just like water pump, AOS etc.

My car is starting to experience this and has destroyed my catalytic converters. On initial start I have to let it warm for a few minutes before I can drive it without backfiring. They aren’t clogged enough to cause any misfiring but I want to get this fixed asap. I’ll be replacing the fuel pump and all 6 injectors along with new coils packs, plugs, and oil change on my 99. My question is on the injectors. From searching I have noticed some places notating that the Bosch 0280156211 are an upgrade to the Bosch 0280150455 (what comes stock on the 99). It’s quite the price difference is the main reason I am asking if the ‘upgraded’ ones are useable. They flow roughly a pound more which shouldn’t be that much of an issue with a full bolt+ car.

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Glad to see that you are doing these injectors. Back when your engine was built we were only having the injectors professionally cleaned during an engine build. We had yet to connect these dots concerning injectors, and of course, the injectors were 7 years newer at that time as well. Concerning the injector mods, basically the groove that holds the retention clip is not deep enough in the replacement injectors to use the earlier rail/ retention clips. This groove can be made slightly deeper, and wider (when necessary) to accept the earlier clip. I plan a Rennvision video for this as soon as we get the chance.

They aren't that much as I said earlier they are available in uk from design 911 for �75 each!! photo252.jpg

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Just throwing in something here. Has anyone sent old/bad injectors to one of these specialist places that checks/cleans/measures them? Surely they would flag them as bad and they should have seen quite a lot of these by now?

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Aren't these the same part # as 3.6 injectors at only 23 pounds each? https://www.mg-rover.com/inc/sdetail...6211/1164/6470

Chris If you scroll the photos there's one showing a picture of the injector, the one you pictures looks like the later model 3.6 it's different and that one looks aftermarket aswel, the ones I've quoted are Bosch oem and porsche

From a quick google of the 996-1 Vs 996-2 injectors it looks like there is an extra groove where a metal clip anti-rotation feature fits. (green and red arrows). I also noticed the distance between the inlet sealing O-ring and the main retention groove is longer on the newer injector; although this may not matter depending on what it fits into.

The .2 injector you are showing is not the oem Bosch number. That number is the one I referenced in question to slightly up on this page if it can work. The 996.2 Bosch number is 0280156053.

I have a recently acquired 3.8L FSI motor built by Jake (was originally a 2002 M96 3.6L). The torque this motor puts down is really impressive - LOVE IT DEARLY!!! Plan to keep it long term. Time to change the AOS. Motor has only run on DT40 since the build in 2013.

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I’d suggest the UAOS. Open a ticket with Jake and ask him. I can guess, but he definitely knows. You most likely will have to pay for his consulting time, but he will know all the answers. It will almost certainly be worth the money spent.

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Hey Jake. Goes without saying, I always appreciate so much of the free information you have provided as a practitioner and contributions that you have made in the Porsche and VW community. Sorry for reviving a very old thread but I was wondering your thoughts on the following. Talking water cooled engines only here: Isn't the reason the Mezger is immune to this because of the Nikasil, of course, but also because it's not direct-injected? When you say "Nikisil will streak and consume oil when too much fuel is present, but they will not score" and "The only thing that will touch the surface of a Nikisil bore is a diamond" does that effectively mean that Nikasil (and SUMEbore) are completely invincible? For example, I have seen Charles state in the past "no cylinder solution is 100% impervious to damage when the engine is not operating properly, like with a leaky injector, or conditions like a vacuum leak that lead to over-fuelling." Trying to reconcile these statements. Thank you for your time.

Even Nikisil can be damaged from excess fuel. It takes a lot, and the Nikisil is very tough, but rings can glaze and cause issues. Nothing can live through too much fuel.. SUMEBore appears to be even more resilient than Nikisil, and my testing to see just how much fuel SUMEBore can retain ring seal with is happening very soon. The Nikisil is honed with a diamond... If you have too much fuel in the equation, and the oil is washed off the wear surfaces, you'll have problems..

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Thank you very much for the response. You work on engines every day and I only read white papers about them so I always appreciate the opinion of experience (the best way to learn engines is to work on them). But talking Nikisil and excess fuel, I would think DFI engines would be even more vulnerable to this since a bad injector or leaky injector is spraying it directly onto the cylinder wall vs a pre-DFI engine where it's further upstream.... leaking injector is bad news in either type of injection, port injected or direct injected, not disputing that, just seems especially bad with DFI and those injectors shoot at much higher pressures. I hypothesize this is why with a port injected Mezger that has Nikasil cylinders you will never see a case of bore scoring under normal circumstances (you can correct me if that's not accurate, I used to own one and bore scoring is pretty much completely unheard of on a 996/7 Mezger that I have ever seen). I would be infinitely grateful if you could share your SUMEbore results in the future.

Nearly every marque out there with DI ,,, is/has/or will have problems.. 1. Carbon buildup on the valves 2. Cylinder wall damage when the DI injector fails, remember some of these put 2000 psi on the fuel when they trigger, so they fail much harder than the old ones. 3. on almost all the small displacement high power motors you need a intake off valve and runner clean about every 60K.. ) Eco Tec, Eco-boost, VW's motors, audi..

Agree that DI has issues/considerations as a technology that are not brand specific and owners should be cognizant of all the things you stated. IMHO the thing most people in the turbocharged DI market are going to need to be paying attention to is soot formation which includes damage of timing chains/tensioners, etc. You can help yourself out here by running a "good" oil. I use Driven DI line because it has a low volatization and I make it a top priority to monitor and maintain AOS/PCV/crankcase vacuum with a manometer and preemptive replacement. The reason I'm thinking about this is because after the market calms down I will buy another car at some point but only one with Nikasil or SUMEbore cylinders and want to be informed. SUMEbore is probably the most exciting technology I have seen in this space in recent memory. This may be a stupid question but has Nikasil been used with a GDI engine? Nickies started out as air cooled and obviously made it to water cooled engines before it was phased out. If I am not mistaken Porsche implemented direct injection in the 997.2 but the last Mezger TT, for example, died at 997.1 -- as the 997.2 TT is a drastically different engine including the switch to Alusil. I believe the last Mezger was the 2011-2012 997 Porsche 911 GT3 RS 4.0 but I'm assuming it's still not direct injected? What I'm landing on is it seems like a 997.1 Mezger, which is not GDI, is still the most bulletproof engine you can buy even today over 10 years later. Someone can correct me if I'm wrong or have missed anything, only looking for the best/most accurate information. Thank you.

@Quaz (OP): Hartech (Baz) has documents in detail how (he hypothesises) bore scoring occurs, I.e., it’s not related to fuel injectors but to the geometry of the pistons and piston skirts relative to the crank. He provides a lot of data, as opposed to anecdote, so it makes a lot of sense. Easiest solution would be to send injectors to an injector shop such as Witchdoctor and ask them to run the leak-down test “hot”. They would be able to validate Jake’s theory with real data. FWIW, I’ve had injectors cleaned and blueprinted from a 150K-mile BMW and a 100K-mile Spec Miata with only very slight improvement in flow rates (I.e., not significantly dirty), and no (cold?) leak-down; they do look for that.

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I have over 300 sets of "real data" from injectors that were tested/ cleaned. Over and over again the cylinders that were scored had injectors that were leaking down, or had poor spray patterns, or both. I have seen people build engines after bore scoring, and not change injectors, only to have the replacement engine suffer immediate cylinder issues during or just after break in. In 3 cases the new factory engine consumed oil immediately and did so on the exact same cylinder that the old engine previously scored. The installers swapped ancillaries and never even removed the injectors, so this was an absolute conclusive set of data that proved my theory better than anything. No single thing causes bore scoring, it is a sum of many things that play into the scenario. Cylinder surface finish is one of those things, but if you have solvent (fuel) washing the protective layer of oil from the bores it will always be a catalyst. The reason you didn't see any big differences after injector servicing is because the injectors had mechanical wear, and will never be as good as a replacement with a new injector. "Rebuilding" injectors means cleaning, and changing external O rings. Due to the methods that injectors are manufactured you can't disassemble them to replace the items that see mechanical wear. You throw them away. The issue has never been injectors being dirty, in fact the trait is the modern fuels lack lubricity that help to reduce the mechanical wear. All my engines get new injectors, not rebuilt, and not cleaned. It's not even an option.

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So the injector leaks after you shut the engine off and fuel dribbles down and makes its way into the cylinder? How much fuel do you think or what would it take?

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Yes.. That's one way they create issues. This is responsible for a lot of the "blue smoke" at start up, since the fuel wicks oil from thew ring pack into the cylinder, and appears to "burn oil" at start up. Fuel has the same effect on oil, as paint thinner has on paint. I have caught fuel puddling inside intake ports from this exact issue, and also found that fuel pressure was not being held at engine shutdown. This has been creating hot re- start issues with these cars in summer months for years. Long story short, you never want liquid fuel in your cylinders/ intake ports.

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Will good injectors hold fuel pressure till the next start up? Seems like a gauge on the fuel pressure may be a good idea so one may be alerted early

On another note, I have always noticed all my Porsches have had "slow" throttle response. It bugs me when I'm trying to rev match on downshifts. Why don't these cars have a quick rev pick up off idle?

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The fuel pump (and pressure regulator on mk1 996s) will determine some of this as well. Fuel pressure should be maintained for a hot re- start. Put simply, if you have a 996, the car has seen enough time in service to require new injectors. Not rebuilt. Not cleaned. Time in service dictates this, not mileage. This is based on my empirical data, and replacement of fuel pumps, and the corrugated tubing inside the fuel tank isn't far behind the injectors. You can ask @dporto about that experience.

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Sounds like you have "e-gas" cars with electronic throttles.

When the fuel is injected into the system it has to be atomized/vaporized to combust. There are different modes of injector failure that can all have the same end result -- eg. If it doesn't leak after the engine is shutoff it can also spray improperly such that the result is the fuel not being completely atomized and all the things Jake says about the effects of fuel on oil. This is one of the reasons I pay attention to my fuel dilution and also periodically measure my fuel trims.

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I pay attention to the color of the oil when draining. Aside from the data from a UOA, I can tell everything I need to know from how the oil feels on my fingers, how it smells, and the color.

Agree on all accounts. I pay attention to basically everything about the oil both when it goes in and comes out.....and I take notes (consumption measurement, etc). On several occasions when mentioning this over the years on forums (one the reasons I had to take a break) I have been mocked by people saying literally I'm a complete fool and I think I can do real science by just looking at oil. I never said all oils were the same or that I was going to try to send a rocket ship to the moon on the back of using that data....but these people that laughed at me and think I'm stupid for saying that clearly are the type that have never changed their own oil otherwise they would have some clue what I'm talking about if they had any sense.

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I had a 964 that I incredibly stupidly sold.....that I installed a RS flywheel on to try and improve the throttle response. I monkey ed with the barn door and a few eproms from a well known mostly 3.2 tuner (you're probably cringing LOL). nothing helped. otherwise, the car ran great I thought. It put out 248 HP on a dynojet 248. There's was a delay between a blip and a reaction It was stock internally. . also has a 2000 boxster s and a 06 cayman s that had delays

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You should see how people react when you tell them that you compare oil based on how it tastes.

Going so far as to use taste? Now that's REAL dedication to science. I'll consider adding that to my notes after my oil change next week.

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Charles from LN and I have both tasted oil as a comparison.

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[Image-only post; no author-written text. Original image references:] https://cimg4.ibsrv.net/gimg/rennlist.com-vbulletin/600x462/taste_oil_3236ef31a57951682c3e74de4afcf8d3301335d8.jpg

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Speaking in the general context of injectors and all engines, so not just Alusil or aluminum but also traditional cast iron etc, do you have an opinion and general guidance on the service interval for injectors? Edit: I have read Bosch, for example, says their injectors should be good for a billion cycles which after doing some back of a dirty napkin math is more than the lifetime of an engine.

There's currently 47 blends of gasoline used this summer in this country. The fuel constantly changes, and because of that any claims that are made are not substantiated with these fuels and other variables. Modern fuels started causing issues with Diesel engines after 2007 or so, and my old Duramax had two sets of injectors in 13 years. To me anything beyond 10 years is borrowed time for an injector, so if you own a 996- it needs injectors based on my direct experience.

Thank you for the information. I knew fuel blends could be different and they change seasonally but didn't realize there were almost 50. "The fuel constantly changes".... sounds like the oil companies; I recently needed to buy a quart (liter) of oil in Denmark in a pinch and while I was checking the spec I noticed it said "we reserve the right to change the composition of this oil at any time". Anyway, one thing I have noticed empirically is that people that live in places without major name-brand gas seem to have injector issues much more often (then do silly things like try to clean them rather than just replace them only to have them keep failing again). I have always only used Top Tier fuel in my cars and I fill-up with 93 at the BP right by my home probably 98% of the time...then run a bottle of Techron just before my oil change. Here in the city no one sells Ethanol free gas (per www.pure-gas.org ) but my father owns property in the country and when he commutes back and forth there are several gas stations that he uses listed on that website as Ethanol free. I noticed that none of the Ethanol free stations are Top Tier though... even when I look in Georgia for example it's almost the same story, almost all of the Ethanol free gas stations are not Top Tier. I was telling him it's great he's getting Ethanol free gas.........but at the expense of using an unknown fuel detergent package and that part scares me. Thank you for the information about your injector experience.

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Silver, wasn't aware of the website. Thanks for Link.

Not a problem -- always happy to help with information when I can. Cheers

My 2001 996 with 30k miles is getting a "misfire cylinder #1" code. the misfire is at startup and sometimes at idle when warmed up otherwise it run perfect. I'm guessing it's either the plug/coil pack or the injector? Any way to determine which without pulling the plug/coil pack ?

Quotes source post: 15593194

This past year I replaced mine with 0280156053. I looked all over in Canada to find them and ended up ordering from the USA. Now when I search, a new Bosch product number is coming up on a few sites covering the 996.2 NA cars, Bosch W0133-1646826. I can't find any information on this injector from Bosch and wonder if it is correct. All sites claim it fits my 2002 Carrera 4 and the seller told me it is the same as 0280155053. I'm trying to find out because they are cheap at the moment. Is anyone familiar with that Bosch code?

If it were me, I'd only purchase fuel injectors from some place I truly trust, LN. https://lnengineering.com/genuine-bo...injectors.html I know that LN won't sell junk. They test their products constantly. They refused to sell the cheap chinese NAPA Gold oil filters that were not up to the previous Wix quality. (Most suppliers don't test products after they have decided to sell them) If LN will sell them, then they should be good to go. If they won't sell them, then they're not really identical. Some places will sell "same as" or "identical" which only means they fit. But cheap fuel injectors could cause a world of costly problems!