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YOUR RESEARCHUOA High Fuel Dilution = Replace Injectors?
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Install tomorrow, along
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Read evidence and context
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My 03 4s is getting new injectors installed tomorrow, along with Skip's UAOS, new coil packs/plugs and a 997 GT3 shifter.
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I�ve owned the car for 6.5 years and I�m still somewhat shocked at how much these injectors have changed the behavior of the car.
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I feel like it has even changed the exhaust note somewhat.
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Suggestion · Original poster
Just wanted to follow up with my latest UOA after changing injectors.
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Suggestion
I have my car apart to install the UAOS and wanted to replace the injectors at the same time but every supplier I try to order from has them on back order.
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I've had my '03 C4S for about a year now. Just over 50k miles (of which I put about 2.5k). Over the past 6 months or so it has consumed about a quart of oil in ~600 miles. I just got the oil changed and the report shows high fuel dilution. From reading on here I take it replacing injectors would be the right move? Would there be any other suspects at this point?
Steve you may want to run a complete fuel system cleaner in the fuel tank. I like Techron, a lot of other people like sea foam. Wait till you are 1/4 tank or less, put the product and fill, do not fill again until you run it down to a quarter. If you have access to a durametric check your fuel trims. Your engine may have blow by. Mine basically doesn�t uses any oil. But I got a 3.4. Make sure your intake is clean. Use carb cleaner for throttle and I like to use CRC GDI, spray it thru the throttle with someone holding rpms steady at 2,000. After the can is empty let it sit for at least an hour to soak. Then drive the car for at least 10 minutes at highway speed, you�ll see quite a bit of white smoke. I would do all of these before changing the injectors. Also watch your oil consumption you may have a more serious problem.
That's a lot of oil consumption. Mine has 95K and uses a non-noticeable amount between 5K oil changes. There are a lot of things that can be wrong. Get your AOS checked. Have the blow-by checked. Get your injectors checked. Techron or Seafoam are a good ways to clean things up, but it will take another oil change round to see if you've fixed it. Fuel dilution causes bore scoring in these engines. You might not want to wait the 3-5K miles for the next oil test to see if the injectors are fixed. Good luck!
Thanks for the replies! Sounds like changing injectors based on the report may be an overreaction, but I am definitely not wanting to take any chances with bore scoring. I'm hoping this is my smoking gun for the oil consumption. I also moved away from the M1 0w-40 to a 5w-40 hoping that could help as well.
That fuel dilution is off the charts. Wow!
You need to perform some short service intervals and more UOA.
People are finally starting to listen when it comes to changing injectors in these engines proactively. Usually by the time fuel dilution gets this high you've already seen some level of bore wear as collateral damage.
Maybe not. Keep an eye on it.
I got a similar report back from my UOA just a few months ago. If you look there is a thread with my report lots of good conversation there. Showing lots of fuel in the oil
I am replacing the injectors proactively hoping this will help. I burn no oil. While I'm there I'm doing secondary air system, because it won't pass emissions, and the AOS. I'm going deep since it will be apart. There is also a thread of mine on that topic that i will be updating in August.
It seems like these injectors wear out pretty quickly as compared to others based on conversation here on the forum. It seems like it will help give some life back and prolong the inevitable engine swap.
Best,
I have a 94 Ford Ranger with 175K miles on it. Runs great. I replaced the injectors on it last year and it runs better, but not any more power. Kind of makes wonder why the 996 injectors are only good for 50K or so.
I'm guessing the old injectors were spraying gas everywhere inside the cylinders. Cast iron blocks are good for these kinds of things.
Best,
The injectors in these engine work hard. In some instances they are near max duty cycle, which makes fuel atomize well when the injector is healthy.. This also makes the injector fail soon.
At the same time, these cars are old. The injectors are old. I don't give a damn how many miles the car has seen the injectors are in service 24/7-365, as they are exposed to fuel. Since around 2007 this fuel has continually been screwed with, and the ethanol content and other additives are not kind to the injectors.
Every 996 in the USA that has original injectors needs them replaced. Not cleaned. Not "rebuilt". REPLACED.
Just do it.
Used to when I posted that 5 years or so ago people thought I was crazy. As time has gone on these UOA and experiences people have had proved that I wasn't quite as crazy as people hoped I was.
Now, before some jackass says that I am stating this to "make money" I'll say that I don't sell or install injectors. In fact the recommendations that I am giving each of you here is screwing me. How? Because there's a shortage of the injectors that these engines use, and every set that one of you buy is a set that I may not be able to source later for one of my engines.
Try that one on for size before you call me a fear monger that's just trying to sell something.
Should injectors be replaced on a maintenance schedule, e,g, some number of years or miles, or just when fuel dilution gets to a certain level? Since the injectors are always exposed to fuel maybe based on so many years life?
When doing the AOS job, installing injectors took me no more than 30 minutes so it's a perfect opportunity. I talked about this in my DIY write up for the UAOS. With the intakes out you have very good access. My previous UOA had a fuel dilution value of 1.81% which is not bad but creeping up there. At the time the oil had 4k miles on the old injectors and 1k miles with new injectors before I sent the sample in. Curious to see what the values will look like with the next oil change and analysis. As far as differences I couldn't tell any. The goal here is not really performance oriented at all but just preventing other issues from occurring. The only difference you could see is a lower dilution value, as in OP case.
Does anybody know if the Bosch 0280150455 can be replaced with Bosch EV6172GPMIN? From what I understand the flow rate of the replacement is 43.5 psi @ 3 Bar 23lb per hour 172 G per min VS 43.5 psi / 3 bar 22.5 lb per hour 169.7 G per min. or is this some sort of BS?
I recently changed the injectors on my �99 to the later style and the change in the engine�s behavior has been eye opening. The engine now revs differently, it drops revs differently, and the off-idle throttle response is way more smooth and linear. I feel like it has even changed the exhaust note somewhat.
I�ve owned the car for 6.5 years and I�m still somewhat shocked at how much these injectors have changed the behavior of the car. For reference, my last UOA showed a fuel dilution of 1.9%.
.....and still people want to argue about this "needing to be done". They won't listen to me- maybe they'll listen to you.
Glad you noted the differences..
I'll post up another UOA later in the summer once I have some miles on the latest oil change so we can compare it to the last one. I can't say I saw a difference in drivability, but I felt good checking off a box on my list of things to do to keep it healthy.
..and it took less than 24 hours for some jackass to send me a message saying how I was fear mongering people into buying injectors from me!
I shredded him! He doesn't even know that we refuse to sell parts!
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Anyone have a lead on where to get the Bosch 0 280 156 053 injectors. I have my car apart to install the UAOS and wanted to replace the injectors at the same time but every supplier I try to order from has them on back order.
I bought mine from �partscontainer�, which is an eBay front for eEuroparts.com/NewParts.com. They were real Bosch with the authentic holograms on the boxes.
https://www.ebay.com/itm/For-Porsche...-127632-2357-0
I'm putting this on my to-do list for projects soon. For you guys that have changed them, did you do it with the engine in the car? I read over the steps and photos on Pelican's website, and even lowering the engine it looks almost impossible to get to some of the rear bolts. Any special tools? Did you remove the intake?
Thanks.
I replaced my injectors while doing the AOS job. I had both intake plenums out and that made the job a breeze. It can definitely be done with the engine in the car. I did not need or use any special tools. Upon first start up I'd suggest a second set of eyes to monitor for any potential leaks.
I am in process of installing the UAOs have lowered the engine and removed Lt side intake so at this time will make it easier access to replace injectors.
Just wanted to follow up with my latest UOA after changing injectors. Everything seems to be looking good. I do still burn a bit more oil than I'd like but it is technically within Porsche spec...
Thanks for following up.
It's nice to see the change. If you have a few extra dollars that you don't know what to do with, send the old ones to an injector service shop. See if you can get a picture of the spray patterns to see how bad they were. I missed this opportunity with my 996. I will definitely do it with my Cayenne injectors later this year.
Does it run any better?
Your fuel dilution was still above 1 percent. You may had some residue from the previous oil so check your next oil change. Watch your oil consumption if it�s stays about the same don�t worry 😉 too much, if you are topping your oil you are adding fresh additives. Motor on.
The injector change was about a month after the last oil change so I am hoping it was just residual!
I haven't noticed a difference in behavior before or after the change.
Oh that's fantastic. Thank you.
Time for another stupid question though.... There are a half dozen Bosch options. Color me confused 😞
https://www.partsgeek.com/catalog/20..._injector.html
Oh ok, thank you. I saw that SKU listed above for a 99'. I guess I was thinking a 3.6 X51 might have a different injector, but I guess not.
Much appreciated! Now just need them back in stock lol
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