Fuel pressure sensor replacement guide with pics

I have had a hard start problem only under certain conditions - warm parking garage - sitting for between 3hrs to 7hrs - any longer or shorter no problems whatsoever so after some reading on this forum I figured it may be a problem with incorrect fuel pressure being sent to the engine So I figured I'd try replacing the fuel pressure sensor Hope this helps someone else I chose the Bosch version for half price from pelican Remove battery compartment shroud Disconnect terminals and in my case strut brace Remove battery and battery tray Locate sensor sitting right under the battery tray you removed <br/><br/>Disconnect old sensor and replace - there is no chance of screwing this up <br/><br/>Put everything back together

Very simple, did it work?

good info, thanks for sharing

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I will report back in a few days... Hasn't recurred in the past few days since I did the fix.... keeping fingers crossed....

One thing that has been apparent is that my fuel economy has improved, I no longer get the overly rich fuel smell in between short starts...

Interesting. That sensor should have no effects on fuel control. It's sole purpose is monitoring the fuel pressure during emission related leak test.

BTW, the sensor is not measuring the fuel rail pressure. It's measuring the fuel tank vapor pressure solely for evap tests to satisfy OBDII requirements (in case someone misinterprets that). More from the Porsche service manual here: "20 Tank Venting System From model year '98, a test for tank system leakage will be required for vehicles with OBD II. This test can detect leaks in the tank system measuring up to 1 mm in diameter. Apart from the already familiar components of the tank venting system (e.g, carbon canister and tank venting valve), a pressure sensor for differential pressure in the tank and a shut-off valve for the purge air line used to seal the tank venting system are also to be installed to make this new diagnosis function possible." Then the manual goes on to describe the sensor and its functionality.

Best deal right now for fuel tank pressure sensor is $122 from https://www.google.com/search?q=fuel...569&gws_rd=ssl

hmmm I didn't have a misfire whilst running, just a hard start condition where the engine wouldn't catch at certain conditions - especially in parking garages after around 5 hrs. MAF is definitely a common problem - but would usually throw a code. Fuel Pressure Sensor is an inexpensive / relatively cheap fix that doesn't throw any codes....

" I figured it may be a problem with incorrect fuel pressure being sent to the engine " Glad that replacing the sensor worked(?) on yr car. Like others I am surprised too. How did you eliminate the Fuel Pressure Regulator as a cause of a heat soak(?) restart problem/fuel pressure problem? Maybe it was just a fortunate guess? Just asking to help others who search and find this rather common issue. Thank you. http://www.pelicanparts.com/catalog/...FULFUL_pg2.htm

Hi folks - since replacing the sensor it completely resolved the problem I had (at least for the subsequent 5 months I owned the car after replacing it)

And other people had similar good results: https://rennlist.com/forums/996-foru...-starting.html

Helpful link .Thanks for sharing. Hope the fix works in hot weather also. Sure beats some of the convoluted alternative repairs !

Thanks for the guide & pics roadsession, this helped me with this replacement. Pretty easy overall, hoping it cures my remaining hard start issue. Initial symptoms were frequent hard start, getting progressively worse & infrequent starter squeal. Starter motor & y-cable replacement yielded substantial improvement and now the lone remaining symptom is infrequent hard start (mostly at the garage at work).

Update - daily driving for a week and start behavior appears to be 100% normal. The first start or two after installation were relatively slow, and everything since then has been fast & reliable (hot or cold, same duration to fire it up). It'll take more time to see if it's 100% fixed, but results so far are encouraging. items replaced: - fuel pressure sensor - y-cable - starter motor - crank position sensor (done for another issue, but it's possible it influenced behavior change) lagging issue with warm starts - particularly in the garage at work in the afternoon - appear to be fixed with the FPS.

Hmmmm, I wonder if this is something for me to consider for my hard start/stumbles I've been seeing lately. Could be totally unrelated, but I did also replace that bohemoth of a battery just before all this started...wondering when "dropping" it in place vibrated something loose?

I had no code related to the hard starts that I'm aware of, but the crank sensor on my car was just about done & would intermittently work at hot temps with moderate throttle. I don't think the two were related, so between the new y-cable and fuel pressure sensor I eliminated sluggish to no start when the engine compartment is hot. Yesterday was 95F and I took it out several times with no issue restarting while warm.

Hello, can anyone kindly comment on how the fuel tank pressure sensor (located under the battery tray in a 1999 996 C2 is removed and replaced). It appears that the sensor is sealed and held secure with friction on the rubber gasket base (photo of sensor below), I attempted to remove the existing sensor on my 996. After removing the single philips screw I applied a lot of pressure to pull off and sepearte the sensor from the housing component it sits in that is connected to fuel lines, and the sensor unit can pivot but it resists being pulled apart. Has anyone completed the removal and if so was it necessary/effective to pry or apply a large force? Also, the sensor has a barbed nozzle on it. Should this nozzle have a venting hose attached to it? Thank yoy for any insights that may be provided. I am incidentally engaging the fuel tank sensor replacement due to an occasional P0453 check engine code "eavporation emissisin system pressure sensor switch high" and evident abundant pressure in fuel tank upon cap removal.

Reviving an old thread here, but I recently began to encounter the same issue as OP, but on a 996TT (random hard starts after sitting in a hot garage for ~4-5 hrs, hard start defined as a strong crank, but delayed/anemic sounding fire-up once the engine finally turns over). Per the suggestion here, I replaced the sensor mentioned above, but just had the same hard start issue today (about 1 week later). I then replaced the fuel pump relay since I had one on hand and will see if that solves it. I also have (IMO) an unstable idle when warm (idle fluctuates in a ~200 RPM band), which another poster mentioned replacing this sensor coincidentally resolved for him, but that issue did not resolve upon replacing the sensor for me. My next areas to look (assuming the relay does not fix the issue; I am not optimistic on this front) are the fuel pump itself and the fuel pressure regulator. The order of priorities here is mostly driven by how annoying I perceive the repair/replace job to be. Unless anyone else has other ideas?

https://rennlist.com/forums/996-foru...l#post18825409

so just cause I'm thinking .. wonder what teh chances are you fixed the starting problem by removing and reattaching the battery cables when you swapped the sensor..

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Thanks. My symptoms are slightly different, but maybe could be the same issue. I get a hard (long crank time) start if I let the car sit for between 3 and 7 hours from last shutdown. If it fully goes cold overnight I have no issue, and if I start within a couple hrs of the last shutdown no issue as well. I got a fuel pressure tester and tested a cold start, followed by letting the car sit for 3 hrs, then starting again and here is what I found: Startup - 0psi before start, then a build to 50 over about 5 seconds after ignition Idle - 50psi At shutdown immediate drop to 45psi 3 min later 48psi 30 min after shutdown 42psi 1hr after shutdown 30psi 2 hrs after shutdown 17psi 3 hrs after shutdown 10psi 3.5 hrs after shutdown - 0 hard start after sitting for 3.5 hrs, after ignition, pressure took a full 2 min to get to previous idle pressure (50psi) My two questions are: 1. Could this timeline also be the pump check valve failure referenced in the other thread? 2. based on the repair manual my idle pressure looks a little on the low side (supposed to be 55 +/- 3, and I�m at 50. What should I be checking for this, or is this not a concern? Edit: I�d also throw out there that the car seems to have a more sluggish response in the very low end (ie needs more throttle than it used to when letting clutch out to avoid sputtering, although it has not stalled on me), but this could just be in my head.

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My Answers 1 Yes. Easy check: bridge the fuel pump relay so it runs independently of a turning crankshaft. Let the pump run 30s before you start the engine. If it starts shortly after cranking, then you havethe confirmation. 2. 3 psi is not much of a deviation from spec and could be you measuring tool or the spring inside the fpr getting weaker. Having said that at idle the fuel pressure can easily be reduced by 3 psi of the fpr is vacuum referenced

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1. out of curiosity on how the fuel system works- why exactly does the failing check valve create this issue for semi-warm starts but not for true cold starts? 2. makes sense. I will have to replace my SAI pump at some point in the not too distant future so will likely just replace the fpr as a prophylactic then (this is a turbo so fpr is buried under the sai)

The time it takes to let an engine cool down so much as to call it a cold start is long enough that fuel to bleeds back into the fuel tank till pressure in the fuel rail is (almost) equal to ambient pressure While cranking any fuel that is injected is too little to ignite but also too little to flood the engine. So you just crank a bit longer till fuel pressure is built up and then it starts whereas with residual pressure the engine stutters to life because mixture is far from ideal . Since you most probably have a defunct check valve you could give it a go and tell us if you experience what I described. 😀

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will have a go at it when I get time this weekend thanks!

Another development for those following my saga: I was googling for a replacement FPR and by chance ran into a thread on another forum about the FPR vacuum reference coming loose on these cars. Stuck my hand down there to check and sure enough my FPR vacuum line is just waving in the breeze. Sounds like the sluggish throttle response I�m experiencing could be a result of this (and also the leaner mixture I noted on a recent road trip evidenced by the car averaging 22 almost 23mpg); not sure if it could cause my startup issues. Going to check the check valve anyways next week, not unrealistic to have multiple fuel system issues at once here.

FPR pipe No.15, where does that go to. I changed my fuel injectors and with dropping the engine and removing the fuel rail I now have a delayed start when the engine is hot.

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that is the vacuum reference I mentioned. Connects somewhere to the intake manifold in back.

Thank you, I hope I can find out where it attaches, not much room back there

Not entirely sure but I believe the thin vacuum line in the picture goes from FPR to the crossover tube to get the needed vacuum reference.

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Think you may be right on manifold location based on the below parts diagram, although I believe the vacuum line is hard plastic, not flexible as it looks in your pic (note this is for a 996TT):

The 6TT is rather different, it's got a mile of vacuum lines in there. At least on the 6TT the line is nylon with two rubber end pieces (that have a 928 part#!).

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yes I may have hijacked this thread inappropriately. I am dealing with a 996TT, not sure about the other posters here.

I didn't realize you had a 6TT. Yes the vacuum line to the fpr is very important, much more so than on an NA car. Run lean under high boost and you'll ruin the engine. Lots of us 6TT guys put zip ties on each vacuum fitting to prevent them coming disconnected.

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Yes I�ve intentionally kept off boost until I can sort out this starting issue for this very reason.

An update here: Completed @hardtailer �s test- I can reliably get a hard start after sitting for 6-7 hrs, but if I activate the fuel pump 30 sec before starting in this same timeframe, the car starts up no problem. I think I�m to interpret this as a likely failure of the fuel pump check valve. I now believe I have a few concurrent, not necessarily related, problems: - fuel pump check valve - disconnected vacuum reference on FPR (confirmed by feeling around the FPR by hand) - malfunctioning fuel level sending unit (completely by coincidence- I was intentionally running the fuel low knowing I would need to pull the pump to replace the check valve. I think I may have run it lower than it has gone in a while because now the fuel gauge is stuck on empty. Suspect the sender is probably stuck in place- at least I hope so since I�d prefer not to go out the $500 to replace it) - failing SAI pump (whines at startup) Planning to: - Replace SAI pump (had been putting this off but now that I have FPR issues the opportunity has presented itself) - Replace FPR and reattach vacuum line (I figure the FPR is annoying to access so may as well replace if I have to get to it anyways) - replace fuel pump check valve - repair / replace fuel level sending unit FPR arrives Monday so I have a fun project ahead of me this week!

Hi, I had a hard to start problem when hot, after about 45 minutes after shutdown. It started fine straight after shutdown and fine when cold. I replaced the hard pipe between the Fuel Pressure Regulator and the intake plenum which had snapped while I was changing the fuel injectors. All fine now.

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Thanks. Could be all tied to the FPR after all...I may hold off replacing the check valve until I test the FPR replacement. Although I do need to go into the gas tank to fix the level sender...

Thanks for posting the results of the test and happy to hear it made a difference in how it started. The missing vacuum line is not as big a contributor as the non-functioning check valve, obviously, as the vacuum line wasn't attached in either scenario tested. The difference in starting behaviour can therefore be entirely attributed to the non-working check valve. Nonetheless reattaching the vacuum line will improve things further.

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You have the 996 Turbo? I would leave the original FPR alone, unless you are sure it needs to be condemned. The new ones are not nearly as high quality. Do reconnect the vacuum hose though. The fuel level only needs to be below 1/2 tank to completely expose the fuel pump. There is a check valve in the pump plumbing octopus nightmare, it's a little silver thing. Porsche does not sell the check valve separately, you'd need to buy the entire fuel pump assembly. There may be aftermarket check valves available that could replace just the check valve, this one was recommended: https://www.finjector.com/eng/sytec_...a-p-733975-153 My fuel pump, which I had to take out at Lime Rock during a track day to fix: Also if you run the fuel level below 1/2 tank then add a small amount of fuel the fuel level sender can't see that and the "fuel level" shown on the dash continues to decrease. When the fuel is below 1/2 tank the dash estimates remaining fuel based on consumption. This is because the fuel level sender can only read down to 1/2 tank due to the tank's internal design. I's also possible for the sender to fall apart. I fixed this on my car a few weeks ago, write up is here: https://rennlist.com/forums/996-turb...l#post18877453 And this is what the sender looks like.

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Very helpful reply and answers what I believe are all my issues. I just got done with the FPR / SAI pump job. Wish I had read this earlier as I ended up replacing the FPR and it doesn't appear to have made a difference whatsoever. I did note the one I removed had a made in Germany stamp, while the new one is made in Brazil. Gave me pause, but I replaced it anyways. Was annoying enough to get to I wasn't going to turn back then...figure a 20 year old German part vs a brand new Brazilian one has to be at least a fair trade? I will save the original in any event. Interestingly the vacuum line was actually connected. The looseness I felt by hand earlier before getting eyes on it was due to the fact that the nylon line it attaches to is very lightweight and easy to move. I have no way to confirm the other end of the vacuum line is in place since I couldn't trace to where it attaches, but I have no other reason to believe it's detached for now. Other than getting rid of the annoying SAI whine at startup, my repair work today doesn't seem to have solved much of anything. That said I think my answer is in the fuel tank. Other than the hard start, would you expect this check valve to cause any other performance issues?

Answer to your last question: no, nothing else

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The other end is connected just to the left of the throttle body (left, while looking at the engine standing behind the car). It's behind the oil filter.

I just replaced the silver check valve (flowing away from pump). Waiting for fumes to dissipate before reconnecting battery. What is the purpose of the white plastic check valve on the line flowing back toward the pump? Should this be replaced as well?

The check valve on the return line is to prevent the fuel siphoning out of the tank in case of a break in the line. Does not need to be changed.

May have run the tank too low. Car wouldn�t start at all after I put it back together. A lot of fuel came out of the green line when I disconnected it at the sender, so hopefully this is just a matter of repressurizing the system.

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Hunch was correct- adding gas worked. Will let it sit for 6 hrs and see if the hard start issue recurs.

The fuel system in the tank is fiendishly complex. The white can the fuel pump sits in is actually a surge tank. When the fuel level is below 1/2 tank the fuel is sucked up by the "jet pumps" in each tank lower lobe and delivered to the surge tank. Trouble is, you need fuel in the surge tank to create the flow that creates the suction to bring fuel into the surge tank. To get around this the short black corrugated hose attaches to the fuel filler neck inside the tank and diverts some gas directly into the surge tank while refueling.

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Was wondering what the purpose of that hose was - that explains why refueling even just a bit solved the problem. Will report back on the hard start issue later tonight, but I�m hopeful this means I�m on to other things with this car.

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Same issue just now. Wouldn't start. Added another 2 gal of gas (size can I have), tried again, it struggled but eventually turned over. I drove to the gas station and filled it to a bit over 1/2. Started up fine after fill up. On the drive back just now I decided to rev it out a bit and it felt like it lost a ton of power around 5k RPM / full boost in every gear. Car does not have a tune. Only thing I can think of is I didn't love the fit of the hose clamp I put on the plastic tube end of the check valve (was a little large for the job, so more of a clamp than a cinch if that makes sense) so maybe this is leaking fuel pressure? Not sure what else to make of it. Edit: just tried to start it again after sitting for maybe 15 min post fill up and it caught for a second then immediately died. Going with my hose clamp theory and will investigate tomorrow. That or the $8 check valve I got off Amazon is bunk.

I have had those fittings on the pump self-disconnect more times than I care to remember, and I have gotten quite good at pulling the pump out and fixing them on the side of the road.

Replaced the fittings and got the car to start, but after sitting for an hour it did the same thing (start, catch and the immediately die) as before. Let it sit for a minute then started it again and it started hard but did catch and continued running. My theory is now maybe the check valve I got is just not designed for the pressure of this system? Below is what I bought. I looked at that Sytec valve upthread, but by the time I pay for shipping, I'd be halfway to the cost of an entire new pump assembly. Would like to find an option that ships from the US... Amazon Amazon

Before changing any more parts I would get a fuel pressure tester and see what the fuel pressure is doing unless you have already done that. And if you have done that I'd retest fuel pressure loss over time with your new check valve installed.

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Good idea. Will report back. I have a timeline on fuel pressure readings I posted upthread from before I replaced any parts.

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Think we can finally close the book on this one. TL;DR: Turns out replacing the Amazon check valve I got with a higher quality option did the trick. Before switching out my Amazon valve, I tested the fuel pressure in the system after shutdown and it was dropping fairly rapidly; even when running the pressure was on the low side relative to spec. On a hunch the new check valve I put in was still the issue, I swapped it out for a different (and more expensive) one I found online. I�m not sure whether it was poor internal build quality of the Amazon unit (could be as the listing advertised it for carbureted engines like lawn tractors), or the design of the barbed fittings (the Amazon one was relatively loose in the plastic hose in particular, really relying on the clamp to make a seal) that caused the problem. This is the part I ended up using: https://www.highflowfuel.com/quantum...alve-8mm-5-16/ As you can see in the picture, the barb design of the fittings much more closely mimics the oem design (smooth fitting with one large barb at the end as opposed to the sawtooth barbs on the Amazon piece). This new one fit very tightly in the hoses on both ends. Also would note the build quality at least feels very high- the thing is solid brass, and the internals are metal as well. Looks and feels better than the oem unit by a mile. It�s only be a day, but since swapping out the check valve (again), the car now starts no problem: cold, hot, warm, semi-warm. It also turns out my oem valve had failed on two fronts: not only was the back flow direction not holding pressure, but the flow direction was very clogged up. The car used to porpoise and buck under initial acceleration, would lag in higher rev ranges, and had a somewhat unsteady idle. Acceleration and top end power are now buttery smooth, and the idle has improved noticeably. Frankly it took switching out the valve to even notice I had some of these problems in the first place, but the improvements were dramatic even so. In the end I may have unnecessarily replaced an FPR, but I�ll chalk it as a win since it spurred me to do the SAI pump replacement I had been putting off (and which wasn�t nearly as bad as I thought to boot). Thanks all for the input on this journey.

Maybe I spoke too soon. To be clear, I have not had any starting issues whatsoever since changing to the 2nd new check valve, but my imperfect idle has returned as well as *some* of the bucking under light load (the latter could just be in my head fwiw, it's very subtle). The first couple runs with the new check valve, the idle was dead steady, both at high warmup idle and when settled into warm idle. Now the previous behavior has returned (idle hunts in a ~200rpm range both hot and cold). I had previously brought the car to an indy shop to check for vac leaks because of this and was told this idle behavior is "normal" so I gave up trying to fix it. However, now that I've seen the car is capable of a much more stable idle, I'm back on the hunt as to what could be the cause, and now obviously leaning toward the fuel system, but really at a loss as to what exactly. Seems unlikely the new check valve could already be clogged up or otherwise misbehaving.

Not so sure that this will help any, but you can always try the shade tree tune up. Motul makes a couple of fuel system/ injector cleaners that worked on my old German car that I was too cheap to put premium gas in . Not saying that is what you�ve done, but if you live in Cali their gas might be suspect. Great to learn that the check valve cured the hard start syndrome. I�ve got that problem as well. Was wondering that if the check valve was fairly worn out would the fuel pump be far behind? I will most likely replace the whole assembly as losing a pump while traveling is no fun.

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My valve was very clogged. Not sure about the pump, but before I swapped the valve and ran the pump (via the relay with the car not running), the pump would whine pretty loudly. After replacing the valve, the pump doesnt whine anymore. Was concerned it could have been damaged based on the whining, but other than my idle the pump seems to be running fine.

Both my 6TT's idle perfectly stable like the tacho needle is glued to the gauge. Hunting idle is not normal. Things to check, 1. Throttle body sensor can get dirty or defective and the ecu can't see the throttle plate position which means the throttle plate jumps around. Can check this with durametric or some other scanner, just watch throttle position (not gas pedal position) while it's idling. 2. Vacuum leaks, although the shop you brought it to allegedly didn't find any they also lied to you about idle characteristics. 3. Intake/boost leaks. These are a part of life with a turbo car, a boost leak check should be mandatory when troubleshooting any rough running condition. 4. These cars eat MAF's for breakfast. Usually a bad MAF will throw the trifecta of trouble codes: check engine, PSM failure, ABS failure. 5. Plugs/coil packs. I think you need to do some datalogging to figure out what is going on.

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Good to know that an even slightly unstable idle is not normal- I thought it didn't seem right so was surprised to be told otherwise (by a very reputable indy shop no less). 1. Will check throttle body sensor with Durametric later today- will note I cleaned the throttle body itself ~2 yrs / <10k miles ago. Edit: I just checked - there are multiple values on durametric related to throttle position (Spec. throttle, actual throttle, throttle potentiometer 1, throttle potentiometer 2, etc). I assume Spec. throttle = ecu specified throttle position? If so, this value moves around a bit (constantly changing anywhere from 2.3 to 2.8%). "Actual throttle" is much more steady, but does move even at idle (jumps from 2.3 to 2.7 and sometimes 2.5). All the other values (potentiometers) move constantly, similar to the spec throttle value. My idle RPM moves a bunch as discussed, mostly between 800-900 RPM, and my spec RPM at idle (AC off) is 840 RPM. Is "spec RPM" specified RPM? If so 840 is high, no? My understanding is idle RPM should be 740 +/- 40 RPM. 2. I misspoke slightly on this one earlier- The shop that checked for vacuum leaks stated they did actually find one small one (on diverter valve) and repaired it. Fairly confident there are no longer any leaks, but no way to be 100% certain here as I don't have personal access to a smoke machine. 3. Shop claims no boost leaks either, although I imagine this is something I can theoretically check myself. 4. Car is not throwing any codes at all, so inclined to think MAF is not the issue 5. Plugs/coil packs were also done 2 yrs / <10k miles ago so likewise disinclined to suspect that here I keep coming back to the fuel system just given the change in idle behavior when I replaced that check valve with a good one. The couple starts immediately after replacing the valve were the only time in recent memory I've seen the idle behave as it should (glued to tach as you say). Is there anything else that could be at issue in the fuel system? I'm wondering about the pump itself, but I also hesitate to throw a $600 part at the car on a whim. Re: datalogging- are there any specific parameters in Durametric I should log over a drive / at idle to help diagnose?

You are correct about Spec RPM etc, that's what the ECU wants. The throttle pot 1 and throttle pot 2 are the readings off the throttle body potentiometers, if they are changing in a similar way to each other then they are most likely OK. What can happen is one pot develops a dead spot around idle and this causes the idle to hunt as the pot crosses that dead spot. I can't believe the fuel pump would cause idle hunting unless it was on the verge of death. Even with a huge split in the fuel hose in the tank my car idled fine, it just would not take more than a tiny bit of throttle before it started bucking badly. When the fuel line completely let go it would not run at all. When was the last time the fuel filter was changed? Data logging probably won't find a vacuum leak, it can find the presence of a large boost leak although not the exact location. However 90% of the vacuum system is pressurized with boost when under boost so a boost leak check should find 90% of vacuum leaks. Using a smoke machine to check for vacuum leaks on this car is a waste of time because of this. Basically to boost leak check disconnect both turbo to intercooler hoses at the turbo, cap one off, use the other to pressurize the intake system. The shut off the pressurized air. It should hold 16-20 PSI for several seconds (mine holds for 30+ seconds before slowly decreasing). The factory manual says to boost leak check by pressuring the system from where the MAF is. This is worthless because of the oil tank vents etc and because this section never sees pressure. Dura has trouble logging more than 7 or 8 at a time. I stopped using it and now use my Cobb Accessport. I have not datalogged to find idle problems so don't know where to start there. In realtime just sitting there idling I would look at each cylinder's misfire count (should be 0) and ignition timing. I can't remember what Dura calls this ignition timing, it's what the ecu uses to control knock. Check each bank's lambda may tell you if the fuel pump is working properly at idle. Using your fuel pressure test gauge while idling can show if the idle fluctuations are related to fuel pressure. Do note that when I had a dead injector on #5 the ECU recorded misfires on every cylinder except the one that had the dead injector so I am not sure how valuable the misfire counter is. I found the dead injector by touching the exhaust pipes looking for the cold one. When I was looking for boost leaks I logged: engine RPM injector duty cycle setpoint manifold pressure actual manifold pressure N75 valve duty cycle Lambda bank 1 (need to convert to AFR) Lambda bank 2 then ran some 3rd gear pulls. This would also test fuel delivery as Lambda ought to be 10-ish AFR at full boost and full load. If not suspect fuel delivery somewhere. If I have time tonight I'll load up dura and see what my car says when idling.

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Thanks, this is all helpful info and gives me some homework to do. Will play around with dura tonight as well. One thing I just realized on the fuel point- the other big variable that hasn�t been mentioned is that the battery is disconnected for a solid 30-45min every time I go in the fuel tank, which disconnect I think causes a soft ECU reset? So maybe not fuel system related as you say; could just be coincidental that it ran well for a bit after a reset.

Thanks for all the help- I am still working to sort out this idle issue, but since this has gone way far afield from this threads original topic, I made a new thread here: https://rennlist.com/forums/996-turb...l#post18940687