Still fighting a lean misfire.

The Car: 1989 Nissan 240sx - Aristo 2JZ-GTE - AEM EMS V2 - Single turbo kit setup - FIC 750cc injectors and Rail - Aeromotive FPR - Deatschwerks DW300 fuel pump - Russell fuel filter.

Part Replaced : New battery (February 2014), New NGK 3330 plugs gapped at .028 (May 2014) , Newer low miles coilpacks (August 2013) New coil pack connectors & Terminals (August 2013) AEM 3.5bar Map and IAT sensor (January 2012) Fuel system (Spring 2012)

Parts Tested: Unplugged front cam position sensor #1 car ran dramatically worse. so that seems to be ok, will test resistance on it still. Tried known good working ignitior and noise filter, Swapped out to another set of NGK 3330's @.028 Gap. Tested the AEM Map sensor it testeed within range. The IAT sensor tested slightly off so i got a new IAT sensor that tests closer to spec but still not 100% spot on where AEM states it should be, car ran slightly better. Tried known good working Wideband 02 sensor no change, Replaced injector o-rings and bungs after finding out there was a leak when i sprayed choke and carb cleaner around them the car ran different. Once fixed i tried the same test and there was no change in the way the car ran when i sprayed choke and carb cleaner car seemed to run slightly better but only for a little while. Car holds 43-44psi of fuel pressure at idle and climbs when the car comes into boost Fuel pressure doesn't change when the misfire occurs. Tested the new battery that see's 12.8-13.0 Volts when the car is running misfire or not.

Thing's i haven't checked: Having he injectors cleaned and flow tested, but they are only a couple years old and have maybe 2500 miles on them. Crank position sensor, ECU itself, Wiring harness, and the fuel pump (Though the fuel pump if going bad i would see a loss of fuel pressure i believe?

The issue: The misfire/lean issue started last fall (September-October 2013) It was relatively cold out and i noticed it was missing and running lean so i took the car home and thought the 40 degrees. weather is the issue as the car doesn't typically see temps that cold and it was tuned in mid-high 90 degree temps. Took the car out this spring with No changes other than a new battery and it does the same thing, car seems to run better when the engine is cool, But once water temps start getting into the 155+ degree range the misfire happens slightly at idle (AFR goes between 15.8 - 17+ AFR) does the same thing on light and partial throttle. But the car seems fine when you go WOT or give it a certain amount of gas, but almost on tip in it goes lean and trying to maintain speed then it goes real lean and misfires. Sometimes when the car is idling and the AFR's go real high (16-17 Range) the car will die. But it will start back up no problem.

Could bad gas be the issue? We put gas in it just before last fall, then drained it out for world of wheels then put new gas in the car in April, been troubleshooting ever since.

you sure it doesnt have a vacuum leak some place

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Originally Posted by Reverend Cooper

you sure it doesnt have a vacuum leak some place

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Don't believe so. Only have a few vacuum lines
Wastegate-Turbo Which is fine.
Turbo to intake manifold - Which is fine as well.
FPR to intake manifold - Which is newly replaced and tight
Blow off valve to intake manifold, which is relatively new and in good shape.

I will go back through and check them. The intake manifold didn't seem to leak when i sprayed some Choke and carb cleaner by it, i'll give it another shot.

Thanks Coop.

You didn't say anything about a boost leak test. Did you do one?

I haven't done one yet, i will try that on thursday.

i know pretty much zero about these engines but is the EGR deleted, blocked, etc. Could there be a leak on a block off on intake manifold? are there any npt fittings in the intake side that are dissimilar metal where temperature could introduce a small vac leak?

Can you narrow down to which cylinder is misfiring? I assume you have a boost gauge, what happens with the vacuum when it shoots lean at idle. Also what is your normal vacuum at idle? What do the new plugs look like? When you did the wiring for the swap did you use any butt connectors or did you solder them all? Would be nice If you could data log before and after this happens.

Updates?

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Originally Posted by WickedSix

i know pretty much zero about these engines but is the EGR deleted, blocked, etc. Could there be a leak on a block off on intake manifold? are there any npt fittings in the intake side that are dissimilar metal where temperature could introduce a small vac leak?

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No leaks from the intake manifold

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Originally Posted by spooln30

Can you narrow down to which cylinder is misfiring? I assume you have a boost gauge, what happens with the vacuum when it shoots lean at idle. Also what is your normal vacuum at idle? What do the new plugs look like? When you did the wiring for the swap did you use any butt connectors or did you solder them all? Would be nice If you could data log before and after this happens.

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Vac is usually in the 18-20 Range, when the car starts to miss it starts to lower the rpm and thus lowering the vac. The place that wired the harness up originally did both butt connectors and solder.

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Originally Posted by LIL EVO

Updates?

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Did a boost leak test, found i had a tore coupler from the hot side to the intercooler itself. replaced that and found there was a vacuum cap that was loose on manifold, fixed that issue. Now it seems to run lean all the time.. .

Is it possible that the car was tuned with a vacuum leak? Now that you fixed the leaks and it's running lean. What are the afrs now?

Actually wait, if that was the case then it would be too rich now. Oops. Lol

Check supply voltage to injectors and coils. Verify ground resistance to ignitor at the least. Best to check with a scope on the dyno.

Could also be the tune but it can be hard to get a solid AFR from it if its breaking up so that can be sort of chicken and egg.

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Originally Posted by WhatsADSM

Check supply voltage to injectors and coils. Verify ground resistance to ignitor at the least. Best to check with a scope on the dyno.

Could also be the tune but it can be hard to get a solid AFR from it if its breaking up so that can be sort of chicken and egg.

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Thanks Murray.I've checked a few other things, replaced and tested stuff, car seems to run ok now, Just starts and runs around 14.7ish then dips way down into the low-mid 10's once the car gets warmed up the afr's go pretty much full lean. I'm leaning on it being a tune issue just based off the fact that there was so many little issues that have since been fixed/solved. So if the tune was tuned around an issue and the issue got worse, now it's fixed in theory i believe the tune would now be off. Correct?

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Originally Posted by Flicktitty

Thanks Murray.I've checked a few other things, replaced and tested stuff, car seems to run ok now, Just starts and runs around 14.7ish then dips way down into the low-mid 10's once the car gets warmed up the afr's go pretty much full lean. I'm leaning on it being a tune issue just based off the fact that there was so many little issues that have since been fixed/solved. So if the tune was tuned around an issue and the issue got worse, now it's fixed in theory i believe the tune would now be off. Correct?

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If issues were "tuned in" its certainly at least suspect and worth having someone look at it (they hopefully should be able to do some diagnostics with the electronics too to help point you in the right direction?). I don't know the AEM system at all so I don't know how much it can self-correct.

Too many variables aem. Is it set up for o2 feedback to "self maintain"? If so that could be a problem if the sensor is going bad or there's now an exhaust leak.

Assuming whoever tuned it didn't lock it, if you want to drive down here some day I can take a look at the car/tune for free. Or you can email me the tune and I'll look it over to see if there's anything wacky.

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Originally Posted by LIL EVO

Too many variables aem. Is it set up for o2 feedback to "self maintain"? If so that could be a problem if the sensor is going bad or there's now an exhaust leak.

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Wideband is new (as in like 15 minutes of run time as of now) The Car with the new and old sensor ran the same way.
Starts and runs at 14.5-14.9 then it riches up to
11.4 - 11.6 @ 115F (water temp)
12.2 - 12.4 @ 130F (water temp)
14.3 - 14.5 @ 150F (water temp)
14.8 - 14.9 @ 160F (water temp)
15.5 - 15.8 @ 165F (water temp)
16.0 - 16.2 @ 170F (water temp)
17.0 - 17.5 @ 175F (water temp)
17.5 - 17.8 @ 178F (water temp)
17.8 - +++ @ 170F (water temp)

After doing a couple of free rev's the car seems to have a big idle surge. and has a rough idle. Here is a screenshot of the fuel map,
http://i2.photobucket.com/albums/y47...ps10aed21f.png
http://i2.photobucket.com/albums/y47...psa7e6aac7.png

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Originally Posted by LIL EVO

Assuming whoever tuned it didn't lock it, if you want to drive down here some day I can take a look at the car/tune for free. Or you can email me the tune and I'll look it over to see if there's anything wacky.

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The tune isn't locked, Sound Performance doesn't believe in doing that. I've talked to Larry and he insists it's not the tune but i just have a hard time believing that anymore at this point in time. Where are you located now a days? Not sure how much i want to drive the car if it's running bad. but it might be worth doing cause i'm just about stumped.

6 mile and 32, right off the lake.

If it ran fine when tuned then usually the tune isn't the issue. The tune can't "go bad" without external changes.

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Originally Posted by LIL EVO

6 mile and 32, right off the lake.

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hmm that might be a bit of a stretch to pussy foot the car down there, i'll see what i can do, otherwise i'm more than willing to compensate your time/travel.

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Originally Posted by LIL EVO

If it ran fine when tuned then usually the tune isn't the issue. The tune can't "go bad" without external changes.

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Correct me if i'm wrong, but say the car had a small boost leak, or a sensor was going bad (let's say water temp sensor) And the car was tuned. The sensor condition gets worse and the boost leak get's bigger. Than you repair the boost leak and the sensor. and now the car runs goofy cause the car's tune was done when the voltage to a sensor or the sensor was reading wrong, and it was seeing air via a boost leak and now neither of those problems are present, wouldn't that make the tune "off"

Maybe i'm looking at it from the wrong direction, i'm just so fed up with the car and the issue as i can't seem to make any headway on the problem.

Well any good tuner will do a boost leak test and ensure all system sensors are good to go before tuning. If something is flaky during a tune it will definitely present itself and make tuning a nightmare.

Boost leak with a MAP based tune isn't going to really matter. The only thing you'd have to worry about is compressor efficiency and extra heat. A boost leak won't really effect the tune.

Water temp sensor should be simple to see if it's bad or going bad. You can see the sensor voltage or reading while driving around otherwise log it and go drive around. I've had a coolant temp sensor spike down to like 30 degrees a bunch of times, but never would have known if I wouldn't have seen it in the log.

Where are you and when are you available?

I see from your screenshots an issue already. O2 feedback is setup and running and you can see it compensating and taking out 10% of fuel to get to the target AFR. It shouldn't be taking out that much fuel at any point. If the tune is setup well and car is running good the O2 feedback should be less than 2-3% +/-. It's really just there to make the tune "perfect", not to fix any issues or be the actual tune.

Also there could be some coolant temp enrichment map that's wacked out.

Is your O2 really 9.0 at that one point?

Did you free air calibrate the wideband o2 sensor before installing it? That is weird that it richens up then leans out at idle. I honestly don't think it's the tune unless the AEM is internally messed up. Wouldn't be the first Aem that I've seen go bad. It's a version 1 Aem correct? And is it a early serial number unit? I know there were a couple bad batches of them so if you bought a used one I'd check with Aem if the serial number falls in those bad units.

Looking at your data log I noticed your intake air temp was 100°F what was the ambient air temp that day? My Supra on a 75-85° day with decent humidity I would see 70ish intake air temps.

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Originally Posted by LIL EVO

Well any good tuner will do a boost leak test and ensure all system sensors are good to go before tuning. If something is flaky during a tune it will definitely present itself and make tuning a nightmare.

Boost leak with a MAP based tune isn't going to really matter. The only thing you'd have to worry about is compressor efficiency and extra heat. A boost leak won't really effect the tune.

Water temp sensor should be simple to see if it's bad or going bad. You can see the sensor voltage or reading while driving around otherwise log it and go drive around. I've had a coolant temp sensor spike down to like 30 degrees a bunch of times, but never would have known if I wouldn't have seen it in the log.

Where are you and when are you available?

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Thaks, I'm in the Menomonee Falls,Brookfield boarder off Pilgrim and Silver Spring area.

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Originally Posted by LIL EVO

I see from your screenshots an issue already. O2 feedback is setup and running and you can see it compensating and taking out 10% of fuel to get to the target AFR. It shouldn't be taking out that much fuel at any point. If the tune is setup well and car is running good the O2 feedback should be less than 2-3% +/-. It's really just there to make the tune "perfect", not to fix any issues or be the actual tune.

Also there could be some coolant temp enrichment map that's wacked out.

Is your O2 really 9.0 at that one point?

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I will have to look into the o2 setup and double check the wiring from the wideband to the ecu.

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Originally Posted by spooln30

Did you free air calibrate the wideband o2 sensor before installing it? That is weird that it richens up then leans out at idle. I honestly don't think it's the tune unless the AEM is internally messed up. Wouldn't be the first Aem that I've seen go bad. It's a version 1 Aem correct? And is it a early serial number unit? I know there were a couple bad batches of them so if you bought a used one I'd check with Aem if the serial number falls in those bad units.

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As far as i know, the AEM Uego doesn't require or need an open air calibration, and it's the AEM EMS V2.

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Originally Posted by spooln30

Looking at your data log I noticed your intake air temp was 100°F what was the ambient air temp that day? My Supra on a 75-85° day with decent humidity I would see 70ish intake air temps.

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I believe it was mid-high 80's with the car running in the garage, so no fresh, or cool air, also the intercooler i believe is pretty much past it's efficiency range.

Yeah the V2 are good standalones.

have we checked the ecm temp sensor to make sure as coolant temps rise that its not reading way to hot causing car to lean out?

Its the same reading as in the software

yeah the ECM Temp sensor and the Gauge sensor are pretty close in reading (within 5 degrees typically) Had an issue when i replaced the alternator something with the electric fans broke so i had to replace that this weekend and now something with the alternator is bad (had it tested and it's fine) So i get to look into that now.

Jason - I redid the wiring to the o2 sensor the AEM and the AEM now sees it, but only sees it as O2 #2 and not as #1 so i had the #1 o2 sensor have an error so it defaults to 02 #2. car pretty much still ran the same way it always has, yet it's not showing as much correction anymore.

You should turn o2 feedback off until you figure out the issue with it.

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Originally Posted by LIL EVO

You should turn o2 feedback off until you figure out the issue with it.

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Gotcha, Thanks i'll be sure to try that out.