187

100% chance it was leaking boost, the egr has been nonoperational since the resistor install so I'm just pulling the switching valve and capping everything that is left. This also deletes the one vacuum switching valve near the fuel pressure regulator. I'm guessing it's useless anyway.

Ali SC3

iTrader: (10)

yeah the black vsv by the FPR is the egr one. I leave all that stuff attached to a stock intake manifold so I don't have to figure out how to reroute everything when the time comes.

187

Well I deleted everything and capped it all properly but it didn't help at all, however it does look much cleaner.

The car still misses on the start up 1 3 5 random, they all look like lean misfires with the idle being high. Pretty much been stuck here for what seems like forever.

Ali SC3

iTrader: (10)

can't come up with a good reason why it would just misfire on start up and go away later, maybe since you are saying its lean also the computer is not seeing you in cold start? maybe check the coolant temp sensor and plug, its possible something could be different for those 2 years coolant temp wise between a GE and GTE, or even a bad coolant temp sensor. maybe try unplugging it and see if the ecu throws a different code, if not maybe the ecu can't tell what the temp is. longshot but maybe that could explain some stuff?

the coolant sensor is used by the ecu directly for cold start fuel enrichment, so could explain alot of things.

187

I get an accurate reading when using my scanner but I'll double check the pins now.

I think it used to cold start fine and be at like 13 then come down idk what changed.

joe diego

iTrader: (3)

Do you or anyone else know what size cap I can use to cover the hole in the runner where the EGR pipe was?

Ali SC3

iTrader: (10)

I used a plate.

187

So here is what my short term fuel trim looks like when trying to hold 1500rpm not moving. Basically just trying to add fuel but it cant and it maxes out at 19.53(causing full lean condition) . At idle the trim behaves pretty normal as you can see right before it.

I'll have to do another cold reset to confirm this but its pretty bad. Any thoughts?


Also if anyone is lurking and has no idea what short term fuel trim is its a pretty interesting and useful to look into.

aznexus

I used this (-10an)





plus this







The bolt holes lined up perfectly. Cheap but works.

Ali SC3

iTrader: (10)

187 you on the VPC right?, try boosting the signal for those loads to increase fuel off idle.
I thought the vpc solved that stuff, I guess there are still more issues with it?

either that or you are somehow getting a false lean misfire, as in when you have a misfire, the oxygen is not burnt up and the o2 sensor picks it up as a false lean, and adds more fuel usually making the problem worse cause the extra fuel might be further causing the misfire.

considering posting a message saying not to do the mod on USDM ecu's anymore. Ill still help anyone wanting to do it but not sure I would call it successful feels like we have been troubleshooting this forever now.

187

You can't boost the "gain" which is the fuel across the band away from idle without the ecu just correcting for it slowly. Its the same thing at idle, I can crank that **** but the ecu will just immediately trim it back.

I didn't get any misfire codes or lean codes but I really didn't want to push my luck driving after seeing that. I think everything leads back to the tps honestly. I still can't explain the misfires on 1 3 & 5. I think it's time to ring something up with the tps.

Ali SC3

iTrader: (10)

it may correct slowly, but it changes the behavior when you rev it, or at least I thought it does.
yeah its a bit of a mystery to me as well I don't see how all these people are single turboing their supras on the stock US ecu with a piggyback then. maybe that is why many swap to a standalone in the US, but hard to say since its na-t it could be something that is off some but for most of you guys to get misfires tells me its probably in the tune or a common issue we are missing the n/a motors have. I find it hard to digest because it doesn't make much sense but yeah, It should be working.

187

Well I reset the tps just now and its running fine at idle, I actually unplugged the 02 sensor and turned up the idle fuel to idle at 14.7. It doesn't even throw a code for no main 02 sensor, but I can see the secondary 02 reading about .8v at idle.

I must have done something because that picture I posted before is still an issue, I can rev the car but anything past 1000rpm is full lean.

HiPSI

iTrader: (2)

I've been daily driving the car for about 6 months now.

I've noticed that on cold starts the car will idle fine, but will hesitate slightly in the 1500-2500 range when I go to rev up or pull away I can see the wideband A/F go to the 16:1 range, you can feel the power go away like its holding back.

I suspect maybe I need to check the spark plugs, ignition? Would the injectors cause this? Once the car warms up it clears up and everything is perfect. Keep in mind this is a recent issue, car has been driving perfect.

Ali SC3

iTrader: (10)

HIPSI, gonna guess your tps is set too far back from the IDL switching point. you want to be a hair before it so when you first start pressing the throttle the IDL is no longer connected. whats happening is it sees revs but its still on the IDL pin so you don't get the extra fuel from accelleration that you get in the main fuel map.

187, that is odd, did you connect the FPR so it bypasses that blue vsv. make sure that was done and it could be a tps issue, can you read if the IDL pin is active and when it goes on and off, try tapping the throttle id should go off as soon as you hit the throttle, and return right after you let go, if its hanging up there could be an issue. If anything the stock twins should flow more air at those lower rpm's than a single turbo, so not sure on the full lean issues here unless you have so much fuel you are hitting a false lean.
do you ever hear popping out the exhaust? these cars will only pop if extra unburnt fuel enters the exhaust.