Car Won't Idle and Hard Time Starting, I've tried everything

[Z32mike]

Ok guys I really wanted to try and self diagnose this before I asked for help on the Forum but I have litteraly ran out of options. Let me start going down the list. The car never really idled since I bought it and it always had a hard time starting, one of the first things I did was pour seafoam into the oil and gas tank and for some odd reason it decided to idle, up until I shut off the car for more than 20 minutes and it cooled down, it seems like it forgets it's idle. I took the car to a buddy who has a program that reads the voltage of the TPS and the timing and all those things and we calibrated it perfectly and it idled pretty good.. Untill the car got cold and I started it again.. It lost the idle again.. So I did a compression test and give or take 5 psi all pistons are running at about 160.. So the motor is good, or so I think.. Then under full boost it always performed how it's supposed to I guess.. I pulled the motor out and I changed the turbos which were orginal.. at 160k miles.. eww.. And I put T28 upgrades in there, minor but makes a nice difference.. I also changed out the wiring harness just in case I had bad grounds or bad sensors etc.. I changed out the Throw out bearing becuase the clutch was making a weird noise when I pressed the clutch, I changed all the spark plugs, I changed the Intake plenum and I put a new intake mani gasket, I put new motor mounts, I changed pretty much F*****G everything essential on this thing.. I put the car back together and same crap, Idle still sucks, the car runs for about 20 seconds and it shuts off.

MODS on the car are Selin Dual Intakes, ASH spec Intercoolers, Turbo back Exhaust, Upgraded Piping, 740CC injectors, New Syle CAS, New Style Injectors & Fuel Rail. CZP Chip tuned for Injectors, intakes, CZP Chip tuned for most mods except intercooler piping.

I tried Swapping out the MAF sensors, I changed out the IACC, I Swapped out the CAS, I Set the timing and I set the voltage on the TPS, I swapped the TPS..I even had a buddy try a different Czp chip.. there are no gaurantees that the chip he used was tuned properly but he was sure it was, he checked all the little codes on the Chip.

I've pretty much covered every single thing.. Under boost the car pulls pretty hard and consistent, I don't hear any boost leaks, and the boost was consistent and didn't jump around on the gauge..

2nd big problem.. After the Turbo Swap I was testing a few pulls between 2nd and 3rd gear and my wideband was pegged at 10 AFR which means it was probably even richer than that.. Under full boost the Wideband was reading straight rich.. On my third pull the car back fired extremely loud 2 or 3 times and just shut down, Tach was reading 0 rpm while I was in gear and wouldn't start back up.. I pulled over and checked everything and everything was fine, no smoke, motor wasn't hot, had oil pressure, no leaks of any sort, everything was fine... I checked everryyytthiinnng and everything was good.. I tried turning it on and no luck, the motor would turn over and it would some times read some RPM movement but not a lot. Got towed home and when I got home I tried to turn it on for s*** and giggles and it turned on........ Shoot me now.. I'm assuming the problem could be that the injectors are firing way to much fuel and it flooded.. Maybe it's the same problem with my idle? any one have any clue what the hell could be wrong?

[t.mcginley.jr]

Have you ever changed the coolant temp sensor on the front water pipe? (the one with 2 wires, not just 1) If it goes bad, it throws off timing, prevents starting and idling, basically it tells the ecu that the engine is either way too hot/cold and messes up the ignition timing and A/F ratio.

And have you verified that your IACV itself is good?

iacv-aac-cleaning-and-testing-tutorial-t251133.html

[Z32mike]

Have you ever changed the coolant temp sensor on the front water pipe? (the one with 2 wires, not just 1) If it goes bad, it throws off timing, prevents starting and idling, basically it tells the ecu that the engine is either way too hot/cold and messes up the ignition timing and A/F ratio.

And have you verified that your IACV itself is good?

iacv-aac-cleaning-and-testing-tutorial-t251133.html

Dear God I have not lol.. and I read up on that too, it just totally slipped my mind.. in 3 hours that is exactly what I will be changing, I will be looking up the DIY. I will reply once I've changed it to report the status! Thanks man, great tip. Can't wait to get out of work now lol.

And yeah I cleaned it out completey and I took it off a perfectly running car. I wouldn't dount that the coolant sensor is bad, it wouldn't throw a code would it ? I'm throwing 55.. so nothing on the ecu

[t.mcginley.jr]

It usually does throw at code 13, but even though it didn't it could still be bad. I had the code but my check engine light wasn't even on. Hopefully that's all it is. My fuel temp sensor was also bad but I'm not sure what the effects of that are. I know for a fact a bad CTS causes all kinds of problems.

[Z32mike]

It usually does throw at code 13, but even though it didn't it could still be bad. I had the code but my check engine light wasn't even on. Hopefully that's all it is. My fuel temp sensor was also bad but I'm not sure what the effects of that are. I know for a fact a bad CTS causes all kinds of problems.

I swear this car has sucked out $5k from me so far, I also restored the entire interior but jesus, this is really frustrating :/ I wish I had a knowledgable Z guy here in Miami. I can't just go replacing every posibility, my wallet is turning into a black hole I'm really good with cars and pretty knowledgable but this car has given me more headaches than any other car I've ever owned and I've had a fair share of different cars.

[Z32mike]

It usually does throw at code 13, but even though it didn't it could still be bad. I had the code but my check engine light wasn't even on. Hopefully that's all it is. My fuel temp sensor was also bad but I'm not sure what the effects of that are. I know for a fact a bad CTS causes all kinds of problems.

I just bought 2 O2 Sensors and a coolant temp sensor, I will have the sensors on thursday and the CTS probably in by today. Bought the O2's for s*** and giggles because they looked rough and had carbon build up on the inside of the sensors.. Just Sounds bad saying that.

[t.mcginley.jr]

Yeah I was going to ask about your O2 sensors, they will cause the super rich condition if they are bad, or if you use a cheap brand.

[ZL8NING]

Interested in knowing how this was resolved. I think you have it stated in another thread, but this one still has no resolition, for when someone performs a search and hit this one.

[NolimitZ32]

OP: you bought a Z32, your wallet will henceforth be a black hole.

[solaire]

Is the CTS really that bad? I've got a 91 NA doing similar thing. It will try to idle around 1000RPM when the car is cold and seems like the VTC isnt working quite right so it's running pretty rough barely stays running til it warms up.

[hendersonw2012]

Really interested to see how this worked out. Did the o2 sensors or the coolant temp sensor help at all?