Car starts, but won't stay running

[emuskovitz]

I own a 1987 300zx non-turbo and I for a while now I haven't been able to get it to run properly. It starts fine, but after 15-30 seconds it starts to idle rough, and if you don't give it gas it will sputter and die. If you do give it gas it only seems to prolong the inevitable. Interestingly I've found that pumping the gas peddle will usually recover it for a while where flooring it does not, which might make sense if it was a carbureted system, but it's fuel injected so I don't know what that's about. I've replaced the fuel filter, battery and distributor cap (and rotor) and I've installed an inline schrader valve in the fuel system near the filter to test the fuel pressure. The distributor doesn't seem to be the problem, I suspected it might have been misaligned but that doesn't seem to be the case, and the pressure in the fuel lines is a healthy 30psi at idle to 40psi at full, so that doesn't seem to be the issue. At this point I'm at a loss for what the problem could be, any ideas?

[evildky]

Welcome to NICO. Step one wiht any OBD injected car si the check the ecu for codes.
http://xenonzcar.com/z31/ECUcodes.html
Check for codes and let us know what you find. One issue that might not present a code is the idle air valve, sometimes they just get gunked up and need cleaning other times they simply need adjusting, and sometimes hacks will adjust the idle at the cable or the TB and once making it difficult to adjust the iacv.

[emuskovitz]

In mode 3 I'm getting a code 41 which seems to be the fuel temperature sensor. In the past there have been a number of problems that made me suspicious of this sensor, namely that the climate control doesn't manage switching well and the car has an unending thirst for coolant. The ECU didn't throw any other codes, but I'm not sure if the code 41 was from an old error or is currant, since it's stored in memory. I did remove the battery yesterday which may have reset it.

[evildky]

The fuel temp sensor is usuaooy just a bad connection, clean up the contacts and it usually clears up.

"Thirst for coolant", un oh! Where is it going? If you have a leak you need to find and fix it, hopefully it's not a headgasket, but a leaking headgasket could explain your idle issues. Often coolant will leak into a cylinder and foul the plug, and or the loss of compression.

[emuskovitz]

Update on this: The head gasket seems fine, and there's was coolant leak in the radiator. This is fixed and there no longer seems to be a leak in the system so I think it was the only one. The engine is pretty loud but of you stick your head in it you can hear a hissing sound coming from the right side of the engine near the compressor. There's obviously a vacuum leak somewhere but I can't seem to pinpoint it. I don't have access to a smoke machine and I haven't had any luck with spraying things with water. Any suggestions?

[emuskovitz]

Today I found part of a metal brush in one of my intake lines and a marble in the air filter. This wasn't the original problem but it was so weird I had to share it with the world.

[evildky]

If you have a known coolant leak, you should definitely fix it and any other known issues before you begin troubleshooting, these known issues can throw additional variables into the mix making it tough to fix the unknown issues.

[emuskovitz]

Okay, due to unfortunate weather very little work has gotten done in the last month. Here's where we stand:

The fuel temp sensor is fixed, and ECU gives only code 44 - the "nothings wrong" code.
The coolant system is now sealed and pressurized, the leek was in an old radiator.
Check engine light is off.
Fuel pressure is a normal 30-40psi.
EGR valve is not stuck and seems to be fine.
PCV valve has vacuum pressure and seems fine.
Most but not all of the upper vacuum lines have been replaced.
The upper intake collector has been removed, cleaned, and reattached with a new gasket and quality sealant.

It's worth noting that:
The car can be recovered sometimes if you pump the gas pedal, but not if you hold it.
This problem came on gradually, over several months. It started with me having to turn up the idle so it would sit better, then having to rev the engine when it started or it would stall, and now its a challenge to drive more than 10 feet.
I've found no mixing of oil, coolant or fuel.
When you give power to the car you can hear the fuel pump priming, but if you put your head under the hood you can also hear a hissing sound coming from under the fuel pressure sensor.

Right now the two things I am most suspicious of are It's behavior when you pump that gas pedal (seems to indicate a sensor/ecu issue) and the hissing noise from under the hood. However i can't find anything that should have vacuum pressure in that part of the engine, and interestingly it only makes the sound after sitting for 30 seconds or so. If you power the car to listen for it you have to wait to give it power again for a little while in order to reproduce it, so maybe it losses pressure slowly? I'm honestly not sure.

[evildky]

I'd take off the ficv and iacv and give them both a good cleaning, also the TB as well. While you are at it make sure the rubber boots from the mas to the tb are all in good shape and no unmetered air is entering. Reset the tps, and make sure the tb is adjusted properly.

[GMan4030]

so this is going to sound like I'm an idiot but I'm really just new to all of this.
when i went to change the valve cover gaskets i took the distributor out and did not properly put it back it took me a while to realize this but when i did and set the car to TDC it would start and then rapidly decline in RPM and die however two teeth after TDC i can get the car to start if the distributor is turned all the way to the left but if i don't center it shortly after starting it, it dies it is also burning rich at first. any idea where i need to go with this?

[evildky]

Follow the direction in the fsm, it details how to set the engine at tdc and where the rotor button should be pointed when you instal the distributor. Then you need to use a timing light to set your ignition timing.

[GMan4030]

Is it normal for the belt to slip teeth I replaced the belt with one that has marks and they no longer match the gears

[evildky]

No it's not normal to slip teeth. Are you sure it's off? The thing is one revolution of the motor does not equal one revolution of the belt, the belt takes many engine revolutions to cycle around once, and even then it's likely not an even number to crank revolutions to equal one belt revolution so it might take a hundred revolutions, maybe more to get all the belt dots back on all the gear dots. So once installed the dots aren't important, set the crank at tdc and then look for the dots on the cam gears to align wiht the dots on the backing plate. If the dots don't line up and the belt actually skipped, your tensioner either isn't tight or you put the belt on wrong to start with, getting the crank gear lined up with the engine in the car is difficult.

[GMan4030]

Well the belt has almost lined up once or twice but I haven’t gone in and turned it until it perfectly lined up before, is that something I should try to do?

[GMan4030]

I did drive the car and it was really smooth and the there was no hesitation in the power