Dies at low rpms, blakt sut on new plugs, checked everything i can think of

[gfisch]

So, having trouble w/ my s14.

It dies when i let up on the throttle and the rpms drop below about 2500 after the cr has been running a few min.

It started by dying when decelerating from highway speeds (exit ramps & toll booths) and now dies at every stop light, etc. It also stuttered abit over 80mph.

Now it dies tries to die after idling for a few min or if i rev it with no load and release the accelerator below 2500rpm. I can sometimes save it by giving it some gas (not necessarily full throttle). When the trouble starts, I can smell the gas in the exhaust. Seems to be flooding the engine.



The code I get is P1320 so I checked the distributor, etc as the FSM suggested an all is fine.
Sparks are fine (or were when i started troublshooting), i pulled out each wire when idling and noticed a marked drop in perfomrence for each.

Next check the fuel injectors. Took of the rail and primed the pump with no noticible leaks. The I pulled out each plug when idling and noticed a marked drop in perfomrence for each injector when off.

Next checked the engine coolant temp sensor. Measured the resistance as i put it in heated water and seems within specs.

Next checked the vacuum. The ERC solenoid and the EGR valve seem to be fine.

I have replaced the plugs, oil filter, air filter since i first noticed the problem. I just noticed this morning when I pulled out a spark plug to try to see if the engine was flooded and to let some fuel evaporate that the brand new plugs (less than 1 week) were completely covered in black soot and also there was a strong smell of gas coming from the cylinders. The air filter and fuel filter were a bit dirty (maybe waited a lil too long between tuneups) when i replaced them.


Sorry for the long post, but I am quite frustrated here. I don't know what else to check. It seem like the components are working, so there is probably a sensor or computer problem that is causing the engine to run rich & flood.


Thanks a lot,
Greg

[i20ar]

i had the same problem it turned out to be a leaky injector... i just swapd out my o-rings. and my problem fixed... you could also check your throttle position sensor.. that was a problem my friends coupe had

[rancid240]

Definitely running way too rich. My suggestion would be CTS, but youve already done that. I would still check the electrical connections for the temp sensor and measure the injectors resistance to make sure they are in spec. Did the temp sensor seem dirty? Try to clean up the actual sensor part of it as well.

Wouldnt hurt to test the voltage on the MAF or just replace it with one that is working, or unplug it when the car is running etc.

[gfisch]

Thanks for the replys.

I don't think that it's a leaky injector because i didn't see any leaks when i pulled the fuel rail off and ran the pump. But, I ordered new o-rings a couple days ago, so I will try swaping them out.

TPS is fine, i checked with with my sacn tool and it goes smoothly between 0% and about 97% (seems to not reach 100% which I need to take a look at, but thats a separate small issue i think).

I thought it mught be the CTS from searching similar problems. It was a little dirty, but not too bad. I pulled it out and tested it independently and it was fine. Cleaned it up too when it was out. Also, the scan tool CTS repsonse and the dash temp gauge seem accurate.

The MAF seems to be functioning because the scan tool response shows a ramp up and down in air flow when i rev the engine. It may be out of calibration though, so i'll try to unplg it and see what happens.

Any other suggestions? I think I've already hit up most of the obvious ones.

[NIK90s13]

A Vacume leak will cause it to die like you said, I ran in to that and it was a vacume leak. How's your timing?

[gfisch]

I was thinking a vacuum leak sounded probable, but I don't have any experience diagnosing that. The only think I checked it terms of the vacuum is if it pulls a vacuum on the egr valve when reving th engine which it does.
What's the best way to troubleshoot a vacuum leak?

Same w/ the timing, how should I check that out.

Thanks.

[rancid240]

For vacuum the easiest would be just to feel the lines for cracks, air etc. Also try to listen for any kind of hissing sound. I would still check the injectors resistance, but I dont think new o-rigns are necessary especially if you have no leaks.

Timing, I havent done before.

[gfisch]

Well, I can't see or hear any obvious leaks. Notices the intake to throttle body hose clamp was a little loose, but tightening that didnt help. Is there any better way to diagnosis a vacuum leak?

[NIK90s13]

Get some carb cleaner and spray your lines intake ect if the motor revs up or if there is an idle change than there is a leak.

[gfisch]

Got it running again!!!

Looks like the IACV and maybe some other parts were clogged up. I ran a bottle of seafoam through the vacuum line to the iacv and the throttle body and after a whole bunch of smoke it seems back to normal. Idle is nice and steady, and runs as well as ever.

Gotta say, that sea foam is pretty amazing stuff. Fixed it right up after a week of troubleshooting all of the components.