Help! 95GT With Rough Idle

dubbsix · Apr 29, 2009

Help! 94GT With Rough Idle

My newly purchased 94GT is suffering from a rough idle. the car doesnt seem to run bad when im driving it, but it idles like crap and it also crank a few times before it starts. while running every now and then the engine will "stutter". I recently changed these parts:

cap and rotor
spark plugs
spark plug wires
new air filter

Tonight I hooked up a fuel pressure gauge and with the Key On, but the engine not running the fuel pressure was: 37PSI and steady. It didnt leak down at all.

with the key on and engine running the fuel pressure was stead at 32psi at idle and went up each blip of the throttle.

I tried pulling codes and the ones i got were: 116 and 314.

Since there is plenty of fuel can i rule out: regulator, fuel filter and fuel pump? Could a faulty ignition coil cause this? the car seems to be running rich.

Thanks in advance!

dubbsix · Apr 29, 2009

Please delete... posted in 5.0 tech instead.

mustang1994 · Apr 29, 2009

try changing your IAC

dubbsix · Apr 29, 2009

mustang1994 said:
try changing your IAC

Not getting any IAC related codes.. and would that attribute to my hard start condition on top of the rough idle?

86T-Top · Apr 29, 2009

Did you check for vaccum leaks? What is your RPM at idle?

I had a problem with a rough idle and tracked it down to a broken vaccum line, fixed the line and I am good to go. I only found the leak after I inspected the fuel system and the ignition system.

Mario

dubbsix · May 3, 2009

86T-Top said:
Did you check for vaccum leaks? What is your RPM at idle?

I had a problem with a rough idle and tracked it down to a broken vaccum line, fixed the line and I am good to go. I only found the leak after I inspected the fuel system and the ignition system.

Mario

I did check for vac leaks, but havent found any. I had one that threw code 314 for the air pump but i repaired that vac line and still have the idle issue. My idle is at about 1050 -- but thats because i jacked around with the dizzy trying to stabilize the engine.

Im a little new to the 5-0 world. Is there a vac diagram i could look at so i can check the vac lines systematically. I just looked under the hood at what i could easily ID as a vac line.

Nick95GT · May 4, 2009

Im having a very similar problem!!! Its not really a rough idle but it feels like the engine struggles or stutters every once in a while and i had the codes checked...i guess my engine is running lean and he said it was either a vacuum leak or a problem with the intake. it wouldve takin another hour to figure out the exact problem and i had to be somewhere so i havent gotten around to fix it yet...but if it feels like my engine strugles sometimes ( inless im flooring it) or stutters is that because of the engine running lean???

dubbsix · May 4, 2009

Nick95GT said:
Im having a very similar problem!!! Its not really a rough idle but it feels like the engine struggles or stutters every once in a while and i had the codes checked...i guess my engine is running lean and he said it was either a vacuum leak or a problem with the intake. it wouldve takin another hour to figure out the exact problem and i had to be somewhere so i havent gotten around to fix it yet...but if it feels like my engine strugles sometimes ( inless im flooring it) or stutters is that because of the engine running lean???

What were the codes that were stored on PCM?

99FiveOh · May 5, 2009

I too have a rough idle. When I fire the car up in the morning it sounds like there's a cam in it! It smooths out a little, but even at a red light I can feel the car shaking. Mine also runs and drives fine, but I'm sure whatever is causing this problem must be robbing a little power as well.

I used some carb cleaner and sprayed around trying to find a vac. leak but came up with nothing. I've replaced everything in my ignition system besides the wires.

Nick95GT · May 5, 2009

dubbsix said:
What were the codes that were stored on PCM?

it was like P172 I think...i have to double check cause i have it on a piece of paper in my car but im in school right now so ill make sure thats right and post on here again later on...

Nick95GT · May 5, 2009

alrright yeah its P0172, Lean Bank 1. i have no idea what this means but i hope the check engine light has something to do with the engine stutttering and sometimes the rear end will make a quite pop noise...idk whats wrong with it cause 75% of the time it drives perfect

TheDamned · May 5, 2009

I'm having a similar problem... no problem at idle but people think I have a cam.
But my engine sometimes doesnt accelerate like it's supposed to be.. very weird.. that damn ERG valve I guess.

Chern_889 · May 6, 2009

Nick95GT said:
alrright yeah its P0172, Lean Bank 1. i have no idea what this means but i hope the check engine light has something to do with the engine stutttering and sometimes the rear end will make a quite pop noise...idk whats wrong with it cause 75% of the time it drives perfect

Dirty MAF, i had the same problem, Lean on Bank 1 and 2. Car ran like ****, CEL would come on and off. Turned out to be an extremly dirty MAF sensor form a dirty and over oiled K&N filter, took the sensor out of the housing, and sprayed it down with sensor safe brake cleaner, and used a few Q-tips and gently rubbed it to get the residue off. It made it a whole new car, from barely able to spin the tires, to roasting it into second.

Help! 95GT With Rough Idle

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