Oddity when coasting

[WhiteMonteZZZ]

Some of you may remember my slight off-idle stumble I have w/my car (doesnt happen every time). (95 Z34)

 

For reference, here's the list of replaced items:

 

TPS, IAC, upper/lower intake gaskets, cleaned EGR/replaced gasket, o2 sensor ~15-20k ago (still had stumble before and after that was changed), cleaned MAF and TB, most if not all vac lines gone over (breather filter eliminating one of the long vent vac lines), and another computer was swapped to eliminate that possibility. Fuel filter also brand new.

 

The car has also developed the following issue:

When cruising through a subdivision (around 20 mph or so) and coasting, the rpms will drop then pop up and do that a few times until I either speed up, or until the car slows down to about 15 mph. Then the idle is smooth. Doesn't really jerk the car, but it IS noticible. Almost like it wants to try to stall.

 

Also, my car sat a couple days, and upon cold startup, the car idled rough for a matter of a second or so (like starting a carbureted car w/no choke).

 

Now I don't know which of these sounds like the culprit, if any:

 

Fuel Pressure Regulator, Fuel Pump, ICM.

 

I might talk to someone I know and ask them if they can check fuel pressure - as of right now I don't have the means to. But what would you guys look at next?

[slick]

ICM solved my problem.

[88Regal Limited]

HOLY FUCK THATS A NICE TRANS AM!

 

Ahem.....sry. I'd guess FPR, but thats just me.

 

 

[Spoon]

Sounds like youv'e got the same problem I do, Any ideas, I've been trying to figure mine out for months.

[94CutlassSLCoupe]

you didn't mention that you have changed your fuel filter...try that as it is cheap and easy...and causes a lot of driveablity issues when plugged.

[Kalgorn]

I actually have the same thing going on. The RPMs fluctuate from like 900 rpms - 1300 rpms, back and forth when I'm coasting. You can actually feel it change the rate at which the car moves. Barely, but noticeable. I wasn't sure what it was but I have a feeling it could be a reason my car has been stalling. I've got a fuel filter sitting here ready to be installed so perhaps I'll do that tomorrow too once I figure out what else is wrong with my car.

[WhiteMonteZZZ]

Yeah, um forgot to mention that. Fuel filter has been changed a month or so ago. No change.

 

And thanks about the Trans Am

[3pt1lumina]

could a weak or bad coil cause this?? how about bad plugs/wires?

[fastbird232]

I actually have the same thing going on. The RPMs fluctuate from like 900 rpms - 1300 rpms, back and forth when I'm coasting.

 

Same problem here. Fuel filter did nothing. I'm going to try a new IAC and replacing all the intake gaskets.

[WhiteMonteZZZ]

could a weak or bad coil cause this?? how about bad plugs/wires?

 

I have some MSD coils to install (too bad on my car they are a PITA to get to), but new wires/plugs didn't help me.

 

Nor did new intake gaskets. I'm just glad others have the same issue as me :?