So I took my fiero in for emissions a couple weeks ago and failed for NOx, everything else was perfect, bearly even on the scale. Pretty clear cut case of a bad EGR valve, so I swapped a new one on. Directly after, I began to have a hesitation comming off idle (much like a carb with too small a shot in the accelerator pump would have). Also, there is a distinct loss of power. It seems as if you need to push the pedel down much further in order for the engine to "pick up" (not to be confused with the transmission kicking down). It does this in open and closed loop, so its not the O2 sensor. Also, if you just rev it in park it'll begin to miss a good amount past 2000 rpms. This causes a slight miss while diving obviously, but only seems to occur during low throttle cruise situations, it runs fine while accelerating, albiet with less power than usual.

So far, Ive checked for any vacuum leaks, as I thought there was just a leak between the EGR valve and the intake, causing the engine to go lean. However, I've pulled the plugs and they didnt show any signs of running lean, they were a nice tan color. Ive changed my plugs, tried swapping the old EGR valve back on, tried disconnecting the vac. hose from the EGR vavle, and tried a different MAP sensor I had lying around. Im going to test the TPS sensor soon too but I doubt thats the problem.

Any input anyone has on this would be appreciated, Im thinking now its a fluke coil or ICM failure that just coincidently started right after the EGR swap. Thanks for any help in advance.

EDIT:
Couple other things:
No SES light, no glowing manifolds, no overheating, cant think of anything else right now

EDIT Again:
Changed my fuel filter too, forgot to mention that.
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1987 Fiero - 2.5L, auto tranny, stock
1970 Firebird - built 455+.030, lots 'o mods

[This message has been edited by PontiacMan (edited 06-20-2005).]

Sounds like the injecter gasket. Check for good spay pattern. or dripping. I guess you may have taken off the TBI to get the EGR? Also check the connecters. Perhaps the IAC is loose. Or some other one..... Just a thought, easy checks anywho.....

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White 1984 Fiero SE, Holley TBI, High Flow Cat, MSD coil, ported intake

[This message has been edited by Esquire (edited 06-20-2005).]

Nope, didnt touch the TBI to pull the EGR valve. All I pulled was the plate that bolts to the intake which holds the pulley for the throttle cable and TV cable. I replaced the injector about 5 months ago and it has a nice even spray pattern with no leaking. Ive pulled and reseated all the electricalconnectors I could find just to make sure. The idle is pretty steady at just about 500 rpms.

I'll pull the injector tomorrow and check out the gasket though. Thanks

Keep the ideas comming, this one has me stumped.

[This message has been edited by PontiacMan (edited 06-20-2005).]

Sounds like the injecter gasket. Check for good spay pattern. or dripping. I guess you may have taken off the TBI to get the EGR? Also check the connecters. Perhaps the IAC is loose. Or some other one..... Just a thought, easy checks anywho.....

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White 1984 Fiero SE, Holley TBI, High Flow Cat, MSD coil

<bump> for more ideas

Cleaned your injectors lately?
Could the cat be clogged?
Clogged fuel filter.
Bad gas?
Fuel pump going out?
Poor electrical connection? I've had loose spark plug wires do the same thing your getting.
Check your spark plugs too.

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Failing to prepare - Is preparing to fail....

I am the signature virus, please put me in your signature so I can spread

Cleaned your injectors lately?
-Only a few months old

Could the cat be clogged?
-That'd give bad CO and other readings when I went in for emissions

Clogged fuel filter.
-Replaced

Bad gas?
-Filled up a couple times now

Fuel pump going out?
-Possible, but that'd usually only cause problems at higher RPMs

Poor electrical connection? I've had loose spark plug wires do the same thing your getting.
-Pulled and reseated all my wires

Check your spark plugs too.
-Replaced

=/

What you describe seems similar to what my car did when one of the ignition coils started going bad. If you have a spare or two, swap them in and see if the situation improves. While you're at it, check the crank position sensor. Those things have an affinity for cracking.

So I think Ive figured out part of the problem. It appears my TCC is starting to go out, and is causing the studder Im experiencing. If I lightly tap the brake while its studdering, it goes away. This would probably account for the loss of power since its not disengaging when I hit the throttle, keeping the engine in lower RPMs and causing it to lug.

I still want to test my TPS though, Im betting that it has a dead spot in it, but one of my multimeters has gone MIA, and the other has a dead battery.