WEIRD 3.4 Idle problem...

[fleetwoodguy79]

Alright, when I bought the car it had a strange idle, thought it may have been either the timing, or plugs and wires. So far I've managed to replace upper and lower intake gaskets, timing belt, plugs, wires, and IAC module. I STILL have a very VERY rough idle. Sounds like a cammed car, hesitates for a second when you go from idle to throttle. But when cruising, or anything past 2k rpms, its AWESOME. No misses, strong all the way to redline. I can't think of what else to check! I've heard some talk about VSS sensor maybe causing idle issues? Where is that at on the 3.4? Its a 94 GTP, need some help! Thanks!!!

[White93z34]

at this point i'd say a bad injector.

[loominaz34]

Mine's got those exact symptoms. how do you test the injectors? or is it a guess and check type of thing? (meaning for a sure fix, replace 'em all)

[Dan94Z34]

To test the injectors, you need a multi meter. Put the setting on Ohm's. Unplug the electrical connector that goes to the injector. Put one test lead one one pin, and the other lead on the other. The reading should be in the 12ohm range.

[loominaz34]

So i took off the little plastic "twin dual cam" cover from the fuel rail and i figured out my problem: I have only three injectors!!!!!!! :shock:

 

ok now back to reality, where are the rear 3 injectors? Are they under the plenum? and if so am I going to need a new gasket to replace the plenum correctly? Oh and all three fronts were 12.5 ohms. is this good?

[gp90se]

yup, under the plenum, id replace the gasket if you havent already, its like $5 and its good security.

[DaveFromColorado]

aren't those the exact same symptoms from the 13 degree exhaust redard mod?

 

also, a bad injector will cause more problems up top, then it will down on the bottom, unless it's stuck open, in which case you'd have extremely hard start problems, too rich at idle to the point where you can smell gasoline and other things like that.

 

--Dave.

[fleetwoodguy79]

See i thoguht the same thing about the 13* retard. But I've retimed this motor twice now and i am SURE it is timed correctly. Usually when it isnt timed right you kind of hit a wall where you can rev anymore. And yes, on startup there is a LOT of smoke, and the car dies. You have to try to start it 3 or 4 times to get it to go. I'm at a loss here!!! Would an O2 sensor do something like this?

[GrandPrix34]

i have the same issues with my car right now. IT could be whats called a Phantom Stalling condition, check it out:

http://60degreev6.com/index.php?name=PNphpBB2&file=viewtopic&t=1084

 

But my car does the same thing, from a stop sign or stop light, when I press the throttle the car seems to stall for about 1 sec then it picks up. So if anyone can help fleetwood, you'd help a whole bunch of us as well...

 

 

Hey fleetwoodguy, ready for another 14.1 DOHC?

[fleetwoodguy79]

Haha, to put it kindly, NO!!!!!! After 5 months and $3000, i will NEVER rebuild or try to muster power out of this motor EVER AGAIN! After owning a 99 GTP, spending less than $300 and getting a car that was JUST as fast as my $3000 DOHC, I'm just waiting on the right time for an L67 swap! Granted, this is a facinating and rather impressive motor, problems like this just want to make me pull it from the bay, and chuck it over a cliff. Onto rocks of course, that way I can see it die the WORST and most HORRIFIC of all deaths.

[CuttySup]

From the NATIONAL HIGHWAY TRAFFIC SAEFTY ADMINISTRATION:

OFFICE OF DEFECTS INVESTIGATION:

Technical Service Bullitin:

 

Make : PONTIAC Model : GRAND PRIX Year : 1994

 

Manufacturer : GENERAL MOTORS CORP.

 

Service Bulletin Num : 990604005A Date of Bulletin: APR 01, 2001

 

NHTSA Item Number: 619360

 

Component: ENGINE AND ENGINE COOLING:ENGINE:GASOLINE

 

Summary:

SOME OWNERS MAY COMMENT ON DRIVEABILITY SYMPTONS OF LONG OR HARD STARTS, CHUGGLE, ROUGH IDLE AND LIGHT OR INTERMITTENT MISFIRE DUE TO CLOGGED FUEL INJECTORS. *TT

 

This is also applicable to all GM vehicles with V-6 engines

3100, 3.1, 3400, 3.4 DOHC, specifically.

 

In other words, I wouldn't call it "normal," but it's to be expected.

[CuttySup]

My friend's '94 GP SE with the 3100 just started phantom stalling the other day.

[fleetwoodguy79]

ITS FIXED!!!

 

Turned out to be the EGR gasket causing a NASTY vaccuum leak! Thanks all for your help!

[95 3-4]

Damn my 95 always had the off idle stumble too, really saved tires since they would never spin

 

Vacuum leak aye, I'll never know darn it