Surging on startup (and not just in cold weather)

[fastbird232]

Like it says, the 3.4 ('95 vintage, GTP) will rev up and down for about 10 minutes on startup; plus, it takes longer than usual to crank it over. What's up?

[GP1138]

Sounds like intake gaskets to me. I'm not sure though, I'm not a 3.4 expert by any means.

[hosser]

I replaced my uper intake gasket and my idle prblem was still not fixed. These gaskets stock are really cheap and when i pulled mine out it was cracked i a dozen places. For a while it idled nice and once in a while i am able to start the car in the winter and leave it without worrying about it stalling. I honestly think it has to do with wear and tear. The car smells too, to me its like the fuel isnt being adjusted right by the ECM, the 3.4 was not ment to idle. People are talking about the ECM editors i think that once they start using them the idle issue will go away. I have changed my fuel filter and ONLY run 93 octane gas, ive tried sae foam right into the intake, octane boosters, just about ever gimic 'injector cleaner' and fuel treatment there is, and still it wont idle right for the life of me in the winter time. good luck!

[gp90se]

in all honesty, throw in $5 of 89 octane and see if it smells any better, its harder for a low compression motor to burn off higher octane gas which can lead to a gassy smell. the 3.4 injectors also have a unique spray pattern (so ive been told) which could be allowing more fuel then needed into the cylinder, so ohm check and replace if needed

[joberlee]

Have you cleaned the carbon buildup out of the throttle body and intake? Check your temp sensor, sounds weird but, the computer runs the car on presets until it warms up a little bit. So if your temp sensor is not reading right it could be telling the car it's warmed up when it's not.

[WhiteMonteZZZ]

I had a similar problem. Then found the LOWER gaskets were leaking. Didn't think they were, but had to pull the plenum off for something else, and figured wtf, why not. It's been idling pretty good now. May wanna check them. Now if I can get rid of my off-idle hesitation

[Jeorge]

Check to see if the vacume adapter on the pass side of the intake is broken .... thats what was wrong with the z34 when it Surged like that... trys to stay running then Drops off then Revs then Drops and untill finally it dies...about 5 mins later..

[WhiteOut]

Its a vacuum leak. And its most likely your upper or lower intake gasket, they like to die around 100k. If you'd like to check into cheaper options first, check all the PCV hoses, the intake tube, EGR lines, brake booster hose, and cruise vacuum lines. But my guess is that since it goes away after ten minutes or so that you've got a leaky lower intake gasket.

 

Don't worry too much though, its an easy job. I did mine with a basic metric socket set and other basic tools in about 4 hours with no prior mechanical experience beyond a brake job. The gasket set is like $45, and you can pick up new EGR gaskets for another $3 while your at it. And if you really don't want to deal with it, you can take it to a shop for around $400.