Cold idle prob on 3.4 GTP

[barryc]

First I'd like to say I'm glad I found this forum. You guys seem to have it together. I have a 95 Grand Prix GTP, DOHC 3.4, auto, with about 78k on it. Since the winter, it displays the following behavior on cold start:

Car idles up to about 2500-2750 rpm

Idle slowly falls until it reaches about 600 rpm

sputter, sputter, sputter

idles back up fairly quickly

repeat

As the engine warms, the fluctuation gets less and less. Sometimes it drops enough to stall.

The SES light hasn't come on, and there are no trouble codes set.

I have been suspecting a vac leak, possible intake. Any thougts? By the way, the car passes emissions with flying colors.

Thanks in advance!

[Redfox340]

That would be the place to start out; use some thottle body / carburator cleaner and shoot the gaskets while the car is running cold... if the RPM's fluxuate, it's the manifold gasket.

 

However, since it's not throwing any codes (yet), check all vacuum line and hoses and make sure the Idle Pintle Valve on the thottle body is not malfunctioning. Also, clean the thottle body (if you haven't already done so) and double check the gasket around the EGR valve. Other than that, it should be semi-easy to locate and fix the problem! Best of luck!

 

- RedFox340

[bbender85]

possible intake.

 

that's where my money is at.

[AWeb80]

Well, i don't have a 3.4 and i don't know much about them. But, from what i've read since i've been a member, i'd put money on your intake gastket. Just my $.02

[RedZMonte]

Intake manfold gakets is your problem.

 

I would do the upper and lower as well and the injector seals. that will take care of your problem. And don't over torque the bolts on reinstall.. Only like 16ft/lbs tq or somthing minute like that. I would recomend Felpro gaskets.

 

Shane

[CPSMonteZ34]

Yup, intake gaskets have bit another owner in the ass.

 

...and if you're mechanically inclined, I highly suggest doing it yourself. We can help with the entire process from start-to-finish. Taking it in to a mechanic for this one can cost you when you consider the vast majority of the cost to repair is all labour. There's a whole lot to take apart, and the parts don't even come to $50 - so the labour is rediculous.