idle issues/ lower intake tips

[stratford_boy]

Hi everyone:

have a 99 malibu w/290k kms on it. Ever since buying this car a year ago, when started cold the car spits and sputters just before starting, then hunts for idle speed for 30 sec. or so. Any ideas?? Checked everything I could think of: IAC/ MAF/ fuel press. / 2 fuel inj. flushes/ 2 throttle body and air int. cleans/ vacuum leaks etc. Any help/ info./ or answers would be appreciated.

Also:

Anyone with a 3.1 or 3.4:

THe reason that the intake gaskets fail on these vehicles is because over time the lower intake gaskets "crush" causing the bolts to become loose eventually causing gasket failure. Tightening these bolts after the first oil change will signifigantly reduce gasket failure. (Mine have over 200k on the second set of gaskets. (I'm a licensed tech...) Try this and see what you think!!!

[tczer34]

So you are saying that 3000 miles after the gaskets are changed, remove the upper intake once again to re-tighten the lower intake bolts, which causes you to replace the upper intake gasket again and tear apart half of the engine compartment? If so, my car is going straigh to the used car lot!!!

[stratford_boy]

well, the gaskets can be reused, they are dry gaskets. Pretty simple job to remove the upper intake, then the pwr steer pump to get at the bolts on the pass. side...

[bcopeland]

Yes it is a pretty simple job removing the uppers. Can't answer the idle problem. I seemed to have that associated with the lower intake problem.

[stratford_boy]

So, after you did your intakes, this exact same problem that I am having went away???

[stratford_boy]

Nobody else??? Find this hard to believe....

[richtazz]

On your spitting ans puttering issue, how old are the plugs and wires, and if newer, what brand did you use?

On the intake gasket issue, Fel-Pro has come up with a new designed intake gasket that is metal/rubber instead of the plastic/rubber crap GM used from the factory. It is a kit that includes the valve cover gaskets and EGR gaskets necessary to change the lower intake gaskets.

MS98003T fits 99-up 3.1 Vin-J (it also fits the 97-up 3.4 vin-E used in minivans and other GM products)

MS98004T fits all 96-up vin-M 3.1's (97-01 in the Malibu)

The issue isn't that the gaskets crush (they are made of rigid plastic with rubber beads), it's that the low torque value of the intake bolts allow the intake to move around and eventually cracks the plastic of the gasket. This allows coolant to escape past and get in the oil. The new Fel-Pro gasket mentioned above is stronger material, which will not crack like the factory plastic gaskets do. I also use threadlock on all the lower intake bolts to keep them from loosening due to the low torque value and expansion/contraction of the metals. If GM would have used threadlock, the factory gaskets may have been sufficient. I have done many of these intake jobs, and the outer bolts on the lower plenum were almost finger loose on every one.

[stratford_boy]

I realize that there is a new design for the lower intakes on these motors, and am going to use a set when I get around to relacing them. They are still not leaking oil or coolant yet.... The plugs and wires were replaced by a gm dealership approx. a year ago and I have since removed the plugs to verify gap. Torqued the plugs back in. This issue was there when I first bought the car and the plugs and wires were new. Everything checked out fine to me. Might try a set of ngk plugs just to see. Might be a cheap fix. Who knows... Plugs and wires currently in the car are ac delco platinum and ac delco wires as well.

[dwalmop]

Threadlock on the intake bolts? Does that ever lead to a problem removing them if needed? (Hopefully they would never need to be removed again).