Starting and idle problem. 95 3.4 DOHC

[Lucky736]

Hey all I am new here and really need some help. My father owns a 95 Cutlass 4 Door with the 3.4 DOHC. I remember when I convinced mom to buy this new 11 years ago, lol. C'mon mom it's a much better motor, and faster too, lol. That's what happens when your 15 at the time.

Anyway, here is the problem:

Car starts, revs to 1500, 2500, 3000, back down to 1000, 500, and stalls.

Car starts, revs to 1500, 2500, 3000, back down to 1000, 500, and stalls.

Car starts, revs to maybe 1200, comes back down, bogs for a min and almost stalls, then runs fine with a little miss here and there.

Dad replaced the battery, lol, dunno why, it probably needed one anyway but I knew that wasn't the prob and told him. Replaced air/idle control valve, not the probem.

I am sure it is something simple, but the fact of the matter is not many people know what they are doing with these motors.

Any help would be appreciated and thanks all.

Mike

[Scott205]

I would look at one of the following things.

First test these two items,

Fuel Pressure Regulator - does it maintain 40psi on the rail?
TPS - is it something like 5volts +/- .5 at start or something like that.. have to look it up to be sure.

Most likely you will need to replace one or the other.

[masternuggetsGTP]

the problem could be a vacume leak...might wanna change out your upper and lower intake manifold gaskets...my gtp used to do the same thing before i changed the intake manifold gaskets out then it worked perfectly

[Lucky736]

I know before he had a small vacuum hose that had split and was replaced and the car seemed fine after that. Might be a good idea to double check though.

[Kyles93Z34]

Exact thing happened to my 93 Z34. The local chevy dealer said that something wasnot grounded properly and it was shutting the computer off and shutting the fuel pump on and off.

Kyle

[Juglenaut]

Looks like an intake manifold leak to me.

A bad regulator typically won't cause erratic rpms. The pressure should vary with manifold vacuum.

[Lucky736]

I can tell you after it is over 1/4 on the temp gauge it runs just fine, even most of the loopy idle is gone. You think it might be an intake manifold leak? New gasket time?

[sunny_8]

same thing happened here.....would do the same as what you are saying..
replaced the upper and lower manifold gaskets and it worked like a charm.
Dont by the gaskets from murrays auto..they will not fit...go to napa or carquest .....

[Juglenaut]

1/4 on the temp gauge it runs just fine

That reinforces the possiblility

Since when it warms up the intake manifold gaskets expand some.