Ok, so it hasn't stalled yet, but I'm sure that it will at some point when it gets colder. The car will bog from a stop when its cold, once you're going, there are no issues. It will also be fine after about 15 min of driving (no more bog). No codes, any idea what this could be?

4.9 pushrod engine, throttlebody injection, right ?? (Update your profile.....)

Sounds like the cold weather enrichment signal (the electronic "choke") is incorrect. Does your car have an ambient air temperature sensor somewhere near the front of the radiator and is it functioning?

..............maybe the intake air charge temp sensor.......

4.9 pushrod engine, throttlebody injection, right ?? (Update your profile.....)

Sounds like the cold weather enrichment signal (the electronic "choke") is incorrect. Does your car have an ambient air temperature sensor somewhere near the front of the radiator and is it functioning?

[I].

Yes. Does that mean that its running to lean when its cold, then its at the right a/f when its warmed up? Not sure to the last question....

Wait a minute. Isn't the 4.9 multiport injected?

Whoops, just read pushrod. Yeah, its MPI.

Either way, injector timing is changed to supply a richer mixture at cold starts and during the first phase of warmup. That enrichment function is controlled by the various temp sensors and MAF input to the ECM/PCM.

Yeah, I meant mine must be running lean, and then when the engine is warm it can run that leaner mixture w/o a problem but for the first little while it hesitates. So how many different sensors are there?

For starters, the IAT (Intake Air Temp), the coolant temp, and maybe the ambient air temp is tied in there. One, two, or all three can combine to set fuel ratios along with the MAF.

My 04 Deville would run like it was congested for the first mile or two in cold weather. Turned out it was the parking brake not releasing fully.

My 04 Deville would run like it was congested for the first mile or two in cold weather. Turned out it was the parking brake not releasing fully.

I know that my auto release is messed up, but I never set the parking brake, so it couldn't be that

EGR sticking

Had that checked.

Is your parking brake release vacuum operated? If it is, and you have a vacuum leak in that system (not uncommon), then that's a distinct contributor to your hesitation.

Yes, his brake release is vacuum operated. Probably a bad diaphragm.

Ok, so it hasn't stalled yet, but I'm sure that it will at some point when it gets colder. The car will bog from a stop when its cold, once you're going, there are no issues. It will also be fine after about 15 min of driving (no more bog). No codes, any idea what this could be?

I hope this isn't silly or insulting in anyway. I am no where as technical as these others are, but my 92 Brougham starting doing that bog thing late sept early oct. I changed plugs, wires distrbtr/rotor. No more bogging. Just a thought and all I can contribute.

Is your parking brake release vacuum operated? If it is, and you have a vacuum leak in that system (not uncommon), then that's a distinct contributor to your hesitation.

But it would only affect the vehicle when its cold?

I hope this isn't silly or insulting in anyway. I am no where as technical as these others are, but my 92 Brougham starting doing that bog thing late sept early oct. I changed plugs, wires distrbtr/rotor. No more bogging. Just a thought and all I can contribute.

No worries, any input is welcome. But the distributor was just changed as well.

Originally Posted by submariner409 View Post
Is your parking brake release vacuum operated? If it is, and you have a vacuum leak in that system (not uncommon), then that's a distinct contributor to your hesitation.
But it would only affect the vehicle when its cold?
No..

So its most likely running lean and I should check into the other things first?

Check for a vacuum leak at the brake release diaphragm.