Hesitation On Initial Throttle Apply When Engine is Cold

[Kaline]

I've searched the forum and cannot seem to find an exact post on my problem...

 

I've got a 1990 Oldsmobile Cutlass Supreme with the 3.1L/auto. The car has 115K miles. It seems to have been relatively well maintained before I bought it but I did not get maintenance records with the car. When the engine is cold, the car will hesitate and occasionally stall when you tip into the throttle. This goes away after the car has been running for about 5 minutes and the throttle becomes 100% smooth. Also, it occasionally has a miss at idle. The car does NOT set an SES light and uses NO fluids. It gets consistent and acceptable fuel economy (18mpg city / 24mpg highway). In the last 5K miles I have performed the following work:

 

1. New plugs, wires, air filter

2. Cleaned the IAC and throttle body plates

3. New fuel pump and fuel filter

 

Initially I suspected the Throttle Position Sensor, but since it goes away once the engine is warm I'm not sure if that is the problem. Now I'm wonder if I should run Top Engine Cleaner, or if it might be an ignition problem. The plugs, wires and fuel filter were original when I replaced them, so I would bet the coils and ignition module are original as well.

 

Any insight is appreicated.

[slick]

Hmm... kinda poor when cold eh.

 

Check your intake gaskets.

[Guest donkeykongrape]

I have this EXACT same issue with my 3.1 as well, it's been like that since I bought the car, I just figured it was an old engine and I shouldn't expect much from it...If you figure out what it is, let me know

[Dark Ride]

I have this EXACT same issue with my 3.1 as well, it's been like that since I bought the car, I just figured it was an old engine and I shouldn't expect much from it...If you figure out what it is, let me know

 

 

Both My Grand Prix and Buick Regal do this, I just kinda ignored it. Would be nice to make it stop doing it. It also occasionally misses on idle. I put new plugs and wires in it also.

[slick]

Check your intake gaskets.

[Guest donkeykongrape]

what would intake gaskets have to do w/ it? (not a flame, just wondering)

[FastSE2DR]

maybe because its cold period? it only happens when the weather is REALLY cold on my car

[slick]

what would intake gaskets have to do w/ it? (not a flame, just wondering)

 

Until the metal around the intake gaskets warms up enough to soften up the gaskets so they would expand, any slight crack or leak would cause these symptoms.

 

It's free to check. Just take some carb cleaner and spray where the lower intake meets the heads, and where the upper meets the lower intake manifold.

[cutlass1991]

Mine also does this. 91 3.1L. Replaced the following with no results:

 

fuel filter

air filter

plugs

wires

pcv valve

intake gaskets

cleaned:

egr valve

throttle body

 

Theres actually been a couple of times it gets so bad the engine stalls, but most of the time I don't have the problem at all.

[DaveFromColorado]

It could be one of a few things ... Either the injectors are sticking when cold, The FPR is sticking wide open when cold, or the fuel pump hasn't warmed up enough to flow the proper ammount of fuel required when it's cold.

 

just my thoughts.

 

--Dave.

[kknobl]

I have this EXACT same issue with my 3.1 as well, it's been like that since I bought the car, I just figured it was an old engine and I shouldn't expect much from it...If you figure out what it is, let me know

 

 

Both My Grand Prix and Buick Regal do this, I just kinda ignored it. Would be nice to make it stop doing it. It also occasionally misses on idle. I put new plugs and wires in it also.

 

Count me in as someone who has experienced the cold weather hesitation as well. I've always just chalked it up to the age of the engine. I've never had it stall on me though (knock on wood).

 

Once the engine is warmed up some, the issue goes away.

 

Kevin

[ShockTherapy]

what would intake gaskets have to do w/ it? (not a flame, just wondering)

 

Until the metal around the intake gaskets warms up enough to soften up the gaskets so they would expand, any slight crack or leak would cause these symptoms.

 

It's free to check. Just take some carb cleaner and spray where the lower intake meets the heads, and where the upper meets the lower intake manifold.

 

...nothing, and my DOHC still does it.

[WhiteMonteZZZ]

My car's done this since I've owned it as well. I replaced everything cutlass1991 did, but am currently driving with my EGR valve connector unplugged due to a sticking solenoid. Ironically, the hesitation occurs even less noticible now, only really does it upon extreme cold temperatures. But now I've just learned to live with it, as aggrivating as it can be

[Guest donkeykongrape]

Hey it never dips below 40* here and it still does it to me...even on 90 degree days, it will still do it when I first start the engine up after it's been sitting for a few hours...

 

What would carb cleaner on the intake gaskets do?

 

And yes I have experienced it stall as well, it just hesitates to the point where the RPMS drop too low to keep it running and it just plain stalls...kinda rare though

[slick]

What would carb cleaner on the intake gaskets do?

 

Spray it at the intake gaskets while the car is idling. If the idle fluctuates, means bad intake gaskets. If it stays the same, your all good.

[Kaline]

I thought I would update the group on my stalling issue. Once I replaced the fuel pump, fuel filter, cleaned the IAC, poured a bottle of Chevron Techron fuel injector cleaner in the fuel tank and did the PROPER idle re-learn, the car runs MUCH better. Occasionally it'll stall on initial shift from Park to Drive, but very rare now. I am going to replace the O2 sensor (looks to be original and the car sometimes hunts a little at idle), clean the IAC again and see if that takes care of the rest of it! I'll keep you posted!

[92SL]

Bloody hell, my 92 supreme sl does it with no prejudice(warm or cold). I rescently thought about the o2 sensor, please let me know if it helped.

[ns87]

My Supreme still does this occasionally. It got worse when some wire insulation rubbed off the connector to the Mass Airflow Sensor. Check those wires as mine broke at a kinda weird spot right next to the connector

[Kaline]

Replaced the O2; that was not the problem. Cleaned the IAC again with a Scotch-Brite pad and the initial stalling problem has pretty much gone away. I think it may have been the combination of weak fuel delivery, dirty IAC and not performing the idle learn procedure. Thanks for all the help!

[Kaline]

FINAL UPDATE - I replaced the fuel injectors on my car this weekend to cure another problem I was having (miss at idle, stalling at stoplights). 3 of my 6 injectors tested low resistance when I pulled them, so I replaced all 6. The hesitation is totally gone now! I think the injectors were the root cause of the problem, and the other items (dirty IAC, old fuel filter, etc) just amplified it.

 

FYI, watch out for United Automotive Remanufactured injectors. I bought these, and one stuck in the ON position! Totally flooded my engine. Spend the $$$ and get new ones!