Weird Problem

[CdnCutty]

Well since I can remember I`ve been around the engine bay of a 3.1 and this problem blows my mind...the car runs great,gets kick ass mileage, great kick down....but lets say the car has been sitting for a few hours unless I wait 2-3 minutes before leaving she hesitates when go to accelerate ...I have cleaned the TB, new air filter, fuel filter...I haven`t done the plugs and wires as of yet because the car just hit 58,000kms this week...so I imagine the plugs are still in good order....anyone got any ideas

[1990lumina]

How is the tranny fluid looking??

[slick]

Have you pulled the plugs to verify that they are indeed in good condition?

[CdnCutty]

Tranny fluid is cleaner than clean....I haven`t had a chance to look at the plugs..but I figure i may just change them for the hell of it cause it will hit 60,000kms in the coming months and a delco platinum upgrade would be nice

[SigEpCutlass]

It's almost time for that change, so maybe if you change the wires and plugs early you'll be doing yourself a favor. Chances are you'll probably not have the problem after that.

[tdaye]

How is the tranny fluid looking??

not sure what the trans fulid has to do with the motor hesitating...but I have the exact problem. Changed: Fuel Injectors, TPS, IAC, ECM, and EGR, fuel pressure is good and filter is new. Plugs and wires are new. My hesitation goes away after about 2 mins of driving as well

[Dirty Rockstar]

How are your guys' coils looking? Just throwin other ideas into the pot

[CdnCutty]

I work with tons of mechanics and 2 of them are GM nuts...they both own impalas, regals, and have had a cutlass or two..after passing my issue with them ..they said it happened in there cars and over time they made it a habit to wait the 2-3 mintues and the idle would settle and theyd leave...besides that they told me that its never really good to start your car and split right off the bat..

[SigEpCutlass]

How are your guys' coils looking? Just throwin other ideas into the pot

 

Good call Steve I forgot to mention them.

[19Cutlass94]

I work with tons of mechanics and 2 of them are GM nuts...they both own impalas, regals, and have had a cutlass or two..after passing my issue with them ..they said it happened in there cars and over time they made it a habit to wait the 2-3 mintues and the idle would settle and theyd leave...besides that they told me that its never really good to start your car and split right off the bat..

 

I have to wait to leave like that as well. Everytime my car sits outside for hours, I turn it on and its like a misfire the way it runs, but if I wait a couple minutes, then drive it away ( to where it gets a little heat in it before I start driving ) the misfire goes away and it runs fine..

 

I know my problem is with the plugs ( they are prolly very shotty by not ) So I duno if this could be the same thing that you have going on or not, but I just though Id give my .02

[GP1138]

delco platinum upgrade would be nice

 

Don't use Delco Platinums with your 3.1. It has a waste-spark ignition system that fires three plugs reverse polarity and will totally fry the plug. I'd just stick with regular ACD's.

[slick]

besides that they told me that its never really good to start your car and split right off the bat..

 

I have always followed this rule of thumb. Especially in the wintertime when the oil gets nice and thick, and doesn't flow as well until it gets warmed up.

[tdaye]

I work with tons of mechanics and 2 of them are GM nuts...they both own impalas, regals, and have had a cutlass or two..after passing my issue with them ..they said it happened in there cars and over time they made it a habit to wait the 2-3 mintues and the idle would settle and theyd leave...besides that they told me that its never really good to start your car and split right off the bat..

I always let my car run for a min before leaving, if I drive for 2 hours and shut off the car for any ammount of time then drive again there is the hesitation for a few mins, it almost fels like a dead spot on the TPS, but I have changed mine 2 times. Coils seem to look ok, and in my problem there is no miss at any time.

[RJansen658]

Guys, 3.1L are pretty bulletproof when it comes to idle quality if everything is working properly in the system....

 

All of this is asuming your ignition system is in good working condition, ie; decent plugs, good wires and coils.

 

Take off the IAC Motor and clean the pintle with a soft wire brush. You can clean the spring with carb cleaner but don't get it into the motor. Use a wire battery terminal brush to clean the IAC pintle seat inside the throttle body. Remove the IAC Plate from the top of the throttle body and clean inside with carb cleaner, replace the gasket if it looks damaged or if you damaged it taking it apart. It is still available in a kit thru GM for about $8

 

With the proper scan tool you can test the EGR Valve flow, and desired and actual position. EGR Valve can cause cold hesitation on theses motors. I have taken apart a few 3.1L's that had almost completely blocked EGR passages in the UIM and stuck open valves.

 

Any vacuum leak will cause cold hesitation, so spray all around you LIM gasket and basically anywhere downstream of the IAC with starting fluid and listen for a raised idle.

 

You may have a slow 02S (oxygen sensor), again requiring a scan tool for a proper diagnosis. If you don't know how an oxygen sensor should look on a scan tool PM me. An 02S graph can reveal a lot and actually, 02S technology is rather interesting in general as far as how much impact it has with most of the computers decision making processes as far as fuel and economy.

 

And lastly (yes the best for last)..... CARBON.... carbon is like a sponge. It will suck up most petroleum based liquids with great proficiency. Carbon forms inside your combustion chamber, both on the top of the piston, and underside of valves. It forms due to poor ignition quality, rich/lean situation, oil entering the combustion chamber, etc. SO! you get carbon in the combustion chamber which acts as a sponge. Then you add your fuel. GAS! Which the carbon will suck up. Gas evaporates fairly quick as far as automotive fluids are concerned. So why does that matter?

 

Whenever you shut of your engine after it has been running the gasoline immediatley begins to evaporate from the carbon since it no longer has a supply. It doesn't take long, usually before the engine is cold soaked. The next time you start your engine the carbon begins drawing in more fuel. Fuel that is intended for the combustion process. This causes a lean condition, lowers power, and increases emissions. It only takes a minute of so for compression to "fill up" the carbon again.

 

Also carbon buildup holds heat. A lot of heat, so much so that sufficient carbon deposits can cause pre-ignition and back-firing.

 

Fuel Injection Cleaning, the true kind... not the kind you pour in the tank, not the kind you suck in thru an engine vacuum port... you have to do it the correct way. Disable the fuel pump. Close off and pressurize the fuel rail with CLEANER, not fuel. Then run the engine off of only the cleaner. This removes almpst all carbon deposits but beware... if the engine has extreme carbon deposits too large of chunks may break loose and cause engine damage (never seen it happen, but the Saturn TSB's warn all mechanics about it).

 

Anyways... that about covers it.... oh yeah... and a spark quality tool is very useful for cold hesitation ignition diagnosis.

 

[CdnCutty]

delco platinum upgrade would be nice

 

Don't use Delco Platinums with your 3.1. It has a waste-spark ignition system that fires three plugs reverse polarity and will totally fry the plug. I'd just stick with regular ACD's.

 

Thanks for the advice...you just saved me 40$ or so

[CdnCutty]

Guys, 3.1L are pretty bulletproof when it comes to idle quality if everything is working properly in the system....

 

All of this is asuming your ignition system is in good working condition, ie; decent plugs, good wires and coils.

 

Take off the IAC Motor and clean the pintle with a soft wire brush. You can clean the spring with carb cleaner but don't get it into the motor. Use a wire battery terminal brush to clean the IAC pintle seat inside the throttle body. Remove the IAC Plate from the top of the throttle body and clean inside with carb cleaner, replace the gasket if it looks damaged or if you damaged it taking it apart. It is still available in a kit thru GM for about $8

 

With the proper scan tool you can test the EGR Valve flow, and desired and actual position. EGR Valve can cause cold hesitation on theses motors. I have taken apart a few 3.1L's that had almost completely blocked EGR passages in the UIM and stuck open valves.

 

Any vacuum leak will cause cold hesitation, so spray all around you LIM gasket and basically anywhere downstream of the IAC with starting fluid and listen for a raised idle.

 

You may have a slow 02S (oxygen sensor), again requiring a scan tool for a proper diagnosis. If you don't know how an oxygen sensor should look on a scan tool PM me. An 02S graph can reveal a lot and actually, 02S technology is rather interesting in general as far as how much impact it has with most of the computers decision making processes as far as fuel and economy.

 

And lastly (yes the best for last)..... CARBON.... carbon is like a sponge. It will suck up most petroleum based liquids with great proficiency. Carbon forms inside your combustion chamber, both on the top of the piston, and underside of valves. It forms due to poor ignition quality, rich/lean situation, oil entering the combustion chamber, etc. SO! you get carbon in the combustion chamber which acts as a sponge. Then you add your fuel. GAS! Which the carbon will suck up. Gas evaporates fairly quick as far as automotive fluids are concerned. So why does that matter?

 

Whenever you shut of your engine after it has been running the gasoline immediatley begins to evaporate from the carbon since it no longer has a supply. It doesn't take long, usually before the engine is cold soaked. The next time you start your engine the carbon begins drawing in more fuel. Fuel that is intended for the combustion process. This causes a lean condition, lowers power, and increases emissions. It only takes a minute of so for compression to "fill up" the carbon again.

 

Also carbon buildup holds heat. A lot of heat, so much so that sufficient carbon deposits can cause pre-ignition and back-firing.

 

Fuel Injection Cleaning, the true kind... not the kind you pour in the tank, not the kind you suck in thru an engine vacuum port... you have to do it the correct way. Disable the fuel pump. Close off and pressurize the fuel rail with CLEANER, not fuel. Then run the engine off of only the cleaner. This removes almpst all carbon deposits but beware... if the engine has extreme carbon deposits too large of chunks may break loose and cause engine damage (never seen it happen, but the Saturn TSB's warn all mechanics about it).

 

Anyways... that about covers it.... oh yeah... and a spark quality tool is very useful for cold hesitation ignition diagnosis.

 

 

Thanks for all that advice...my little brother is a Mechanic...So I`m gonna jack his scan tools tomorrow and see what I can come up with......For the most part as Iève seen many other members occured the same minor problem, and my fathers cutlass did the same..so I guess after all is said and done and I find nothing Ill learn to live with it

[89GP_SE]

LOL I always thought this was a normal thing..

 

I have never really worried about it though, never caused me any problems.

[CdnCutty]

LOL I always thought this was a normal thing..

 

I have never really worried about it though, never caused me any problems.

 

I may just learn to live with it

[tdaye]

My O2 sensor is new, EGR valve is ulplugged and fully closed . IAC is also new on my motor.no vacuum leaks either. I've replaced pretty much everything trying to find the problem but I've learned to live with it now too lol

[CdnCutty]

I had a tought well at work...the original owner who was in his 70's rarely drove the car at all..note why the low Km's, I think that maybe since the car sat for such a long time with the same gas for weeks on end and the car never being driven past 60km and hour I see that it may be the injectors needing a good flush and maybe the exhaust is a little clogged...whata think?