99 Lesabre engine hesitates at idle...

Hi everybody.Im having a problem with my engine hesitiating when in idle.It doesnt do it in park or neutral, but when I put it in drive or reverse it starts acting up.The engine will sound like its going to die and the dashboard lights fade in and out with the stumbling.I put in new sparkplugs about 1 year ago...I had the fuel filter changed about 3 years ago.The car has 45,000 miles on it.It had a probelm with stalling when I first go it 3 years ago but it was a fuel pressure regulator that they replaced.Any help would be appreciated......also lately Ive noticed a big lack of power when the ac is on...dont know if that has anything to do with it.

Does the engine still hesitate or have the same problem when in drive or reverse with the A/C turned off?

Does the engine still hesitate or have the same problem when in drive or reverse with the A/C turned off?
yes...but it doesnt seem as bad...

yes...but it doesnt seem as bad...

I recommend replacing the fuel filter first. Then run a check of the fuel pressure at the front fuel injection rail at the Schrader valve on the fuel pressue regulator to make sure it is is specs. That way you can rule out the fuel pump.

Another suggestion is to clean the throttle body with spray carb or TB cleaner. Clean the idle air controller (IAC) since this is the sensor that helps control the idle. Clean the spring loaded pintle and the seat on the throttle body where it mounts. Throttle bodies get alot of soft carbon buildup.

Also, make sure all vacuum lines around the intake manifold and throttle body are in good condition and tight. Good luck.

I recommend replacing the fuel filter first. Then run a check of the fuel pressure at the front fuel injection rail at the Schrader valve on the fuel pressue regulator to make sure it is is specs. That way you can rule out the fuel pump.

Another suggestion is to clean the throttle body with spray carb or TB cleaner. Clean the idle air controller (IAC) since this is the sensor that helps control the idle. Clean the spring loaded pintle and the seat on the throttle body where it mounts. Throttle bodies get alot of soft carbon buildup.

Also, make sure all vacuum lines around the intake manifold and throttle body are in good condition and tight. Good luck.
ok thanks...I will give these things a try...

ok this may seem like a dumb question but how do I clean the throttle body??And where exactly is it?? Is it the part on the front right hand side of the engine next to the airfilter?Do I have to take anything apart to do that? Sorry..I knew I should have took mechanic classes in highschool...

ok this may seem like a dumb question but how do I clean the throttle body??And where exactly is it?? Is it the part on the front right hand side of the engine next to the airfilter?Do I have to take anything apart to do that? Sorry..I knew I should have took mechanic classes in highschool...

No problem, there are no dumb questions when it comes to automotive.

You'll have to remove the rubber duct to clean the throttle body bore. Be sure to remove the electrical connector to the IAT sensor on it and remove the screen located at the input of the throttle body. In the pic below the throttle body is circled in yellow and the IAC valve is circled in green and red arrow points to it. Two Torx T20 screws secure it to the TB.

http://i5.photobucket.com/albums/y186/lizzywiz/3800tb.jpg

Thanks for the pic! Thats a huge help.Every pic I looked for on the web was either too small or not very detailed...I will try this tommorow. Also....whats the thing circled in red? The other day when I started up my car it idled really rough and the check engine light came on and stayed on....I put the car back in park and it slowly came back to normal.On my way home from work the check engine light went off. The car started up fine this morning.Can the code checker still see the codes that caused it even after the light went off. I was going to take it to Autozone to check them for free until the light went off.

Thanks for the pic! Thats a huge help.Every pic I looked for on the web was either too small or not very detailed...I will try this tommorow. Also....whats the thing circled in red?

That is the fuel pressure regulator which has the Schrader valve where you can connect a fuel pressure tester. Good luck and keep us posted.

Can the code checker still see the codes that caused it even after the light went off. I was going to take it to Autozone to check them for free until the light went off.

If the light came on, more than likely it stored a code. It could be either inactive or active. Since the light is no longer on, I would assume it is an inactive (history) fault code. Yes, take it to have it scanned!:grinyes:

Autozone policies vary nationwide but generally they will not perform a scan unless the SES/CEL light is on.

But I'm quite sure he can find a shop that will.