Thread: 88 fire bird with irratic idle

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I have 1988 formula with a 305 tbi...... when I start the car the idle comes up. But after a few second the rpm start bouncing up and down. Right now she idles in drive after warming up at 500 rpm I have to reset it to about 600 - 650......... To me I think I might be the tps sensor............ any thoughts from you folks???
I just had to remove all my lifters and clean them........ after 2000 mile they got all sludged up and would not pump up any more.............. Never use Exxon oil again or a cheap filter.........

Put her back together and found that one of my rocker arms are letting out way to much oil.......... its a straight stream.... which I imagine is taking away from the other lifters. When I am at a light she almost want to stall........... but she's probably dipping down to 450 rpm which is way to low...................

I adjusted the rockers once around so far.............

Any help would be appreciated
Kenny

have you checked the ECM for trouble codes?

sound like you are having multi problems with the engine.
my wife has a 86 firebird transam, the original 305 in it bit the dust 4 years ago,

I had a problem with my electrical and ECM for far to long and I had to remove all and rewire the whole car. I dont think is your problem I just wanted to share that with you.

did all of the lifters build back up?
if it were me and I had them out to clean them I would have replaced them.

when you removed the intake and other parts to get to the lifters did you take pictures of the vacuume hoses and where they go, as to make sure they went back where they should be?

when installing the new intake gasket did you make sure it didnt move out of place, did you torque the bolts in an alternating sequence like it shows in a shop manual?
and did you torque them in stages of 3 to prevent warping the intake?

the reason im asking is you could have a vacuume leak from a hose or the intake itself.

if you have more oil coming from one pushrod than the others , did you clean all pushrods and I would have checked them for bent.

if you pulled the lifters and reinstalled them could you have gotten them mixed up?
they should go back in exact where they came from, or you will have problems.

hope you get it fixed.

Thanx for the tips

every thing went back where they were before with the exception of the lifters..... Only had 2000 miles on them (roller lifters) and at 200 dollars for a set I decided to reuse them....
intake gasket was put ontop if the silcone and left for an hours to set in place as per manual and then hit the opposite side with silicone........ and torqued to 30 foot pounds in the propper sequence................ plus I had this problem before the engine started ticking on me............. I believe it to be the tps sensor.......

It seems like it doesn't know what to set it self out..... plus might also be causing my bad gas mileage I was having prior to the last set of events................ I will recheck all vacuum lines But I know the car inside out by now...........

Thanx for the idea's thoo
Kenny

all the push rods were new as well and check all of them all have oil coming out jus one has an excess of pressure

Originally posted by drumsk
Thanx for the tips

every thing went back where they were before with the exception of the lifters..... Only had 2000 miles on them (roller lifters) and at 200 dollars for a set I decided to reuse them....
intake gasket was put ontop if the silcone and left for an hours to set in place as per manual and then hit the opposite side with silicone........ and torqued to 30 foot pounds in the propper sequence................ plus I had this problem before the engine started ticking on me............. I believe it to be the tps sensor.......

It seems like it doesn't know what to set it self out..... plus might also be causing my bad gas mileage I was having prior to the last set of events................ I will recheck all vacuum lines But I know the car inside out by now...........

Thanx for the idea's thoo
Kenny

if your sure there are no vacuume leaks, then I would suggest that you either call around to see what shops near you have diagnostice equipment, to test sensors and look for trouble codes.
or you can buy a cheep code reader with book from a local autoparts , like the one in the picture below , that sells for around $25-$30.

when checking for codes the code you want to see flash up is a code-12. this verifys that the ECM is working.

and if for some reason you find no bad codes "trouble codes". then your problems are internal and that could mean the your valvetrain is in need of help. check for codes and let me know what happend.

The classic symptom of a vacuume leak is idle that surges up and down.
Get a can of Quick Start and lightly sray it around the engine until you find it. The motor will rev up when you hit the spot.

alright I will check for vacuum leaks ................... and double check my valve adjustments.......... did throw a code a day ago have to check by jumping out the computer........... btw I am a mechanic just looking for some advise from those wiser than I............ my friend owns a snap on scanner we hooked it up but really didn't come up with anything solid.................

all help is appreciated
Kenny

what does the engine do when you step on the gas?

and does it try to surge when driving?
unable to maintain a steady speed on highway?

She responds quite nicely.............. amatter of fact while leaving work tonight around 11:00 pm the old firebird felt her rear tire break free from the pavement.............. : ) sounds great pretty smooth........ I will check my egr circuit as well................. see if it on all the time or not i just change both egr valve and the solenoid....... too

if its running fine on the highway and acts up only at idle, tham I would say while the car is at idle remove airclaener and with a flashlight in hand look down inside the tbi and see what the spray pattern comming from the injector looks like, it should by very fine fuel mist and no dripping . if not get a good fuel system cleaner and let it run through for a while and then replace the fuel filter.

on these cars a little water in the gas can cause the same problems, so look for that as well.