Too fast idle

I'll keep u posted but looks like bad wires...#5 wire when I pull it off the coil does not surge..so will know in a bit..

When you did the heads you never changed the spark plugs shame on you especially when you described what they look like.Also keep me posted on ho it works out with the plug wires.I would remove the egr valve clean it and with the egr valve off start the engine for a few seconds.The engine should race and you should hear a loud exhaust leak?That helps blow the loose carbon out that can can make the new egr valve stick.

You must be talking about the the guy doing the engine overhaul. I never did such a thing. :). I got the wires hope to give you an update tomorrow.

This is exactly why I usually make people start there own questions it just gets way to confusing who did what who iam actually talking to etc.So greghoward please start a question for your car.Start it off by saying this one is for saturntech9 and they will leave the question for.That way I can continue helping you nothing personal its just hard enough helping someone over the internet fix there car but then two different people on the same question that's too much.

Replaced wires seems to be working. Have only had two hiccups in 50 miles of driving, and 8 starts and stops. Looks as if the reset of the wiring of the ignition control module has this possibly (the second problem) for the moment fixed. There's great acceleration and the car sips fuel instead of gulping. I've not seen an issue with the O2 sensor. All is good for now.

Thats what we like to hear keep me posted on how it works out.

Ok now I'm stumped...
Ignition system everything has been changed but the ICM...plugs, wires, coils. still misfires but is intermittently. guess on my next few days I will check to make sure it pulses...I did check the contacts on the pink wire...I get 12 volts, and each coil when I pulled them off, I checked for voltage on the contact pins, and they do get 12 volts..the only thing I did not check is the pulse...with a led light...three fuel injectors i checked on the forward side is pumping fuel...the misfire is very random any clues??

Possibly a dirty injector i have seen them cause very random missfires.

so what I need to put some fuel cleaner in the tank??

You can try that i would use a product called bg 44k you can get it on ebay.The best way to clean them is have it cleaned by running it off a pressure canister with some cleaner.Plus putting cleaner in the tank.

Ok...I'm like running low on funds...LOL and I have been reading about the BG44K that is supposed to be at professional repair centers. Anything on the market that seems to work really well? Something I can get at an automotive store or maybe at walmart?

You can buy the 44k on ebay an it works well i used it for many years at the saturn dealerships i worked at.

will try a cleaner

here's the latest..
After all the replacing of components, I believe I told you the high idle issue is gone, and the next troubling issue was random misfire. To get you up to speed I had done the following:
1. Replaced the plugs, coils, wires
2. Checked for power to the ICM, and it was good.
3. Cleaned the EGR passages and replaced the gasket.
4. Checked the Fuel Injectors for power and operation.
5. Checked the positive terminals on the ICM for power with coils removed all good.
6. Put Seafoam cleaner in fuel tank for first tank after all the maintenance, improved performance, but still had initial ramdom misfire but not as severe as before, and only lasted till the car was warmed up.
7. Replaced the fuel filter ( it was a mess plenty of trashy fluid came out). Replacing the fuel filter has also improved engine performance, although still slight misfire, but even less than before.
8. One more Seafoam application this morning after I filled tank with misfire, and now (fingers crossed) I do not seem to have the misfire. After the Seafoam application in the vac system, and fuel, whatever was there, seems to be gone.
I will update you later for progress...I can say that I have, for the first time, accelerated the car above 90 MPH!! I've never been this fast in my car LOL. so acceleration is very peppy, and the car sips fuel....again a final update later.
Dennis

Alright sounds good keep me posted.

Update:
Still have random misfire. I'm not sure at this point if the issue is the CAT, or a bad ICM. The car initlally surges when cold, but after about 5 min of running, it still is a little sluggish, but not as bad as before. Anytime the car has sat for more than 20 min, and restarted, the initial engine performance is bad but soon gets better. If the Cat is bad, would it cause these issues??

I don't suspect the cat, because I have no Cat codes...

oh and the ONLY things I have not replaced would be the EGR valve Map sensor and the ICM...I really think it has to be vacuum, cause it shudders and misfires as if the Vac hose is removed from the egr...I'm just at a loss...

Its not a cat have you replaced the coolant temp sensor yet?It could explain the symptoms.

Ok finally got to changing the cts...how long will it take for the ECM to learn this part, or is there no learning? It still idles erratic at start, but settles quickly. I'm thinking the hose I ordered is not good.

Try unhooking the negative battery cable for about a min then hook it back up and see how it runs?

Well I'm convinced the issue I s the pcv tube...do you remember that tube I replaced three months ago? It looks like the hose I got from autozone. So I've ordered the hose from a gm parts store. Will let you know how it turns out.

Whats wrong with the tube is it bad again?

It's not holding a seal where it goes into the valve cover

Have you tried putting on a hose clamp to see if it takes care of the problem?

Can't be clamped. I think the aftermarket hoses do not have the right dimensions for the hole the tube "t" goes in. The oem plug part is rubber and has a better fit. The aftermarket hose has a plastic "finned" plug that does not offer a tight enough fit for the hole, so there must be a grommet needed if you use the aftermarket hose. The problem with trying this, is you would have to take the throttle body off, and remove a clamp to do all this. Then I'd need a gasket and other things. I've ordered another hose, but this one is supposed to be oem. I will see when it gets here on Monday.

Sounds good keep me posted.

Well replaced the line and as always the initial start sounds good, then the random misfiring starts up. It seems that anytime something is replaced, it changes but not really fixed. It seem that when I replace a part, the engine goes thru a high rev that seem to cycle for about four accelerations. I attribute this to the engine computer relearning for idle mixtures. Of course when the engine goes though the rough idle cycles with the misfires, the intake air sounds like its being blocked or rerouted. I'm wondering if my mass airflow sensor is bad..cause when I unplug it and let the engine run, it seems to settle to normal. I did get to replace the coolant temp sensor but that has not changed anything. I'm almost running out of options.

Try lightly tapping on the mass air flow sensor with a screw driver handle see if it runs any different?You could also try cleaning the mass air flow sensor with some mass air flow sensor cleaner.

I unplugged and plugged the sensor, ran engine no change... cleaned the MAF sensor last month, got no appreciable difference in performance. I'm not ruling out some sort of either gasket leak or possibly maybe even really bad fuel injector clogging.. however I have read it will cost me quite a bit for gasket work, and I'm not gonna spend this much money on it. Ive only known about this misfire condition until I fixed the high idle issue. I'm at a loss now. the only part I have not changed is the ICM and Ive read that this component is either good or bad.

So do you have any codes right now in the computer?Also did you check for vacuum leaks?If so how did you check for them?

still have the random misfire...I don't have a smoke generator, I don't smoke a cigar or cigarette ( the cheap smoke generator so I read :) ) I have sprayed the top of every seam and gasket of the car with a mild soapy solution to chase a leak, and have not found one. I have read that 99 Buick centuries are famous for clogging fuel injectors, I've run two cans of seafoam in my tank and there has been a slight increase in performance. the ransom misfire and idle stumbling does not happen when the engine is first started. It runs fine for about 20 sec. then as the engine runs, I guess the electrical signals from whatever goes through the engine computer. The engine then starts the cycle of high revs with the first one higher revving then tapers about every 10 seconds for roughly 5 cycles...then the engine settles with the misfire. When the engine throttle is moved instead of a smooth acceleration, it stumbles and at a certain point will quickly accelerate.. So I think one of two things is going on...either i have a vac leak still, or I have a horribly clogged fuel injector. the misfire does seem to go away, but not entirely..

I really dont see how soapy water can find a vacuum leak since a vacuum is the absence of air pressure so no bubbles are going to form.You use carb cleaner and look for rpms going up or down stumbling etc.

Will try again but got no rise in rpms

Iam thinking vacuum leaks with the unstable idle have you tried cleaning the idle air control valve?

Replaced the idle air control valve

Merry Christmas.
I'm really at a loss...it seems like what ever I think maybe the issue is not. I am thinking now it is some sort of seal leak. when the engine is cold initially it runs nicely for about a minute, then the random misfires occur, and stay until the engine reaches optimum temperature. Once the engine is allowed to cool, then the misfires come back, then goes away when the engine has reached the optimum temp. when the misfires occur, the engine is very sluggish to the point of stalling. then once warm, the acceleration is normal, and so is the idle. I'm thinking intake manifold from the throttle body?? my intake manifold is NOT plastic, but looks like cast alluminum. Is this gasket normally an issue or is it somewhere else??

I have seen clogged fuel injectors cause random miss fires a smoke test is the best way to find vacuum leaks.

Can a bad O2 sensor cause this problem or is it truly a leak?

You are gonna love this...
Had run out of options and tired of buying parts so... I looked at routing of spark wires and all of them were good plug to right coil. However... I did find the #3 plug wire NOT clipped I the top of the plug. So I checked them all and started the car and I had a single hiccup and surge and immediately the idle went away. So for anyone who reads this thread to the end random misfire check all cables for connection. Random multiple misfires DO typically point to something in the ignition/timing discrepancy. It took three months to get to this point and I believe that if I would have changed the ICM I may still have not fixed this. Truly the craziest and most challenging of problems always have the simplest corrective action. I did have some minor initial drive rumbles with acceleration but the ECM quickly returned the engine to normal operating parameters. Thanks for your assistance and suggestions for fixing this idle/rpm misfire dilemma.
Dennis