1998 Pontiac Sunfire poor idle after doing many repairs/rep

IZZY_AND_LADYS_GRANDMA

MEMBER
1998 PONTIAC SUNFIRE
4 CYL
FWD
AUTOMATIC
13,500 MILES

My daughter and son-in-law is having trouble with their car. He has replaced the cams, exhaust carrier set, intake carrier set, timing chain, gears, throttle postition sensor, map sensor, cam sensor, iac valve, fule pressure regulator, replaced all the vacuum hoses, new water pump and thermostat.

Replaced top of motor because it had a lifter knocking on intake carrier so they replaced them both.

It runs at 1000 rpms for a few seconds but then drops to 500. When open the throttle just a little it runs fine. He rigged it up with an air flow valve from an air compressor it runs. The IAC valve is doing the opposite of what it should be doing, when started the car the valve closes all the way but when shut off it opens all the way.

The cooling fan turns on when the engine is cold and turns off when the engine is hot. The temperature gauge is fine.

He's tried to reset the valve, tried to get it to relearn idle by shutting off, waiting, accelerating, deccelerating, etc. As someone else told him to do.

He hates to give up on that car, he's put so many hours into trying to get it to work and they can't afford another car. He's 19 and my daughter's 21, they have a 6 month old and are living with me. I'm on disability because of my neuromuscular disease and am bedbound on homecare and oxygen now and can't afford to help them out.

He's really smart and can do about anything on the car if you could help we would greatly appreciate any ideas. He's thinking of replacing the PCM, but since he replaced the top of the motor, and I think it has sensors on it, could that be the problem or would a new one set to the VIN just do the same thing? We don't know what to do.

Thank you & God bless you all and your familes, Lisa

5 Replies

RACEFAN966

MECHANIC
5,029 POSTS

If I understand right it does start and run right? Ok I need to know if he has a digital multi meter so we can do some tests. Also has he double checked to make sure that nothing has been overlooked on plugging everything in right? Get back to me and I will look over the wiring diagram and we will do some tests on the IAC motor first and go from there. Thanks and God be with you.

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Monday, April 20th, 2009 AT 12:19 PM

IZZY_AND_LADYS_GRANDMA

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3 POSTS

Yes, he has a multi meter and he said he made sure everything is plugged.

The car does run, but in order to get it to stay running and not have poor idle and die he rigged something up and got it to run today.

This is what he's done to get it to stay running. He took the vaccum hose that goes to the master cylinder hooked it up to a t-pipe, put one of the hoses to the throttle body to the t-tipe, one in the air cleaner, and another to the master cylinder then took a hose a put where IAC valve was and hooked shut off valve up to it to adjust the idle, then inside the throttle body he plugged that up with jb weld. He has a filter on the end of the shut off valve.

He said that the check engine light is back on now after he did the rigging because something about some of the sensors aren't hooked up because of the way he had to rig it up. He said he needs to get a one-way air valve to finish rigging it to where the rpms don't flutter when he's either accelerated or deccelerated, I don't remember and he's already in bed.

He'd like to be a mechanic or an engineer. Right now, he works at Sam's in the maintenance department in order to support himself, my daughter & granddaughter.

Thank you for your help on this and he said he'll drop by his dad's and get his multi-meter, tomorrow. If you need pics or anything, he can get those for you, too.

Philippians 4:13 "Christ gives me the strength to face anything" (CEV) Contemporary English Version www. Biblegateway. Com

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Monday, April 20th, 2009 AT 9:32 PM

RACEFAN966

MECHANIC
5,029 POSTS

Ok can you send me a pic of where the JB weld is? If not thats ok we will have to remove that though. When you have the multi meter get back to me and we will do some testing on the wiring to the IAC motor first ok. Today's reading for me is Psalms 39:4-7 and 11-12. May the lord keep you strong.

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Tuesday, April 21st, 2009 AT 10:34 AM

IZZY_AND_LADYS_GRANDMA

MEMBER
3 POSTS

He went ahead and did a few things that a local mechanic that had looked at the car told him to do. He thought the timing was off since he had replaced the timing chain. It was off a tiny bit because the tensioner was loose.

He put a new throttle body on it to deal with the jb weld issue and replaced the cam & throttle position sensors.

He replaced the IAC valve, and it has an adjustable plunger, he adjusted it a little different and it is running a little better, now.

It's not idling as poor but when he hits the gas and it gets it up to 3000rpm then lets off and it comes back down, it dies.

He's getting the multi meter from his dad today, sorry it took me so long to get back to you. He's just really frustrated with it, and they don't have other transportation and they're borrowing my wheelchair van to get back and forth and the gas is costing a fortune.

I'll write back as soon as he has the multi meter and is ready.

Thank you & may God continue blessing you with His Love & Grace,

Lisa & son-in-law Chris

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Thursday, April 23rd, 2009 AT 7:53 AM

RACEFAN966

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Ok thanks for keeping me up to speed with where things are at. This car should have a mass air flow meter too if I remember right. Any way when he has the meter that is what I would like to test first and talk it from there. Keep informed and God Bless.