Drowned

I think mine is stuck or doesn't seem to work anymore. The RPM needle tends to go crazy, jumping the RPMs all over the place. The engine hesitates when this happens so I assume the RPMs are REALLY changing. This happens mostly when idling or when coming to a stop. Sometimes the RPMs go so crazy the engine will die. Are all this problems cause of a dead IAC valce? I took the valve out and it stuck. I measured the little thing with the spring and it was like 110 mm long... and somewere I read it's supposed to be 280mm. Any help?

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Drowned

Oh yeah... since this started happening I've had trouble with the engine stalling in the morning or when cold really annoying.

[This message has been edited by Drowned (edited September 10, 2000).]

Pablo

iTrader: (1)

that doesnt sound like an iac problem.. but just to elminiate it have you tried resetting minimum idle using the correct procedure?
also, be sure to spray some carb cleaner in the IAC orifice.. alot of times carbon builds up in there and causes and erratic idle.

this does however sound like something else not related to iac

Drowned

I found the tech article about the IAC resetting right now. I'll do that tomorrow. You think the RPM crazyness could be an Ignition module problem? What else could cause this?

D_Amlee

Do a quick check of all your accessories on the car, such as alternator, power steering pump, air pump, etc., making sure that none of them have bearings starting to go bad. Shot bearings in an accessory can cause an erratic drag on the engine, making the thing hunt all over trying to idle. Also: watch your voltmeter when you see the idle changing. If you see the voltage needle dropping suddenly and then jumping back to the normal range, and this coincides with the rpm jumping, your alternator is going on you. This can also cause an erratic idle because of the sudden change in load on the motor.

Drowned

Thanks, I'll do that too. Oh yeah, can a bad ECM do this too? I hope not

Kevin G

One other you might want to check is the Throttle position sensor. If you have a volt meter, you can check and see if the voltage is fluctuating at idle. The voltage should hold at idle between .4-.9 mvs........ I usually set mine to around .62 mvs. Also, with the key on and not started, slowly open the throttle all the way open, and watch the voltage. It should steadily climb to over 4 volts.

Also, you might have a vacuum leak , causing an erratic idle.

Pablo

iTrader: (1)

a bad ecm can do anything

BUT

they rarely go bad.. ive found that people blame the ecm for things that are not the result of a bad ecm entirely tooo many times. They are more rugged than people give them credit for, and ive found that the only things that generally make them go bad are shorts in the electrical system zapping them with power. For example my car killed an ecm but it was the result of a relay that sorta went crazy.. ended up shooting 12 volts back into the ecm on a 4 volt output if i remember correctly.
So dont worry about the ecm for now

Drowned

The erratic idling doesn't happen all the time. It can be normal for hours, but suddenly the jumping needle begins dancing and then stops. Usually it lasts for only a few seconds but can happen repeatedly. The car dies sometimes and sometimes it doesn't It won't die if I give it some gas but it hesitates.

I've been so tense when driving cause the car dies when it's idling/stopped so I get kind of angry when it happens on a stop light and people start honking at me

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Kevin G

Arent intermittant problems fun LOL

if you want to test the ECM, slightly tap on the ECM with a screwdriver, and see if it starts acting up. I have diagnoised many of bad ECMS by doing this...usually if the ECM is bad, when tapping on it, it will act up . it should be under the passanger kick panel. Good luck.

Drowned

Oh yes! No fun if your car runs perfectly! I love finding problems on my TPI Way better when you don't get any codes like I do right now

WECoyote

My $.02 worth

I would get real bad idling at times. I found that the CCV(crank case vent) line coming from the passenger side rocker cover (terminates at the throttle body behind the TPIS) was leaking.

I happened to be working on the car while it was running when it began to idle like crap.....I think it even died once or twice on me. I looked at all the vacuum hoses and emission lines and noticed the rubber grommet for the hose/line that comes off the passenger valve cover was partially off. Well aparently from age and heat it had softened up and lost its ability to seal well against the valve cover. I also found that the 'elbow' hose that is just down line from that valve cover grommet was not sealing to the aluminum tubing. I cleaned that grommet up with soap and water(it was quite oily too) and used miniature hose clamps on that elbow and that particular idling problem ceased.......... I have since bought a replacement grommet and elbow piece from the GM parts department. Need to install them yet! The hard tubing is now discontinued.

Mike

Drowned

Hey, I've seen that. I'm 100% sure mine is leaking. It's really old and worn out

Would that cause the RPM crazyness? Cause it doesn't idle bad... it just goes crazy sometimes.

[This message has been edited by Drowned (edited September 10, 2000).]

WECoyote

Oh yeah! It will cause erratic idling...it did for me. If the engine bay became 'hot' it would be more prone to occur. Also vibration and the torquing of the engine assembly would result in the elbow losing its seal to the hard tubing...and the grommet would wiggle around in the valve cover opening.

Go and get three miniature hose clamps and install them at the end of the grommet and on both ends of that elbow.....clean the grommet with Dawn dish soap and 'Armor-All' it....and see if that helps you.

Mike



[This message has been edited by WECoyote (edited September 10, 2000).]

JP84ZROC

I had a similar problem with erratic idle and stalling and it turned out to be the MAP. Try disconnecting the MAP and see if the idle improves.

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"84Z28/'91 305TPI comp cam flowmaster TB coolant bypass/shutoff valve to heater core MAT relocated Ram-Air(home-made) gutted air-box IROC ground effects/wheels GY245/50's 700R4 superior shift kit/ corvette servo(excellent shift kit BTW) Rebuilt engine and transplanted it myself. Love this engine!
LOW performance people should drive low performance vehicles!

Kevin Irving

He has TPI, isn't that the voltage for a TBI TPS?.... The voltage for the TPS needs to be .54vdc +/- .075vdc. I have mine set at .60. A bad TPS can wreak havoc with a TPI car.



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Kevin Irving
85 Trans Am WS-6, 305 TPI, custom burned '86 PROM with '87 "165"ECM, Accel Supercoil & 8.8 Wires, MSD 6AL, Aluminum Driveshaft, TB Coolant Bypass, Ported Plenum, Modified MAF, Cyclone Fuel Pump, JET Airfoil

Veiw my car at: http://www.geocities.com/transam85tpi/TransAm.html

pianiy

iTrader: (2)

My car is doing very much the same thing but here's the kicker, its not TPI.. its TBI so it doesn't have an IAC valve. When its cold in the morning it would lope, with the rpms ranging from 1000 to about 200, almost stalling then suddenly recovering. Then when its got a load in gear it stumbles at half throttle and stalls out at full throttle. I HAVE gotten a code for this too, 44 which is for lean exhaust coming from the oxygen sensor. I replaced it upon somebody's suggestion and it didn't fix it, just got more codes again. The problem seems to go away when the car warms up but still from a stop it will stumble a bit. I get codes consistently when cruising at about 1000rpm around 40-50 mph. Still haven't figured it out - I think I'm just going to send it to my mechanic and let him deal with it.

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'91 Firebird
305/TBI/700R4/T-tops
Catco high flow cat
K&N Air Filter
Trans Am tail light conversion
Pioneer DEH-P8200R
Pioneer 6x9's
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'87 Firebird
2.8L/MPFI/700R4/220K Miles on its original, never been rebuilt engine!
Car being parted and sold, just ask what I have.