can anyone tell what could be making my car idle really rough?

i've replaced all the plugs, wires, cap & rotor. before i did this the car would idle smoothly but at 400rpms.

now with the new parts on it still idles low but keeps sputtering. the car runs fine so i don't think it is missing.

also i have this ticking or pinging noise that coinsides with the rough idle.

what could be causing this?

thanks

mark

 

pinging.....maybe you are getting dentonation for too hot of sparkplugs, did u use the same heat range as the old ones?

 

The ticking noise you are hearing could be a spark leaking from a wire or the distributor. Check the spark plug wire routing to be sure there are no wires grounding at exhausts, or pinched/damaged wires. Make sure the distributor cap is seated fully on the distributor base. Check the coil connections.

It is also possible that the ticking you are hearing is caused by the injectors operating, which is completely normal.

The idle speed should also be much higher. Since L98s were all supposed to be delivered with an automatic transmission, I'll guess that's what you have. In that case, the target idle in DRIVE on a fully warmed engine should be 650 RPM. If the idle is very low, you should clean the IAC air passages and throttle body with a spray-type carburetor/intake cleaner that is safe for oxygen sensors (most of them are safe, but check to be certain). This alone may solve the low idle problem.

Another possible cause of low idle is a sticking or plugged PCV valve. Either clean the PCV with the spray cleaner until it is cleared or replace the PCV valve. If you replace the PCV, use only an AC/Delco replacement part, since they seem to be the only ones properly calibrated for the correct air flow on DFI engines. (I had a very frustrating experience with a Fram PCV.)

If none of those solve the missing and idle problems, check back with the results.

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Later,
Vader
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"Let the bodies hit the floor!"
Adobe Acrobat Reader

[This message has been edited by Vader (edited August 18, 2001).]

 

ok i got a stupid question.

where is the IAC and how hard is it too clean or replace?

the wires are not grounded on exhaust but they are touching some hoses. does that matter?

i'll replace the PCV, clean the TB, & IAC (if i can) tonight and see if that helps.

thanks

mark

 

Boy, this sound's like the note I almost wrote last month! I was sure a had all the plug wires on (I always feel the gap between the boot and the metal part of the plug to make sure the boot is all the way on). However, the clicking noise and miss in the daylight (tried to convince myself it was an injector - 86 IROC with 305 TPI) turned in to a small scale lightning display that night. The number 5 wire sure felt like it was on all the way and right. But when I pulled it off and stuck it back on both the clicking noise and the flash were gone. Check it out in the dark!

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Z's r Best

 

Is it safe to spray the throttle body cleaner into the air duct toward the air filter or would that hurt?

also i got another dumb question.

Is the pcv valve covered by hoses on both ends? cause i can't seem to find it.

still have not found where the IAC is either. but for $500 i think i should do this myself.

thanks

mark