90 wont pass smog

[tccrab]

Originally Posted by TonyTZR1

I checked the idle myself, brought it up to the 2500rpm required for the smog test and after a couple of seconds, engine at normal operating temp, the idle drops down by 400 to 500 rpm then immediately goes back up to the 2500rpm.

Really appreciate everyones help, what the hell is a computer? Man what a cluster.
Tony

Tony:

If I read this correctly, your idle is up around 2500 rpms?!!

If your idle is this high, then your problem sounds a little like what my buddy Joey Gibson had about a year ago. I will attempt to dig up his posts and his answer, but in the end I think it turned out to be a bad ECM.
I'll go digging around...
The posting is over on the CF and I'm no longer a member there, but if one of you guys will go searching for user name JoeyGibson you will hopefully find his thread on solving his high idle.

My idle was running around 1000-1200rpms at most and was variable. No where near the 2500rpm you mention.

Tom

[tomtom72]

This was the thread I found...it was the coolant temp sensor...is this the one ya mean TC??

http://forums.*************.com/show...ight=high+idle


Tom

ps this link will not work. don't know why I musta did it wrong, sorry. Let me know & I'll try to search over "there" again.

[tomtom72]

Jez ya think that a dealer would know to do a leak down test. If the injectors are OEM there is a chance that they could be falling victum to the ethanol in the gas. The early 90 - 92 or 91 were not intended for use with ethanol.

I also hope the dealer did not try to clean the OEM injectors....that usually makes them worse.

I'm with you...look over the plugs & ohm out the wires + coils...you can do a set at a time. 4 coils, one coil drives two plugs. So if ya ohm a wire you are reading the ohms from that plug ya start at , thru that coil, to the other plug wire in that pair. I believe there is a thread about that here plus a thread about checking the injector resistance over at ZR1specialist.com....Mr. Haibeck's site...

I really think that maybe the CTS could be n/g or a better bet maybe that the injectors are fubared.....they should have done a leak down test with the plenum off

Can you smell her...is she rich? When my injector coils went, man did mine smell lean, make your eyes water she was soooo baaad!


Tom

[tccrab]

Originally Posted by tomtom72

This was the thread I found...it was the coolant temp sensor...is this the one ya mean TC??

http://forums.*************.com/show...ight=high+idle


Tom

ps this link will not work. don't know why I musta did it wrong, sorry. Let me know & I'll try to search over "there" again.

Tom:

Nope, that's not the posting, the right guy, but not the right post. It was in one of his last few posts as he sold his ZR1 late last year and had finally fixed the high idle after messing with it for months and months and months.
A search based on just "JoeyGibson" and sorted by ascending date should dig it up fairly quickly.

As far as the link not working, I'm beginning to see a pattern...
And I'm totally in agreement with the obvious new policy.

Tom

[tccrab]

Found it!!
Don't ask what I had to do in order to use the search function at that other forum. I'm so ashamed, I feel so dirty...

I had an extremely high idle from first startup for about 20 - 30 minutes or so every morning. Turned out to be a bad ECM. Also found the ECM ground was bad, and a new one was run.
<snip>
..He ran a new ground for the ECM, and then diagnosed it as an ECM problem. I bought one from White Racing Products, put it in.......and the entire car acts differently. My gas mileage went up, secondaries seem to kick in harder, seems to have more power.

[TonyTZR1]

Tom;

The smog test requires bringing the idle up to 2500rpm and holding it for a short period of time. What is taking place is, at the 2500rpm the idle will drop down by 400 to 500 rpm and then will go back up to the 2500rpm. If just sitting in a normal idle condition, it is around 950rpm but will increase to 100 to 1200rpm then drop back to the 950.
Here is some information I got from the dealer. I don't have an actual read out because they didn't want the car going into the system and be labled a gross polluter. But they gave me the are of failure which is co reading. The left bank is fine, it's the right side that the reading fluctuates, from 65co to 450co.
Sorry if my original post on the rpm was vague.

Everyone, your help is really appreciated.

Tony

[tomtom72]

Tony,

That was nice of them. I'm just not sure what's wrong with that bank. It would appear that it gets too much fuel or not enough spark to burn the fuel(? that don't make sense) at 2500 but why just at 2500... I'm not getting this...I'm sorry man, my only input is useless.

I'll pull a guess outta my arse...that O2 sensor is n/g? but that would show up big time on the scan's cross count numbers.

I think if I have time at lunch I'll look in my helm FSM in section 6E, emissions. If I learn anything I'll post up.

hang in there man, somebody knows this answer & they'll post up.

[TonyTZR1]

Hey, thanks again. I am going to a friends shop this morning and put on a scan. I know the dealer didn't do that. They don't do anything unless given direction to do so. By the way, I went to pull a pluk on it and found every plug finger tight. Pull all the plugs, they looked good all the same color, none wet, checked the gap and reinstalled them. The plugs have about 300 miles on them. I took the car car for a drive, and the idle is still the same.

Frustrating.
Thanks again

[TonyTZR1]

Forgot to mention, one idea was a crappy ECM tune, but with one bank being affected I am inclined to say that is not the problem? But then what do I know?

[tccrab]

Tony:

Which local dealer did you take it to? The Lithia Chevy shop in Redding has a guy there that knows ZR1's, he used to take care of mine when it lived up there. I'll have to ask the previous owner what the guy's name is.

There are at least two ZR1's in Redding, a Yellow '94 owned by Steve (IttlFly) on that "Other Forum Who Shall Remain Nameless" and another one but I don't know much about it.


Tom