89 z51 wont idle etc

[Corbusa]

I hope someone can help me with this one. My 89 usually idles a little high . but yesterday it was perfect . I stopped for some lunch , came out and she wouldnt idle and was stalling. .I finally got her running and idling smooth , them when I pulled in the garage she did it again and this time it sounded like spark knock. and wouldnt idle.. She has 39k miles , ... Not sure if the injectors have been changed or filter . ( can I tell if they are factory injectors by looking? any Ideas on the idling issue ? a while back I bought an Innova 3140 I guess its time to learn to use it.. Thanks

[XfireZ51]

Originally Posted by Corbusa

I hope someone can help me with this one. My 89 usually idles a little high . but yesterday it was perfect . I stopped for some lunch , came out and she wouldnt idle and was stalling. .I finally got her running and idling smooth , them when I pulled in the garage she did it again and this time it sounded like spark knock. and wouldnt idle.. She has 39k miles , ... Not sure if the injectors have been changed or filter . ( can I tell if they are factory injectors by looking? any Ideas on the idling issue ? a while back I bought an Innova 3140 I guess its time to learn to use it.. Thanks

That would be a good idea.

[vilant]

Do you have the FSM for your car? AN 89 should have an ALDL connector. You can pull codes by grounding one of the pins on the ALDL connector. The FSM can walk you through any codes that come up.

[Corbusa]

Thanks guys , I'll try it this weekend and see what I get . I started it up today and it was fine. ( but was yesterday too until I drove 40+ miles ).
whats good / type injectors ? ( if needed )

[ZRXMAX]

Inspect the MAF for the wires being intact. I have had intermitant running problems with those before. They also have a small circut board in them that isn't designed to come apart. I had a mechanic fix one because he did take it apart and knew what to look for. It has been so many years I don't remember what he did to it. The easiest way it to locate a good one and swap it out to see how it runs with a different MAF in it. If you know somebody with a 89 that will swap you for a test drive you can easily verify whether or not yours is starting to fail. Last time I bought one it was $150 so I wouldn't run out and buy one to check it unless you can return it.

[Corbusa]

UPDATE kind of I scanned for codes heres what I have a code 41
DTC ( code whatever DTC is ) but 41 , 42 43, 46, 51 52, 54
then live data code 24, 25
It ran great to the ZR1 NCM meet this year . after I drove it about 30 miles and it acted like it wouldn't run or stay running , but seems to be when it get hot. I let it idle in the driveway yesterday and after 10-15 minutes it started dying and running bad . It acts like when a distributor module in an HEI is going bad and messing up when hot.
I think the radiator should be flushed at 40k miles for an 89 not many miles and could be slightly plugged ( yet never overheats ) . any advise it appreciated .

[gbrtng]

I hate to be the bearer of bad tidings, but that sounds like the ECM is going south. My L98 91 did similar stuff and after lots of trouble shooting, replaced it with a unit from the local graveyard and all was well again. At least it's not a ZR-1 - those ECMs are made of unobtainium ...

[Corbusa]

thanks Bro...

[batchman]

Wow I didn't see this thread until just now, but a couple years ago on the boss's 88 Z51 we had a very flaky problem that I thought was the ECM but it turned out to be the fuel pump wiring. Where the harness passes through the filler neck plate, the wiring went bad inside the molded strain relief.

I eventually found that smacking the strain relief with the back of a screwdriver could change the symptoms.

Hope that helps you. Took me a *lot* to figure that one out. Hope you're subscribed to this thread and find this before you burn a few C-notes like I did.

Cheers,
- Jeff

[Corbusa]

Hey Guys , it turned out being the ECM .. I put 2 aftermarkets one and finally went with a factory and Bamm all fixed ... Gordon K said the 89's are a little different - he was correct