1990 corvette runs rough

[Darryl L]

Darryi I have owned a 1990 ZR-1 for some time but never had your problem. I think one of the best people to ask this question to would be Marc Haibeck www.ZR1specialist.com. He knows these cars inside and out. Good Luck

 

[Darryl L]

I got a hold of him and he gave me a few things to look at. I'm going to tinker with it a bit tomorrow and I'll let you know how it went

 

[Darryl L]

Hi Darryl. This sensor work as your choke use to work on your old carburated engine so ambient temperature should not be a probleme as long as the ohm reading of the sensor fallow the coolant temperature. warm it up until the problem is present, turn the engine off then take the reading on the 2 pins of the sensor. Also check for traces of coolant in the connector, these sensor use to leak. I remember back then I was using a variable resistor to simulate the coolant sensor, this way I could see if the PCM was working OK with a good reading.

Stephane

My buddy had the same symptoms recently with a ‘90 he was plannng to flip.
In his case it turned out to be the Throttle Position Sensor(TPS).
He got the car running so well he decided to keep it for a while..
New rims, tires, paint stripe, polish, and a good detail...
He now has a C3, C4 & C5 in the garage.

I hope you find your issue soon.

Graham

My buddy had the same symptoms recently with a ‘90 he was plannng to flip.
In his case it turned out to be the Throttle Position Sensor(TPS).
He got the car running so well he decided to keep it for a while..
New rims, tires, paint stripe, polish, and a good detail...
He now has a C3, C4 & C5 in the garage.

I hope you find your issue soon.

Graham

I installed a new TPS and it runs good in the shop. It hasnt flooded out yet It's winter here and to snowy to test drive to be totally sure but I'm keeping my fingers crossed lol

 

[Black 03 Z06]

Snow? Man I hope you have found the cause and made the repair, spring is just around the corner.

Good luck with it Darryl.

 

[Corvetteplus]

customers of mine had the same problem, couple of them had a burnoff relay issue ( relay was toasted and killed the wire plug as well ) it is right nexy to coolant/MAF relay package next battery, some others had to changed all injectors, those are common problems on the L98 engines. call me if you need more infos

 

[Darryl L]

customers of mine had the same problem, couple of them had a burnoff relay issue ( relay was toasted and killed the wire plug as well ) it is right nexy to coolant/MAF relay package next battery, some others had to changed all injectors, those are common problems on the L98 engines. call me if you need more infos 514-955-3419

Hi! Nice to meet you, and thanx for the info. This is my first C4 lol. Iv'e owned a few C3 cars and a C5. I only worked on the C3 which is a totally different beast lol. As I write this, a good friend of mine is picking up a factory shop manual with supplement to help me learn the car a lot better. I have to admit, I saw what I thought was a bit of crappy looking wiring and some sort of relays behind the battery but didn' know what that area was all about lol. I better pull the battery and have a seriously closer look! Thanx again for the tip! I will let you know for sure what I found ttyl...
Darryl

 

[seppi]

Find the culprit?

 

[Darryl L]

Find the culprit?

Not yet. I have a code 22 low voltage tps that's intermittent. Ive already replaced the tps with no improvement. My car shows a err message when I try to pull the ccm codes through obd1 port. It reads the ecm history code 22 but won' read the ccm codes! A.c. fuse is ok. I' still hunting lol!

 

[seppi]

Well I’m no expert but I’ve had the pleasure of re re one the these engine completely on my own. I’m sure you’ve set the tps. It’s pretty simple. Leaking injector maybe?

 

[Darryl L]

Well I’m no expert but I’ve had the pleasure of re re one the these engine completely on my own. I’m sure you’ve set the tps. It’s pretty simple. Leaking injector maybe?

The TPS on the 1990 L98 is fixed and does not require .54v setting like the 89 and older ones. Leaking injector may be a possibility. I may just replace them due to their age at any rate. Possibly upgrade them a bit to suit the engine build specs. It' Now running a LT1 cam with 1.6 rockers, custom ported heads with 10.5-1 pistons. I still have a few ideas up my sleeve. It' winter here and its hard to have to heat the shop up to tinker so I've been doing work on the warmer days to save energy lol.

 

[seppi]

Right. I just bought an 87. Didn’t even realize about the tps changing although I installed a 91 l98 into a 88 c4. I’ve read your posts. Only thing I can think of is leaking injector filling the cylinder. Winter here also Darryl but my car is tucked away and I have no access to tinker. Hope you find the issue.

 

[seppi]

I had a leaking injector with the 91 engine btw. Didn’t stall or smoke slow leak after shutdown while hot. Only affected hot starts just took a few more turns to fire.

 

[Darryl L]

I had a leaking injector with the 91 engine btw. Didn’t stall or smoke slow leak after shutdown while hot. Only affected hot starts just took a few more turns to fire.

Hi! My injectors seem ok. I am finding a low voltage on the tps! I cannot figure out why though. It has a new tps installed with no results. Still kicks error code 22! I also found an err code from the ccu to the pcm. I' going to pull the bottom of the dash and check out what's happening underneith. It has a aftermarket stereo in it and I'll have to see what they used for power, ground etc...