Help for my 89 ????
Thread Starter
Cruising
Joined: Apr 2007
Posts: 10
Likes: 0
Help for my 89 ????
a little history of the car.
I have an 89 corvette L98 AT that I have recently purchased from a friend who had it sitting in his garage the last 10 years. He purchased it new and drove it for its first 40,000 miles and parked it when the tires got bald and the Dash cluster started giving him problems. He would start it a couple times a year. Every year it started harder and run rougher until it no longer ran.
I trailered it home and found 8 psi fuel pressure and 2 injectors at 2 ohms. Replaced the injectors and fuel pump, cleaned egr and thottle body/MAF and it started right up a ran fairly decent for sitting all them years. I then replaced cap/rotor, plugs, replaced all fluids, new tires, repaired digital dash.
I drove it for about a week without any problems and loved it.
Then it started acting up were I need some help.
The SES light will come on and it doesn't want to idle and will kill if it is in gear. If you give it just a little pedal it will stay running but rough. If you step on it normally like when leaving a stop light it will pop multiple time thru the throttle body (like its lean) and will quit. If you give it more than 1/3 throttle it will launch and run right thru that off idle spot and run fine until you get the RPMs low enought to get back under that 1/3 throttle. During this the SES light will be on. Some times the light will be on solid, sometime it is flickering like a bad connection with no pattern to it at all and sometimes its not on at all.
It gets wierder, when I try to flash the codes by jumpering A to B the SES light will flicker like described above with absolutely no pattern, this is when its acting up, I have noticed when it is acting up the fan will come on right away when the key is turned on.
The above desribed problem is not always there. Sometimes I jump in it and drive the hell out of it and its perfect and I shut it off when I get where I'm going and hop back in it it acts up. When it's not acting up the fan doesnt come on when I turn the key. I can jump A and B and the fan will come on and it will flash code 12 at me forever like nothing wrong.
I have searched this all C4 forums a lot for and answers and have try alot of things. The collant temp sensor Ohms out to almost exact ohms for what my pyrometer is telling me. I have not replace O2 sensor yet but like to find problem instead of just replacing parts.
Could bad injectors stressed ECM so it flakes out sometimes. Any suggestions out there? Sorry this is so long but don't know how to explain the other wise. I have monitored the fuel pressure and thats fine, ohmed out new injectors again fine. unplugged Vacuum line to EGR , still runs fine one time not the next. Acts up cold or hot, no pattern I have been able to figure out yet.
HELP !!!!!!!
I have an 89 corvette L98 AT that I have recently purchased from a friend who had it sitting in his garage the last 10 years. He purchased it new and drove it for its first 40,000 miles and parked it when the tires got bald and the Dash cluster started giving him problems. He would start it a couple times a year. Every year it started harder and run rougher until it no longer ran.
I trailered it home and found 8 psi fuel pressure and 2 injectors at 2 ohms. Replaced the injectors and fuel pump, cleaned egr and thottle body/MAF and it started right up a ran fairly decent for sitting all them years. I then replaced cap/rotor, plugs, replaced all fluids, new tires, repaired digital dash.
I drove it for about a week without any problems and loved it.
Then it started acting up were I need some help.
The SES light will come on and it doesn't want to idle and will kill if it is in gear. If you give it just a little pedal it will stay running but rough. If you step on it normally like when leaving a stop light it will pop multiple time thru the throttle body (like its lean) and will quit. If you give it more than 1/3 throttle it will launch and run right thru that off idle spot and run fine until you get the RPMs low enought to get back under that 1/3 throttle. During this the SES light will be on. Some times the light will be on solid, sometime it is flickering like a bad connection with no pattern to it at all and sometimes its not on at all.
It gets wierder, when I try to flash the codes by jumpering A to B the SES light will flicker like described above with absolutely no pattern, this is when its acting up, I have noticed when it is acting up the fan will come on right away when the key is turned on.
The above desribed problem is not always there. Sometimes I jump in it and drive the hell out of it and its perfect and I shut it off when I get where I'm going and hop back in it it acts up. When it's not acting up the fan doesnt come on when I turn the key. I can jump A and B and the fan will come on and it will flash code 12 at me forever like nothing wrong.
I have searched this all C4 forums a lot for and answers and have try alot of things. The collant temp sensor Ohms out to almost exact ohms for what my pyrometer is telling me. I have not replace O2 sensor yet but like to find problem instead of just replacing parts.
Could bad injectors stressed ECM so it flakes out sometimes. Any suggestions out there? Sorry this is so long but don't know how to explain the other wise. I have monitored the fuel pressure and thats fine, ohmed out new injectors again fine. unplugged Vacuum line to EGR , still runs fine one time not the next. Acts up cold or hot, no pattern I have been able to figure out yet.
HELP !!!!!!!
Thread Starter
Cruising
Joined: Apr 2007
Posts: 10
Likes: 0
Thanks Aardwolf and Gattor vette,
How low is low battery vlotage? Dash is showing 13.7 to 14.2 depending on rpm and my digital Fluke meter is agreeing with it. It does seem a little low but it is charging. I figured it was just the voltage regulator on the low side .
I see lots of posts on grounds I'll jack it up and look for them grounds by the O2 sensor. I am wait for my manual from HELM and my cable for my lap top from ALDLcvable.com. In the mead time can somebodt tell me were the ECM is located on a 89. New to vettes, but not cars. Hate taking dashs apart to find its not there. Guessing Passanger side.
How low is low battery vlotage? Dash is showing 13.7 to 14.2 depending on rpm and my digital Fluke meter is agreeing with it. It does seem a little low but it is charging. I figured it was just the voltage regulator on the low side .
I see lots of posts on grounds I'll jack it up and look for them grounds by the O2 sensor. I am wait for my manual from HELM and my cable for my lap top from ALDLcvable.com. In the mead time can somebodt tell me were the ECM is located on a 89. New to vettes, but not cars. Hate taking dashs apart to find its not there. Guessing Passanger side.
Safety Car
Joined: May 2005
Posts: 3,682
Likes: 1
From: Scappoose Oregon
St. Jude Donor '11,'14
My ECM went bad and my 89 ran rough and would kill at low rpm's. ECM is under dash on right side. Take the kick panel off and look up for silver box. Take two screws out and it will come down. Kevin
Thread Starter
Cruising
Joined: Apr 2007
Posts: 10
Likes: 0
Thanks everybody,
I cleaned up the grounds, pulled the ECM out, pulled the PROM out of ECM. I then cleaned the socket were the prom plugs in with contact cleaner and sprayed the whole board down with the cleaner and the connectors that plugged into ECM as cleaned up.
I have taken it on 2 rather lenghty trips with no problems, they arte really fun to drive when everything works right, I'm crossing my fingers that it was a bad connection
I cleaned up the grounds, pulled the ECM out, pulled the PROM out of ECM. I then cleaned the socket were the prom plugs in with contact cleaner and sprayed the whole board down with the cleaner and the connectors that plugged into ECM as cleaned up.
I have taken it on 2 rather lenghty trips with no problems, they arte really fun to drive when everything works right, I'm crossing my fingers that it was a bad connection
