Aussie needs help with 90 C4
Thread Starter
4th Gear
Joined: Feb 2010
Posts: 4
Likes: 0
From: Nelson Bay NSW
Aussie needs help with 90 C4
I have had my 1990 C4 for 17 years without problems Still only 46K on the clock.
Recently, the "Service Engine Soon" illuminated and the digital displays malfunctioned. When I started at running temp, the engine coughed, spluttered, backfired back through the manifold and missed on multiple cycinderd. Since that time, when I start cold the car runs fine,but the service engine soon light is always on and the digital display malfunctions (wrong readings). When I start the engine warm or running temp, it misfires and runs rich.
The local workshop ran a computer diagnostic but nothing showed.
I also notcied that if the cooling fan cuts in at running temp at idle, the engine runs smooth until the fan cut out, the it starts missing again.
It appears that the EMS is getting wrong signals and thinks the engine is cold, when it's hot, but i could be wrong.
Living in Oz, there are few local knowledgable resuorces, so I need help big-time.
Thanks in advance
Strawberry
Recently, the "Service Engine Soon" illuminated and the digital displays malfunctioned. When I started at running temp, the engine coughed, spluttered, backfired back through the manifold and missed on multiple cycinderd. Since that time, when I start cold the car runs fine,but the service engine soon light is always on and the digital display malfunctions (wrong readings). When I start the engine warm or running temp, it misfires and runs rich.
The local workshop ran a computer diagnostic but nothing showed.
I also notcied that if the cooling fan cuts in at running temp at idle, the engine runs smooth until the fan cut out, the it starts missing again.
It appears that the EMS is getting wrong signals and thinks the engine is cold, when it's hot, but i could be wrong.
Living in Oz, there are few local knowledgable resuorces, so I need help big-time.
Thanks in advance
Strawberry
Team Owner
Joined: Jan 2009
Posts: 73,568
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From: Somewhere in Mo
St. Jude Donor '09-'10, '14
Race Director
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Last edited by Joe C; Mar 1, 2010 at 09:30 AM.
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Le Mans Master
Joined: Aug 2007
Posts: 8,735
Likes: 412
From: WV
I have to agree, it does sound like the computer is screwed up. If it was only one of these problems I wouldn't suspect the computer, but with all these at once it does point to the ECM. Pull codes first...WW
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
http://www.corvettebuyers.com/c4vettes/codes.htm
http://www.corvettebuyers.com/ecm.html
Sounds like a dodgy CTS
Last edited by rodj; Mar 1, 2010 at 05:36 PM.
Thread Starter
4th Gear
Joined: Feb 2010
Posts: 4
Likes: 0
From: Nelson Bay NSW
Problem Solved
Thank all for your help.
I replaced the computer but problem persisted. I replaced the performance chip with the original that I was holding for a spare and problem solved.
I plan to buy another performance chip and use the OEM as a spare once again.
I replaced the computer but problem persisted. I replaced the performance chip with the original that I was holding for a spare and problem solved.
I plan to buy another performance chip and use the OEM as a spare once again.
