ECU and constant fan operation
Thread Starter
Racer
Joined: Feb 2012
Posts: 442
Likes: 23
From: Seattle Washington
ECU and constant fan operation
My 85 C4 has a problem with the fan constantly running. My Corvette mechanic spent about 2 hours searching for wiring problems and came up with no problem. He has decided that the ECU is causing the problem. He also feels that someone has installed a high performance chip. So, he ordered a new ECU. I might mention the coolant temp. runs at about 165 tops and the oil temp. won't come on (150) for about 8 miles of freeway driving. I'm getting about 13 MPH. This C4 has the Z51 option. What do you think? Are we going in the right direction?
Thanks'
JW
Thanks'
JW
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
The tune for the engine is programmed onto the chip ,the chip that may be modified is removable
You only remove and replace that chip ;not the whole ECM.
Sort of like buying a new DVD player because you have finished watching one movie
Last edited by rodj; Mar 13, 2012 at 07:38 PM.
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
Like as soon as you turn the key on before engine starts?
So he has confirmed the fan is being turned on only by the ECM?
No mechanical fan switches involved
No mechanical fan switches involved
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Check to see if the hi-pressure switch (smaller one) in the A/C pressure line is connected.
If so, pull the switch and short the two pins and cycle on/off the ignition switch to see if the fan stops.
If so, pull the switch and short the two pins and cycle on/off the ignition switch to see if the fan stops.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Team Owner
Joined: Mar 2012
Posts: 27,118
Likes: 135
From: Montgomery, Alabama
2017 C6 of Year Finalist
had the A/C worked on a couple weeks ago. But then I have been having a few senior moments since I passed 66.
There was a very small leak where the piping connected to the canister. The mechanic said someone had apparently leaned on the piping, which is not secured anywhere, causing it to crack. Could they have not reconnected something.
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
There was a very small leak where the piping connected to the canister.
Race Director
Joined: May 2001
Posts: 14,165
Likes: 9
As far as your 12.5MPH, try the pedal on the right.
I assume you mean MPG. If the engine is running too cold the computer will possibly never enter closed loop operation. Or even if it is in closed loop it will try to richen the mixture due to the low coolant temp. Kinda like driving a carb with the choke on all the time.
Team Owner
Joined: Mar 2012
Posts: 27,118
Likes: 135
From: Montgomery, Alabama
2017 C6 of Year Finalist
