hesitation
Thread Starter
Le Mans Master
Joined: May 2004
Posts: 5,866
Likes: 60
From: Hellinois
Finalist 2020 C4 of the Year - Modified
hesitation
My 85 L98 has a hesitation when I tromp on the gas from idle. My throttle position sensor is set correct and timing is slightly advanced. It has a Comp Cam that is computer friendly. Does anyone know what needs to be done to eliminate this problem? I'd like to see what she will do at the strip but until it'll leave the line strong I'd be wasting my time. :confused:
Le Mans Master
Joined: Oct 2003
Posts: 6,130
Likes: 2
From: seattle WA
Re: hesitation (Midnight 85)
Could be a faulty coolant temp and faulty oil temp sensor, A friend had that problem. What happens is the ecm tries to correct the problem without storing the fault. Therefore it corrects the problem before it reaches the fault code. ;)
Instructor
Joined: Jun 2003
Posts: 200
Likes: 0
From: Tempe AZ
Re: hesitation (rick lambert)
I have the same problem and its being caused by the coolant sensor (among a myriad of other problems I have in my 85). I don't know WHY a coolent temp sensor would cause it, but thats what my trusted mechanic tells me. My main problem anyway.
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
Re: hesitation (Corvettaholic)
I have the same problem and its being caused by the coolant sensor (among a myriad of other problems I have in my 85). I don't know WHY a coolent temp sensor would cause it, but thats what my trusted mechanic tells me. My main problem anyway.
It's basically like all other computer related input/output: Garbage in, garbage out.
Jake
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: hesitation (Midnight 85)
With a cam and maybe some exhaust mods you likely need an AFPR to add more fuel at WOT. Start with the current fuel pressure; take it to the strip and vary fuel pressure for the best trap speed.
Also, with your stock 2,000rpm TC, it would help to launch at about 1,600-1,700rpm.
Indeed coolant temp seen by the ECM is quite important to performance. Measure resistance of the sensor in the intake base just under the front of the TB. It should be well into the 100k Ohm range cold and drop to a few k Ohms when warm. If the cold reading is too low the ECM will think the engine is very warm and cut fuel when you go to WOT.
Also, with your stock 2,000rpm TC, it would help to launch at about 1,600-1,700rpm.
Indeed coolant temp seen by the ECM is quite important to performance. Measure resistance of the sensor in the intake base just under the front of the TB. It should be well into the 100k Ohm range cold and drop to a few k Ohms when warm. If the cold reading is too low the ECM will think the engine is very warm and cut fuel when you go to WOT.
