Timing Tricker for L98????
Thread Starter
Race Director
Joined: Mar 2000
Posts: 17,602
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From: Palm City Florida
Timing Tricker for L98????
I have a LS1 that I used a 4.7K ohm Resistor to fool the PCM into thinking it is 57 degree out.. I just plugged it across the terminals of the IAT socket..
If I unplug the IAT on the L98... What resistor value will give me a sub 60 degree reading?
If I unplug the IAT on the L98... What resistor value will give me a sub 60 degree reading?
Safety Car
Joined: Dec 2000
Posts: 3,767
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From: Jacksonville Fl
Re: Timing Tricker for L98???? (chuckster)
You could measure the resistance of the IAT in the morning, and write the ambient temperature down, then do the same at the hot part of the day...and make a ratio of temperature to resistance change and then extrapolate the needed value.
Burning Brakes
Joined: Jul 2002
Posts: 871
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From: Costa Mesa CA
Re: Timing Tricker for L98???? (chuckster)
I put a 4.7K ohm resistor across the IAT leads on my '87 L98 and it ran "bubbery" and was getting 8.6 MPG according to the computer. I took it off and put everything back the way it was but it still hasn't ran exactly the same since.
I don't advise doing this unless you have the ALDL interface and a laptop to see what's really going on.
I don't know how much help this is.
BIG JIM
I don't advise doing this unless you have the ALDL interface and a laptop to see what's really going on.
I don't know how much help this is.
BIG JIM
Team Owner
Joined: Dec 2000
Posts: 90,675
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From: SE NY
Cruise-In II Veteran
Re: Timing Tricker for L98???? (BIG JIM 54)
That rather dispells the thinking that the IAT isn't used by the ECM to control fuel or timing.
A reference suggests a 640 Ohm resistor across the CTS leads to tell the ECM that coolant temp is only 145-150 deg F.
The same ref mentions that 185 Ohm is about 210 deg F and the thermister has a negative coeficient that is rather linear near room temps. So, to simulate say 50 deg F air you would use an 800 Ohm resistor.
Of course these "cheap tricks" are recommended for use at the track only.
A reference suggests a 640 Ohm resistor across the CTS leads to tell the ECM that coolant temp is only 145-150 deg F.
The same ref mentions that 185 Ohm is about 210 deg F and the thermister has a negative coeficient that is rather linear near room temps. So, to simulate say 50 deg F air you would use an 800 Ohm resistor.
Of course these "cheap tricks" are recommended for use at the track only.
Thread Starter
Race Director
Joined: Mar 2000
Posts: 17,602
Likes: 20
From: Palm City Florida
Re: Timing Tricker for L98???? (65Z01)
That rather dispells the thinking that the IAT isn't used by the ECM to control fuel or timing.
A reference suggests a 640 Ohm resistor across the CTS leads to tell the ECM that coolant temp is only 145-150 deg F.
The same ref mentions that 185 Ohm is about 210 deg F and the thermister has a negative coeficient that is rather linear near room temps. So, to simulate say 50 deg F air you would use an 800 Ohm resistor.
Of course these "cheap tricks" are recommended for use at the track only.
A reference suggests a 640 Ohm resistor across the CTS leads to tell the ECM that coolant temp is only 145-150 deg F.
The same ref mentions that 185 Ohm is about 210 deg F and the thermister has a negative coeficient that is rather linear near room temps. So, to simulate say 50 deg F air you would use an 800 Ohm resistor.
Of course these "cheap tricks" are recommended for use at the track only.
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: Timing Tricker for L98???? (chuckster)
It occures to me that though the IAT may not be used for timing & fuel maps perhaps the interaction is hard coded into the CPU's PROM and not into the EPROM that resides within the CalPac.
Anyway, I've done the MAT relocation mod.
Anyway, I've done the MAT relocation mod.
