L98 tuning problems
Thread Starter
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Joined: Sep 2004
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L98 tuning problems
The engine has a large flat spot once its warmed up and you roll into the throttle hard in or out of gear it will do the same thing,this is not present when the engine is under 140°?
383 with a mini ram
tps is .740
timing is 10° base
40# fuel pressure,problem does not get any better with higher psi.
383 with a mini ram
tps is .740
timing is 10° base
40# fuel pressure,problem does not get any better with higher psi.
Safety Car
Joined: May 1999
Posts: 3,651
Likes: 5
From: Atlantis
Cruise-In I Veteran
Scan it and see if you are getting KR during the flat spot.
You may need to modify the attack & decay rate.
In any event you will need a good data scan or two to analyze the problem.
You may need to modify the attack & decay rate.
In any event you will need a good data scan or two to analyze the problem.
Thread Starter
Advanced
Joined: Sep 2004
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resonds the same way with the tps@.54
I have no way to data log.
What is KR?
This does not happen when the engine is cold.
Why does this matter?
Does fuel pressure only make a differance @ open throttle?
I have no way to data log.
What is KR?
This does not happen when the engine is cold.
Why does this matter?
Does fuel pressure only make a differance @ open throttle?
Drifting
Joined: Oct 2003
Posts: 1,594
Likes: 0
From: CALGARY ab
Originally Posted by 1uke
The engine has a large flat spot once its warmed up and you roll into the throttle hard in or out of gear it will do the same thing,this is not present when the engine is under 140°?
383 with a mini ram
tps is .740
timing is 10° base
40# fuel pressure,problem does not get any better with higher psi.
383 with a mini ram
tps is .740
timing is 10° base
40# fuel pressure,problem does not get any better with higher psi.
Race Director
Joined: Sep 2003
Posts: 16,836
Likes: 337
From: Database Error Indiana
I suggest you goto the scan&tune section and click on the FAQ thread at the top. I had real tuning problems a year ago and learned much reading this. Good luck and have patience, tuning a computer car can be a challenge. 
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Team Owner
Joined: Dec 2000
Posts: 90,675
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From: SE NY
Cruise-In II Veteran
At what RPM is the TPS showing .74Vdc?
If at around 600-700RPM, it sounds about right.
Is this a new problem or an old one?
Has the knock sensor been out since this problem started?
If at around 600-700RPM, it sounds about right.
Is this a new problem or an old one?
Has the knock sensor been out since this problem started?
Thread Starter
Advanced
Joined: Sep 2004
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This is a fresh build,iac and Knock sensor are removed and chip has been adjusted for this.
I have 2 holes in the tb .140 dia the tps has been down to .54 with no change.
Tach isn't working presently,when I check timing at idle it wanders a bit but engine is not surging.
I have 2 holes in the tb .140 dia the tps has been down to .54 with no change.
Tach isn't working presently,when I check timing at idle it wanders a bit but engine is not surging.
Drifting
Joined: Feb 1999
Posts: 1,289
Likes: 11
From: long island NY
i have a 422 ci motor with a mini ram that has that same flat spot.
mine happens at 3000 to 4000 rpm. i am still trying to get it tuned.
but the chip burner can not get rid of it. i have i have logged my event with diacom.
mitch
mine happens at 3000 to 4000 rpm. i am still trying to get it tuned.
but the chip burner can not get rid of it. i have i have logged my event with diacom.
mitch
Thread Starter
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Joined: Sep 2004
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update,
changed to a 3 wire o2 now the car runs much better.
It only has a flat spot @1400 or lower now which is frustrating at this point.
TPS is set fine,good timing around 6/7 at base and FP bout 38 is good
But if you powerbrake past the flat spot it will burn the ET Streets into 3rd.
changed to a 3 wire o2 now the car runs much better.
It only has a flat spot @1400 or lower now which is frustrating at this point.
TPS is set fine,good timing around 6/7 at base and FP bout 38 is good
But if you powerbrake past the flat spot it will burn the ET Streets into 3rd.
Le Mans Master
Joined: Jan 2003
Posts: 8,596
Likes: 19
From: Portland Oregon
Originally Posted by 1uke
update,
changed to a 3 wire o2 now the car runs much better.
It only has a flat spot @1400 or lower now which is frustrating at this point.
TPS is set fine,good timing around 6/7 at base and FP bout 38 is good
But if you powerbrake past the flat spot it will burn the ET Streets into 3rd.
changed to a 3 wire o2 now the car runs much better.
It only has a flat spot @1400 or lower now which is frustrating at this point.
TPS is set fine,good timing around 6/7 at base and FP bout 38 is good
But if you powerbrake past the flat spot it will burn the ET Streets into 3rd.
Thread Starter
Advanced
Joined: Sep 2004
Posts: 59
Likes: 0
update:changed to Mustang O2 sensor whiched helped drivabilty 100%
but still have huge flat spot off idle.
changed fuel pump to a 190gph Mustang pump which boost's pressure to 58# when adjustting the reg this made an improvment but did not eliminate the flat spot.
Some of you guys suggested a scanner,where do I find this and what do they cost? Thank you
but still have huge flat spot off idle.
changed fuel pump to a 190gph Mustang pump which boost's pressure to 58# when adjustting the reg this made an improvment but did not eliminate the flat spot.
Some of you guys suggested a scanner,where do I find this and what do they cost? Thank you
Racer
Joined: Jan 2004
Posts: 300
Likes: 1
From: Wollongong NSW
383 with mini ram here also and i have a flat spot at about 1900rpm, but only upon light load, if i accellerate firmly i can drive straight through it. everything on the car has been checked at least twice but the tuner still could not get rid of it completely. emailed jesse about making me a chip but i cannot easily access my ecm so i just dont drive at part throttle around 1900rpm anymore. Have been informed that it may be due to air pulsations combined with large cam and short runner length of the miniram, not to sure about this but hopefully someone will know the answer.
good luck bro.
good luck bro.