ON TPS VOLTAGE...
Thread Starter
Le Mans Master
Joined: Oct 2001
Posts: 5,302
Likes: 2
From: Atlanta GA
ON TPS VOLTAGE...
I believe my ECM was contradicting itself this weekend worse than a politician.
When setting the TPS voltage, 0.56VDC being the "stock" setting and 0.65VDC being the "performance" setting, does the higher setting tell the ECM to add more fuel (i.e. increase pulse width or pressure or something)? If so, then last week, while cruising on the highway for about an hour, I got a code 44 (too lean). Then, a little later that night I got a code 12 (TPS voltage too high). If the higher TPS voltage adds more fuel, how the hell could it have been lean at the same time???
Yesterday I checked my TPS voltage. It was at 0.645VDC, and about 4.4VDC at WOT. I know it's supposed to be 4.6-4.7VDC at WOT, but after playing with it for about 20 minutes, I just could not get the WOT voltage set properly without making the idle voltage 0.8-1.0VDC.
I finally ended up setting the idle voltage to about 0.605VDC, which still made the WOT voltage 4.4VDC. I haven't seen any codes since last Friday night.
Tell me, is my computer just stupid, or is it a case of the operator having to be more intelligent the equipment that he is operating? :confused: :banghead:
When setting the TPS voltage, 0.56VDC being the "stock" setting and 0.65VDC being the "performance" setting, does the higher setting tell the ECM to add more fuel (i.e. increase pulse width or pressure or something)? If so, then last week, while cruising on the highway for about an hour, I got a code 44 (too lean). Then, a little later that night I got a code 12 (TPS voltage too high). If the higher TPS voltage adds more fuel, how the hell could it have been lean at the same time???
Yesterday I checked my TPS voltage. It was at 0.645VDC, and about 4.4VDC at WOT. I know it's supposed to be 4.6-4.7VDC at WOT, but after playing with it for about 20 minutes, I just could not get the WOT voltage set properly without making the idle voltage 0.8-1.0VDC.
I finally ended up setting the idle voltage to about 0.605VDC, which still made the WOT voltage 4.4VDC. I haven't seen any codes since last Friday night.
Tell me, is my computer just stupid, or is it a case of the operator having to be more intelligent the equipment that he is operating? :confused: :banghead:
Burning Brakes
Joined: Nov 2003
Posts: 1,234
Likes: 5
From: Herriman UT
Re: ON TPS VOLTAGE... (dtorc4)
All that I can add is that a voltage reading of 4.0V dc or greater is sufficient to signal the ECM of a WOT condition. I've experimented with the entire range of settings and never thrown a code.
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: ON TPS VOLTAGE... (dtorc4)
Indeed that "power" TPS setting was determinec empiracally. I increased the voltage at base idle (450rpm) till I got the code 21 and then backed off about 20mV. Actually your ECM is throwing the code 21 because it sees TPS voltage >2.5Vdc with <3.5gm/sec of air flow.
I think you have two issues here 1) the TPS voltage and 2) something causing the lean code. The latter could be due to a leak in the exhaust system before the O2 sensor or a leak in the EGR diaphram.
BTW, indeed .65Vdc IS a "performance" setting as it ECM sees greater than stock throttle opening and so provides more timing and fuel.
I think you have two issues here 1) the TPS voltage and 2) something causing the lean code. The latter could be due to a leak in the exhaust system before the O2 sensor or a leak in the EGR diaphram.
BTW, indeed .65Vdc IS a "performance" setting as it ECM sees greater than stock throttle opening and so provides more timing and fuel.
Thread Starter
Le Mans Master
Joined: Oct 2001
Posts: 5,302
Likes: 2
From: Atlanta GA
Re: ON TPS VOLTAGE... (65Z01)
Indeed that "power" TPS setting was determinec empiracally. I increased the voltage at base idle (450rpm) till I got the code 21 and then backed off about 20mV. Actually your ECM is throwing the code 21 because it sees TPS voltage >2.5Vdc with <3.5gm/sec of air flow.
I think you have two issues here 1) the TPS voltage and 2) something causing the lean code. The latter could be due to a leak in the exhaust system before the O2 sensor or a leak in the EGR diaphram.
BTW, indeed .65Vdc IS a "performance" setting as it ECM sees greater than stock throttle opening and so provides more timing and fuel.
I think you have two issues here 1) the TPS voltage and 2) something causing the lean code. The latter could be due to a leak in the exhaust system before the O2 sensor or a leak in the EGR diaphram.
BTW, indeed .65Vdc IS a "performance" setting as it ECM sees greater than stock throttle opening and so provides more timing and fuel.
Burning Brakes
Joined: Jul 2002
Posts: 871
Likes: 0
From: Costa Mesa CA
Re: ON TPS VOLTAGE... (dtorc4)
Well...
There are so many things that can dictate what voltage setting on the TPS works the best for you.
When my car was stock, it idled and ran best at the factory setting. The came the cam and the porting and the AFPR. 6.8V-7.0V worked best for me then. Now with the 52mm TB, it idles and runs best at 8.0V. No codes at 8.0V either. With 50lbs FP I'm still running lean because I can't run more than 4 degrees of initial timing or it hits off the knock sensor.
The next thing is running a heavy gauge dedicated power wire to the fuel pump. Then if I'm still running lean, it time for a new high-output pump.
I believe it's the O2 sensor that tells the ECM how rich or lean your exhaust is running and it's suppose to compensate. Based on that, I think your prob could be O2 related. Or the ECM itself.
BIG JIM
There are so many things that can dictate what voltage setting on the TPS works the best for you.
When my car was stock, it idled and ran best at the factory setting. The came the cam and the porting and the AFPR. 6.8V-7.0V worked best for me then. Now with the 52mm TB, it idles and runs best at 8.0V. No codes at 8.0V either. With 50lbs FP I'm still running lean because I can't run more than 4 degrees of initial timing or it hits off the knock sensor.
The next thing is running a heavy gauge dedicated power wire to the fuel pump. Then if I'm still running lean, it time for a new high-output pump.
I believe it's the O2 sensor that tells the ECM how rich or lean your exhaust is running and it's suppose to compensate. Based on that, I think your prob could be O2 related. Or the ECM itself.
BIG JIM
Le Mans Master
Joined: Jan 2003
Posts: 5,858
Likes: 7
From: Santa Maria CA
Re: ON TPS VOLTAGE... (65Z01)
BTW, indeed .65Vdc IS a "performance" setting as it ECM sees greater than stock throttle opening and so provides more timing and fuel.
I set mine to .65Volts from the factory setting. I felt a noticeable difference in throttle response right away. I have left it at that since. I still get 4.3Volts at WOT and do not throw any codes.
[Modified by 86PACER, 3:00 AM 4/9/2004]
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Drifting
Joined: Jan 2002
Posts: 1,261
Likes: 4
From: Middle River MD
Re: ON TPS VOLTAGE... (Black87c4)
Idle is .xx volts, can't go to 6- 8 volts even at WOT. Like i said the ecm resets it to zero when you turn the key on
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Re: ON TPS VOLTAGE... (dtorc4)
I have done some TPS testing, after not being able to get any intelligent answers from locals. I cranked the idle voltage, way up, and headed for the track. On the way to the track, I noticed it was difficult to maintain a steady cruising speed. The throttle sensitivity was way up. On the track, I observed a difference of ZERO. Upon reflection, this make sense. If there is sufficient voltage at WOT to trigger the PE mode, TPS adjustment isn't going to gain you anything. There is no additional power to be had. If someone prefers the additional "snap" from a part throttle variation, then fine. If you mash it, there will be nothing more. I don't like the reduced control. I have mine reset to stock specs.
I hope the code 12, above was a misprint. Code 12 merely verifies that the ECM is functioning. It is the precursor to any other codes that may follow.
A lean condition can be caused by a leak in the intake system, as well as the exhaust. If air gets into the engine after is has been monitored by the MAF, the mixture is likely to go lean.
RACE ON!!!
I hope the code 12, above was a misprint. Code 12 merely verifies that the ECM is functioning. It is the precursor to any other codes that may follow.
A lean condition can be caused by a leak in the intake system, as well as the exhaust. If air gets into the engine after is has been monitored by the MAF, the mixture is likely to go lean.
RACE ON!!!
Thread Starter
Le Mans Master
Joined: Oct 2001
Posts: 5,302
Likes: 2
From: Atlanta GA
Re: ON TPS VOLTAGE... (CFI-EFI)
II hope the code 12, above was a misprint. Code 12 merely verifies that the ECM is functioning. It is the precursor to any other codes that may follow.
:banghead: I"M :banghead: SO :banghead: STUPID :banghead:
:jester
Pro
Joined: Jul 2001
Posts: 557
Likes: 0
From: Taxahoma
Re: ON TPS VOLTAGE... (CFI-EFI)
On the track, I observed a difference of ZERO. Upon reflection, this make sense. If there is sufficient voltage at WOT to trigger the PE mode, TPS adjustment isn't going to gain you anything. There is no additional power to be had.
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
Re: ON TPS VOLTAGE... (Black87c4)
Has anyone actually tested to see exactly what is being changed when the TPS voltage is increased or decreased?
Does injector "on time" change? Does ignition timing advance change? Both, neither?
Jake
Does injector "on time" change? Does ignition timing advance change? Both, neither?
Jake
