Throttle Position Sensors and Pre Facelift Cars
01-29-2007, 06:00 AM
#12
Rain on the parade, Or "As the log rolls"
Paul I am happy for your results with the TPI.
My results are not so rapsodic as yours. This TCC behaves "differently" after the TPI exchange, but still hunts at low revs. Bah!!
Logs of Groups 7 and 9 confirm similar throttle position indication and TCC solenoid N218 activity correlation before and after the component exchange. (Reviewing the scope data from the morning drive now)
A very interesting observation is that the TPI variation is observed even before the transmission fluid has warmed enough to allow modulation or lock up modes. That is, the "capricious" nature of the TP indication is always observed. To see TPI values of 0 bracketed by values of 9% (Tom, please note that I have shifted the spurrious behavior from the N218 onto the TPI. Not the electrical unit, but the indication!:-)
The data shows N218 mode change to "modulation" with as little as 4% change in TPI. Very sensitive! The undesired excursions are sometimes recorded over 1.2 second time shot. I am quite certain that I am not making these wild inputs. (The case of Pilot induced oscillation?) Though certainly these changes could be the result of the mechanical arrangement to which the right foot is part.
Cable chatter?
Just now, I see the rood cause to be either an overly sensitive response of the TCC control to TPI inputs, or simply an overly sensitive TPI.
If bad or shared grounds are driving signal transients that are sensed as legitimate commands, then the system is responding correctly. If these signal inputs should receive a different resonse, then that is a different issue.
I still would like to see a greater range of Modulation current for N218,
In addition, I would like to see less noise in the TPI signal and hence the N218 response.
A comprehensive understanding of the TCU ECU design parameters would be wonderful.
The hunt continues
CalG
My results are not so rapsodic as yours. This TCC behaves "differently" after the TPI exchange, but still hunts at low revs. Bah!!
Logs of Groups 7 and 9 confirm similar throttle position indication and TCC solenoid N218 activity correlation before and after the component exchange. (Reviewing the scope data from the morning drive now)
A very interesting observation is that the TPI variation is observed even before the transmission fluid has warmed enough to allow modulation or lock up modes. That is, the "capricious" nature of the TP indication is always observed. To see TPI values of 0 bracketed by values of 9% (Tom, please note that I have shifted the spurrious behavior from the N218 onto the TPI. Not the electrical unit, but the indication!:-)
The data shows N218 mode change to "modulation" with as little as 4% change in TPI. Very sensitive! The undesired excursions are sometimes recorded over 1.2 second time shot. I am quite certain that I am not making these wild inputs. (The case of Pilot induced oscillation?) Though certainly these changes could be the result of the mechanical arrangement to which the right foot is part.
Cable chatter?
Just now, I see the rood cause to be either an overly sensitive response of the TCC control to TPI inputs, or simply an overly sensitive TPI.
If bad or shared grounds are driving signal transients that are sensed as legitimate commands, then the system is responding correctly. If these signal inputs should receive a different resonse, then that is a different issue.
I still would like to see a greater range of Modulation current for N218,
In addition, I would like to see less noise in the TPI signal and hence the N218 response.
A comprehensive understanding of the TCU ECU design parameters would be wonderful.
The hunt continues
CalG
01-29-2007, 09:20 AM
#14
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FWIW, my non hunt/thump box drops out of lockout on decel from ~65-60 and maintains
1800 rpm the whole time. picks back up again on throttle application and does it all smoothly. your prob sounds like a problem maintating TC slip, so I agree that it probably is a load signal/sensor problem...
and congrats on the TPI- glad to hear that one is fixed!
and congrats on the TPI- glad to hear that one is fixed!
01-29-2007, 04:29 PM
#16
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My car is at the dealer for this right now. If
you are right and I think you are this will avoid me getting a complete transmission replacement which probably won't fix my problem either. The trany fluid is clean and there is no metal on the pan magnets. My car worked perfect for 170,000 miles then went into total hunt and limp mode. Dealer says it works in reverse or forward if it is on the lift but in forward it immediately trips the speed sensors. I'm betting or TPS or that potentiome part you photographed. I asked them to order one for me and I'll let you know. Funny how so many 1997's all crapped out at the same time. By brother in law has one also and his just started acting up this week as well.
01-29-2007, 04:32 PM
#17
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My car is at the dealer for this right now. If
you are right and I think you are this will avoid me getting a complete transmission replacement which probably won't fix my problem either. The trany fluid is clean and there is no metal on the pan magnets. My car worked perfect for 170,000 miles then went into total hunt and limp mode. Dealer says it works in reverse or forward if it is on the lift but in forward it immediately trips the speed sensors. I'm betting or TPS or that potentiome part you photographed. I asked them to order one for me and I'll let you know. Funny how so many 1997's all crapped out at the same time. By brother in law has one also and his just started acting up this week as well.
02-18-2011, 05:53 PM
#19
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Paul- Did you replace your TPS with a new one, or do the TPS mod??
Can someone elaborate on the "hunting" problem and the "thump" problem? Could either of these fall in the category of "harsh downshifting"?
Can someone elaborate on the "hunting" problem and the "thump" problem? Could either of these fall in the category of "harsh downshifting"?
02-19-2011, 08:15 AM
#20
No. The "hunting" is felt around 35-50mph, slight uphill when the car can't decide on what gear to be in. Caused by a worn vb. "Thumping" is when you coast on the freeway down from around 60-70mph, the tourque converter dropps out, and the thump you feel is when the tc re engages or locks back up, still in 5th gear. Change the TPS and see if it helps 
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