High Idle-TPS not hooked up

g_rizzo · 10-21-2011, 08:11 PM

i have a 90 turbo, with the TPS hooked up the car will surge at anything higer than 1500rpm and is not driveable. I have unhooked the TPS and it will not surge put the car seems low on power and will quick shift not going above 3000rpm unless i push it. can't seem to find the reason for this, i have installed a new TPS which didn't change anything, checked any visable hoses, cleared all computer codes. the car has new plugs,wires, coils, i have cleaned the iac valve, replaced many hoses. I need ideas to help find this problem

cre · 10-22-2011, 12:11 AM

Don't expect a consistent idle with the TPS unplugged... the TPS is used to control the idle afterall.

1500RPM sounds like a fuel cut issue, could be due to a number of factors.

You say you cleared codes... what codes? When did this problem start? Have you done any work on the car prior to this problem starting? If so, what?

g_rizzo · 10-22-2011, 10:37 AM

i replaced the coils since the car was not starting and there was no fire, in the middle of that i noticed the orginall tps was missing the bottom screw, when i unpluged the tps after still not getting fire the car started. the codes where mainly tps related and a 02 sensor code that is always on in my car. when driving the car prior to the no start issue, the car would run with lots of power but holding a steady speed the rpms would drop 2-300 rpm consitantly and cause a driveablity issues, sad part is with the tps unplugged that went away.

cre · 10-22-2011, 08:19 PM

TPS and O2 sensor issues will not prevent the car from starting. It may be a little rough starting without a valid IDL signal to the ECU but that's all. The IDL switch isn't *required* for the ECU to idle the engine; It's primarily a trim that's used to prevent stumbling when coming off throttle quickly and used in certain cases to ensure that base parameters are met in order for proper calibration of other parts (such as ignition timing). The TPS does play a greater role in automatic transmission equipped cars though, so make sure it's properly calibrated.

Saying that the codes were "mainly" this or that just tells me you disregarded valuable information and aren't posting everything which may be relevant to diagnosing the problem properly... pay attention next time and write things down if need be.

Did you properly calibrate the TPS? Have you checked your ignition timing (look in the FAQ for a how to on it)? What were the exact codes which you do know were stored? Have you made sure there are no intake or exhaust leaks?

Has the KVAFM been altered in anyway? Is the air bypass screw on the side exposed (It's hidden in a cylindrical extrusion on the side)? Have you (or as far as you can tell has the previous owner) screwed with anything on the throttle body other than the TPS?

10-21-2011, 08:11 PM	#1
g_rizzo Stock Join Date: Mar 2011 Location: Canada Posts: 6	High Idle-TPS not hooked up i have a 90 turbo, with the TPS hooked up the car will surge at anything higer than 1500rpm and is not driveable. I have unhooked the TPS and it will not surge put the car seems low on power and will quick shift not going above 3000rpm unless i push it. can't seem to find the reason for this, i have installed a new TPS which didn't change anything, checked any visable hoses, cleared all computer codes. the car has new plugs,wires, coils, i have cleaned the iac valve, replaced many hoses. I need ideas to help find this problem

10-22-2011, 12:11 AM	#2
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	Don't expect a consistent idle with the TPS unplugged... the TPS is used to control the idle afterall. 1500RPM sounds like a fuel cut issue, could be due to a number of factors. You say you cleared codes... what codes? When did this problem start? Have you done any work on the car prior to this problem starting? If so, what? __________________ If something breaks or you need to contact a member of the administration please post HERE. Unless it's a private or administration matter please post it on the forum. It benefits no one else if car related questions aren't posted for future users and takes away from the time I'm able to spend helping on the rest of the forum. If you're so inclined I'm always more than happy to accept tips via PayPal. Tip Jar --->

10-22-2011, 08:19 PM	#4
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	TPS and O2 sensor issues will not prevent the car from starting. It may be a little rough starting without a valid IDL signal to the ECU but that's all. The IDL switch isn't required for the ECU to idle the engine; It's primarily a trim that's used to prevent stumbling when coming off throttle quickly and used in certain cases to ensure that base parameters are met in order for proper calibration of other parts (such as ignition timing). The TPS does play a greater role in automatic transmission equipped cars though, so make sure it's properly calibrated. Saying that the codes were "mainly" this or that just tells me you disregarded valuable information and aren't posting everything which may be relevant to diagnosing the problem properly... pay attention next time and write things down if need be. Did you properly calibrate the TPS? Have you checked your ignition timing (look in the FAQ for a how to on it)? What were the exact codes which you do know were stored? Have you made sure there are no intake or exhaust leaks? Has the KVAFM been altered in anyway? Is the air bypass screw on the side exposed (It's hidden in a cylindrical extrusion on the side)? Have you (or as far as you can tell has the previous owner) screwed with anything on the throttle body other than the TPS? __________________ If something breaks or you need to contact a member of the administration please post HERE. Unless it's a private or administration matter please post it on the forum. It benefits no one else if car related questions aren't posted for future users and takes away from the time I'm able to spend helping on the rest of the forum. If you're so inclined I'm always more than happy to accept tips via PayPal. Tip Jar --->

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10-22-2011, 10:37 AM	#3
g_rizzo Stock Join Date: Mar 2011 Location: Canada Posts: 6	i replaced the coils since the car was not starting and there was no fire, in the middle of that i noticed the orginall tps was missing the bottom screw, when i unpluged the tps after still not getting fire the car started. the codes where mainly tps related and a 02 sensor code that is always on in my car. when driving the car prior to the no start issue, the car would run with lots of power but holding a steady speed the rpms would drop 2-300 rpm consitantly and cause a driveablity issues, sad part is with the tps unplugged that went away.