Idle from hell

wurvan · 09-13-2009, 12:55 AM

This problem just happened literally overnight, went to bed it was fine got up started the car and holy crap, my idle jumped to 2600rpm then fell to 1100 then up and down over and over. got it to slow down some but but the lowest i could get it to was 1100. Now on to p of that its misfiring on one plug, when it wasnt earlier that day, will replace plugs wires cap rotor see what happens. I have never had to deal with a TPS, is it possible for it to cause this type of problem when it fails or am i looking at the wrong area for this type of issue?

corrosivecopper · 09-13-2009, 03:51 PM

When it comes to electrical, anything weird is possible. It's possible for a sensor to just give up, but the cap and rotor could be corroded as well. Had a Prelude before that ran good, then suddenly it wouldn't start. Pulled off the cap and rotor and wow was it corroded. Cleaned it with emery cloth and it was fine after that. Sometimes the simple things hold back performance.

wurvan · 09-13-2009, 11:05 PM

Ok got the misfiring problem fixed, however the idle still is going crazy originally 700rpm starts at 1600 and jumps up and down between that and 2600rpm. Any help here as I am down to one c ar due to an accident and the supra is all i got now. It will drive but will overheat rapidly due to the extra rpm running like that. Can a bad TPS cause this issue or would it more likely be the Idle control Sensor? I forgot to plug in the tps last time i started it and it made no difference to the running of the engine when i did that, nto sure if it would though.

mikeoc1 · 09-14-2009, 02:32 AM

have you checked for any codes yet? Also Sometimes if an engine is starving of fuel or running real lean (getting way too much air) it will rpm surge. Maybe make sure all your intake accordian/ducting is sealed tight? But maybe I would start with the ISC.

http://www.cygnusx1.net/Supra/Librar...spx?S=FI&P=106

1990supraguy · 09-14-2009, 04:21 AM

I have had the same problem with my 94 toyota pickup. It would rev up and down when at idle. I asked my brother, which is a toyota mechanic, and he said that I was low on coolant. Maybe you are low on coolant, it would'nt hurt to check.

09-13-2009, 12:55 AM	#1
wurvan Stock Join Date: Jan 2007 Location: Arlington, TX Posts: 5	Idle from hell This problem just happened literally overnight, went to bed it was fine got up started the car and holy crap, my idle jumped to 2600rpm then fell to 1100 then up and down over and over. got it to slow down some but but the lowest i could get it to was 1100. Now on to p of that its misfiring on one plug, when it wasnt earlier that day, will replace plugs wires cap rotor see what happens. I have never had to deal with a TPS, is it possible for it to cause this type of problem when it fails or am i looking at the wrong area for this type of issue?

09-13-2009, 11:05 PM	#3
wurvan Stock Join Date: Jan 2007 Location: Arlington, TX Posts: 5	Idle From Hell Ok got the misfiring problem fixed, however the idle still is going crazy originally 700rpm starts at 1600 and jumps up and down between that and 2600rpm. Any help here as I am down to one c ar due to an accident and the supra is all i got now. It will drive but will overheat rapidly due to the extra rpm running like that. Can a bad TPS cause this issue or would it more likely be the Idle control Sensor? I forgot to plug in the tps last time i started it and it made no difference to the running of the engine when i did that, nto sure if it would though.

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09-13-2009, 03:51 PM	#2
corrosivecopper Stock Join Date: Jul 2009 Location: Bonnyville, Alberta, Canada Posts: 20	When it comes to electrical, anything weird is possible. It's possible for a sensor to just give up, but the cap and rotor could be corroded as well. Had a Prelude before that ran good, then suddenly it wouldn't start. Pulled off the cap and rotor and wow was it corroded. Cleaned it with emery cloth and it was fine after that. Sometimes the simple things hold back performance.

09-14-2009, 02:32 AM	#4
mikeoc1 Stock Join Date: Jun 2009 Location: tn Posts: 20	have you checked for any codes yet? Also Sometimes if an engine is starving of fuel or running real lean (getting way too much air) it will rpm surge. Maybe make sure all your intake accordian/ducting is sealed tight? But maybe I would start with the ISC. http://www.cygnusx1.net/Supra/Librar...spx?S=FI&P=106

09-14-2009, 04:21 AM	#5
1990supraguy Stock Join Date: Aug 2009 Location: Tri-Cities Posts: 9	I have had the same problem with my 94 toyota pickup. It would rev up and down when at idle. I asked my brother, which is a toyota mechanic, and he said that I was low on coolant. Maybe you are low on coolant, it would'nt hurt to check.