Erratic Idle

motosparky · 06-18-2007, 05:11 PM

I have a 89 N/A that I just did a head gasket on.
I have verified all of my vacuum lines are hooked up correct, set the TPS per the TSRM and re-verified correct timing twice all the way down to the pulleys.
However the darn thing will not idle. It fluctuates from 1200 to 1600 RPMs in a steady pulse. When I drive the car it appears to be running right under acceleration.
I am getting no codes of any kind when I scan it.
I am at a loss. If anyone has any ideas, throw them my way. I am about to surrender and send her to the graveyard if I cannot fix this issue.
Thanks,
Jim

chash360 · 06-18-2007, 05:39 PM

Check your MAF (Mass Air Flow) Sensor plug on the air intake near the air filter.

motosparky · 06-18-2007, 05:46 PM

I will check the MAF tonight.
A few more things that might help.
There is no difference in operation when I unplug the TPS and the Idle Control Sensor. It is like they serve no purpose.
The idle control sensor does click as stated in the TSRM but I have not done the electronic check yet.

dcrusupra · 06-18-2007, 05:55 PM

Pull codes...

http://www.toyota-supra.info/forums/...read.php?t=323

motosparky · 06-18-2007, 06:17 PM

I did and I had no codes : )

Quote:

Originally Posted by dcrusupra

Pull codes...

http://www.toyota-supra.info/forums/...read.php?t=323

dcrusupra · 06-18-2007, 06:22 PM

I c. It sounds like a vacuum leak. Can you hear anything? Check to make sure all the clamps on the intake are tight and it has no holes in it. Did you replace the gaskets on the intake?

chash360 · 06-18-2007, 06:23 PM

When doing routine checks I have forgotten to re-hook up the MAF plug before and it behaves exactly like you describe, reving up then dropping, almost dying then rev up, on and on..... I suspect that a faulty MAF sensor would also cause this same behavior. It is also possible that its only partially plugged in causing it to not throw a code, the manipulation of getting the airfilter back in and clamped can easily unseat the plug. Best check is to unplug it completely, start the car, note any changes in operation, turn off, then plug it in firmly again, to see if that clears the problem. (I never rely on a computer to tell me the problem, it can point you in the right direction but they are not a replacement for real trouble shooting). If the behavior is different with it unplugged you may have another issue, if it is exactly the same and it does not clear up after plugging it back in fully, suspect your MAF wiring or the sensor itself. Look for physical obsrtuction in the sensor too. A pine needle in the wrong place can foul up the readings without throwing a code. The O2 sensor can also have affects here (but slower reacting) as the 2 are working together to optimize your mixture.

dcrusupra · 06-18-2007, 06:26 PM

A faulty MAF would throw codes. Especially if it was unplugged.

motosparky · 06-18-2007, 06:26 PM

I put all new gaskets on except one. The ICS is on back order but I did silicone it very thoroughly.
I have sprayed starter fluid around every possible area of potential leaks and it does not change at all !!!

Quote:

Originally Posted by dcrusupra

I c. It sounds like a vacuum leak. Can you hear anything? Check to make sure all the clamps on the intake are tight and it has no holes in it. Did you replace the gaskets on the intake?

dcrusupra · 06-18-2007, 06:30 PM

No codes, no leaks. I'm stumped my good man. Spark problem maybe? No clue now, lol. Good luck.

06-18-2007, 05:11 PM	#1
motosparky Stock Join Date: Nov 2006 Location: AV California Posts: 22	Erratic Idle I have a 89 N/A that I just did a head gasket on. I have verified all of my vacuum lines are hooked up correct, set the TPS per the TSRM and re-verified correct timing twice all the way down to the pulleys. However the darn thing will not idle. It fluctuates from 1200 to 1600 RPMs in a steady pulse. When I drive the car it appears to be running right under acceleration. I am getting no codes of any kind when I scan it. I am at a loss. If anyone has any ideas, throw them my way. I am about to surrender and send her to the graveyard if I cannot fix this issue. Thanks, Jim __________________ 89 N/A Supra Previous: 90 Turbo 86.5 N/A 85 GT http://s81.photobucket.com/albums/j2...%20For%20Sale/

06-18-2007, 05:46 PM	#3
motosparky Stock Join Date: Nov 2006 Location: AV California Posts: 22	I will check the MAF tonight. A few more things that might help. There is no difference in operation when I unplug the TPS and the Idle Control Sensor. It is like they serve no purpose. The idle control sensor does click as stated in the TSRM but I have not done the electronic check yet. __________________ 89 N/A Supra Previous: 90 Turbo 86.5 N/A 85 GT http://s81.photobucket.com/albums/j2...%20For%20Sale/

06-18-2007, 05:55 PM	#4
dcrusupra 500whp yet? Join Date: Aug 2005 Location: Plantation, Fl. Posts: 1,052	Pull codes... http://www.toyota-supra.info/forums/...read.php?t=323 __________________ New Rebuild My CarDomain

06-18-2007, 06:22 PM	#6
dcrusupra 500whp yet? Join Date: Aug 2005 Location: Plantation, Fl. Posts: 1,052	I c. It sounds like a vacuum leak. Can you hear anything? Check to make sure all the clamps on the intake are tight and it has no holes in it. Did you replace the gaskets on the intake? __________________ New Rebuild My CarDomain

06-18-2007, 06:23 PM	#7
chash360 Stock Join Date: Dec 2006 Location: Oregon Posts: 14	When doing routine checks I have forgotten to re-hook up the MAF plug before and it behaves exactly like you describe, reving up then dropping, almost dying then rev up, on and on..... I suspect that a faulty MAF sensor would also cause this same behavior. It is also possible that its only partially plugged in causing it to not throw a code, the manipulation of getting the airfilter back in and clamped can easily unseat the plug. Best check is to unplug it completely, start the car, note any changes in operation, turn off, then plug it in firmly again, to see if that clears the problem. (I never rely on a computer to tell me the problem, it can point you in the right direction but they are not a replacement for real trouble shooting). If the behavior is different with it unplugged you may have another issue, if it is exactly the same and it does not clear up after plugging it back in fully, suspect your MAF wiring or the sensor itself. Look for physical obsrtuction in the sensor too. A pine needle in the wrong place can foul up the readings without throwing a code. The O2 sensor can also have affects here (but slower reacting) as the 2 are working together to optimize your mixture. Last edited by chash360; 06-18-2007 at 06:47 PM.

06-18-2007, 05:39 PM	#2
chash360 Stock Join Date: Dec 2006 Location: Oregon Posts: 14	Check your MAF (Mass Air Flow) Sensor plug on the air intake near the air filter.

06-18-2007, 06:26 PM	#8
dcrusupra 500whp yet? Join Date: Aug 2005 Location: Plantation, Fl. Posts: 1,052	A faulty MAF would throw codes. Especially if it was unplugged. __________________ New Rebuild My CarDomain

06-18-2007, 06:30 PM	#10
dcrusupra 500whp yet? Join Date: Aug 2005 Location: Plantation, Fl. Posts: 1,052	No codes, no leaks. I'm stumped my good man. Spark problem maybe? No clue now, lol. Good luck. __________________ New Rebuild My CarDomain

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
won't idle	3.0trd	MKIII Supra	6	06-15-2009 07:23 PM
Car doesnt like to idle in the morning	XxSupra4LifexX	MKIII Supra	11	12-24-2007 07:27 AM
Finally, Idle Set!	scruffboy	Non-Generation Specific Questions	6	01-16-2007 02:39 PM
1987 Toyota Supra Idle	spycialost9999	Non-Generation Specific Questions	3	06-14-2006 06:33 PM
HELP!!!! '87 Supra idle problem	Morpho	MKIII Supra	0	10-03-2005 02:40 PM