Timing issue

cre · 01-08-2010, 07:14 AM

The ignition timing isn't an RPM control... it controls when the computer applies spark to the cylinder. It affect the RPM indirectly.

The more likely suspects are pirate air (unmetered air entering the system either via an opening in the intake piping AFTER the airflow meter or vacuum leak), a bad air flow meter, or a malfunctioning ISCV (Idle Speed Control Valve.

Here is information on diagnosing the ISCV... You may also need to take it off and clean it out (don't remove the three screws holding the stepper motor together though, there's nothing in there that you can service, just clean the valve.
http://www.cygnusx1.net/Supra/Librar...ction=FI&P=106

I'm going to guess that you've gone and blindly screwed with the ignition timing given the text of your post.... here's how to correct that: Before adjusting the ignition timing (also know as spark advance or ignition advance) you MUST resolve any stored diagnostic error codes. Then make sure you don't have an intake leak or a vacuum leak. Do you have any error codes?

Diagnostic codes:
http://www.cygnusx1.net/Supra/TechTi...ror_codes.aspx

Setting spark advance (requires a timing light):
http://www.cygnusx1.net/Supra/Librar...aspx?S=IG&P=20

And I'm sorry about your brother.... even with superior genetics in a relatively clean gene pool, these things do happen.

Hah!

01-08-2010, 07:14 AM	#2
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	The ignition timing isn't an RPM control... it controls when the computer applies spark to the cylinder. It affect the RPM indirectly. The more likely suspects are pirate air (unmetered air entering the system either via an opening in the intake piping AFTER the airflow meter or vacuum leak), a bad air flow meter, or a malfunctioning ISCV (Idle Speed Control Valve. Here is information on diagnosing the ISCV... You may also need to take it off and clean it out (don't remove the three screws holding the stepper motor together though, there's nothing in there that you can service, just clean the valve. http://www.cygnusx1.net/Supra/Librar...ction=FI&P=106 I'm going to guess that you've gone and blindly screwed with the ignition timing given the text of your post.... here's how to correct that: Before adjusting the ignition timing (also know as spark advance or ignition advance) you MUST resolve any stored diagnostic error codes. Then make sure you don't have an intake leak or a vacuum leak. Do you have any error codes? Diagnostic codes: http://www.cygnusx1.net/Supra/TechTi...ror_codes.aspx Setting spark advance (requires a timing light): http://www.cygnusx1.net/Supra/Librar...aspx?S=IG&P=20 And I'm sorry about your brother.... even with superior genetics in a relatively clean gene pool, these things do happen. Hah! __________________ 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 --->