Ok guys, this one has been driving me nuts. I need some serious help.

What I have:
1989 Toy 2x4, xcab, SR5, V6, (3vze), AC, cruise, PPS (progressive power steering.) The engine has just been rebuilt.

I have a copy of the factory service manual.

The problem:
When trying to set the timing I can not get the engine to ‘kick down’ by jumping the test points.

What I’ve done:

Checked and replaced the temp sensor. It works and the engine kicks down when warmed up.

New TPS.

MAF tests fine

I have and have tried a newer ECU and it acts the same with either.

AC and PPS idle up circuit unplugged.

Distributor tested fine. There was one wire in the harness that originally was open, but it has been fixed.

I’ve had the wiring harness out and have tested a good portion of it point to point.

I’ve run through the factory service manual and have tested the ECU point to point and every number comes out right except for IDL to E2 is low @ about 4 volts.

I am assuming that this is an electrical problem as there is something over riding the test circuit.

Any ideas, help or abuse appreciated.

 

You said that "when the engine is warmed up it kicks down" Thus, you don't have a problem if it's warmed up and she kicks down! You should be checking your timing w/a warmed up engine and the diag. connector jumped. If when warm it doesn't kick down it's usually your TPS but you said you replaced your TPS, did you spec it out w/a multimeter? Could be your wiring of the TPS not necc. your TPS. Good Luck!

 

Yes, when it gets warm the temp sensor works and the idle kicks down a bit. I did test and set the TPS and circuit with an ohm meter. The one test that did not pass was at the ECU terminals with the ignition switch on points IDL to E2 are supposed to be 8-12 volts (if I remember right) and mine test at 4 volts.

When jumpered at the test terminals (engine warm) the dash check engine light flases an 'ok' code BUT the idle timing does not change. I can not adjust it under +10 degrees. I have set the distibutor back one cog, but this does not help. I am guessing that I am missing a mssed up circuit that over rides the timing. I have unplugged the AC and PPS (progressive power steering)cicuits. I do not know where else to check.

:pat:

 

Recheck the TPS, only measure the resistance at the TPS itself. You need to have the IDL-E2 setting within spec to make the ECU aware that you are at idle:

http://www.4crawler.com/4x4/CheapTricks/TPS/index.shtml

 

Yes, I measured at the TPS when I installed the new one. My point about the low voltage is that I have gone through everything the factory service manual said and then some and have not yet figured out the problem. The low voltage is the only indicator of a source of the problem, but the manual says nothing of low voltage only 'no' voltage at the ecu.

I am a newbee to the forum, but not to beatin Yotas into submission. My professional mechanic friends scratch their heads at this one, too. I was just hoping that somebody in cyberland had an idea that would spark a solution.

THX