cold start and idle problems

mizuboi

New Member
Feb 26, 2007
86
0
0
cypress
okay so here is my problem. it started out with me backfiring alot and having inconsistent idle. so i went through the steps of re installing the cps and setting the timing and still nothing. so then i just for the hell of it put on a lexus afm and it almost completely settled the idle. however it fluctuates ever so slightly about 50 rpms. Also when it is going through a cold start it will fire right up and then shoot to 2k rpm then go all the way down to about 500 to 300 rpm as if it is trying to die then shoot back up and do this maybe one or two more times. i cannot figure out what is going on. none of this makes sense to me. if it helps i have code 24 and a vacuum leak.
 

89supracrazy

New Member
Oct 31, 2009
317
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0
wise
I would start with the code 24 which is intake air temp. sensor signal. Get rid of that code first and then I would check the iscv if it does not go away. Fix one code at a time. Don't assume it is something else. Take what the ecu gives you and go from there. The temp. sensor is built in the afm. Take the afm off your car and check it by this link. Take your meter and go from THA and E2 and go by the chart. One more thing a vaccum leak will not cause idle problems. Good luck.


http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?Section=FI&P=96
 

hvyman

Dang Dude! No Way Man.
Staff member
Apr 17, 2007
12,568
1
38
Fullerton,CA
Afm is prolly bad and the tps needs adjustment.

Take the lex off if you dont have 550's.

And fix the vacuum leak that will give you a bad idle as well.
 

89supracrazy

New Member
Oct 31, 2009
317
0
0
wise
Did you get rid of the code 24. If so check the cps connector and make sure the wires are not broken anywhere. They are bad to get baked by the exhaust manifold. Try pulling on them a little and see if the come off. Do it on both sides of the connector.
 

mizuboi

New Member
Feb 26, 2007
86
0
0
cypress
p1627543_1.jpg

well i've only got time to rip her apart at the moment but i've considered the possibility of a bad iscv and i took it out and looked and there might be something missing because i put this engine together a while ago and its been a long project. if nothing is missing in that picture then i'll just put it back and see if its the iscv and as for the code 24 i'll check that once i put it all back together with the original afm
 

hvyman

Dang Dude! No Way Man.
Staff member
Apr 17, 2007
12,568
1
38
Fullerton,CA
Clean that out it should be orange.

As for the vac leak not causing a bad idle iirc jetjock proved some thing else. I had a bad idle from the power steering vac line unplugged. Also vac leaks is at the top of almost every trouble tree in the tsrm.