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Old 06-19-2002, 07:59 AM
algae1 algae1 is offline
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Join Date: May 2002
Posts: 27
86 560SEL cold start/rough idle

I continue to frustrate myself trying to find the source of this annoying cold start problem. I have diagnosed to the point where I observe the following:
-Engine cranks hard (about 7-10 sec) and then requires throttle blips to keep running first 30 sec or so.
-Idle is very much slower than spec at about 400 rpm and rough UNTIL the smog pump relay kicks out and the pump shuts off --as I understand it this is when Lamda takes over and at that point the idle smooths out (slowly) to about 700 rpm or normal.
-Car runs fine at low and high speed once "warm" and there is no smoke from exhaust at any time.
- I have checked EHA and Idle Air Valve for basic resistance and they are fine. I took the idle air valve out and checked it on the bench and it operates at 12 V. I put the VOM on the disconnected two pin conn to the idle air valve and started the car (it starts just the same as above) and the voltage (DC) bounces around intermittently at a peak of about 3 volts-- is this normal or should the idle speed controller be putting out a constant voltage level??

A few more questions for u experienced wrenches:
-Per SB's ground braking article in DIY can i get fault codes out of my 86 126 chasis--USA version??? factory docs are confusing on this point. If so, can i use Steve's technique on pin 3 of X11 and meausre the pulse widths??
-Since I have not been able to find any sensors bad is it possible that basic engine timing is so off that the car wont idle until the lamda takes over???If so, can that timing be adjusted???

Since my problem is at start up before Lamda - do the codes tell me much (if anything???)..

Any help appreciated.
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