'91 Coupe Inconsistent Idle

[Guest Kingsley]

Reprsentative out of 9 key starts - 2 slightly extended crank time before starting, 3 start and without accelerator help struggle and die, 4 start and settle in about 700 RPM idle. From normal idle to 1500/2500 RPM good performance. Excessive gas smell on occasions. Despite problems seems to always do one of the above.

ECM Codes: 01 - .42: 04 - 94: 06 - 109.1; 07 - 0.45; 08 - unsure as cannot read my writing; 10 - 11.08; 11 - 0; 12 - 0; 16 - 0; 10 - 11.8; 11, 12, 16,17 all - 0; 18 - unsure; 19 - 0; 20 - 128; 22 - 80; 23 - 42; 24 - 14.7; 27/30 - 0; 31 - 110; 98 - 8; 99-1424.

A bit confusing to me in view of all the zeros.

Underhood comment - remanned MAP sensor. Servo - one vacuum line intact, , one vacuum line fitting broken - tubing has broken piece and is open. Is servo function related to cruise only.

I look forward for the usual Forum expertise.

[padgett]

This looks more like key on/engine off readings (11 - engine rpm - 0 )

[Guest Mc_Reatta]

When was the last time you cleaned the Idle Air Controller and its seat?

Nothing jumped out of the numbers you posted but not sure what conditions you took them under, and some key items aren't there.

Try using the diagnostics to take an ECM snapshot and reporting that data for us to analyze.

Instructions can be found on page 8D-8 of the 91 FSM

[Guest Kingsley]

Padget - McReatta , thanks. Code readings are certainly questionable and the IAC was first logical thought. Very limited access to the car but will see if I can have another shot at it and will use the page 8D8 approach.

Edited September 21, 2011 by Kingsley (see edit history)

[Guest Kingsley]

Latest update. Had limited time and did not get snapshot as suggested but did a quick review of the data. No significant changes in readings from before but did get "ec No codes"

HOWEVER, in the course of this, with the key in RUN but engine not running,

during the time that was pressing the proper keys the ENGINE STARTS. Does not respond to accelerator at that time but does stop when key turned off. Did this several times. Does this bring into play Padgetts comments?

Excessive gas odor still present and, on occasions of slow start, it is helped by pressing the accelerator and clearing the excess gas.

For one thing, looks like it is the IAC but appears like something else is coming to play

More help, please.

Edited September 27, 2011 by Kingsley (see edit history)

[padgett]

Sounds automagical. "Does not respond to accelerator ". If running it must even if just to stall. That is a hardware connection and there is no choke.

[Guest Kingsley]

Padgett - thanks.

"Automagical" it must be because he called me to double check on it, went back and it did it again. He still thinks IAC -separating the weird action and working on the idle and excessive gas aspect of it.

[Guest Mc_Reatta]

Has the vacuum line to the fuel pressure regulator been pulled to see if it might be leaking gas into the TB? Could explain odor, hard starts, non response to accelerator.

Not sure what to make of self starting from the run position. What keys were being pushed?