BAC ok, but never turns on. AC stalls car on new engine.
Thread Starter
Rotary Freak
Joined: Sep 2001
Posts: 1,500
Likes: 7
From: Lawrenceville, ga
BAC ok, but never turns on. AC stalls car on new engine.
Heres one for the EXPERTS.....
(Cause this non-turbo expert is stumped.....)
Okay, I have just installed a new engine with good compression in this 1991 convertible.
It runs just fine, idles at 750.
HOWEVER.....
The AC stalls it.
Th Power steering effects idle more than it should.
(and the headlights too.)
I have:
Adjusted the timing all over the place.
Tested (OK) and adjusted the TPS.
Adjusted the idle. (750)
Compression tested. (all faces/both rotors pulse equal & strong.
The O2 Sensor is tested and good.
The water sensor is good.
the air intake sensor is good.
the BAC has the proper resistance and +12v makes it open.
I used the factory service manual and the Haynes manual to test all I could find.
the only thing i can think of is a mystery vaccum leak, (which i checked for by tearing down and re-assembling the intakes)
OR
The BAC signal is not being sent.
At idle, I used a scope on the connector to the BAC and saw that it was pulsing +5v at 50-40% duty cycle.
HOWEVER, when I remove the BAC connector at idle and the FSM says that the idle should INCREASE.
It makes no difference.
The car idles the same and behaves as if i never remove the BAC connector.
BUT..
The ECU will show the "failed BAC" code when I remove the connector and check the codes.
There was a time that I had it sustaining idle with the AC on as if the BAC was coming on, but the idle surged.
As far as any timing oddities....
there is this one thing....
The timing light shows that the yellow mark will alternate from 4 degrees advanced to normal over and over. This can be made to go away.
and i have doe that.
however, its still dies at IDLE!!!
ARGH!
HELP!
(Cause this non-turbo expert is stumped.....)
Okay, I have just installed a new engine with good compression in this 1991 convertible.
It runs just fine, idles at 750.
HOWEVER.....
The AC stalls it.
Th Power steering effects idle more than it should.
(and the headlights too.)
I have:
Adjusted the timing all over the place.
Tested (OK) and adjusted the TPS.
Adjusted the idle. (750)
Compression tested. (all faces/both rotors pulse equal & strong.
The O2 Sensor is tested and good.
The water sensor is good.
the air intake sensor is good.
the BAC has the proper resistance and +12v makes it open.
I used the factory service manual and the Haynes manual to test all I could find.
the only thing i can think of is a mystery vaccum leak, (which i checked for by tearing down and re-assembling the intakes)
OR
The BAC signal is not being sent.
At idle, I used a scope on the connector to the BAC and saw that it was pulsing +5v at 50-40% duty cycle.
HOWEVER, when I remove the BAC connector at idle and the FSM says that the idle should INCREASE.
It makes no difference.
The car idles the same and behaves as if i never remove the BAC connector.
BUT..
The ECU will show the "failed BAC" code when I remove the connector and check the codes.
There was a time that I had it sustaining idle with the AC on as if the BAC was coming on, but the idle surged.
As far as any timing oddities....
there is this one thing....
The timing light shows that the yellow mark will alternate from 4 degrees advanced to normal over and over. This can be made to go away.
and i have doe that.
however, its still dies at IDLE!!!
ARGH!
HELP!
HAILERS
Joined: May 2001
Posts: 20,563
Likes: 27
From: FORT WORTH, TEXAS,USA
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