Runs Bad in Open Loop
Thread Starter
Intermediate
Joined: Sep 2009
Posts: 49
Likes: 0
Runs Bad in Open Loop
Having a problem with my 92 Callaway. the car runs bad in open loop mode. If i start the car from dead cold, it idles ok untill i stab the gas, then when it comes down it starts shaking bad and idling bad. If i let it get up to temp and shut it off then turn it back on, it is in closed loop and runs great. Also, i am getting intermitant connection problems from my scantool. I have swapped the map and IAC with good known pieces and it is fine. The Coil and ICM are new. Any ideas? I am not getting any codes.
Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 207
From: Orlando FL
Make sure voltage coming off the wiper is smooth. Just because closed and WOT are good, doesn't mean the pick off voltage is. (But I agree if you changed it its probably not the problem).
I’m thinking of the ECT. But its probably OK if your temp reading on the spedo seems to be working normal.
Otherwise maybe the ECM or MAF.
I’m thinking of the ECT. But its probably OK if your temp reading on the spedo seems to be working normal.
Otherwise maybe the ECM or MAF.
Last edited by pcolt94; Sep 29, 2009 at 04:57 PM.
Thread Starter
Intermediate
Joined: Sep 2009
Posts: 49
Likes: 0
Make sure voltage coming off the wiper is smooth. Just because closed and WOT are good, doesn't mean the pick off voltage is. (But I agree if you changed it its probably not the problem).
I’m thinking of the ECT. But its probably OK if your temp reading on the spedo seems to be working normal.
Otherwise maybe the ECM or MAF.
I’m thinking of the ECT. But its probably OK if your temp reading on the spedo seems to be working normal.
Otherwise maybe the ECM or MAF.
Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 207
From: Orlando FL
This is just a shot in the dark. You might try un-plugging the MAF. Some people have had success with this procedure. If it runs better, you might be on to something.
But I’m not really sure if the ECM utilizes the MAF in open loop, as it does in closed loop.
**I stand corrected, MAP, but its the thought that counts.
But I’m not really sure if the ECM utilizes the MAF in open loop, as it does in closed loop.
**I stand corrected, MAP, but its the thought that counts.
Last edited by pcolt94; Sep 30, 2009 at 02:56 PM.
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Burning Brakes
Joined: Aug 2006
Posts: 1,061
Likes: 99
From: Seattle WA
I had the PROM go bad on my '87 Callaway (probably from my handling) so it's not out of the question. I doubt it's bad in your case though since you're getting no codes. Sounds like either a bad MAP sensor or vacuum leak somewhere. I'd also ohm your injectors, although when they go, you usually see the reverse - good open loop, bad in closed loop.