91 Berreta Rough Idle When Cold Before Closed Loop

AlkalineProdigy · 11-08-2007, 12:04 AM

Once it goes into closed loop it runs fine. First off the car sets no check engine light. So I took out the IAC vavle and put it back to default I reset the ecu by removing the battery cable. I took it ran it at between 35-40 so it would reset both the iac and ecu. But after a cool down it still has the rough idle. The fuel injector run runs a little rich and speradic before closed loop but again once it gets hot enough to go into closed loop it runs fine. Since its a 91 autozone or checker have the code checker for the computer but since its not showing the check engine light it might not even have any codes. Also I checked all the vacuum lines and they are all connected.

loosenut74 · 11-10-2007, 12:23 AM

Quote:

Originally Posted by AlkalineProdigy

Once it goes into closed loop it runs fine. First off the car sets no check engine light. So I took out the IAC vavle and put it back to default I reset the ecu by removing the battery cable. I took it ran it at between 35-40 so it would reset both the iac and ecu. But after a cool down it still has the rough idle. The fuel injector run runs a little rich and speradic before closed loop but again once it gets hot enough to go into closed loop it runs fine. Since its a 91 autozone or checker have the code checker for the computer but since its not showing the check engine light it might not even have any codes. Also I checked all the vacuum lines and they are all connected.

Datastream and bad O2 sensor...

AlkalineProdigy · 11-10-2007, 12:53 AM

What do you mean by datastream. Also shouldnt the O2 sensor not make a difference until the car is in closed loop. I thought that the ECU does take readings from anything other than the IAC untill it hits closed loop. Any help would be appreciated I really cant drive the car in the condition its in and this is my only car.

loosenut74 · 11-10-2007, 01:41 AM

Quote:

Originally Posted by AlkalineProdigy

What do you mean by datastream. Also shouldnt the O2 sensor not make a difference until the car is in closed loop. I thought that the ECU does take readings from anything other than the IAC untill it hits closed loop. Any help would be appreciated I really cant drive the car in the condition its in and this is my only car.

sound like you have been talking to too many back yard mechanics...lol.. I meant take it somewhere do a datastream, and i'll bet you you also have a bad 02 sensor...

AlkalineProdigy · 11-10-2007, 01:21 PM

well my question is why would the o2 sensor not work properly in open loop and fine in closed loop. I read in the mitchells that the ecu doesnt read anything other than IAC valve while in open loop. But I will check it out thanks for your help

jsgold · 11-10-2007, 07:00 PM

Just a couple of thoughts, are your plugs OK, wires, filters(air and fuel)? How about the intake hose on air box? One item is that maybe you have a weak coil pack on there and one plug may be firing weaker than rest. Possible injector problem too, but check your fire on each cylinder for a long 2" plus BLUE spark. If anything shorter than than you could have a weak one. Common problem. Again, just some thoughts...

AlkalineProdigy · 11-10-2007, 10:29 PM

Ill try all that and reply with what I find.

loosenut74 · 11-17-2007, 03:10 AM

Quote:

Originally Posted by AlkalineProdigy

Ill try all that and reply with what I find.

find out anything yet?...

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