Cold Start issue on 89GT
06-08-2023, 10:58 AM
#46
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I assume that you are using the stock NB02 to drive the LH and not the WBO2 in NB simulation mode.
After the engine has run for 5 minutes, is it still lean at idle?
06-08-2023, 01:35 PM
#47
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Sharktuner systems rely on separate wideband O2 sensor systems.
06-08-2023, 01:50 PM
#48
Former Sponsor
Words of caution: "Good used" had a whole different meaning, when these cars were not all 25+ years old. For about the first 10 years (or so) they were in business, I used lots of "good used" parts from 928 International.
Now I tend to hope for a "rebuildable core"
All I can tell you is that your symptoms are the classic MAF failure symptoms.....exactly.
However, it is certainly possible that some other issue is causing your symptoms...but I can not think of what component would do this, especially given the list of things you've already done.
"Two cents of experience gets one two cents worth of advice."
You got my 2 cents...
Now I tend to hope for a "rebuildable core"
All I can tell you is that your symptoms are the classic MAF failure symptoms.....exactly.
However, it is certainly possible that some other issue is causing your symptoms...but I can not think of what component would do this, especially given the list of things you've already done.
"Two cents of experience gets one two cents worth of advice."
You got my 2 cents...
Last edited by GregBBRD; 06-08-2023 at 01:56 PM.
06-08-2023, 03:38 PM
#49
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06-09-2023, 11:21 AM
#50
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Thread Starter
What I want to know is if the lean idle condition occurs in open- or closed-loop operation or both. The gauge reading isn’t conclusive. The WBO2 sensor is quicker and provides info far earlier than the NB02.
I assume that you are using the stock NB02 to drive the LH and not the WBO2 in NB simulation mode.
After the engine has run for 5 minutes, is it still lean at idle?
I assume that you are using the stock NB02 to drive the LH and not the WBO2 in NB simulation mode.
After the engine has run for 5 minutes, is it still lean at idle?
Last edited by kmascotto; 06-09-2023 at 11:25 AM.
06-09-2023, 11:24 AM
#51
Rennlist Member
Thread Starter
Words of caution: "Good used" had a whole different meaning, when these cars were not all 25+ years old. For about the first 10 years (or so) they were in business, I used lots of "good used" parts from 928 International.
Now I tend to hope for a "rebuildable core"
All I can tell you is that your symptoms are the classic MAF failure symptoms.....exactly.
However, it is certainly possible that some other issue is causing your symptoms...but I can not think of what component would do this, especially given the list of things you've already done.
"Two cents of experience gets one two cents worth of advice."
You got my 2 cents...
Now I tend to hope for a "rebuildable core"
All I can tell you is that your symptoms are the classic MAF failure symptoms.....exactly.
However, it is certainly possible that some other issue is causing your symptoms...but I can not think of what component would do this, especially given the list of things you've already done.
"Two cents of experience gets one two cents worth of advice."
You got my 2 cents...
06-09-2023, 11:35 AM
#52
Rennlist Member
Cold starting difficulty and less of a problem with a warm engine is a clear sign of ISV problems . When the engine is warm and uidling, if you switch on the ac and the motor dies that is pretty much a confirmation of such. I thought that possibility was dismissed earlier in the thread?
06-09-2023, 04:19 PM
#53
Rennlist Member
Thread Starter
Cold starting difficulty and less of a problem with a warm engine is a clear sign of ISV problems . When the engine is warm and uidling, if you switch on the ac and the motor dies that is pretty much a confirmation of such. I thought that possibility was dismissed earlier in the thread?
When I removed the intake to change the TPS (a month ago) I added the ISV extension. I'm going to go back and take if off again an see what happened.
06-09-2023, 04:27 PM
#54
Rennlist Member
If the ISV is not functioniung there is a carefully calibrated air gap that supports hot idle with the ac off. Switch the ac on- the load increases and a working ISV seamlessly keeps the rpms stable. If the ISV is not working you should see the rpms drop or possibly see the motor die on you. If this does not happen then I doubt the ISV would be non functional.
06-09-2023, 04:50 PM
#55
Rennlist Member
Thread Starter
For years I ran the ISV with the spring clip removed- never had a problem. Then I made an extension with modern type quick release clip a few years ago and no problem with that.
If the ISV is not functioniung there is a carefully calibrated air gap that supports hot idle with the ac off. Switch the ac on- the load increases and a working ISV seamlessly keeps the rpms stable. If the ISV is not working you should see the rpms drop or possibly see the motor die on you. If this does not happen then I doubt the ISV would be non functional.
If the ISV is not functioniung there is a carefully calibrated air gap that supports hot idle with the ac off. Switch the ac on- the load increases and a working ISV seamlessly keeps the rpms stable. If the ISV is not working you should see the rpms drop or possibly see the motor die on you. If this does not happen then I doubt the ISV would be non functional.
06-09-2023, 05:16 PM
#56
Rennlist Member
Kent,
You might be able to get a metallic probe or preferably stethoscope onto the body of the ISV and listen to see it makes any noise when applying a 12 volt signal and releasing it.
On the other hand if you have a scope you could also check to see if the signal is getting thorugh.
You might be able to get a metallic probe or preferably stethoscope onto the body of the ISV and listen to see it makes any noise when applying a 12 volt signal and releasing it.
On the other hand if you have a scope you could also check to see if the signal is getting thorugh.
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kmascotto (06-10-2023)