98 z -28 idle surge issues
04-22-2016, 07:42 PM
#1
98 z -28 idle surge issues Just picked up a z28 convertible a couple weeks ago and we can't figure out this idle issue for the life of us!
It's was giving us the lean in bank 1 and bank 2 codes along with idle air control idling high. Noticed the connector was coming apart so we put a new IAC motor and new connector on, . Cleared the code and it's still doing it.
Sometimes the car is fine and runs like it should, but when it decided it's going to surge it runs very hot and the air pump kicks on and off.
When it runs properly it runs at the temp it should and no issues.
Also tried an idle relearn and it did nothing.
All the vacuum lines look good but noticed the brake pedal is really stiff. Didn't know if it was related because vacuum. Only other thing I can see is the throttle body blade is missing 2 screws that hold it in the housing and gets hung up a little. Car is completely stock!
Have read a bunch of related threads but haven't found the answer.
Any ideas?????
It's was giving us the lean in bank 1 and bank 2 codes along with idle air control idling high. Noticed the connector was coming apart so we put a new IAC motor and new connector on, . Cleared the code and it's still doing it.
Sometimes the car is fine and runs like it should, but when it decided it's going to surge it runs very hot and the air pump kicks on and off.
When it runs properly it runs at the temp it should and no issues.
Also tried an idle relearn and it did nothing.
All the vacuum lines look good but noticed the brake pedal is really stiff. Didn't know if it was related because vacuum. Only other thing I can see is the throttle body blade is missing 2 screws that hold it in the housing and gets hung up a little. Car is completely stock!
Have read a bunch of related threads but haven't found the answer.
Any ideas?????
04-22-2016, 08:46 PM
#2
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Sounds like you are facing several issues, any/all of which could be causing your idle problem. The throttle blade being loose can certainly cause odd idle behavior when it gets hung up in the bore. The lean codes can be due to either a weak fuel system or a vacuum leak, but the vacuum leak sounds more likely if you're noticing poor vacuum assist from the brake booster.
You'll need to properly address these issues before further assessing the idle concern. You may find that repairing these problems will also fix your idle problems.
You'll need to properly address these issues before further assessing the idle concern. You may find that repairing these problems will also fix your idle problems.
04-22-2016, 10:15 PM
#3
Sounds like you are facing several issues, any/all of which could be causing your idle problem. The throttle blade being loose can certainly cause odd idle behavior when it gets hung up in the bore. The lean codes can be due to either a weak fuel system or a vacuum leak, but the vacuum leak sounds more likely if you're noticing poor vacuum assist from the brake booster.
You'll need to properly address these issues before further assessing the idle concern. You may find that repairing these problems will also fix your idle problems.
You'll need to properly address these issues before further assessing the idle concern. You may find that repairing these problems will also fix your idle problems.
I think we decided we are going to pull the in manifold and install new gaskets and while we are back there change the oil pressure sensor,. Also change the pcv valve and check those lines again etc. Hopefully that does the trick.
We did notice a hissing sound when the car was hot on the passenger side after it was shut off. Sounded like it maybe coming from the intake Pcv area.
Only does it when running poorly and overly hot.