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Frosted Flakes

By Frosted Flakes
in Ask A GM Technician

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Frosted Flakes Enthusiast

Frosted Flakes

Posted
  • Author
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I know everyone has said to replace the manifold gasket, but I did the carb cleaner thing, no change in idle. Starts and idles fine, no hesitation in the motor when stomping on it. I want to know for sure before I throw more money at this beast. I know I have a lean in the motor somewhere, is there anything else thats been a culprit for this, outside of replacing the manifold gasket?

 

I don't mind doing the work, just hate wasting time on stuff that doesn't fix the problem. Me and youtube can tear this whole motor apart if I have to!

Jsdirt Senior Enthusiast

Jsdirt

Posted
Posted

Any air that gets into the engine without going through the MAF sensor, & throttle body is a problem. Fun part is trying to find where.

txab Senior Enthusiast

txab

Posted
Posted

The reason I mention intake gaskets is because that was my problem at one time. Similar situation 75+ mph and would only flash when coasting, especially downhill. Gaskets cleared the issue. Is it your problem, I dunno. That's why you go step at a time and rule things out

Frosted Flakes Enthusiast

Frosted Flakes

Posted
  • Author
Posted

How many steps are there? I thought I've went threw all the steps!! This is why I'm a welder, you screw something up, cut it and reweld…..done!

 

I'm going to my trusted mechanic who has a good friend who he trusts, so this should be interesting what he come back with. If he tells me intake gasket, I'm going to kick myself into next week!

efritz Enthusiast

efritz

Posted
Posted

You cannot accurately diagnose the problem by spraying around the manifold, the rise in idle speed will be quickly corrected by the IAC and you will get an inaccurate test. It really sounds like the intake gaskets are bad. Can you plug in a scantool and get us freeze frame information at the time of the DTC setting so we can see fuel trims and O2 sensor data?

rdnkcpa Enthusiast

rdnkcpa

Posted
Posted

What about hooking up a vacuum gauge and see what it is pulling at 2500 RPM and above? That will give you a very general idea of the health of the engine, and a vacuum gauge is pretty cheap.

 

Eric the Car Guy on Youtube has some nice videos on using the vacuum gauge and using the scan tool to look at fuel trims and O2 sensors voltage.

Jsdirt Senior Enthusiast

Jsdirt

Posted
Posted

Yep - between him and ScannerDanner, you'll have everything you need to know about troubleshooting.

 

Gotta love Youtube. Been watching vids all week as I dive into my first German car repair.

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