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Old 09-21-2020, 09:41 AM   #3
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AstraFasta has a spectacular aura aboutAstraFasta has a spectacular aura about
Join Date: May 2015
Posts: 745
Default Re: Airflow issue? Please help.

Misfire might be from spark plugs (check service manual as replacement is 25k or 30k). If plugs are not replaced on schedule, the increasing gap tends to stress and kill the coil pack. So those are typical issues for misfire. If the plugs are new (and properly gapped) you may need a coil pack which is easy to replace.

You can't see the edges of the butterfly valve or the corresponding part of the TB without opening the TB 90 degrees.

We clean the TB without removing it from the car. We remove the plastic intake hose. Clean exposed area of TB with TB cleaner (carburator or brake cleaner can destroy coatings and MAF cleaner might be too gentle).

Then have someone sit in car, push and hold accelerator to the floor (engine is not running). If it is hot outside, the butterfly valve might not open FYI; I don't physically push it open to avoid breaking it or knocking it out of calibration.

Once butterfly valve is open we can access the edges and back of the butterfly valve and deeper into the TB, particularly where the butterfly valve parks, which probably are the most important.

Removing the TB could give you a better cleaning I suppose but is more work.

***Be really careful not to lose fingers as the butterfly valve is heavily "sprung".
To clean the MAF sensor, use only MAF sensor cleaner.

On my purge valve, one of the hoses was difficult to fit so it was split at the valve end and not fully seated. Check that out.
The valve cover gasket and the PCV flap (integrated into the valve cover) are common failure items. As FS noted, tell-tales to leaking valve cover gasket are oil on top of the sparkplugs (at ceramics) or you can see oil weeping below the valve cover, or leaks in that area. PCV issues might be seen when you remove oil dipstick or oil cap. None of these quick tests are definitive.
Some people had issues with the gas cap or the refill tube but I don't remember the codes there.
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