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Back Firing and Popping

6.1K views 5 replies 3 participants last post by  mukan121  
#1 ·
So my 84 has been running great until recently. I hadn't really driven her for for about 2 months. I finally got a chance to take her for a drive. I had about a1/4 tank so I stopped and topped off using premium. In the past I would fill up with plus, but taking some advice I decided premium would be better for the turbos. Now I am not sure it was the change in fuel grade, but at full throttle, she starts to backfire and pop. She idles great and at lower rpm drives great. What do you guys think?
 
#2 ·
Check your spark plugs for fouling , (so clean them)
Possible check your leads and distributor cap and rotor.

Check vacuum line towards your distributor (although you'd have to nice a flat spot in acceleration if the advancer is the issue)

Vacuum line to your catalytic air injection can occasionally cause it too.
Are the backfires when you let off the gas and revs drop to around 3-2.000?
 
#3 ·
Thank you for the quick response!
I feel like an a**! Went under the hood, and discover the vacuum line from the under the distributor had come off. Put it back on and she runs great again! Hopefully I did not cause any damage.