Back fires thru intake

Chris Beck

Asked by Oct 20, 2013 at 07:08 PM about the 1988 Ford E-150 Econoline Ext

Question type: Maintenance & Repair

did a full tune up and changed tranny filter and fluid. it has old gas, but we added new gas (90 octane) with sea foam. Backfiring thru the intake. idles with a small miss, but backfires thru intake when you accelerate medium to heavy. just miss's with easy acceleration. I did some checking and found the EGR sol. got no change when i unplugged it. What do u think?

8 Answers


stuck intake valve, vacumn leak, cracked distributor cap, firing order wrong. if not for the miss, i would suggest accelerator pump. a few things to double check.


oops, thats injected isn't it. forget the accelerator pump.


Did you change plugs wires? If so are they in the correct order? Which engine do you have 4.9 , 5.0 or 5.8?

1 out of 1 people think this is helpful.
Chris Beck

yeah i double checked by the book. its all new plugs, wires, cap and button (MSD). I checked for vaccum leaks and didnt find any. the only thing i could find was the EGR sol and in the book it causes all the symtoms. so thats what led me to that.

Chris Beck

sorry, 5.0 and yes fuel injected

2 out of 2 people think this is helpful.
99,525 ---


Had it been sitting for a while without being driven? Or was is driving ok before the tune up?


Could be a lean air/ fuel mixture. Check for vacuum leaks. Pull the spark plugs and if the electrodes are white you've got a lean condition. HTH. -Jim

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