Greetings, all!

I’m have a misfire issue with my 93 Accord LX.

I get a lot of popping which seems to be backfiring thru the air box. If I accelerate, it gets better until I let off the gas, at which time I get more popping and loss of power.

It’s not much of a problem when cold, although it has stalled several times. It gets worse as the engine warms up, to the point where it’s almost undrivable.

We changed the sparkplugs, the sparkplug wires, and the distributor cap and rotor. I do get oil into the sparkplug wells, I just did the o-rings for the fifth time in the past 4 years.

The EGR valve had a lot of carbon, we cleaned it, didn’t seem to do much. I’ve been told there’s an EGR hose under the intake that needs to be cleaned. I looked on AllData and don’t see anything. Anyone know anything about this?

I’ve also been told it could be the distributor itself?

Anything else I should be looking at?

Thanks!

 

Suggest checking crankshaft/camshaft timing. Backfiring through intake is caused by either mistimed spark arrival or mistimed valve opening. Make sure spark plug leads are correctly routed; 1-3-4-2 sequence around distributor. #1 should be marked on distributor.

good luck

 

Sounds like a jumped timing belt, inspection of the timing alignment marks would be prudent.

 

Valve stuck open due to carbon buildup will also cause backfiring through intake. Compression check should show lack of compression on faulty cylinder.

good luck

 

Compression check is a good idea, because jumped timing would cause loss of compression on all cylinders.

 

Had a vacuum test done, everything was fine. I was told by the mechanic that a vacuum test would have shown if there was a problem with compression.

Changed the distributor today, didn't make a difference.

Seems like the only thing left is the timing belt?

 

A vacuum test is very subjective. A compression test will give you a better idea if you are having an issue on one cylinder.

 

Did a compression test today, readings were as follows:
#1 195; #2 205; #3 185; #4 190

 

Timing was fine, did a new timing belt anyway.

Car is still misfiring thru the airbox.

No clue what to check next!

 

Did you replace the seals in the valve cover and under the rocker assembly to stop oil from leaking into the spark plug tubes? Which spark plug tubes are getting oil in them?

Since the engine is running poorly, are you getting any check engine light codes? If yes, what are they?

Sounds like from your description that the problem is worse at idle, which could be a vacuum leak. Get a bottle of water and spray around the engine bay especially around the intake and vacuum tubes (stay away from the distributor). Does the idle change?

For ruling out the EGR, remove the vacuum tube from the EGR valve or use a hose clamp on the vacuum tube. Does the misfiring stop?