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ESR · Nov 20, 2012, 06:58 AM

About 6 weeks ago I put Marvel Mystery oil in my gasoline according to the directions, and a weird new symptom developed over the next couple of days.. I noticed a sputter in the engine every now and then. It was as if one explosion of one cylinder would mess up every couple minutes. It only was apparent at idle.

It continued at that rate until yesterday when I pulled out onto a road relatively quickly. It seemed that I had perfectly miss-timed my acceleration from a stop just as one of those little sputters happened because the car kind of kept sputtering. It basically ran really rough. Then I noticed that if I didn't accelerate while driving, the engine normalized and ran smoothly. But, when I accelerated again at any normal rate, it would dive back into the sputtering. If I backed off, it would smooth out again.

After about 5 minutes of this, the car basically smoothed out and seemed to be fine, but it is still running a little rough and kind of coughs every now and then, especially at idle. When I rev the engine, it seems to die out for the most part.

Any thoughts?

Thanks!

perkinsj88 · Nov 20, 2012, 07:13 AM

My vote is that it was just coincidence, the marvel had did not cause this. Could be quite a few things, let it continue to sputter until you get a CEL and pull the code, more to go on then.

TxGreaseMonkey · Nov 20, 2012, 09:33 AM

. Install new spark plugs (NGK only), if they have not been changed in 25,000 miles or 3 years.

. Change fuel filter.

Candian1987 · Nov 20, 2012, 10:29 AM

I think that the mystery oil did exactly what it was meant to do but because they tell you to add it to your tank. Not only does it clean your injectors but it also cleans all the crud in the tank and then pushes it through your fuel lines, filter and finally your injector. I would check fuel presssure, then inspect the fuel filter for signs of it being restricted and go from there.

ESR · Nov 20, 2012, 12:21 PM

The spark plugs are only about 2 months old. I think it may be a clogged fuel filter..

ESR · Nov 21, 2012, 01:21 PM

Changed fuel filter and the problem is the same as it's been the last couple days :( I guess I'm not sure how to check fuel pressure, but it seems like it's OK because it runs fine at high speeds (as long as I'm not trying to accelerate).

TxGreaseMonkey · Nov 21, 2012, 01:46 PM

I'm back to suspecting the ignition system. I would replace the Ignition Control Module (ICM) and coil, located inside the distributor, if they have not been replaced in 120,000 miles or 10 years, whichever comes first. This will likely solve the problem.

ESR · Nov 21, 2012, 01:49 PM

I just replaced the ICM/ignitor and the distributor coil about 5,000 miles ago..

TxGreaseMonkey · Nov 21, 2012, 01:53 PM

Good. If it's an old distributor housing, one of the internal sensors may be bad. Additionally, I only recommend genuine Honda distributor housings--all others are suspect and unreliable.

Have you checked the timing with a strobe light? The timing may be retarded too much. Loosen the 3 distributor mounting bolts and rotate the distributor housing slightly counter-clockwise (CCW), if you don't have a timing light. This may solve the problem. Afterwards, remove the 7.5A Back-up fuse, in the under hood fuse box, for 10 seconds.

TxGreaseMonkey · Nov 21, 2012, 07:00 PM

Other possibilities:

. Leaking intake manifold gasket. Use a spray bottle of water to confirm and isolate any leaks. A leaking intake manifold can cause misfires.

. Check for a faulty Engine Coolant Temperature (ECT) Sensor.

. Check engine compression. Remove all of the spark plugs and use a compression gauge to check for poor compression in one or more of the cylinders. If an exhaust valve is adjusted too tightly, it can burn or crack.

ESR · Nov 22, 2012, 08:19 AM

Whew, I guess I have a lot to do this "holiday" :)

ESR · Dec 2, 2012, 07:31 PM

*chagrined* Replaced the spark plug wires and the car is now purring :)

TxGreaseMonkey · Dec 2, 2012, 08:30 PM

Good work.