92 Accord, Manual, 4cyl

Engine was running rough, backfiring. Replaced distributor cap, rotor, plugs, wires, and it ran better for a while (weeks). When problem returned, tried cap/rotor again, and car ran well for just a few miles. Just tried different brand cap/rotor with the same result. (But made sure to get that blasted lower screw tight, which it may not have been last time.)

Car tends to run better if allowed to idle 10-15 minutes before driving, but even that doesn't help eventually. Not clear whether or not rain really makes a difference.

Note that the exhaust is shot and has mostly been replaced bit by bit from just under the engine up to the muffler. Muffler is bad and could be clogged. There is no converter or anything else left in between, only pipe.

Thinking clogged muffler is at least one issue. Very little exhaust makes it out the tail (but there are leaks along the way, too). However, that doesn't seem to explain why replacing cap/rotor would help for a few miles nor why a 10 minute warm up would help.

Oxygen sensor? Something else in the distributor? This is supposed to be our back up vehicle, but the primary vehicle needs $400 in repairs before it can go on the road, so if there is something I can try that's cheap, that would be excellent news. Considering disconnecting the muffler, but all help appreciated.

 

With the engine cool, if you can get it to start and run fine immediately take a spray bottle with water and work systematically misting both electrical and gaskets for the intake. Listen to the engine while doing so. It may be that the plug wires are jumping spark, there is an electrical short or a leaking gasket on the intake. This is a simple and cheap place to start. If you can rule out electrical around the engine and suspect a leak in an intake gasket you can, again with the engine cool and running rough, carefully spray some throttle body clear along the intake seals. If the engine begins to run smooth for a minute and then goes back to running poorly repeat in the location that when sprayed made it run better. You caution when doing this! Engine must be cool and it is always a good idea to have a fire extinguisher on hand.

 

Thanks. Fairly sure it's not an electrical short.....at least not in the plug wires. Those are fairly new.....and a few weeks ago I tried spraying a sealant on distributor cap and wires.....no difference.

Will look into gasket possibilities, but I don't think that would explain why it runs great for 5-10 miles after replacing the cap/rotor. The one I just took off looked fine. We have a definite pattern of that happening, which strikes me as just plain weird. Even if the distributor is messed up, why would a new cap/rotor make such a big difference so briefly?

One extra note, there's a plastic cover over the distributor....fits on first, then rotor, then cap.....and it's damaged, a hole in the top about 1" x 1 1/2". Would think that would be fine as long as the cap has a good seal, but maybe not.

Also, when I had the distributor top exposed, there was a general browness about the connections. Hadn't looked at it before, so I'm not sure if it is "normal" or if there's some burning....or if it could be tied to the cause or is a result of the roughness.

Great car, and I'd love to just take it in to our mechanic and say, "Fix it all." Money isn't there. Cap and rotor were a stretch at the moment.

(As an aside, I read in the introductory message that some people won't answer messages that don't have the car info in the signature, but I'm having to sign on via Facebook and don't seem to get an option for that. We I tried to register the regular way, I got bumped to a spam removal site.....which told me they had nothing in their lists....but no way to get back and finish the registration.....and add a signature. So if anyone isn't answering because of that lack, there seems to be squat I can do about it at the moment....but will try registering again later.)

 

Suggest confirming that engine timing (crankshaft to camshaft) and ignition timing (distributor advance) are set correctly.

Weak spark from coil might cause these symptoms. A spark tester that allows gap to be adjusted can determine if weak spark is problem.

Low fuel pressure can cause your symptoms, but is much less likely. Check fuel pressure at the service bolt tap on the rail.

good luck

 

Dang, a basic timing issue never came to mind, although the problem seemed to come on fairly quickly. Still could be. Now, a timing light becomes the issue. Wonder if parts store will loan/rent on such since it looks like a good one is a price issue for us, as if anything isn't.

Also planning to take a closer look at the inside of the distributor for bad wires and get pictures.

At least it looks like decent weekend weather for tinkering and don't expect to need to drive anywhere.

Thanks for all the input so far.

 

You can check engine timing by aligning crankshaft pulley TDC mark to pointer on timing belt cover. Remove valve cover to check that camshaft alignment is also at TDC.

If OK, then use timing light to check distributor timing setting, 15 BTDC.

Spark testing would use a tool such as following:
Lisle-50850 Lisle50850 Lisle Ignition Spark Tester - 50850
Others are available.

A fuel pressure test kit can be rented at AZ or ORiellys, but the fuel rail adapter may have to be ordered online.

good luck

 

Spark Test Results: Got spark on coil and 3 cylinders. No visible spark on number 2 (if counting left to right).

Have not done any timing checks yet.

What does this result do to the diagnosis?

 

Okay, so make that cylinder/plug 3 when counting right to left.

 

Extra note: the engine light has never come on during all of this. (Not burned out....checked that.)

(And if I disconnect the wire to number 3, the most distinct sputter/misses go away.) But is this "replace distributor" or are there sensors to be checked? No visible damage to wires in or around the distributor.

 

Cylinders are numbered from driver's side (LH) to Pax side(RH), so No 3 is the third cylinder counting from driver's side to pax side.

Most likely reasons for no spark on No 3, and spark on remaining cylinders is defective distributor cap or No 3 spark plug lead. Spark should be shorting to ground somewhere; cap or engine ground.

good luck