Piston Slap: Total Re-coil?

Sajeev Mehta
by Sajeev Mehta

Ron writes:

1991 Honda civic, built 7/90 in Japan: Been a great car. Occasionally, won’t start. You crank it, it almost seems to want to start, then you get the check engine light and you can crank it forever and no good. Wait 2 minutes, or longer, and it starts right up. Sometimes you have to wait an hour though. Then it will just start fine, like it never had a problem.

Does not seem to be:

– computer (but did replace it, shop diag said it was bad, problem went away for over a year … and came back)

– injectors (at least according to shop manual diag procedure)

– filter (replaced)

– fuel pump

– phase of moon (kidding)

I do get a check engine light but it’s a pretty useless 8-bit car computer, I don’t even recall the flashing-lights-error-code any more, seemed to indicate it was not getting fuel. But I can hear the fuel pump spin up when I turn on the ignition. Most commonly happens when it’s a not-so-warm day, you drive it, it doesn’t really get that hot, the weather starts to get warm, you stop it, and … it may not want to start again. Moisture? More than anything it’s acting like vapor lock in the old days.

Any suggestions (other than “sell it” — I like this car and its big greenhouse). I have a 2007 fit, which I love, but evidently the newer fits are not so tight — they’re less of a go-cart than in former days. :-(

I did have a problem like this once that was paint floating around in a carb float bowl, but how could this relate to today’s cars :-)

Sajeev Answers:

First suggestion? Get some total recall on that flashing error light: the code is absolutely necessary in this case. Your mechanic replaced the computer, which is almost always akin to burning a pile of cash on the floor. Unless they show you a fully executed diagnostic tree that led to that conclusion, I’d avoid that place like a bad rash.

The code is helpful, but two things can also be checked in the meantime: fuel pressure and strength of spark. Since I don’t get paid the big bucks to surf the Civic forums on your behalf, find a way to hook a fuel pressure gauge to the fuel system, note the readings when cold and hot. Then compare them to the factory specified fuel pressure, which can be anywhere from 10-40psi.

Now let’s talk spark: sometimes you can pull a plug, reconnect it to the wire, fire up the car and test for weak spark. Other times, checking the specs (with a voltmeter) of the coil is necessary.

So what’s my final verdict? Bad ignition coil: I suspect it can’t take the heat.

Bonus! A Piston Slap Nugget of Wisdom:

Don’t bother getting a hotter aftermarket unit in a red or yellow container, the stock stuff is normally good enough for even modest engine upgrades. In my time with 5.0 Mustangs, the stock coil was good for 450-ish horsepower, easy. So always spend your money wisely. Unless you enjoy buying fancy parts with cool stickers you can slap on your ride. In that case, go on wit ‘yo bad self.

Send your queries to mehta@ttac.com

Sajeev Mehta
Sajeev Mehta

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  • Pete Madsen Pete Madsen on Jul 23, 2010

    I'm firmly in the igniter camp. Our 1992 Accord started being quite fussy about when it would or wouldn't start, and the igniter was the cause. It sounds like Civics of the era are similarly configured.

  • Microbus Microbus on Jul 24, 2010

    I'd like to thank all of you for the excellent suggestions. I did yank the main relay, found 3 bad solder joints, and redid them all. Still, I doubt that was the problem, and after more looking around I'm voting the coil. But I want to see it fail again after all the trouble of reworking the main relay. If the problem comes back, and the coil does not do it, I'll go for the coolant sensor and then the crank sensor and then the TPS and then the new car dealer. In response to one note: 1) Are you saying that this happens when the temperature in car is warm to hot or just after the engine has warmed up? You drive, say, 10 minutes, stop the car, won't restart. It's always quite warmed up by that point. 2) When you say that you can hear the fuel pump spin up, do yu mean when it doesn’t want to start, you can turn the key to the run position (not all the way to start) and hear the pump running? I can hear the pump running. It's a very characteristic noise in this car. It's a bit hard to hear at first because the seat belt motor of course engages and drowns out the fuel pump noise (this is once you've been caught after four months of perfect behavior, and have stopped listening each time you start the car). So you let the seatbelt do its thing, turn off the key, and listen again: 1. move key to run. Listen and you can hear the fuel pump run and stop, which I assume means it is up to pressure 2. Sometimes, if memory serves, and at my age it may not, you immediately get a check engine light. But that was very rare and usually only after a failed start. (no real good codes thrown after these events ... it's just an 8-bit micro in that engine computer!) 3. If not, turn key to crank, and in 10 seconds or so, you get a check engine light. I did try the 'floor it and crank' trick, being an old carburetor guy, although I knew it would not work ... It also acted like vapor lock (did I mention I used to own VWs? The early 60s ones would get vapor lock in the fuel pump sometimes ... you'd grab the screwdriver and loosen the fuel pump cap and spill gas all over the engine ... ah the old days. Usually it didn't catch on fire). I would in a moment of desperation pop the gas cap and vent the system. And, sometimes, after 2 mins, it would start. It's not an obvious one. It's been a good engine since I redid the main relay solder joints. ron

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