andyring

I've got a 2002 EX manual transmission. I've had it about six months, it has around 215k miles on it. Not knowing any history on it, I replaced the plugs shortly after I got it last fall and they needed it. Replaced the idle air control about a month ago too after that failed. OK, enough history because that's all I know of the history.

Here's the deal. Until yesterday, I haven't really had it up on the highway. But I'm working in another city three days a week for a few months. No problems starting up and hitting the highway for an hour. After driving at 65-75 mph for an hour and getting off the interstate into city traffic, suddenly I get P300 through P303, random misfire and cylinder 1, 2 or 3 misfire and it's very obviously sluggish and almost sounds like it's coughing. If I keep the RPM higher by deliberately using a lower gear, it seems to do fairly OK.

Once the car has cooled off at the end of the work day and I hit the highway back home, again it runs perfectly fine for the hour drive until I get off the highway and into slower city traffic. Then, same thing. A bunch of misfires.

Any ideas where to start?

kinakoes2

What plugs did you replace with? The D17 is known for being quite picky with plugs if they're not the OEM Densos (which are like gapped gold from the dealer, but only a ripoff from Amazon). Denso PN: PKJ20CR-M11, or Honda PN: 12290-PGE-A01. I had really fussy driveability with the new supposedly OEM-spec NGKs in my EX until I spent the dosh on the Densos.

BTW, same with the LAF sensor -- it's very, very pricey (again, much better on Amazon), but substitute at your peril. Denso PN: 234-9017.

andyring

I replaced with "Autolite Single Platinum Spark Plug" from Advance Auto Parts. They were about $3 each.

kinakoes2

There's your misfire.

The coil-on-plug systems used on the D17 are pretty particular about resistance (detailed below), and if the plug used isn't anywhere near the factory Densos (aaaaand a $3 Ford copper plug is definitely in that category)... it won't fire properly.

I have a theory, since this is also a problem on other cars with similar ignition systems... that Honda's ECM for the D17s may use in-cylinder resistance polling as a way to more accurately fuel. That requires a very narrow range of resistance in the plug itself, since it's the 'probe' that senses fuel richness/leanness in the chamber at TDC, when the CDI ignition system sends pulse to the electrode, but not enough to jump the gap.

This is why esp later ('04-'05) EXs use the ungodly-expensive PKJ20CR-M11 plug, which has a thicker side electrode to be more durable with all these free electrons spazzing out there. My old, angle-eroded Denso plugs were still better than the PZFR6F-11s I swapped in, though strangely (they're supposed to be the NGK equivalent according to Honda... though when you ask for a set of Honda-branded plugs from your dealer... you get the Densos, not the NGKs).

ezone

So you can feel it misfiring, and it's running badly in stop and go traffic?

If you still have them, I'd say to put the original plugs back in it and see if that gets rid of the misses. Maybe, maybe not.
Autolite is one of the few non-OE brands I really haven't seen problems with. (Shhhh, don't tell anyone!)


IF you have a single ignition coil getting flaky or going completely dead when it heats up, it can set miss codes for other cylinders (our V6 engines do this a lot, usually set codes for ALL cylinders).

Carry your code reader and check the instant the CEL comes on, see if there is only one cylinder misfire code. Swap that coil to another cylinder, clear the code, and run it to see if the miss moves to the other cylinder.

These don't use ion sensing ignition.

kinakoes2

Ah - - so if they don't, then it's just a particular with the CDI COPs on the D17 then? Must have a certain narrow range of resistance to work properly? What Hondas like the Autolite plugs? (my exp w/ Autolites on even my Ford Escort SE were inferior to the Bosch +4 Fusions I soon replaced them with).

ezone

The ones using them with no complaints, no misfires.

The cheapo DangerZone pushed Bosch Platinum (+3, +4, etc.) made me a lot of money as a driveability troubleshooter.
I will still rapidly install all of your Bosch Platinums directly into the dumpster from 20 paces with one of these



Don't get me wrong, there is a time and place for real Bosch plugs.

andyring

I don't have the previous plugs, but I did go ahead install a set of the OEM NGK ones suggested above at about $10 a pop.

WOW! Talk about a heck of a difference! Now I need new front tires because I have SOOOO much more power. I barely tapped the accelerator and suddenly I had molten puddles of rubber in my driveway. And my mileage went through the roof too! I ran a quick calculation and am finally hitting that coveted 100+ MPG too. Well worth the money!

OK, seriously though. I did install the NGKs on Saturday. Today when I hit the highway for an hour and exited to city streets, the car continued purring like a kitten. No misfires at all. When I removed the Autolites, my dad looked at them and commented that it looked like they were running pretty hot.

kinakoes2

Sounds like my local medical facilty. 'What drugs do I need to avoid to prevent this from happening again?'

'The ones that don't cause it to happen again'... Advice that helps avoid a crisis, is always helpful in answering a question.


On Hondas, maybe (hell they didn't run well with NGKs, which to me are the cream of the quality crop with spark plugs). I've never seen a single application that I've used Fusions in, where they cause any kind of driveability problem. My Paseo was an older speed-density FI (MAP sensor) with fixed valve timing and primitive mapping; Fusions worked a treat (1-2 mpg gain and much better at low rpm over the OEM single-electrode NGKs). They worked a treat on the MAF-equipped, 2V, crap-build-quality Escort SOHC (again, a 1 mpg gain, just with plugs... but it isn't hard to get a gain on that turd of a motor). Dunno about your gimme customers, but I don't think they used Fusions (which are iridium versions of the +4).

And btw, there is no +3. The "+x" refers to the number of ground electrodes. There's a +2 and a +4. I found the regular +2 and +4 Bosch plats to make no difference to the NGK single-elec plats, so never bothered with them. The Fusions were the only plugs that actually made a difference... plus, a single set lasted me three years without any change in mpg, just a check on torque every year or so. Good plugs, I endorse them.

ezone

I start describing stuff and they just tell me to quit watching the drug commercials.