pyronina

Hi - I have a 2006 Civic with the R18A1 engine. It has a brand new short-block (cracked block thing), which has 30K miles on it now. The rest of the engine, head assy and all included has a total of 292K miles. The engine runs PERFECTLY 99% of the time. I still get almost 40 mpg. ISSUE: Whenever I go to high alt, like from 1000ft elev (where I live), to 4000 ft elev (like going over the ridgeroute from LA to Bakersfield), when I come down to lower elev, the CEL comes on and I have almost no power. I pull over, turn everything off, take key out, turn back on, everything is fat, dumb and happy. Run perfectly again. ALSO - every 6-8 weeks or so, just driving in the LA/OC area, the CEL comes on (no flashing). If I attach my OBD computer, it shows P0301-4, P0300 (misfires, random misfires). I clear it, and I am good for another 6-8 weeks. What's going on? Failure of an emissions component? The only thing I've done to address this was to R/R the plugs, which made no diff. Still runs great.

ezone

Check valve clearances?

pyronina

Hi ezone - thanks for the quick advice. I took your advice and others who mentioned it, and checked all valve clearances today. There were 14 nominals right in the lash window, but two valves were just a little big by about a mil. I fixed those ones. So, I don't think lash was the problem... ugh.

ezone

Is this when the high altitude misfire codes began?


Can your scanner display freeze frame data?


Your altitude related situation doesn't yet sound familiar to me, I can only make guesses right now

pyronina

Well, I had to go and look at my log book to find that one out: At 258K miles, I had the "civic block seepage" problem. Had the new short block installed.
Then at 262K miles, I had the first P0300-4 codes. This while on flat ground near home. About a month or so later is when I went up north over the 4000 ft elev ridgeroute and the CEL started flashing. Ever since then, misc CEL light on every 6-8 weeks driving on flat land (it almost seems like the ECM has a counter, like counting up the misfires, and then puking them out when they reach a certain number???). Then every time crossing the ridgroute N and S for like 3X so far. More recently I went to Palm Springs out Interstate 10 and through Banning which is 2349 ft elev., and the CEL started flashing. It seems that altitude (lower O2) just pisses it off for some reason. Or it is just finicky in it's old age now. But man, otherwise it runs so perfect. Power, great mileage. It sounds exactly like the first day I took delivery of it.

Freeze frame: Yes, my OBD computer does. I'll try that option when it comes on again.

Thanks so much for the help!

pyronina

Hi ezone - Here are the freeze frame numbers:

Fuel Sys 1 CL
Fuel Sys 2 CL-Fault
Calc Load (%) 20.39
ECT degrees 185
STFT B1 % -4.69
LTFT B1% -0.78
MAP (inHG) 8.86
Eng RPM 2944
Veh Speed (mph) 68
Spark Adv degrees 45.00
IAT degrees 68
MAF lb/min 1.01
TPS % 18.04

ezone

Looks like probably happened at steady highway speed...What code did it set this time, or which code was this data stored with?

I don't have anything but guesses. If the misfire condition is not consistent enough to be easily duplicated, it's damn tough to pinpoint anything.

Injector connectors, terminals (contacts) lost their grip over time, now breaks connection intermittently?
Coil connectors, same deal?
Wiggle, jiggle and shake wire harness sections while it's running, note anything that makes it change how it runs?


Ever lost your gas cap or left it off and had it rain, or ran through a car wash?

pyronina

Hi ezone - The codes are the same every time: P0300 and P0301-4. I thought about the concept of unplugging connectors and plugging back in, to make a good connection - as you suggested. I deal with computers every day at work and just turning them off, and reseating RAM, misc cards, connectors, plugs, etc., fixes unknown "broken" stuff. I am now treating my car the same way. The real baffling thing is the high altitude situation. I theorize some/many components (yeah I know it has 294K miles on it) are maybe on the brink of failure, and the high alt takes it over the edge...? At least I have the comfort of knowing that if I have good power/performance, and still get 38-40 mpg, things are wonderful. The answer is no to the gas cap, rain and car wash situation(s). When the CEL came on for the very first time ever (about a year ago), I suspected the gas cap. I stopped and took it off and put it back on, tight. The CEL went away. I'll keep you posted as new things arise. Thanks again for helping with this, I appreciate it.

ezone

I kinda wonder about valve guide wear at that mileage.....

D17VTECPOWER

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pyronina

This last weekend I made the trip up north towards Fresno which had me cross the 4000 ft ridgeroute and such. The surprising thing is, the CEL did not come on at all, like it had before EVERY time I went over that pass. I finished my trip just south of Yosemite in Oakhurst where I went over another pass of 3000 ft and then settled at 2200 ft. No CEL !!!! But, the next day I went out to go into town and I started out and like 2 minutes later the CEL came on flashing. I stopped right away and turned everything off. I then went on my way, the CEL was just lit then. So, I am rally baffled now. The engine was still very cold and the CEL starts flashing??? I thought that in open-loop, anything goes. Of course a lot of raw fuel is going down the exhaust pipe at that point. I thought the CEL just gets engaged after closed-loop happens, and things are warmed up to a degree. Anyways, the CEL stayed on for 2 days of just short trips to town of a couple of miles, then one day it went off, by no action of my own. The next day I left for home in SoCal and drove south towards the ridgeroute again. I went up and over the 4000 ft pass, and then on the way down (back to lower elev of around 500 ft or so) it came on flashing. I stopped and then went again, and made it home. Checked my mpg and was getting 39. I'll chk my wiring and grounds as D17VECPOWER suggested.... Valve guides: I'd imagine I'd be burning some oil if I had worn guides. I don't burn any that I can measure.

D17VTECPOWER

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pyronina

Hi D17VTECPOWER - Thanks for the response and suggestion. I'll check it out...

D17VTECPOWER

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