memphis_mike_77

Okay I have a 2003 civic ex with stock 1.7 ~120,000 miles. The other day it started running really rough. Wouldn't rev past 3400rpm, lurches, bucks, etc... So I took it to the shop and they said it was throwing a MAP and IAC sensor codes. So I dropped 500 for the repairs, Like I said, extreme newb. About 3 days later, starts doing it again. I go to a different shop and they scan it with a SNAP-ON scanner and it throws a MAP code, but when they started it, the MAP sensor is working fine according to the diagnostic scanner. The VSS was bad, I knew that so I had it replaced. So sometimes the car runs fine for 2-3 days, then I go start it up and it starts doing the same thing. Sometimes it runs like that all day, other times it stops acting up after a few miles. This is a very sporadic situation. Also, the CEL comes on and goes off, but not always when the car is acting up, sometimes it comes on and the car runs fine. I have had it to the dealer, but it usually stops acting up before I get there. The mechanic told me that everything appears to be working fine when I get there (except for the false code) and that if it isn't acting up, he can't fix it. I know I am not crazy. PLEASE, has anyone had anything like this before? Thanks for any help. Also, I did check other threads, and I found some info, but nothing this jacked-up.

toyomatt84

iTrader: (1)

Have you checked your battery and alternator (both could be checked by a local automotive parts store, like AutoZone)? I ask this, because it seems as though your ECU is not storing codes, and that this would be the first step to verifying that. If they both seem to be functioning properly, I'd say your ECU is not functioning properly and could do with replacement.

memphis_mike_77

Yeah I have checked the battery and alternator. It has a fairly new Interstate battery on it, and the alternator checked out OK as well. As far as the ECU, it is storing the codes. The only reason I say that the MAP is working is because the scanner the mechanic had showed the pressure in the MAP increasing as he revved it a little. Last time I had it there, he scanned it and said that the codes it read were IAC, MAP and VSS. All of which I have had replaced since this whole thing started. A friend of mine said that maybe the catalytic converter could have some loose stuff in there moving around and blocking it off. One more thing, as far as the CEL goes, it doesn't come on and off while the car runs, only after I turn it off and it sits in my driveway overnight or for a few days (if that helps at all). Thanks for the suggestions though.

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toyomatt84
Have you checked your battery and alternator (both could be checked by a local automotive parts store, like AutoZone)? I ask this, because it seems as though your ECU is not storing codes, and that this would be the first step to verifying that. If they both seem to be functioning properly, I'd say your ECU is not functioning properly and could do with replacement.

It Wasn't Me

Sounds like a bad connection / loose terminal somewhere. Should be real fun tracking it down.


I highly doubt it's the catalytic converter. When they (or the O2 sensors) start to go, it'll generally throw a code.

memphis_mike_77

Looks like I need to start investigating connections, condition of wires, etc... Thanks, I will update if I can figure it out. Is it unsafe to drive the car when it does this? Am I doing possible damage to the new sensors that keep throwing codes? I do not want want to spend more money on DENSO sensors. Those things are WAY too expensive to keep replacing.

lazlong

Connectors on the sensor(s), grounds, and where the harness goes thru the firewall are the usual places.

It Wasn't Me

Personally, I wouldn't keep driving it until I figured out what was wrong with it and fixed it.

Which MAP code was it? P0107, P0108, P1128, P1129? I wouldn't entirely rule out the possibility of a fussy ECU, either.


Intermittent problems are such a PITA to figure out.

memphis_mike_77

Yes the "sometimes it is fine, sometimes it is not" problems are the worst. It has ran fine the last two days now, but the CEL is still on ( I have not reset it since the last time it came on). As far as driving it, I really don't have a choice, no other car to drive and the shifts I work are so long, it is impossible to do any troubleshooting after work because I have to be back up at 4am!! I can only hope it runs like it has been until this weekend, when I will have time to check it out. I had the IAC replaced, wonder if there is a broken or cracked vacuum line causing this. Thanks for the ideas, I will keep collecting suggestions and try them all this weekend.

PS. The MAP code was P0108

lazlong

Possible reasons for P0108:

1. Bad MAP sensor
2. Short between the sensor and ECM/PCM (loose connector or bad wire)
3. Bad or un-updated ECM/PCM

If you can, get a scan tool with data feed and see what the sensor is reading at idle when the car is at operating temp. It should read 2.9V or more.

memphis_mike_77

Status update: the light went out all by itself and has been running fine every since. Then it came on Saturday and still ran fine. I checked all the connectors and the wiring all looks good. I read elsewhere that the TPS can cause the MAP to geek out. Not sure about that one, but the troubleshooting continues. One more thing, when I shut it off and pulled the ECU fuse, it ran fine again, until this morning, same problem as before, but no CEL. If the ECU is bad, ideas about how to find out for sure? The dealer can't seem to find anything wrong with it, and everytime it starts acting up and I take it there, it usually starts running fine before I get there. About ready to pull my hair out!!!

suds1485

had almost the same problem. mine was more consistent and predictable though. no cel ran rough no codes. it was the foward o2 sensor. might want to look into that. just a thought

civichxtreme2

I had that happen in 2002 with an 01 Civic and they were new enough that the deaer had no idea what was wrong with it....they replaced the Motor, the ECU and still didnt fix it completly.....ended up being a clogged Catalytic Converter.

memphis_mike_77

Problem solved. lazlong, you were spot on. The ECM was shot. The Honda dealer was lucky enough to find a used one for me and did all the work. The bad news is that by the time they spent several hours diagnosing it, and making the repairs it cost me $850. They also told me that the sensors I had replaced at the other dealership may have been good all along, but since the other dealer trashed them, we will never know. The good news is that the car is running like brand new, no sputters or CEL. And..... the tech that worked on it felt so bad that I paid for the sensors that the other dealer said I needed , he did a full alignment, adjusted the clutch, rear brakes, lubed everything, and checked/tightened every nut and bolt on the car at no additional cost. He also apologized on behalf of the "other dealership" for being so quick to slap $700 worth of sensors on it and not really diagnose the issue. He said techs like that give dealerships the bad reputation they have for being careless and greedy. Super nice guy. Now that's customer service!!

EM2abe

Wish there were guys like that at every shop... Glad to hear it all worked out for you, at least. Sucks that you lost out on so much $$$.

memphis_mike_77

Yeah I hate that I had to spend $$$ on the unneeded sensors, but it runs like a new one, and the fuel economy is back up to 38+ mpg, so if nothing else I keep telling myself it will quickly pay for itself in gas savings especially at $4.00 a gallon!! Plus I think I have myself an excellent tech for future repairs/ advice, which is a real find anymore.