Intermittent CEL codes (Injector & O2 Content) -- solve this mystery please
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Honda-Tech Member
Joined: Mar 2002
Posts: 2,314
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From: Midwest, USA
Intermittent CEL codes (Injector & O2 Content) -- solve this mystery please
Hello,
I ran into a weird problem yesterday that I'd like some input on.
While turning through a green light, the following events happened at the same time / very close:
- The motor began to sound/feel like it was about to stall, and power was quite limited. The more that I applied the gas, the more it would shake. The shaking was proportional to RPM, suggesting that one of the cylinders might not be firing(?) (hence the lack of power)
- The CEL came on. Later on, I was able to recover the two codes: Injector and Oxygen Content
- My wideband O2 sensor was reading very lean (between 17:1 and 20:1 AFR)
- If I turned the car off completely and restarted, I noticed the following sequence
- Started right away like always
- Ran SMOOTH / NORMAL for 5-10 seconds, without a CEL. I'm unsure of what the wideband reading was during this time
- CEL comes on, and then the motor runs rough & AFR goes back to the 17-20 range
I was able to limp it home without any problems (but the above behavior continued). The car sat for a few hours, then I finally got around to looking at it. I started by removing the battery cable for ~10 minutes to reset the ECU. Upon starting the vehicle, it ran normal for several minutes. I thought the problem went away after resetting the ECU, but I started the car an hour later to drive somewhere and the problem was back.
12 hours later, I go out to my car to go to work, and sure enough, the problem is completely gone the whole way to work (about a 30 minute drive). No CEL or anything. Note that I didn't reset the ECU this time.
4 hours later I go to lunch, and it's back to the same list of problems. I'll be able to spend more time on it tonight to test things like injector resistance, etc, but I wanted to post this in case anyone had any bright ideas before I start physically debugging this.
Things I've checked so far:
- No white smoke (or any smoke) out of exhaust on acceleration, etc
- No coolant loss or overheating
- Visually inspected wiring in engine bay and near ECU
- Verified spark plug wires are snug and in good condition
My current setup:
- '91 CRX Si
- OBD0-1 Conversion Harness
- OBD1 P28 ECU w/ Uberdata
- 450cc DSM injectors w/ stock resistor box
- Wideband O2 sensor w/ narrow band output connected to ECU
- JRSC @ 12psi
- Half a tank of gas
- All of the wiring, tuning of ECU, timing, etc HAS NOT BEEN TOUCHED for at least two years, and it has given me nothing but a reliable ride since I originally installed everything
My thoughts / theories:
Since it seems to run fine now and then, I think it's safe to assume that there is no physical damage to the motor. I'm convinced this is something with the sensors or injectors.
Although I don't recall for sure, I'm almost positive you couldn't really drive a car running with a 20:1 AFR. So assuming that one of the cylinders isn't firing, I think it must be a fuel injector. I doubt it's a spark issue, because otherwise my mixture would be reading richer than average.
What's currently puzzling me is why this is intermittent. While it could always be a lose wire, I tend to doubt that's the case here.
ALL INPUT IS APPRECIATED
Thanks
I ran into a weird problem yesterday that I'd like some input on.
While turning through a green light, the following events happened at the same time / very close:
- The motor began to sound/feel like it was about to stall, and power was quite limited. The more that I applied the gas, the more it would shake. The shaking was proportional to RPM, suggesting that one of the cylinders might not be firing(?) (hence the lack of power)
- The CEL came on. Later on, I was able to recover the two codes: Injector and Oxygen Content
- My wideband O2 sensor was reading very lean (between 17:1 and 20:1 AFR)
- If I turned the car off completely and restarted, I noticed the following sequence
- Started right away like always
- Ran SMOOTH / NORMAL for 5-10 seconds, without a CEL. I'm unsure of what the wideband reading was during this time
- CEL comes on, and then the motor runs rough & AFR goes back to the 17-20 range
I was able to limp it home without any problems (but the above behavior continued). The car sat for a few hours, then I finally got around to looking at it. I started by removing the battery cable for ~10 minutes to reset the ECU. Upon starting the vehicle, it ran normal for several minutes. I thought the problem went away after resetting the ECU, but I started the car an hour later to drive somewhere and the problem was back.
12 hours later, I go out to my car to go to work, and sure enough, the problem is completely gone the whole way to work (about a 30 minute drive). No CEL or anything. Note that I didn't reset the ECU this time.
4 hours later I go to lunch, and it's back to the same list of problems. I'll be able to spend more time on it tonight to test things like injector resistance, etc, but I wanted to post this in case anyone had any bright ideas before I start physically debugging this.
Things I've checked so far:
- No white smoke (or any smoke) out of exhaust on acceleration, etc
- No coolant loss or overheating
- Visually inspected wiring in engine bay and near ECU
- Verified spark plug wires are snug and in good condition
My current setup:
- '91 CRX Si
- OBD0-1 Conversion Harness
- OBD1 P28 ECU w/ Uberdata
- 450cc DSM injectors w/ stock resistor box
- Wideband O2 sensor w/ narrow band output connected to ECU
- JRSC @ 12psi
- Half a tank of gas
- All of the wiring, tuning of ECU, timing, etc HAS NOT BEEN TOUCHED for at least two years, and it has given me nothing but a reliable ride since I originally installed everything
My thoughts / theories:
Since it seems to run fine now and then, I think it's safe to assume that there is no physical damage to the motor. I'm convinced this is something with the sensors or injectors.
Although I don't recall for sure, I'm almost positive you couldn't really drive a car running with a 20:1 AFR. So assuming that one of the cylinders isn't firing, I think it must be a fuel injector. I doubt it's a spark issue, because otherwise my mixture would be reading richer than average.
What's currently puzzling me is why this is intermittent. While it could always be a lose wire, I tend to doubt that's the case here.
ALL INPUT IS APPRECIATED
Thanks
Thread Starter
Honda-Tech Member
Joined: Mar 2002
Posts: 2,314
Likes: 1
From: Midwest, USA
Re: Intermittent CEL codes (Injector & O2 Content) -- solve this mystery please (keebler65)
ttt...
I'm still stumped on this one. It's still going back and forth between acting completely normal with no CEL, to CEL and running like crap. ALso once in awhile it will be a hybrid: CEL but it runs perfectly normal (even full boost).
I will need to verify the CEL codes don't change between those two situations, but I'd still like some thought-provoking ideas if possible
I'm still stumped on this one. It's still going back and forth between acting completely normal with no CEL, to CEL and running like crap. ALso once in awhile it will be a hybrid: CEL but it runs perfectly normal (even full boost).
I will need to verify the CEL codes don't change between those two situations, but I'd still like some thought-provoking ideas if possible
Honda-Tech Member
Joined: Mar 2006
Posts: 587
Likes: 0
From: Lima, oh, USA
Re: Intermittent CEL codes (keebler65)
thought provoking ideas... well i can think of some. If the afr's are going to 20 r so when the check engine light comes on . IT would be a apparent it is some sort of metering device (map, sluggish o2) and it throwing the code for fuel injector and or 02 content these means there in a problem not just in the injector and o2 but the metering in this particular area. my 02. i think it has something to do with a map sensor issue (dead spot) then trips it in to limp mode to run off the o2 but if you do no have 02 its going to go off coolant temp. then if its warm its going to lean out the mix. thats just my 2 cents.
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