2000 AP1 engine misfire / poor running
09-26-2013, 07:09 PM
#1
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Thread Starter
2000 AP1 engine misfire / poor running
I am out of ideas, both good and bad. I am putting this up here in case anyone has any new ideas or suggestions. I am open to anything at this point. The car has ~140,000 mi. Thanks to anyone and any ideas, I appreciate it.
Problems/Symptoms
- Engine misses pretty bad at idle. When cold it seems fine for about 30 sec or 1 min, then it shows.
- Car is down on power, probably over complete range. The very first sign of the problem was a sound change in VTEC while on track. The car was 8 sec slower (BFR lap) than last year when it ran well).
- If I roll at ~5 mph in 2nd or 3rd gear and floor it, the engine misses so bad that the car won't accelerate. This can't be reproduced in the garage when in neutral (i.e with only engine load it will accelerate).
- I am basically getting no codes from the factory ECU. Every once in a while I would get a misfire code, but when cleared it would not come back even though the engine was missing horribly.
- The Haltech is not giving any codes either, but it did give P0373 once (never returned). This was the reason for thinking crank sensor problem.
What I have done so far (none of these made any real difference in operation and symptoms)
1) Emptied gas tank and got new gas, from different station.
2) 4 New spark plugs (NGK)
3) 4 New ignition coils (Denso)
4) Adjusted valve lash (did have to change almost all of them, but only a few thousandths).
5) Verified intake and exhaust cams are timed together (dots toward each other at TDC).
6) Verified cams are timed correctly with crank (dots together at TDC and white TDC mark on crank pulley matches mark on timing cover).
7) Checked spark timing with a timing light at idle and it matched what the computer was specifying.
8) Removed 4 injectors, had them professionally cleaned (report shows them all good) and replaced them.
9) Added fuel pressure gauge to rail and fuel pressure checks out (~52 psi).
10) Unplugged knock sensor (in case it was backing off timing).
11) New crank sensor (Honda).
12) Cleaned VTEC solenoid piece (I originally thought it was only VTEC based on the track experience, but now it seems to be much bigger so this likely didn't help).
13) Cleaned IACV.
14) New TPS (Omni) as existing TPS failed the voltage check I found on these forums.
15) Checked compression in all 4 cylinders. All within spec (~220 psi).
16) Replaced factory ECU with Haltech Pro Plugin (actually, did this early and most tests were done with this ECU for better analysis).
17) Used the on-board MAP sensor in the Haltech unit instead of the factory MAP sensor.
18) Unplugged each cam sensor independently (not sure what this would really tell me). It was interesting as if the intake one is unplugged, the engine shuts off. If the exhaust one is unplugged, nothing happens.
19) Switched on and off the O2 closed loop control in Haltech, with no noticeable change.
20) I tried the "lock spark timing" feature in Haltech too, to see if I could find a timing that would work well, but nothing changed (still missed bad).
Problems/Symptoms
- Engine misses pretty bad at idle. When cold it seems fine for about 30 sec or 1 min, then it shows.
- Car is down on power, probably over complete range. The very first sign of the problem was a sound change in VTEC while on track. The car was 8 sec slower (BFR lap) than last year when it ran well).
- If I roll at ~5 mph in 2nd or 3rd gear and floor it, the engine misses so bad that the car won't accelerate. This can't be reproduced in the garage when in neutral (i.e with only engine load it will accelerate).
- I am basically getting no codes from the factory ECU. Every once in a while I would get a misfire code, but when cleared it would not come back even though the engine was missing horribly.
- The Haltech is not giving any codes either, but it did give P0373 once (never returned). This was the reason for thinking crank sensor problem.
What I have done so far (none of these made any real difference in operation and symptoms)
1) Emptied gas tank and got new gas, from different station.
2) 4 New spark plugs (NGK)
3) 4 New ignition coils (Denso)
4) Adjusted valve lash (did have to change almost all of them, but only a few thousandths).
5) Verified intake and exhaust cams are timed together (dots toward each other at TDC).
6) Verified cams are timed correctly with crank (dots together at TDC and white TDC mark on crank pulley matches mark on timing cover).
7) Checked spark timing with a timing light at idle and it matched what the computer was specifying.
8) Removed 4 injectors, had them professionally cleaned (report shows them all good) and replaced them.
9) Added fuel pressure gauge to rail and fuel pressure checks out (~52 psi).
10) Unplugged knock sensor (in case it was backing off timing).
11) New crank sensor (Honda).
12) Cleaned VTEC solenoid piece (I originally thought it was only VTEC based on the track experience, but now it seems to be much bigger so this likely didn't help).
13) Cleaned IACV.
14) New TPS (Omni) as existing TPS failed the voltage check I found on these forums.
15) Checked compression in all 4 cylinders. All within spec (~220 psi).
16) Replaced factory ECU with Haltech Pro Plugin (actually, did this early and most tests were done with this ECU for better analysis).
17) Used the on-board MAP sensor in the Haltech unit instead of the factory MAP sensor.
18) Unplugged each cam sensor independently (not sure what this would really tell me). It was interesting as if the intake one is unplugged, the engine shuts off. If the exhaust one is unplugged, nothing happens.
19) Switched on and off the O2 closed loop control in Haltech, with no noticeable change.
20) I tried the "lock spark timing" feature in Haltech too, to see if I could find a timing that would work well, but nothing changed (still missed bad).
10-01-2013, 07:49 PM
#5
Registered User
Thread Starter
Thanks for the ideas.
Near stock. NA. Intake (AEM knock-off) and exhaust (I think A1 is stamped on the mufflers, but I've never heard of them) done by previous owner. I don't believe it has been rebuilt, but there was evidence the valve cover was off. I was guessing someone did a valve lash adjustment.
The catalyst is an interesting thought. I will keep that in mind and potentially take a look.
No leak down. I don't have the stuff I need in my garage, so had not gone to that length yet.
I had a friend come over and help for a while and we have a working theory, but I need to run a few tests to know for sure. I will post the results so anyone can learn from my experience.
Near stock. NA. Intake (AEM knock-off) and exhaust (I think A1 is stamped on the mufflers, but I've never heard of them) done by previous owner. I don't believe it has been rebuilt, but there was evidence the valve cover was off. I was guessing someone did a valve lash adjustment.
The catalyst is an interesting thought. I will keep that in mind and potentially take a look.
No leak down. I don't have the stuff I need in my garage, so had not gone to that length yet.
I had a friend come over and help for a while and we have a working theory, but I need to run a few tests to know for sure. I will post the results so anyone can learn from my experience.
10-01-2013, 09:59 PM
#6
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Load related misfires are usually ignition related, but since you have replaced the ignition coils and the plugs it is unlikely. I would look toward the cat as well and if not I would also check your fuel pressure under load. It would not be the first pump I've seen loose pressure under demand. Also can you tell if it is a single cylinder miss or does the entire engine lay over?
10-02-2013, 03:42 AM
#7
Did you clean the MAP sensor channel? Maybe it's clogged. (don't know if this will help, but you've done so much already)
Also throttle cable adjustment.
How did you clean the IACV? There are 2 ways, one good, one bad.
Can you install the stock ecu and see if it spits out any CEL?
Check vacuum?
Also throttle cable adjustment.
How did you clean the IACV? There are 2 ways, one good, one bad.
Can you install the stock ecu and see if it spits out any CEL?
Check vacuum?
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10-02-2013, 07:45 AM
#8
I have the same kind of thing " - If I roll at ~5 mph in 2nd or 3rd gear and floor it, the engine misses so bad that the car won't accelerate. This can't be reproduced in the garage when in neutral (i.e with only engine load it will accelerate)."
Mine just bogs a little and then dissapears at the revs starts rising and making speed.
Changed sparkplugs to new oem, coilpack to Okada.
It stayed the same.
Mine just bogs a little and then dissapears at the revs starts rising and making speed.
Changed sparkplugs to new oem, coilpack to Okada.
It stayed the same.
10-02-2013, 09:16 AM
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I had what I thought was a clogged cat. Turned out not to be the case, but billman suggested removing the pre cat
O2 and hanging it with a zip tie safely out of the way, then going for a ride. If the cat is truly clogged, the once trapped exhaust will go out of the O2 bung and should result in, hopefully noticeable, performance improvement.
You can also get a 15 psi gauge and tap 1/4" npt holes pre and post cat to measure across it, but that's def the hard way.
Not sure what a leak down would really tell you if your comp checked out ok. And I guess you have the gauge to watch real time fuel pressures, so the intermittent pump failure is probably not it.
Man, gotta hate not getting dtc's.
your mention of pulling the exhaust cam sensor without it making a difference made my ears perk up though. Can anyone verify if this sensor being unplugged is supposed to be that uneventful??
Just for shits and gigs have you tried bumming a stock ecu key combo from someone? Might help with code delivery. Edit: I see where crissko already suggested this.
O2 and hanging it with a zip tie safely out of the way, then going for a ride. If the cat is truly clogged, the once trapped exhaust will go out of the O2 bung and should result in, hopefully noticeable, performance improvement.
You can also get a 15 psi gauge and tap 1/4" npt holes pre and post cat to measure across it, but that's def the hard way.
Not sure what a leak down would really tell you if your comp checked out ok. And I guess you have the gauge to watch real time fuel pressures, so the intermittent pump failure is probably not it.
Man, gotta hate not getting dtc's.
your mention of pulling the exhaust cam sensor without it making a difference made my ears perk up though. Can anyone verify if this sensor being unplugged is supposed to be that uneventful??
Just for shits and gigs have you tried bumming a stock ecu key combo from someone? Might help with code delivery. Edit: I see where crissko already suggested this.