97 HX Misfire and Low Compression
10-12-2010, 05:46 AM
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97 HX Misfire and Low Compression
So I've done my searching and found a lot of useful information, and I've tried many of the recommended things. None have worked yet, and before I started doing some major work I wanted to get some opinions.
Car is a 97 Civic HX, 5 Speed, 292k miles
Non-CA emissions.
My car has been throwing a CEL since I got it a few years ago, and I had tried plugs/wires/cap/rotor a couple of times to no avail, so I just gave up and drove it as is. Now I have decided to go back and really put some effort in to getting it up to snuff. Even with the misfire and CEL back then I was still getting around 35mpg. Now my FE is down to about 30mpg.
I reset my ECU and drove a bit and the CEL was on again. All cylinders misfiring, random cylinder misfire, and insufficient EGR flow. Pulled off my EGR and HOLY SH*T was it clogged. I mean the runners were completely solid with carbon. So I went through the whole procedure on cleaning the EGR system. That made it better, but I was still getting a misfire after I reset the ECU again.
Cleaned out the ICV, smoother transition to idle RPM when the neutral decelerating. Still misfiring.
Lucas injector cleaner in tank. No change.
Seafoamed the car. Vacuum line, crankcase, and gas tank. Smoke mostly out from under the hood. Saw how fu**ed my exhaust manifold was (cracked damn near in half at the 02 sensor). Changed the exhaust manifold and catalytic converter. I figured after 300k it could use to be changed. Definitely running smoother after this, but still getting a misfire. And I think I still have an exhaust leak, but now it is leaking near the flex pipe under the main cabin.
Changed plug/wires/cap/rotor again. Plugs looked like they were running lean. They looked pretty bad actually. Replaced with all Honda stuff. DENSO plugs, Sumitomo wires, Hitachi cap and rotor. Used dielectric grease on the wires.
It ran a whole day with no misfire, the longest in about 3 years its went.
The next morning I started the car, it idled high for a couple minutes as it always does on startup, then when it came down in RPM to idle it misfired for a few seconds (CEL was blinking) then when I gave it some gas it went off and never came back on. It will not misfire when it is fully up to temp.
This is repeatable. Start car after sitting overnight. About two minutes later after the initial high RPM part, when it brings the idle down, misfire until I give it some gas and drive for a minute to warm it up, then no more misfire. It misfires at damn near the exact same stoplight every morning on my way to work.
Checked compression.
Cyl 1: 135 psi
Cyl 2: 80 psi
Cyl 3: 160 psi
Cyl 4: 170 psi
I know the specs, and I know that's not good, that's terrible. I figured around 160/170 due to the miles. But 135 and 80 is not what I wanted to see. With some oil in number 2, I got it up to 135.
It seems weird to have two rings (especially number 2) so far off from the other two. I'm wondering if it is a head gasket issue? It would explain the crazy low compression in cylinder 2, or I might just have no ring left haha.
No sweet smell or white smoke in the exhaust though. I do lose a little coolant here and there, but I also burn a little oil here and there.
The fact that it also only occurs at that one time when it's warming up also has me wondering about the coolant temp sensor maybe needing to be replaced.
Any suggestions are greatly appreciated. Sorry about this being long as hell, but I figured be thorough.
Car is a 97 Civic HX, 5 Speed, 292k miles
Non-CA emissions.My car has been throwing a CEL since I got it a few years ago, and I had tried plugs/wires/cap/rotor a couple of times to no avail, so I just gave up and drove it as is. Now I have decided to go back and really put some effort in to getting it up to snuff. Even with the misfire and CEL back then I was still getting around 35mpg. Now my FE is down to about 30mpg.
I reset my ECU and drove a bit and the CEL was on again. All cylinders misfiring, random cylinder misfire, and insufficient EGR flow. Pulled off my EGR and HOLY SH*T was it clogged. I mean the runners were completely solid with carbon. So I went through the whole procedure on cleaning the EGR system. That made it better, but I was still getting a misfire after I reset the ECU again.
Cleaned out the ICV, smoother transition to idle RPM when the neutral decelerating. Still misfiring.
Lucas injector cleaner in tank. No change.
Seafoamed the car. Vacuum line, crankcase, and gas tank. Smoke mostly out from under the hood. Saw how fu**ed my exhaust manifold was (cracked damn near in half at the 02 sensor). Changed the exhaust manifold and catalytic converter. I figured after 300k it could use to be changed. Definitely running smoother after this, but still getting a misfire. And I think I still have an exhaust leak, but now it is leaking near the flex pipe under the main cabin.
Changed plug/wires/cap/rotor again. Plugs looked like they were running lean. They looked pretty bad actually. Replaced with all Honda stuff. DENSO plugs, Sumitomo wires, Hitachi cap and rotor. Used dielectric grease on the wires.
It ran a whole day with no misfire, the longest in about 3 years its went.
The next morning I started the car, it idled high for a couple minutes as it always does on startup, then when it came down in RPM to idle it misfired for a few seconds (CEL was blinking) then when I gave it some gas it went off and never came back on. It will not misfire when it is fully up to temp.
This is repeatable. Start car after sitting overnight. About two minutes later after the initial high RPM part, when it brings the idle down, misfire until I give it some gas and drive for a minute to warm it up, then no more misfire. It misfires at damn near the exact same stoplight every morning on my way to work.
Checked compression.
Cyl 1: 135 psi
Cyl 2: 80 psi
Cyl 3: 160 psi
Cyl 4: 170 psi
I know the specs, and I know that's not good, that's terrible. I figured around 160/170 due to the miles. But 135 and 80 is not what I wanted to see. With some oil in number 2, I got it up to 135.
It seems weird to have two rings (especially number 2) so far off from the other two. I'm wondering if it is a head gasket issue? It would explain the crazy low compression in cylinder 2, or I might just have no ring left haha.
No sweet smell or white smoke in the exhaust though. I do lose a little coolant here and there, but I also burn a little oil here and there.
The fact that it also only occurs at that one time when it's warming up also has me wondering about the coolant temp sensor maybe needing to be replaced.
Any suggestions are greatly appreciated. Sorry about this being long as hell, but I figured be thorough.
10-12-2010, 11:59 AM
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Re: 97 HX Misfire and Low Compression
Haha, unless I can get a K20A2 I'm not swapping engines. I'll drive it at 30mpg with a misfire until the other 3 cylinders are at 80psi too. At least until I get past 300,000 miles.
10-12-2010, 04:38 PM
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Re: 97 HX Misfire and Low Compression
I let the car cool down for about 8 hours and did a valve adjustment. Most of the gaps were not open wide enough, so I opened them up to .010" exhaust and .008" intake. So far check engine light is staying off.
I'm also going to recheck the timing. I'll keep this updated for documentations sake.
I'm also going to recheck the timing. I'll keep this updated for documentations sake.
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