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I keep getting CELs for misfires on my 2005 Jeep Liberty 3.7L. Sometimes it’s the P0300 random misfire, sometimes it’s a specific cylinder – nearly always 1 or 2. If I clear the code it will stay off for a few days, but it always comes back.
I’ve changed the plugs and coil packs, which hasn’t helped. Next item on the agenda is a compression test, but before I do that, I’d be grateful for anybody to watch the video below and tell me if they think they can hear the engine misfiring. The Jeep actually drives OK, I’m not getting any noticeable issues with it, but I want to get to the bottom of this.
The video starts in the engine bay (with a lot of wind noise unfortunately), then moves to the tailpipe. Note that at 35sec and 52sec the exhaust sound changes as the AC clutch cycles. Is that normal? I’ve never actually listened to the exhaust as the clutch cycles before.
[video]http://www.youtube.com/watch?v=NfyarLstLrE[/video]
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Hard to tell from the video. Try a power balance test.
have you checked the spark? it could also be fuel.
see if this link helps.http://www.ericthecarguy.com/faq/solving-automotive-performance-issues
It had a new OEM fuel pump installed just a few months ago, but I guess that doesn’t rule out an injector problem. I haven’t done a spark test, but the coil packs and plugs are new OEM parts as well – do you reckon it’s still worth testing the spark?
If the computer can identify a specific cylinder (even though sometimes the wrong cylinder) it is misfiring.
I’m not doubting the validity of the CEL codes, but I’m interested to know if the sound of the engine suggests a *constant* misfire. I’ve had it suggested that if it’s an intermittent misfire, then it’s actually more likely to be electrical than an internal mechanical issue. What I’m worried about is that it’s a mechanical issue, which will obviously be expensive to repair.
The Jeep drives as smoothly as it has ever done, I’m not experiencing any noticeable driveability issues.
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