Mechanics

WORKING ON A . SOMETIMES IT WILL IDLE BUT IDLES VERY ROUGH. DOESN'T HAVE ANY CODES COMING UP.

2002 Jeep Liberty • 203,000 miles

I have already replaced the CPS, CKS, 2 coils, all 6 plugs and cleaned the TB and IAC. Issue has improved but not by much. It is smoking and smells of gas when running.
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JimsAuto
May 9, 2012.



First scan for codes and check fuel pressure including fuel pressure after shut down. Then check for a vacuum leak or hoses disconnected or holes in them

Hmac300
May 9, 2012.
I have already scanned and don't have any codes, also checked fuel pressure and vacuum hoses. One weird thing was while trying to figure this out had fuel injector on #2 disconnected from harness and coil and plug out on #1 and the engine smoothed out a lot.

Tiny
JimsAuto
May 10, 2012.
You cancelled the companion cylinder by doing that and it will run smoother.

Did you do a compression test?

Roy

ASEMaster6371
May 10, 2012.
Haven't yet, does this one recommend operating temp for compression check or not(I don't have a book that covers the 3.7 V6)

Tiny
JimsAuto
May 10, 2012.
Also just talked to the customer and was told a compression check was done about 4 or 5 months ago and was fine then.

Tiny
JimsAuto
May 10, 2012.
Because of the miles also check cam or followeres for wear, maybe a lobe is rounded off and you get compression but valves aren't workin g right. That wold not show up on a compression check or fuel pressure regulator may be screwed up as well

Hmac300
May 10, 2012.
Did compression check today and #1 cyl was 0, all others were between 155 and 175 psi after 6 strokes(first stroke was above 130 on all but #1). Looks like either a valve is stuck open or a valve spring broke. Customer deciding what he wants to do now

Tiny
JimsAuto
May 10, 2012.
It may be more thatn that. That may not be a free spin motor so look for engine damage inside cylinder. Or pump oil in cylinder and seeif compression comes up at all.

Hmac300
May 10, 2012.
I used a small LED snake light to look in through the plug opening and all I could see was the piston, of course don't get to see much that way. Plus with the research I have been doing this model Jeep with the 3.7 has a sludge problem and valves like to stick open. Also some cases of broken valve springs.

Tiny
JimsAuto
May 10, 2012.
You'll see when or if you get teh valve cover off

Hmac300
May 10, 2012.