Jeep Garage  - Jeep Forum

Jeep Garage - Jeep Forum (http://www.jeepgarage.org/forums.php)
-   Troubleshooting/Problems (http://www.jeepgarage.org/f181/)
-   -   3.7 misfire- no start (http://www.jeepgarage.org/f181/3-7-misfire-no-start-57802.html)

Death 04-04-2013 07:56 PM

3.7 misfire- no start
 
First off, hi to everyone.
This is my first post here.

Here's my issue.
I was driving and my engine started to chug while trying to overtake another vehicle. CEL flashed then turned solid. I let off the gas and pulled to a side street to check it out.
Mid turn on to the side street my engine died out.
It would not restart, cranks, starts to catch then dies.

I had it towed home.

I have checked the fault codes and the only code was P0301 cyl-1 misfire.

I took coil 1 and put it on cyl 3, and put plug 1 in to cyl 2.
Cleared CEL and tried to start, trying to set a second or pending fault code on either cylinder 2 or 3 to determine my problem.

I can't get it to set another code... BUT... the truck will also not start.

So...

Things that I know;
Spark plugs are 5,000km old all gapped at 0.40in
There is compression
There is fuel
I can get the truck to run for a few seconds feathering the gas with a heavy dead miss.
When I took the spark plug out of 1 I pulled the fuel pump fuse and blew out all of the excess fuel in the cylinder to prevent fuel wash, then cranked the engine to build up oil pressure again (to coat the oil rings). When I re-install the plug and crank this is the closest it gets to running.

Things I dont know;
Why, if the engine is misfiring, will it not set a code?
Does this engine have known problems with coils or coil wiring?
Am I missing something?

Before changing the plugs I had a slight mis with the engine loaded between 70 and 75 km/h, once and a while at idle.

After changing the plugs the mis went away.

I just put $3k worth of parts on my truck and dont want to spend anymore than I have to to get it back on the road.

I am thinking bad coil, but the last time I changed a bad coil (different car) the engine would still run off of the 5 working cylinders.

Any help would be appreciated immensely.
Thank you in advance.
Mike.

2005JGC 04-04-2013 09:49 PM

Re: 3.7 misfire- no start
 
If you cleared the codes it will wipe the adaptive numerator, no misfire codes will set without the adaptive numerator learned which is done by 5 or 10 hard decel's.

You may want to pull the valve cover off, fortunatly the bank 1 valve cover is REALLY easy to get off... check and make sure the rockers are all in place. IF there is one laying down in the cylinder head then thats your problem. It could be a lifter issue, but more likely something like a dropped valve seat.

BTW, welcome to the forum!

Death 04-05-2013 11:34 AM

Re: 3.7 misfire- no start
 
Thank you.

Rocker arm was laying beside the valve spring...

I have ordered new lash adjusters. Would putting a shim below the lash adjuster help from having this problem again?

Death 04-05-2013 07:54 PM

Re: 3.7 misfire- no start
 
scratch that...
rocker jumped off due to broken valve spring.

are these interference engines? Should I be worried about chunks of my piston missing when I pull the heads off Sunday?

2005JGC 04-07-2013 12:14 AM

Re: 3.7 misfire- no start
 
Interference means nothing if you have a failed valve spring, there is more ability for the valve to deviate from its specified path which could create a collision course itself. You may be just fine, If you have access to a compressor and a leakdown tester you can check cylinder integrity before any repairs are performed or attempted.

Furthermore the head does NOT need to come off to replace the valve spring, you can feed paracord or similar synthetic rope down the spark plug tube with the cylinder mid way down its compression stroke, then roll it over by hand till its snug and viola, OR you can use a leak down tester to pressureize the cylinder, then you just need a valve spring compressor tool, they make them where they hook onto the camshaft and have legs that set on the retainer, you lever it down and remove the keepers, reverse with a new spring and viola.

Pulling the head is WAY more work than is required at this point.


All times are GMT -5. The time now is 06:08 AM.

Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Copyright 2012 - JeepGarage.Org
The Jeep Grand Cherokee Owners Community