2.5 runs but not well - JeepForum.com

 
LinkBack Thread Tools
post #1 of 11 Old 09-09-2009, 10:18 AM Thread Starter
labman1
Registered User
1994 YJ Wrangler 
 
Join Date: Sep 2009
Location: SC
Posts: 5
2.5 runs but not well

Replaced cracked head with a re-manufactured head. Installed rocker arms and pushrods in the exact order they were removed. Torqued per specs. Have not been able to get it to run right since. Loss of power and back fires through the engine. We did not do this right after re-assembly, but since having trouble we have located TDC of piston #1 (compression stroke) and verified rotor pointing to cylinder #1 wiring terminal while timing marks are aligned on "0". Same problems exist, loss of power and back fires through the engine. Any ideas? Help!

labman1 is offline  
Sponsored Links
Advertisement
 
post #2 of 11 Old 09-09-2009, 11:32 AM
redjeep669
Registered User
2009 JK Wrangler 
 
Join Date: Nov 2006
Location: central ny
Posts: 286
cam timing.
redjeep669 is offline  
post #3 of 11 Old 09-09-2009, 01:29 PM
EABiker
Registered User
1989 YJ Wrangler 
 
Join Date: Dec 2004
Location: Frederick, MD
Posts: 1,720
It could also be vacuum leaks in the intake manifold assuming the spark and valve timing is correct.
EABiker is offline  
post #4 of 11 Old 09-10-2009, 03:06 AM Thread Starter
labman1
Registered User
1994 YJ Wrangler 
 
Join Date: Sep 2009
Location: SC
Posts: 5
i think you may be right, how does the cam timing change with the changing of the head? we never have pulled the timing chain cover or timing chain, looks like it's going to be an interesting weekend.
labman1 is offline  
post #5 of 11 Old 09-10-2009, 05:33 AM
EABiker
Registered User
1989 YJ Wrangler 
 
Join Date: Dec 2004
Location: Frederick, MD
Posts: 1,720
Quote:
Originally Posted by labman1 View Post
i think you may be right, how does the cam timing change with the changing of the head? we never have pulled the timing chain cover or timing chain, looks like it's going to be an interesting weekend.

If you didn't touch the cam or chain, then you can certainly rule those out. Are you sure piston 1 was at TDC on the compression stroke rather than the exhaust? The distributer could be 180 deg. out!
EABiker is offline  
post #6 of 11 Old 09-12-2009, 04:25 PM Thread Starter
labman1
Registered User
1994 YJ Wrangler 
 
Join Date: Sep 2009
Location: SC
Posts: 5
As far as cam timing as you said EABiker we did not mess with the chain or cam, but while we were changing the head we did not have the parking brake set. It was in park, no parking brake. Could us leaning on the vehicle while replacing the head move it enough to move the cam timing?

I have tried to verify that we are at TDC of the compression stroke today. I have removed the valve cover so I can see the position of the valves for cylinder 1. With the #1 plug removed and both of the #1 valves closed the #1 piston reaches TDC between 6 degrees and 0. I am sticking a clothes hanger into the #1 plug hole and letting it rest on top of the piston as I turn the crankshaft with a ratchet and socket. The clothes hanger appears to stop rising between 6 degrees and 0. I know this is primitive, but as you can tell I'm not a mechanic.
labman1 is offline  
post #7 of 11 Old 09-12-2009, 04:49 PM
MJMPC
Registered User
1991 YJ Wrangler 
 
Join Date: Nov 2008
Location: Elizabethtown
Posts: 3,064
Maybe a stuck valve ?

MIKE

http://www.dav.org/

MJM Powder Coating
Elizabethtown Ky.

http://www.cityprofile.com/
MJMPC is offline  
post #8 of 11 Old 09-13-2009, 06:02 AM Thread Starter
labman1
Registered User
1994 YJ Wrangler 
 
Join Date: Sep 2009
Location: SC
Posts: 5
How do I check to see if a valve is stuck?
labman1 is offline  
post #9 of 11 Old 09-13-2009, 06:27 PM
RandyYJ
Registered User
1993 YJ Wrangler 
 
Join Date: Nov 2008
Location: Davenport, FL
Posts: 97
The fire is going to be set by the CPS in a 94. I would put a timing light on it, and if the white line is anywhere around the 0 degree TDC then you're not 180 out. IIRC #1 will be firing a touch late until it fires up then it will start firing a little before TDC. Pull your IAC and spray it down with brake cleaner real good and clean all the carbon off of it. If your IAC is stuck it will spit and sputter and backfire when you give it starting fluid, but will not run. These are some things I learned swapping in a 4.0, so they may not all apply, but that's my little bit of experience.

If you're not on the edge, then you're taking up too much room.
RandyYJ is offline  
post #10 of 11 Old 09-14-2009, 03:12 AM Thread Starter
labman1
Registered User
1994 YJ Wrangler 
 
Join Date: Sep 2009
Location: SC
Posts: 5
My son has replaced the CPS (Crankshaft Position Sensor) did not change a thing. Randy I appreciate the feedback, help me out though with the acronyms IIRC and IAC. Thanks, Charlie
labman1 is offline  
post #11 of 11 Old 09-14-2009, 04:14 AM
RandyYJ
Registered User
1993 YJ Wrangler 
 
Join Date: Nov 2008
Location: Davenport, FL
Posts: 97
If I Remember Correctly, and Idle air control.

The IAC is a sensor on the back side of the throttle body with I think 4 torx screws. I couldn't get my 4.0 to run, and once I pulled and cleaned that it fired right up. It might be coincidence, but worth a shot.

If you're not on the edge, then you're taking up too much room.
RandyYJ is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the JeepForum.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.



Email Address:
OR

Log-in









Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Similar Threads
Thread Thread Starter Jeep Forums Replies Last Post
Engine runs rough intermittently, runs rich... Cactus737 TJ Wrangler Technical Forum 7 04-22-2010 08:40 PM
Runs Rich and Runs Rough madjeep1 YJ Wrangler Technical Forum 1 01-04-2010 11:27 AM
Cold=Runs Like Crap, Warm=Runs Good - Help! CheapSunglasses YJ Wrangler Technical Forum 9 11-24-2008 10:56 PM
My YJ RUNS!!!! Nate M YJ Wrangler Technical Forum 42 01-08-2008 10:37 AM
She Runs!!! wessy YJ Wrangler Technical Forum 0 01-07-2008 08:04 PM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome