Loss of power after overheat - JeepForum.com
 
LinkBack Thread Tools
post #1 of 5 Old 09-04-2013, 02:13 PM Thread Starter
ATjeep42
Registered User
1988 MJ Comanche 
 
Join Date: Sep 2013
Location: Sunnyvale
Posts: 2
Loss of power after overheat

I overheated to the point of engine stall after a bad coolant leak. After replacing lost fluid and field patching the leak engine ran OK and I've put a few thousand miles on it since. But I've noticed a significant loss of power (and it sounds like I have a mild misfire at full throttle as well), and 20% lower gas mileage. Noticed engine is running a little rich (blackish tailpipe as opposed to dark brown before), but plugs are clean. No indication of blow-by (oil clean, no visible smoke from tailpipe). No trouble codes. No fluid losses (beyond what deteriorating gaskets have been causing over the last ten years).

FYI 373,000 on original engine w/ no replacements other than typical maintenance (e.g. TPS, O2, crankshaft position sensors, plugs/wires/cap/rotor in the last two years).

Any idea what the problem might be?

1988 Jeep Comanche
4L, 4x4 5 speed manual

ATjeep42 is offline  
Sponsored Links
Advertisement
 
post #2 of 5 Old 09-05-2013, 02:46 PM
TrucksBootsNGun
Registered User
1988 MJ Comanche 
 
Join Date: Aug 2013
Location: Flagstaff
Posts: 46
Not to stray from the topic but you can scan your '88 MJ? I have the same truck ('88, 4L, manual etc) and I've had the dash apart a couple times messing with the dash lights and new radio and not once have I seen anything that I could use to scan the truck.
TrucksBootsNGun is offline  
post #3 of 5 Old 09-08-2013, 06:37 PM
wgirvine
Registered User
1992 XJ Cherokee 
 
Join Date: Oct 2007
Location: Rosamond, CA
Posts: 652
Start with the usual tuneup/sensors/fuel pressure items. Other than those... Hmmm.... I'm just thinking out loud here...

That's a lot of miles. Partially clogged fuel filter will show up as loss of power at heavy loads (high revs, or full throttle.) Or...
Camshaft is wearing out? (not as much lift at the valves.) Or...
The overheat softened the valve springs so now they float at high revs? (misfire)

Start with the easy stuff first...

The road goes on forever, the party never ends....
wgirvine is offline  
post #4 of 5 Old 07-09-2015, 03:40 PM Thread Starter
ATjeep42
Registered User
1988 MJ Comanche 
 
Join Date: Sep 2013
Location: Sunnyvale
Posts: 2
Update

It's been two years. Just an update in case anyone else sees this problem - per a suggestion, I added Seafoam injection cleaner to a nearly empty fuel tank and after doing this a couple of times the power was much improved - no longer needed to drop down a gear to get over the Santa Cruz Mtns , though gas mileage is still down about 2 mpg and occasional misfire still persists. Up to 398,000k on the engine now.Firest
ATjeep42 is offline  
post #5 of 5 Old 07-12-2015, 08:28 AM
Luuca
Typical /f12 Hooligan
 
Luuca's Avatar
2005 LJ Wrangler 
 
Join Date: Apr 2012
Location: Corona
Posts: 4,627
Quote:
Originally Posted by ATjeep42 View Post
It's been two years. Just an update in case anyone else sees this problem - per a suggestion, I added Seafoam injection cleaner to a nearly empty fuel tank and after doing this a couple of times the power was much improved - no longer needed to drop down a gear to get over the Santa Cruz Mtns , though gas mileage is still down about 2 mpg and occasional misfire still persists. Up to 398,000k on the engine now.Firest
Had a cherokee that did the same thing. After a bad overheat it ran, but seemed like it was sluggish. Changed all the fluids and cap rotor but it still ran rich. This was a 93 xj.

He coil on ours was bolted to the block and with the overheating, had gone bad enough to run, but was giving me issues. Changed the coil and it had better spark and ran a lot better. We had a similar miss in the engine occasionally too and that went away.

91 YJ "Alice" 2.5L, AX5, 2.5" OME 36Rs, Revolvers, 32" Yoko ATs, 4.10 D30/35 Aussie Lockers F/R Busted Knuckles YJOTM never
05 LJ Rubicon "Ghost"

Luck Favours The Prepared
Luuca is online now  
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



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