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Check Engine Light--AGAIN!

C

Chux01Cherokee

NAXJA Forum User
Location
Middletown, NY, USA
Hi All,

I'm having a bit of an issue with my '01 XJ Sport (4.0). I recently had my vehicle in for a check engine light which was traced to a faulty gas cap. After replacing the cap with a new factory one and having the induction system serviced it is glowing again--after only 5 days of having it back.

A little background on this issue. I had noticed that I was having trouble at morning startup. (The vehicle is kept in a garage). It would require 2 or 3 cranks of the ignition before it will turn over, and would start and run perfectly the rest of the day. I used a synthetic fuel system cleaner and it seemed to alleviate the problem a little.

With this most recent occurence, I took it on a long trip (approx 170 miles)and then parked it overnight for about 14 hours. Upon leaving in the morning I noticed it refused to start after 4 cranks. I let it sit for about 3 minutes and tried again with no luck until I tapped the gas lightly--at which point it turned over and the light came on--I know for sure the cap was on securely because I had filled it the day before and it ran fine. It ran fine all day today, and I am at a loss to diagnose the problem. I would appreciate any input fellow XJ owners might have as she is my only vehicle and I use it for travelling on the job--so it is imperative that it runs properly with a minimum of down time.

Looking forward to all replies!!!!

Chuck
 
have you ever cleaned out the throttlebody? if not you could be starving the engine of air causing a rich start up mixture, therefore causing a misfire condition.but diagnostic trouble codes are required for more accurate diagnosis.
 
that could be it....i was thinking a bad o2 sensor....but i'm not the most brilliant person on the face of the planet either....hell i'm in Iraq, and yall are home jeepin!
 
Chux01Cherokee said:
Hi All,

I'm having a bit of an issue with my '01 XJ Sport (4.0). I recently had my vehicle in for a check engine light which was traced to a faulty gas cap. After replacing the cap with a new factory one and having the induction system serviced it is glowing again--after only 5 days of having it back.

A little background on this issue. I had noticed that I was having trouble at morning startup. (The vehicle is kept in a garage). It would require 2 or 3 cranks of the ignition before it will turn over, and would start and run perfectly the rest of the day. I used a synthetic fuel system cleaner and it seemed to alleviate the problem a little.

With this most recent occurence, I took it on a long trip (approx 170 miles)and then parked it overnight for about 14 hours. Upon leaving in the morning I noticed it refused to start after 4 cranks. I let it sit for about 3 minutes and tried again with no luck until I tapped the gas lightly--at which point it turned over and the light came on--I know for sure the cap was on securely because I had filled it the day before and it ran fine. It ran fine all day today, and I am at a loss to diagnose the problem. I would appreciate any input fellow XJ owners might have as she is my only vehicle and I use it for travelling on the job--so it is imperative that it runs properly with a minimum of down time.

Looking forward to all replies!!!!

Chuck
Click to expand...
Chuck, I'm experiencing the same problems as you are, and it is specific to the last two model years-possibly 99 my as well. The problems are multiple and trace back to the PCM as a software issue. There are several TSB's that address this and one of them is a multiple misfire issue which is what you are experiencing at cold start up. What I do is treat it like a carberator equipped car and give it a light tap on the gas as soon as it cranks over and it clears out the misfire. I had taken it to the dealer to try and address the misfire and gave them a TSB number (1801001-rough idle at cold temps) dated 04/20/2001 which requires flashing the PCM to a different calibration level (01Cal15B). After that it seems to have helped minimally at cold start up and now I get a check engine light occasionally, run my code scanner and it shows a very small evap leak (P0456) of which I was told was a possible faulty gas cap of which I dont believe to be the source of the problem, so I just clear the code out of the PCM until it lights up again. As for the evap leak, here is the TSB I think may be of value: http://www.wjjeeps.com/tsb_list.htm#2500401

Let me add that WJ jeeps is an excellent source of info and he deserves the credit due.

HTH
-Saga
 
any evap leak codes could be anything from broken or split evap lines to faulty purge solenoids or leak detection pumps. check the rubber hoses that connect the plastic lines together that run from the purge solenoid toward the rear of the vehicle on the underside i have seen some cracked underneath by where the left upper control arm meets the mounting bracket. also check the fuel pump seal. if you see a fuel stain from the top of the tank that could be your prob as well
 
jneary said:
any evap leak codes could be anything from broken or split evap lines to faulty purge solenoids or leak detection pumps. check the rubber hoses that connect the plastic lines together that run from the purge solenoid toward the rear of the vehicle on the underside i have seen some cracked underneath by where the left upper control arm meets the mounting bracket. also check the fuel pump seal. if you see a fuel stain from the top of the tank that could be your prob as well
Click to expand...
Yeah, I'm going to run an evap leak test to rule out any physical leaks. Also, on that site WJ Jeeps, there are multiple TSB's on evap leak codes being erroneously read by the PCM. It to requires flashing the PCM to clear out the faulty reading.
 
FWIW,

My '01 was running pretty rough on cold mornings when it was below 50°F. Never had a MIL. Never was hard to start, always fired right up, but missed really badly. The dealer where I bought it changed the plugs, performed a fuel injection cleaning, and installed a new fuel pump, but it still ran rough. I took it to another dealer and had the PCM flashed under TSB 18-010-01. It cost $54 and they added another key fob for free. Now it runs perfectly on cold mornings.

I will go out on a limb and say that flashing the PCM ~may~ be a good idea in general for '01 '00 '99? owners as it appears the original firmware had quite a few flaws.
 
Maybe consider the filler neck to your gas tank as the leak source. I had a problem with my '98 with the fuel system with check engine light issues. After the dealer replaced most of the fuel system, piece by piece; I had noted a hint of gasoline smell towards the rear of the vehicle while it was parked. I mentioned this to the dealer and they dropped the gas tank. Sure enough, cracked filler neck were it connects to the tank.....

Ivan
 
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