Check engine light flashing

OK I’ll try to keep this short.
Check engine light came on and started flashing when my 2001 4.0 L jeep was pulling a Hill. I could feel high heat coming off the floorboard.
Took it to the shop and they diagnosed with a bad coil rail and replaced.
Two months later it did the exact same thing when pulling a Hill again.
Took it back to the shop and they diagnosed that the cam to crank was off 12° and fixed. I also had them clean the injectors.
I thought the problem was finally fixed, until this weekend it did it again.
The heat coming off the floorboards and the fact that the hood is so hot you can barely touch it throws red flags up for me.
Any suggestions or help is very appreciated!!

Thx

Oh... and it’s also throwing misfire codes in three cylinders .
 
Todd Anderson said:
OK I’ll try to keep this short.
Check engine light came on and started flashing when my 2001 4.0 L jeep was pulling a Hill. I could feel high heat coming off the floorboard.
Took it to the shop and they diagnosed with a bad coil rail and replaced.
Two months later it did the exact same thing when pulling a Hill again.
Took it back to the shop and they diagnosed that the cam to crank was off 12° and fixed. I also had them clean the injectors.
I thought the problem was finally fixed, until this weekend it did it again.
The heat coming off the floorboards and the fact that the hood is so hot you can barely touch it throws red flags up for me.
Any suggestions or help is very appreciated!!

Thx

Oh... and it’s also throwing misfire codes in three cylinders .
Click to expand...


Did u get anywhere with your problem, 02 is doing the same thing,
 
Changed out the Throttle Control sensor and the crankshaft position sensor and that seemed to have fixed it. I did spend a little more and get MOPAR parts too. Good luck
 
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Mine did the flashing cel a couple weeks ago. It was idling rough at a stop light, then a mile or so later the light started flashing. Another mile or so it went out.
When I got home, I put my scanner on it and found no codes active or pending. It has been running great ever since.
 
My 2005 TJ CEL has come on several times over the past month. 1st changed O2 sensors, then spark plugs, also used gas treatment and injector cleaner. All were temp fixes. The CEL comes back on within a week. This last time mechanic said no problems and reset, but came back on. Also, unbearable heat is radiating inside cabin more than usual. Any ideas?
 
Hmmm I'm wondering if my sensors are messed up. My car has been running fine, but that check engine light came on. Like OP, I turned it off to pass inspection. However, I took it in for another issue and had them check everything, and the mechanic said our threw a misfire code, but there were no misfires found. Any advice? 6 Cyl 2001 TJ
 
I have been researching a similar issue and starting to see a trend here hoping anyone can recommend an area to check.

I also have a 2001 with the 4.0L and 3 spd auto which I see a few others also own in this thread. My CEL will come on and flash above 3100 rpm like clockwork. Anything below that it runs like it always has over the 21 years that I have owned it. Even above 3100, it seems to run fine and I actually took it out on an 8 hour wheeling trip with no issues keeping it below 3000. It's just the drive to and from doing over 70 mph where the flashing occurs.

I recently changed out the crank sensor which is when this all started. I had to install an NTK sensor since these are no longer available from Mopar but have not been able to confirm if the issue is related to this and shops do not seem to think this is the problem. Since that change, I have also installed all new NGK plugs as well as a new Mopar coil rail which did not help.

I have had 3 shops look at this the following tests all passed: backpressure, compression, fuel pressure.

The dealer where the Jeep is now indicated that the engine appears to be running lean when the CEL issue occurs. All misfire code which slightly change each time they are reset ranging from 0300, 0303, 0304, 0306 and 0305 pending. Typically 2 of these codes will be listed.

Dealer is going to try cleaning out the engine/injectors to see if that helps and I am prepared to replace the set if I need to. Is there anything else I can do or have checked? I do have an NTK cam position sensor that has not been installed but I have been hesitant to replace Mopar with aftermarket if I do not have to.

I did not notice any change in radiant heat which sounds like it might be a clogged catalytic converter for the folks above.

Thanks.
 
primetime4 said:
I have been researching a similar issue and starting to see a trend here hoping anyone can recommend an area to check.

I also have a 2001 with the 4.0L and 3 spd auto which I see a few others also own in this thread. My CEL will come on and flash above 3100 rpm like clockwork. Anything below that it runs like it always has over the 21 years that I have owned it. Even above 3100, it seems to run fine and I actually took it out on an 8 hour wheeling trip with no issues keeping it below 3000. It's just the drive to and from doing over 70 mph where the flashing occurs.

I recently changed out the crank sensor which is when this all started. I had to install an NTK sensor since these are no longer available from Mopar but have not been able to confirm if the issue is related to this and shops do not seem to think this is the problem. Since that change, I have also installed all new NGK plugs as well as a new Mopar coil rail which did not help.

I have had 3 shops look at this the following tests all passed: backpressure, compression, fuel pressure.

The dealer where the Jeep is now indicated that the engine appears to be running lean when the CEL issue occurs. All misfire code which slightly change each time they are reset ranging from 0300, 0303, 0304, 0306 and 0305 pending. Typically 2 of these codes will be listed.

Dealer is going to try cleaning out the engine/injectors to see if that helps and I am prepared to replace the set if I need to. Is there anything else I can do or have checked? I do have an NTK cam position sensor that has not been installed but I have been hesitant to replace Mopar with aftermarket if I do not have to.

I did not notice any change in radiant heat which sounds like it might be a clogged catalytic converter for the folks above.

Thanks.
Click to expand...

I got a re-gear last week and I have the exact same problem as yours. Whenever I'm above 3K RPM my CEL starts flashing. The Jeep runs great as ever, no bucking or lagging. I replaced the Crankshaft (NGK) and Camshaft sensors but it the problem persists. Please let me know what the dealer finds!!!

Thanks.
 
Tj Jay said:
I got a re-gear last week and I have the exact same problem as yours. Whenever I'm above 3K RPM my CEL starts flashing. The Jeep runs great as ever, no bucking or lagging. I replaced the Crankshaft (NGK) and Camshaft sensors but it the problem persists. Please let me know what the dealer finds!!!

Thanks.
Click to expand...
Interesting, I also recently regeared to 4.10 after upgrading to 33s. I’m wondering if there may be something the PCM does not like about the RPM and vehicle speed but that sounds unlikely as this is the recommended ratio. I’m grasping here.

Dealer has had my Jeep for over a week now and still can’t fix the issue. They tried performing an injection and intake cleaning service with no luck. Mechanic said they have some more things to try but it sounds like they are stumped. I went ahead and ordered a NAPA echelin crank position sensor that was recommended here and asked the dealer to install it as a Hail Mary attempt. Hoping that it was the NTK sensor that was the problem and will update after they report back.

If not, I might have to keep it under 3000 rpms indefinitely which wouldn’t be the end of the world.
 
primetime4 said:
Interesting, I also recently regeared to 4.10 after upgrading to 33s. I’m wondering if there may be something the PCM does not like about the RPM and vehicle speed but that sounds unlikely as this is the recommended ratio. I’m grasping here.

Dealer has had my Jeep for over a week now and still can’t fix the issue. They tried performing an injection and intake cleaning service with no luck. Mechanic said they have some more things to try but it sounds like they are stumped. I went ahead and ordered a NAPA echelin crank position sensor that was recommended here and asked the dealer to install it as a Hail Mary attempt. Hoping that it was the NTK sensor that was the problem and will update after they report back.

If not, I might have to keep it under 3000 rpms indefinitely which wouldn’t be the end of the world.
Click to expand...
Its quite simple really! lol Your engine is constantly rev,ing high, high enough for Gering and tire size you have put on but not for what was intended for the engine much less an older worn engine! People who believe these engines are "Bullet proof" are delusional! They are strong and they have a good reputation for being so until time changed the gearing and wheel/tire specs wanted by everyone! Start at the tire size and re gear before you start suspecting a PMC issue
 
Fishtaco said:
Its quite simple really! lol Your engine is constantly rev,ing high, high enough for Gering and tire size you have put on but not for what was intended for the engine much less an older worn engine! People who believe these engines are "Bullet proof" are delusional! They are strong and they have a good reputation for being so until time changed the gearing and wheel/tire specs wanted by everyone! Start at the tire size and re gear before you start suspecting a PMC issue
Click to expand...
It seems as though primetime4 has had a lot of eyes and hands on his vehicle with no luck, do you have a new suggestion for possible causes?

@primetime4 - I'm going to try resetting my PCM, if that doesn't work, I'll look more closely at the catalytic converters. I've only had my jeep since Sep so I'm not sure how old the cats are but most things on mine look original.
 
Fishtaco said:
Its quite simple really! lol Your engine is constantly rev,ing high, high enough for Gering and tire size you have put on but not for what was intended for the engine much less an older worn engine! People who believe these engines are "Bullet proof" are delusional! They are strong and they have a good reputation for being so until time changed the gearing and wheel/tire specs wanted by everyone! Start at the tire size and re gear before you start suspecting a PMC issue
Click to expand...
Not sure what you are suggesting here but I did regear to 4.10 at the same time I went to 33s. The Jeep runs at right around 2600 rpm at 65mph which is pretty much exactly where it was at stock. I have read that the computer needs to "relearned" when sensors are changed but not sure how that is done. I read in one post touching both battery terminals to the negative post will do it but I've driven about 500 miles with the new sensor with no issues starting or at idle so I am stumped.
 
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