Flashing Engine Light

[Daveos]

I am really at a loss here.

I have changed a bunch of things looking for what could be causing these problems and now the engine light started flashing today for a few seconds, before going back off.

I am still loosing power when I run the jeep on a hot start. It has no problems at all with a cold start. It will run, warm up to operating temp, and still run just fine. When I turn it off while it is hot for a few minutes, and start it, it will loose power for about a minute before going back to running like normal. During this time the engine light has started flashing on two different occasions, but before I can pull over and get a code out the engine light goes back off. It is not throwing any codes. It is not consistent. If I let it cool off to below the 1/4 mark on the temp gauge, it wont do it on the warm up cycle.

I have changed the fuel filter, plugs, battery, TPS, ATS, put seafoam in it, cleaned the evap canister, new purge solenoid, and cleaned the throttle body. Any ideas on why this would be happening only when the jeep is hot?

Thanks

 

[TwoBobsKJ]

I'm wondering if maybe there's an electrical gremlin that shows up when the engine gets up to a particular temperature. Contacts pull apart due to heat expansion.

Pretty baffling considering that it will go back to normal after a while and it isn't throwing any codes. I'll be watching this thread to see if someone has an answer that solves the problem. Wish I could help... :shrug:

Bob

 

[Daveos]

Yeah, I am really at a loss too. It is only happening when it is warm. When I start it in the morning and drive it to class it works great all the way. Has to be a temperature sensor or something.

I just got the kit to reroute the PCV valve today to help prevent the gunk buildup from the condensation under the filler cap. See if that makes any differences after I install it.

 

[Daveos]

I read this on another site with someone having a similar issue:

"When an engine is hot, and turned off, the fuel that is in the lines and injectors must be kept under pressure to prevent vapor lock. If the pressure drops, the fuel turn from liquid to a gas (vapor) then the fuel pump cannot pump the fuel when trying to start. Have the residual fuel pressure checked."

It is acting just like this. Maye bit is possible my fuel pressure is dropping and it takes a little bit to get it primed back up and running right. I bought a used fuel pump assy on ebay. See if it changes anything.

 

[tjkj2002]

I read this on another site with someone having a similar issue:

"When an engine is hot, and turned off, the fuel that is in the lines and injectors must be kept under pressure to prevent vapor lock. If the pressure drops, the fuel turn from liquid to a gas (vapor) then the fuel pump cannot pump the fuel when trying to start. Have the residual fuel pressure checked."

It is acting just like this. Maye bit is possible my fuel pressure is dropping and it takes a little bit to get it primed back up and running right. I bought a used fuel pump assy on ebay. See if it changes anything.

Unless that pump is a OEM pump or Delphi I would just cancel unless you like changing them often.It's a crap shoot on most aftermarket pumps,get to tell customers all the time they get to pay all that money all over again for being cheap the 1st time.


Just my 15 years of experiance but it's your money.

 

[Daveos]

The pump came from a crashed jeep. Guy is offering a lifetime warranty on it, 99.9% positive feedback. If it fails he says he will send another. Guess we will see.

 

[Daveos]

For anyone who is curious. The fuel pressure regulator was "stuck" closed or something. I put a new fuel pump and regulator in and the problem went away.

 

[TwoBobsKJ]

For anyone who is curious. The fuel pressure regulator was "stuck" closed or something. I put a new fuel pump and regulator in and the problem went away.

Great news that you found the problem! arty52:

Thanks for the update - follow up like yours helps other Jeepers who may run into the same problem down the road. Having the resolution to the problem eliminates the frustration of finding a thread that matches the problem with my Jeep - only to get to the end of the thread and the OP doesn't say how he/she fixed it. Ugh! :freak3:

Have fun now that you can drive your Libby with confidence again. :smokin:

Bob

 

[Daveos]

Well, I lied. That did not fix the problem. Now I am getting a P0302 error code, misfire on cylinder 2. It is only happening on hot starts.

Getting so sick of screwing with this. See if they can re-flash the computer on Monday.

 

[Daveos]

I am really perplexed. This just came out of the blue a few weeks ago and I can not figure it out. It runs perfectly when it is started cold. I will warm up fine, and run fine for as long as I drive it. When I stop and turn it off for about 10 - 30 minutes, and start it. It runs good, then acts like it is missing for around 30 seconds to a minute. It will loose power and now throws a missfire on #2. After about a minute, it goes back to running just fine until I turn it off again.

I unhooked the battery for around 4 minutes to change a coil. Should that have been long enough to reset the shift logic? It felt like it lost all programming in a very short period of time. Any ideas as to why that would happen? Brand new battery.

If the IAC was sticking, could that cause enough air loss to make it loose power even when accelerating? It had quite a bit of junk on it last time I cleaned it, about two weeks ago.

 

[ridenby]

You seem to be using a shotgun approach to fixing this. One thing at a time. The only code it shows is P302?

 

[Daveos]

You seem to be using a shotgun approach to fixing this. One thing at a time. The only code it shows is P302?

Well, I have been trying to fix it for over a month now. Just taking it one thing at a time per suggestions I get from other posts and online.

It threw a P302 code one time yesterday. It has been doing this for a while and that was the first time It threw any codes. I cleared the code this morning when I changed out the coil pack and the crankshaft position sensor. I also discovered one of my tensioner pulleys had a bad bearing as well.

I did it again after the new coil pack was put in on #2 without throwing any codes. I haven't had a chance to test it with the new crankshaft position sensor in it yet. It has no codes.

 

[ridenby]

You have not changed the #2 plug ? Or better yet all the plugs? Why would you change the crank position sensor?

 

[ridenby]

How are you reading the codes ?

 

[tjkj2002]

K.I.S.S.

Apply it.


Check for the 3 things needed to make the engine run,spark,fuel/air,and timed right.Then check compression,both cold and hot and a leak down test.Then check for combustable gases in the coolant.

 

[Daveos]

You have not changed the #2 plug ? Or better yet all the plugs? Why would you change the crank position sensor?

I have been messing with this for a while. I started by changing all of the plugs and cleaning the throttle body. I have also changed the TPS, ATS, Cam Pos Sensor, Crank Pos Sensor, as I have read that all of those can contribute to running problems. Changed the coil pack, battery, and did the pcv valve TSB. Also changed the fuel pump (used one). I just cant think of anything that would make it run like crap only on a hot start and for such a short period of time. It is really acting like it is not getting fuel for some reason.

 

[Daveos]

K.I.S.S.

Apply it.


Check for the 3 things needed to make the engine run,spark,fuel/air,and timed right.Then check compression,both cold and hot and a leak down test.Then check for combustable gases in the coolant.

It is acting like it is not getting fuel for the short period that it is running rough, or somehow air is in the fuel. Again, it doesn't last very long, under a minute, then it will run fine until I shut it down again. When it starts running rough, I can spray carb cleaner in the intake and it rebounds and runs better for a few seconds.

I wish I had all of the tools / time to do those checks. I may just have to drop it off at the dealership.

 

[Daveos]

How are you reading the codes ?

I am getting the one code it threw from the off on key method using the odometer. All codes cause an engine light right?

 

[rockymountain]

Have you checked fuel pressure yet? Injectors? Check the #2 injector.

 

[Daveos]

Have you checked fuel pressure yet? Injectors? Check the #2 injector.

I changed the fuel pump. Seemed okay. I havent checked the #2 injector yet. Not sure how to pull the fuel rail. I need to have someone hook a scanner up and monitor it while it is running.