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Jeep Grand Cherokee 4.7 V8 2002 - Cutting out, no ignition #

Posted by Paul Foster on May 9, 2009, 4:57 pm

Year of Manufacture *: 2002
Engine Code or Type *: V8 petrol

Hi Guys.

I suspect I have an ECU issue here but I would appreciate any suggestions!

After about 20 mins running the engine cuts out. The rev counter needle starts jumping around at the same time. When attempting to re-start the engine live data shows an engine speed but the rev counter doesn't move. The ignition amplifer(s) are built into the ECU.

While checking all this out I had the ignition switched on an noticed smoke coming from the valve cover area - on investigation I found five of the eight coils burnt out/melted! The coils are fed by an ASD (auto shut down) relay that should remove the feed to the coils and injectors if the engine isn't run for a given amount of time. This relay is also operated by the ECU.

Someone please correct me if I'm wrong but I wouldn't have thought any electronic ignition system, be it incorporated in the ECU or a seperate amplifier, should leave the coils earthed while in a KOEO situation.

Any suggestions appreciated.

Cheers - Paul.

Re: Jeep Grand Cherokee 4.7 V8 2002 - Cutting out, no ignition #

Posted by Paul Foster <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2680' width='330' height='300' border=0 style='border:none;'> on May 14, 2009, 6:31 pm, in reply to "Jeep Grand Cherokee 4.7 V8 2002 - Cutting out, no ignition #"
Paul Foster

Anybody?

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Re: Jeep Grand Cherokee 4.7 V8 2002 - Cutting out, no ignition #

Posted by Simon Forsey <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5231' width='330' height='300' border=0 style='border:none;'> on May 18, 2009, 10:39 pm, in reply to "Re: Jeep Grand Cherokee 4.7 V8 2002 - Cutting out, no ignition #"

Hi Paul

How did you get on wit this one?

I have done quite a few of these with 'cutting out when hot' issues. Most of the time it has been CAM or CRANK sensors. However, not with burnt out coils, I have, however, had to diagnose a Nissan Skyline burning out its coils as your car is, and that was an ECU issue.

I hope this helps

Simon

Re: Jeep Grand Cherokee 4.7 V8 2002 - Cutting out, no ignition #

Posted by Paul Foster <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2680' width='330' height='300' border=0 style='border:none;'> on May 19, 2009, 1:41 pm, in reply to "Re: Jeep Grand Cherokee 4.7 V8 2002 - Cutting out, no ignition #"

Hi Simon.

Thanks for your reply.

You're not the first person to suggest cam/crank sensors. To be honest I fitted a new crank sensor as a bit of a leap of faith as they're not a fotune to buy. Sadly it didn't cure the fault!

I have just replaced a 4.7 V8 Cherokee engine so I've got a couple of cam sensors I can try. I will post the results.

I put some posts on a couple of the US Jeep forums and it was a Jeep tech from Upstate New York who answered! Handy contact!!

Regards - Paul.

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FIX: Jeep Grand Cherokee 4.7 V8 2002 - Cutting out, no ignition #

Posted by Paul Foster <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2680' width='330' height='300' border=0 style='border:none;'> on June 22, 2009, 11:20 am, in reply to "Re: Jeep Grand Cherokee 4.7 V8 2002 - Cutting out, no ignition #"

Hi.

Simon was right - I fitted the Cam sensor from the blown engine and the fault's cured.

We also had to replace a faulty O2 sensor. It might be of interest to note that these sensors (all four are the same) do not switch at idle. They only start to send any kind of signal when the engine is revved. It took me a while to indentify the faulty one because of this!

Hope that info may be of use to someone!

Sent my KTS back now so diagnostics should be a lot easier!!!

Ne te confundant illegitimi

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