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Hear_Me_Roar96 08-14-2012 06:35 PM

Recurring Check Engine Light
What's up yall I'm a new member here at JeepGarage and I'm hoping to get some better insight as to what seems to be a never-ending problem with my 1996 Jeep Grand Cherokee (4.0). A few weeks ago I noticed whenever my Jeep had to change gears, it was more of a rough transition instead of a smooth one. And it would also idle at a lower RPM before steadying out. Soon after the "check engine" light lit up so I got the codes read and it came back as a bank one sensor one system too lean. I replaced both O2 sensors but now she is acting up again and I'm at a loss of what the problem really is.

On another note, what is the most likely cause of "the death wobble"?

Frango100 08-15-2012 11:02 AM

Re: Recurring Check Engine Light
Is the check engine light back on again as well?
When the mixture is too lean, it could be a fuel pressure problem. I would measure the fuel pressure or change the fuel pressure regulator.
Death wobble is caused by play in the suspension and/or steering components, but also uneven tire pressure can play a role.

Hear_Me_Roar96 08-22-2012 10:09 AM

Re: Recurring Check Engine Light
Thanks for your reply. After some looking into some of the possible problems you described, I did some research of my own and want to check out the EGR but I'm not sure where it is on my jeep. I want to test it to make sure it's not the problem. If you or anyone else knows where I can find it on my jeep that would be much appreciated.

Frango100 08-22-2012 11:44 AM

Re: Recurring Check Engine Light
1 Attachment(s)
Not familiar with the ZJ myself, but a picture of the EGR valve is attached.

VistaCruiser 08-28-2012 06:37 PM

Re: Recurring Check Engine Light
Does the '96 4.0 even have a EGR valve? I thought they deleted that on the '93 up models. If you do have one, it should be off the exhaust manifold, towards the rear of the engine. Death wobble has many causes, primarily loose track bar mount/worn bushings. Bad control arm bushings also.


Hear_Me_Roar96 08-28-2012 07:10 PM

Re: Recurring Check Engine Light
Actually there is no EGR, sorry. I took her in to a trusted shop yesterday and they said that the upstream O2 sensor was bad even though I had bought and installed both O2 sensors just over a month ago. I'm not sure though if the upstream O2 was bad when I bought it or if something caused it to go bad. She ran well for a few weeks before she started getting rough again. I went ahead and ordered a OEM O2 sensor from Jeep instead of getting another (Bosch) O2 from just any part store. I'll let y'all know how it goes though. Thanks

VistaCruiser 08-28-2012 08:31 PM

Re: Recurring Check Engine Light
Bosch and older Jeeps tend not to mix. NGK for plugs and O2 sensors, found @ NAPA, O'reily's.


Frango100 08-28-2012 10:33 PM

Re: Recurring Check Engine Light
The Bosch O2 sensors normally donīt work well on jeeps, because they heat up too slow. Denso is the brand to go with, that is the OEM brand.
You could buy original MOPAR, but they are just from Denso, but only more expensive.

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