Jeep Grand Cherokee Laredo - 2008, warning light

[jijoyattitude]

Hello All,

I have a 2008 Jeep Grand Cherokee Laredo which I bought in 2008. I have a rather disturbing problem which I have been going up and down to the dealer every week for the past 15 months or so.

Let me start by saying, I am not one of those happy customers:

1) Because of the attitude of the dealer who only wanted to rip me off on ever occasion. Changed to a new dealer 150 km away since 2011

2) History of problems

3) Even after reporting to Jeep about the dealer attitude, Jeep never even responded.

Problem:

My car has been showing the warning light once every few 100 or thousand kilometers. Dealer has not been able to give me a fix. When I drive in traffic and idle, the car starts to vibrate / jump and seems its going to run away and then suddenly the warning light comes on. I always have my AC on, due to the weather.

This never happens on straight road without any traffic.

Two weeks back the dealer asked me to replace both relay fuses (HVAC and Engine). Replaced with a 5 pin fuse even though the one present was 4 pin but the dealer said its fine to replace with a 5 pin. The problem still persists.

I have lost hope with the dealer as I have spend weeks with the dealer with no result. Atleast the second dealer is far better than the first.

Any help is appreciated.

Regards,

J

[JeepDxb]

Sorry to hear about your dealer experience.

My educated guess looks like get your AFM (Air flow Meter) and AFM sensor needs to be checked as this sort of rough idling/jumping issue usually caused by poor Air flow.

Reason:

On highway, car sucks big quantity of air to ignite the fuel and small percentage vary doesn't bother the car.

In traffic or on idle it sucks smaller quantity of air, and in that some percentage of air variation cause this noticeable rough idling / blup blup issue.

You can also check if AFM sensor is cleaned and properly plugged to the Air filter tube neck. Hope it help. Good luck.

[jijoyattitude]

Thanks for the reply Roy. I have been guessing the same, but sadly, the dealer does not think the same. The dealer has evaluated almost everything (according to them and they have never seen the same problem when they drive, as they never drive during rush hour), from the transmission to air filter, but my simple or rather basic knowledge leads me to the same guess that the engine is not getting sufficient air during traffic or idling. Any recommended dealers in UAE? I can have a story written about my experience with one of the dealer in UAE.

Can i check the AFM or do I need my car to be taken to a dealer?

[JeepDxb]

For getting AFM checked you can go to many garage who have Jeep computer and they will do computer check in 30 minutes for 200 dhs. Robbies, icon auto, Max garage many are there in Al quoz area.

Get this squared off first and also look into the possibility of CKPS (Crank Position Sensor) most misbehaving sensor when goes bad: rough idling, more fuel consumption etc, cost only 200-300 dhs to change but worth guessing and changing when dealing with these dodgy issues.

[jijoyattitude]

I checked with the dealer in AbuDhabi and he was not convinced that this could be a MAF or CKPS sensor. He said he will replace only if I wanted. I had "check engine" warning light on 2 days back after driving in traffic (idling for almost 15 minutes) but after driving on a straight stretch of road for approx 100 kms, the warning light disappeared. Again I had the prob but this time the check engine light just flashing for few times and not staying on. This happened as soon as i started driving from the parking of a local supermarket and there was no traffic. Only thing I did was to switch on my AC as soon as I started my car (Usually i drive for few minutes and then switch on the AC).

Yesterday I noticed a warning "Transmission Over temp" as soon as i inserted my key and turn on (before ignition). It stays for a fraction of a second that I had to turn on and off my key almost 10 times to read the warning. Never seen this error while driving. The temperature sensor always slays below half.

What I do not understand is, Jeep having so many sensors, why has the system not recorded the specific error as an error code? Each time I take my vehicle the dealer says, they did not find any error.

Hoping for some help

Regards,

J

[JeepDxb]

This is quite tricky, but let me try to help with best of my knowledge and experience. Just to zero down the doubtful area, drive w/o AC and see if this check engine light shows up in traffic or not? And i can advise further based on the finding.

[jijoyattitude]

Thanks Monsterjeep for the quick reply. Something I remembered after seeing your recommendation: few weeks back I had the same prob and I remember how it occurred: what I did was that I switch on the AC as soon as I started the car (as I had a small baby in the car) and as soon as I put the car into reverse and moved the car, I had the warning lights on. There was absolutely no traffic that day. I reported this to the dealer and the dealer suggested to replace the relay fuses as mentioned in the above post.

I will definitely try your recommendation and come back with the result asap (even though driving w/o the AC during this season is going to be fun )

[JeepDxb]

Try w/o AC and see if light pops as monster suggested.

Also have a quick look on below list:

Fuel cap is properly tight?

Battery terminal is properly tight and not moving when try to move them by hand?

What is the age of battery? And which brand it is?

If you can swap a battery with other jeeper and try for few days as i doubted battery when you said that Transmission Over temp showing in cold car must be something really freaky with electronics.

Code gets recorded only if fault stays permanently and not in such intermittent faults. I agree that our car technology should start recording these crazy faults too so that it can be diagnosed and troubleshoot more faster, than this guesswork.

[GrandDubai]

Hi, you might try changing the PCV valve too - if your mileage is over 90,000 km. this is the service time for them. If the PCV is blocked, pressure builds up in the crank case and can force oil down the valves, causing a plug to foul. You will only feel it when in traffic at idle or slow speed.

The other thing to check is the TPS (throttle position sensor) as this can go bad. It sends signals all over the engine and also tells the transmission what's going on.

If you don't have any specific codes, these might be worth checking out. Both are cheap parts too!

Good luck!