Engine Dropping Into "limp" Mode And Engine Management Light O

January 14, 2013

Hi all

Been a silent member for a while now but something happened to me on my way back from a visit to my hometown of Swansea in South Wales travelling along the M4 heading to Pembroke Dock to catch the ferry home to Southern Ireland where i now live.

Im hoping it will be of some interest and if its already been covered in the past i apoligise!

Was cruising at around 70mph last Tuesday in the outside lane of the M4 in misty rainy conditions, had just overtaken a lorry, when i suddenly lost power and had to freewheel my Rav4 2.0 D4D 2002 NRG over into the hard shoulder. As i was doing this i could still rev the engine but something was clearly reducing power (much like if you have ever blown an intercooler pipe).

After coasting to a halt and switching everything off (as it was raining had the light on, windscreen washers going rapid and the AC on to stop the windows demisting (4 of us with luggage in a 3 door = misty windows) i had a quick look under the bonnet with a great little LED torch (Aluminium housing, single powerful LED, Tescos! £10), could not see anything wrong visually, all belts in place, coolant ok, oil ok etc.

I tried to restart the Jeep but she turned over about 5 times slightly sluggishly before draining the Battery reserve. Must add the engine management light was now on. Having waited 2 hours for a tow truck (diverted to police work apparently, just left me there on the hard shoulder of the M4), i finally got my parents to tow me off the next exit and a few miles back to our local motor factors / garage.

Having already missed the ferry, and fearing something major mechanical leaving us stranded, the mechanic and I started to check out the engine bay. 1st thing he did was attach a booster pack to my now dead Battery (2 hours of hazards on and the odd wiper sweep), and hey presto the old girl fired up! After eliminating a failing alternator a drop test of the Battery showed a dead cell!

This cell must of been dying for sometime, and when i had loads of electrics on it must of tipped the battery's capacity to keep up the voltage required and when that finally dropped below a certain value thecomputer said NO and put her into limp mode!

Had i know this i would not of turned off the motor and would of managed to crawl off the motorway and saved myself a lot of hassle and time and money!

New battery fitted and the Jeep feels great again, and with a bit of hindsight i did get one or two early warning signs, (imobiliser sometimes not kicking in, wife complained of a few times it would be sluggish starting, a feeling of not having full power), that something was not right with the battery, but as it was only renewed aroung two years back i just put it down to the cold weather. (company supplied it has since closed down...)

So the moral of my little story is if you are running around and the vehicle feels a bit down on power, maybe a little sluggish starting, or even dropping loads of power for periods of time, get the battery checked, not just for what volts it has, but make sure to do the drop test, it will show up a dead or dying cell and give you the heads up to solve a problem before it finally breaks down on you (hopefully not when your running to catch a ferry!) ha ha.

Cheers :fireman2: