Daily Runner problem - Not Lotus

[Barney]

Hi Guys,
Can those far more knowledgable than me advise on a problem with my daily runner?

Car is a Jeep Grand Cherokee 2.7 CRD (The Mercedes engine and Automatic transmission).
Since replacing the auto-box the car has stalled (only on very cold starts) as soon as I engage R or D when keeping my foot on the brake.

To get around it I engage R or D - only when its safe to move and immediately take my foot off the brake pedal before the gear bites. Once the initial movement has taken place all seems well.

I have noted also that it now has a tendency to creep forward when no pedals are depressed - making about 4/5mph on the flat if left to its own. Idle is 800 rpm, as before.

I have discovered that I can exagerate the symptoms by selecting the 4 Low gear set, where it is difficult to stop the car travelling.

I have little/no experience with Autos and want to be genned up before going back to the "specialist" garage.

Thanks in advance,
Barney

[GrUmPyBoDgEr]

Sounds like a software problem. New transmission to engine compatibility. It will need to have some diagnostic work done & some re-programing or even new management.

Good luck
John

[Jason1]

Hi

If it only happens when cold I would say the engine is not running right, when you engage the drive this puts a load on the engine and it stalls. I used to get this with old Ford Granadas, you used to have to keep the revs at 1200 using both feet and then put the car into Drive or they would stall.

Leave the car idling in neutral cold and switch on all the heavy load items (headlights, heated screens, etc) the engine should slow and then the ECM should speed the idle slightly to counter this. If yours stalls then your engine is not running correct. On old cars you used to pull the choke out more.

When the engine is cold this is the hardest the engine is going to work and any mis-fire or vacuum leak is going to show up as a stall. Unfortunately modern engines mask a lot of common faults like simple vacuum leaks using by automatically injecting more fuel or speeding up the engine revs. Look for simple faults first like vacuum leaks or throttle body gummed up.

Hope this helps

Jason

[Barney]

Sounds like a software problem. New transmission to engine compatibility. It will need to have some diagnostic work done & some re-programing or even new management

Oh Dear! I was thinking more on the lines of incorrect oil (too viscous) or similar

Thanks for the advice to date
Barney