Thread: D2 1999 4ltr V8 rough running, to rich ETC ETC.

Originally Posted by sime007

I have replaced the MAF EddyEddys but that was at the start of what has been a so far long winded operation due to faults not being conclusive to the symptoms and i cant afford to replace everything that could possibly be causing the problem. I know there is a faulty o2 sensor but the system registers the fault then runs a slightly rich default setting that shouldn't cause any issues with the running of the car. The car had a slight hesitation for a little while before these problems surfaced but again a very capable local land rover mechanic couldn't pin-point the problem so we decided not to throw money at it. I think the key to my problem is the fact that the car runs without miss-fire or noticeable power loss while the car is cold. As soon as the car is warm there is a sudden power drop like the ignition is retarded or the car is flooded and then it starts to miss-fire and idle very rough to the point of stalling even while driving. So far the car has Restarted within one or two tries but the symptoms persist from then on. I just cant work out what changes in the system between cold and warmed up.

I beleive the computer only looks at the O2 sensors when the engine is warm...Replacing the O2 sensors in my car significantly improved smooth idling, although mine never stalled from rough idling, I did expect it to a couple of times.

Kieren,


I had a read of rave this arvo and in the emission control section it mentions that if the purge valve sticks open it can cause a rough idle and stalling when the revs drop back to idle, if you have a copy of rave it would be worth having a read yourself.


Roger

Does anyone know if resetting the engine adaptive setting should be done cold or warm? I just did heads and cam (now has 4.6 cam in 4.6 engine instead of a 4.0) but it now get around 34l/100k's and idles like it's a lumpy cam (ordered & received genuine boxed item).

And yes, the O2 sensors are only used when warm, it runs closed loop mode (with fixed map) until warm (at 55deg) then open loop (sets fuel depending on air in, O2 out, temps etc). My terms (open/closed) may be mixed up though.

Doesn't matter when you reset the adaptive values. They should be reset when the O2 sensors or MAF is changed.

The purge valve on the carbon fuel canister should be checked as should the oil separator on the rocker covers.

"Closed Loop" refers to the computer optimising the various settings based on feedback from the O2 sensors/MAF/Air intake temp/Fuel temp etc. It kicks in when the engine operating temperature reaches around 85-88 Deg. C. When it operating in open loop, the computer relies on values from a fixed database for ignition timing/injection operation etc. It switches between both modes even when warm ...for instance under heavy acceleration.

Just a thought: The fuel temperature sensor is critical. If it's playing up, then the rough running /running rich etc. can be a symptom

I'm looking at swapping out O2 sensors on my D2a - 2003.

Will the ECU adaptive learn on its own or would I still need to use a nanocom after installation?

Thanks

Lee

If you have the pro version of the Android "Torque" app on your phone and a blue tooth OBDII dongle, you can use it to reset the adaptive values...!

Thats interesting about the Torque app
I didnt reset mine when I replaced the maf,, not sure BOR did it for the new engine either,,
10K kays on is it worth it?

I've ordered the obd2 diagnostic reader, to see what I can find out.

My D2a V8 seems to be running rich. Its blackening up my drive and smells quite pure 'not sure how to describe the smell' 😊. It appears to be a mix of water and oil droplets that come through the exhaust.

I've recently had the CAM changed and was hoping that would help solve the issue too. My fuel efficiency has also decreased.

I can only find the front 2, O2 sensors (LH Bank / RH Bank) on the downpipes. I don't seem to have any on the rear. My V8 is base model too and I'm sure I've read somewhere about having them on certain models as they only look after the emissions?

I'll have a read up on RAVE, but any pointers are greatly appreciated.

Thanks Lee