Still struggling with the 850R

[bonnietiler]

She starts beautifully and ticks over perfectly.you can mooch along at motorway speeds no problem. Fuel consumption still the same .as you get to 3000rpm it stutters, like hitting a rev limiter on a bike. I found a little pipe at the rear right side of the motor that had come away...no difference looks like a breather I have changed to cat for one that was in the boot when I bought it so no real idea if it's any good.. Lambda light (new Bosche) permanently on..Done an ECU reset always on though. Could my brand new Lambda be duff?
when I looked at the plugs they were VERY white as if the motor had been running hot..Is it possible that its fuel starvation?
At a standstill it'll rev for fun just under load that it gets all sulky.
Anything I'm missing??
Cheers
Bonnietiler

[Doingitsideways]

Does sound like it's running lean.

Air leak somewhere would be my best bet.

Need the codes read really, Fella.

[claymore]

I would bet that you have a split in one of your boost pipe joiners, I've had the same symptoms a few times when I've split a hose, the engine will run fine off boost, even reving fine with no load, but as soon as the turbo starts to boost it opens up the split.
Even with a split like this the car would be ok off boost.




EDIT: ignore my post, as with a split in a pipe the engine would run very rich not lean.

[jamesy12345]

Depending on where a split is, it could be drawing air in & that would make it run lean? Between turbo & MAF for example. Oxy sensor would correct up to a point but maybe not enough

[LeeT5]

Depending on where a split is, it could be drawing air in & that would make it run lean? Between turbo & MAF for example. Oxy sensor would correct up to a point but maybe not enough

Spot on

Any air leak if it's on the vacuum will make a car run lean, not rich.
If the leak is on the pressure side then it should run rich because the car will also be injecting more fuel due to expected boost, but with a leak, it won't reach target and thus will go into overboost protection and limp mode due to it overboosting target boost for a split second when the hole opens up.

If your plugs are white, this is also an indication it's running lean. As long as there is no whitish/yellow buildup on the plugs (which would indicate burning oil).

However, you could also have a lazy O2 sensor. If one does not react quick enough then the car will not fuel correctly.

[Dangerous Dave]

Is it remapped?

[bonnietiler]

I believe so, I found the clip post maf was loose and tightened that the Lambda went out immediately, I have replaced the original 100 cell cat just to see if there is any difference..It is better but still got the 3000rpm jitters. I have removed the battery leads overnight and will have another run later today...Thomas is getting me a TME cat prepared but its quite a price I can tell you!

[Doingitsideways]

I believe so, I found the clip post maf was loose and tightened that the Lambda went out immediately, I have replaced the original 100 cell cat just to see if there is any difference..It is better but still got the 3000rpm jitters. I have removed the battery leads overnight and will have another run later today...Thomas is getting me a TME cat prepared but its quite a price I can tell you!

Worth it though.
I have one on the S70 and a full exhaust. Excellent workmanship

[LeeT5]

I believe so, I found the clip post maf was loose and tightened that the Lambda went out immediately, I have replaced the original 100 cell cat just to see if there is any difference..It is better but still got the 3000rpm jitters. I have removed the battery leads overnight and will have another run later today...Thomas is getting me a TME cat prepared but its quite a price I can tell you!

Have you actually tried a new set of spark plugs?

You'll be surprised at what a difference these can make, especially on a Turbo car. If you have a weak spark then it's possible that the fuel is not being burnt properly under load. This is exaggerated on Turbo cars because of the increased cylinder pressures. I had a similar problem a few years ago (masked by numerous boost leaks) but changing the plugs made a massive difference and it stopped stuttering in the mid range, especially under boost.

[Doingitsideways]

Agreed ^^^^

I had a misfire on boost.
New sparks, HTs/king lead, dizzy cap and rotor arm sorted it.