Turbo lag on CDT

[harrisop48]

Is the K&N filter a oil one there is a school of thought that can contaminate the MAF. You may have contaminated the spare one as well. Is the new one coming from Germany via E-Bay MAF Shop. Original Bosch in BMW housing. Was around £75, maybe £85 now.

[wmick]

Thanks for that, Peter, I hadn't heard that one. It is an oil one but since it's a bit 2nd hand, I haven't re-oiled it.
I'm too mean to spend £55 on an air filter!
Once the new MAF arrives I'll blow £5 on a Britpart filter, after all they're nearly next door!

Mick

[klarzy]

Originally Posted by pletevl

Brian, where is this ? my CDTI has a vacuum pipe going to mine, i have never seen an electrical connection

Pete.

follow the vac hose to the front of the engine...it connects to the solenoid

[grteam]

Hello, keep us posted please, regarding the new MAF, I experience the same. The EGR has the vacuum pipe disconnected and blinded, for the rest is stock, and intercooler Viton rings are done. Once I disconnected the MAF but the outcome was horendous, serious power cuts when accelerating medium/hard, leaving me with more questions than before.

[Bigal2218]

If you have a lot of sooty/oily deposits around the turbo duct then that indicates that the sealing 'O'-ring has failed. Contact Jules for a superior oil-resistant ring. I used to suffer a breathless asthmatic wheeze sometimes when joining traffic on a roundabout, but no longer since Jules upgraded the seal.

[grivas]

Originally Posted by wmick

I've had the saloon 6 years now and it's never been brilliant at pulling away from a standstill, but I've just changed the airfilter for a K&N one, cleaned the EGR (urgh!), changed the PCV and cleaned the manifold pressure sender, and it seems worse than before, although not as smoky.
I've never noticed any "turbo lag" on the Tourer, but it's very obvious now on the saloon. I can accelerate away from a 30 limit in 5th with my foot through the floor and it gathers speed very gently until it gets to 2000 rpm (60 mph) and then it goes like stink. If I want make decent progress I have to go through the gears and rev it, which is pain when towing the van (max legal speed 50!)
Has anyone any ideas as to what causes the difference in performance between the 2 cars (apart from Brian providing me with a new ECU a couple of years ago)?

Mick

I would say that the oil on thr air filter has contaminated your MAF sensor, remove the sensor and see if there is an improvement, if there is then replace filter with OEM version and clean MAF with isopropyl alcohol spray, very gently, but don't hold you breath the sensor may well be goosed.
PS don't use air filters other than good quality paper type, the oiled reusable versions are expensive to buy, add nothing to performance or fuel figures and in the case of the diesel will probably contaminate the MAF sensor, an expensive proposition, good luck.
PPS Exactly how did you clean the MAP sensor, as this might have a bearing on things.?

[grivas]

Originally Posted by wmick

Thanks for that, Peter, I hadn't heard that one. It is an oil one but since it's a bit 2nd hand, I haven't re-oiled it.
I'm too mean to spend £55 on an air filter!
Once the new MAF arrives I'll blow £5 on a Britpart filter, after all they're nearly next door!

Mick

A cheap air filter will quickly goose the MAF sensor, so be careful.!

[Avulon]

Originally Posted by wmick

I can accelerate away from a 30 limit in 5th with my foot through the floor and it gathers speed very gently until it gets to 2000 rpm (60 mph) and then it goes like stink. If I want make decent progress I have to go through the gears and rev it, which is pain when towing the van (max legal speed 50!)

Mick

But what speed are you doing in the 30 limit before you put your foot through the floor? . If it really is thirty then you're asking it to accelerate from sub 1,000 rpm in top gear: how do you expect it to accelerate in any sort of lively fashion before the turbo spools up? Use the gears, change to down if you need to acclerate, get the revs up above 1600 rpm to accelerate - I assume from your 'max legal speed 50' comment that it's a large van you have - cruising below 50mph with a van on the back in top isn't going to be the optimum for the engine. I'd suggest you try an auto, and see where that changes gear. it will use higher revs/ lower gear to accelerate then settle to the best ratio (according to the auto-box ecu ) for cruising.

[wmick]

Thanks for the input everyone.

I don't expect multi-G acceleration from low speed in higher gears, but I would like the same low speed power that my Tourer has, which will accelerate happily in top gear from 30 upwards with no dips in the power and no hesitation.

It's a smooth as a smooth thing!

I don't know if I've been lucky with the Tourer but at 150,000 miles it still pulls like a train, just not as fast a train as the saloon.

It's strange how the dip in the power seemed to coincide with the air filter change.

I've swapped MAFs with the 2 cars and there's no difference in the behaviour of either of them and I've checked the airflow figures, so it's not the MAF.

I'll just have to get it T4ed.

Mick

[lionatus]

I have a ZTT cdt and Ive noticed a huge difference cutting away the air pipe. even after service etc. I noticed now and again my power would blip or even die depending on the wind. I read that either putting a bolt( i.e. screwing in one) into the air channel at the bumper side fixes this or a quick fix cut the channel. As per the pics I did this. Not OEM and not advisable but you may have an air issue which is why the responses for a suspect MAF. Try unhooking your air channel to the filter and see what happens. I cut mine solely because the 3 screws on the bonnet side refused to come out and Id have destroyed the bumper getting them out. Good news is I need not worry as I need a new one(bumper) after an encounter with a pheasant so my cutting has cost me not.

Originally Posted by wmick

I've had the saloon 6 years now and it's never been brilliant at pulling away from a standstill, but I've just changed the airfilter for a K&N one, cleaned the EGR (urgh!), changed the PCV and cleaned the manifold pressure sender, and it seems worse than before, although not as smoky.
I've never noticed any "turbo lag" on the Tourer, but it's very obvious now on the saloon. I can accelerate away from a 30 limit in 5th with my foot through the floor and it gathers speed very gently until it gets to 2000 rpm (60 mph) and then it goes like stink. If I want make decent progress I have to go through the gears and rev it, which is pain when towing the van (max legal speed 50!)
Has anyone any ideas as to what causes the difference in performance between the 2 cars (apart from Brian providing me with a new ECU a couple of years ago)?

Mick