Disco 2 low power under 2000rpm, can it be MAF?

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berg450

berg450

Well-Known Member
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665
Location
Hungary
Hello
Since I have my 2nd D2 (almost a year) I feel low power under 2000rpm (I can start even slight uphill only by reving up and play with clutch). I few months ago I have changed my MAF and installed an italian made Meat&Doria-Hoffer (a local mechanic told me that these are reliable and he got it within a day on a good price). The car runs well over 2krpm and also all MAF readings seems to be correct (from 50 to 600).
Today I have disconnected the MAF and found the car better on low rpm! Seems that even I got good values from the MAF somehow it is still not perfect.
I think I will buy a new MAF... my question is, only genuine LR is the good option (for about 150 pounds) or VDO Siemens also good quality (half price)?
 
Hi, only genuine LR is 100% reliable, the rest are all a lottery...though for bad response at low revs can be many other things too, if you have nanocom record a data log and post it here before you spend on a genuine MAF especially if it's Eu2 engine
 
To clarify, is it Eu2 or Eu3 engine? ... anyway, my first impression is that the wastegate is stuck open so ckeck that and tell me how many threads are left on the actuator rod, the boost is rising too slow IMO

what about oil in the ECU fred plug? cos cyl 5 balance is a bit out of range
 
It is a 2003 facelift so I guess Eu3 (water cooled EGR).
A few months ago I have removed the rod from the wastegate and checked the movement, it was free. I will check the numebr of threads tonight.
No oil in ECU (injector harness changed also a few months ago).
 
After the injector harness replacement the red plug must be cleaned once a week utill it ends up dry cos the residual oil from the engine harness keeps coming, at the wastegate in most cases the problem is caused by the valve which becomes sticky due to internal build-up and it doesnt acuate well the rod or doesnt come fully back to closed if you see what i mean so check the rod's movement which is a bit heavy due to the spring but it must be smooth and complete ... 2003 is certainly Eu3 so the only 100% relaible MAF is genuine LR cos the IQ uis calculateed based on MAF/Rpm inputs... did you clan the MAP sensor too? ... it's visible in the log that the boost is raising too slow at lower revs that's why the modulator is quite inactive too so that's the cause of that sluggishness... at high revs you gain power cos at that point the wastegate is supposed to be open anyway. .... if you find 13 threads left on the rod undo the locknut and adjust untill 10 threads and see how it goes then, also replace the depression control valve(LLN100140L) if you know it's old cos they wear out in time and can't check if they work well or not
 
The red plug is nice and clean. The wastegate moves free. The MAP sensor was already cleaned 2 times in the past 6 months. The wastegate rod is already on 11 thread. Can it be the wastegate solenoid?
 
I doubt it's the wastegate modulator, it usually creates overboost not low boost, i'm affraid it's a boost leak somewhere cos with the actuator already shortened the boost should rise better and you should bet at least 1.35 bar at 600 kg/hr sucction, do you have a de-Cat downpipe ?
 
I am not sure, but I guess it is without catalyst.(WCD106210)
I have just checked. It is with catalyst.
 
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i had a similar situation, which only showed up when the engine was hot, it would be like it was in limp mode for 30 seconds, then it cleared up completely and returned to normal after a little driving.

i changed the MAF to a delphi one (not original manufacturer but quality nonetheless) and it has completely eradicated the issue and improved my mpg some (not a huge amount but still)
 
I had the same with my first D2 few years ago. I guess the MAF in such case not totally bad but ECU does not accept values and this is why it is in limp mode for about 20-30 sec and after ECU start with pre set mode and car runs OK. I also changed my MAF at that time (to VDO) and issue solved.
My situation now is not that "easy" as I have no power only under 2000rpm. For example it is hard to go out from my garage which is under my house. I have to play with clutch and keep rpm high. If rpm falls and I push accelerator I got only black smoke and car almost stops.
Over 2000rpm I have no issue.
 
In order to go a bit more deep to see what could be the reason of the relatively low power under 2000rpm I have put back my old siemens MAF and felt a bit better performance. I have connected Nanocom and evaluated both data (Siemens and Hoffer MAF) in two simple charts. Both are between 50-600 but siemens seems "stronger" under 2000rpm.
Now it would be very interesting to have the same chart showing how a new geuine MAF behaiving. Does anyone of you has such data?
 

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IMO you can't compare your data with others to get to a conclusion cos there are many differencies between vehicles, even the tyre dimensions, weight, driving style, ambient pressure, ambient temp, and so on, etc. are implied, you have to work on your own vehicle and figure it out... IMO your problem is with boost not with air flow cos if it was the MAF the vehicle should have good power with it disconnected and the ECU on default to MAP/rpm IQ calculation...so as long as you dont have enough power with MAF unplugged the problem is elswhere even though a 100% reliable MAF like the genuines are would improve driveability compared to the MAF disconnected status
 
sierrafery said:
IMO you can't compare your data with others to get to a conclusion cos there are many differencies between vehicles, even the tyre dimensions, weight, driving style, ambient pressure, ambient temp, and so on, etc. are implied, you have to work on your own vehicle and figure it out... IMO your problem is with boost not with air flow cos if it was the MAF the vehicle should have good power with it disconnected and the ECU on default to MAP/rpm IQ calculation...so as long as you dont have enough power with MAF unplugged the problem is elswhere even though a 100% reliable MAF like the genuines are would improve driveability compared to the MAF disconnected status
Click to expand...
Yesterday i have checked again wastegate, cleaned again MAP and adjusted rod to 10 thread. No change. Turbo does not go over 1.2 and still weak on low rpms. Any idea?
 
Then IMO it's a boost leak or exhaust gas leak somewhere or the turbo is worn, eventually clogged intercooler? .... undo the pipe from the wastegate actuator valve as to be inactive then go for a ride like that and see at what rpm it goes to overboost... if it's above 2500 it means there's not enough pressure delivered to the inlet for some reason
 
I have disconnected the pipe and no change! I have let the rpm goes above 3500 and nothing happened. The pressure has not gone over 1.2. No overboost.
 
So IMO you have the answer.... not enough boost, exactly what's obvious from the data log.... so investigate in this area, the possibilities are like in my previous post unless your MAP sensor is fubar but the fact is that with wastegate actuator inactive you should have got overboost and that's not the result of MAF sensor whatsoever, so forget about the MAF at this point and concentrate on fhe boost.... though i hope you didnt forget all i've said untill now

btw, make sure that you didnt buy the vehicle with a boost box fitted
 
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