|
||
|
3rd July 2018, 09:33 | #1 |
Avid contributor
Rover 75 Contemporary Saloon Join Date: Apr 2012
Location: Capitol
Posts: 116
Thanks: 37
Thanked 10 Times in 10 Posts
|
CDTi Auto performance lack
Hello to all again.
I have two CDTi 75s, one is manual, one is auto. Manual is perfect with performance, but Automatic is very sluggish and it lacks acceleration performance. Basically, it has average performance below 2000rpm (but very similar to manual i have, so i assume that is what it is meant to be). But, when i try to accelerate on steep or even slight hills it has very bad acceleration. Acceleration is specifically bad after 80 km/h (which is not the case on manual), no matter if i choose SPORT or any other mode. I was travelling for 9 hours few days ago and it is a struggle to accelerate when it is important. What i tried: - Changed viton o-rings on both of them - Did the leak back test on the injectors (everything OK) - Checked injector imbalance values (all around 0.0) - Changed MAF (previous one was bad according to values read on TOAF, and replacement improved performance slightly) After all these, i compared results on the TOAF from both of them and boost pressure, inlet manifold pressure and fuel pressures (low and rail pressure) are the same on both of them. Please, give me some ideas what can cause the problem and what to look after? As well, i searched throughout the forum a lot, but didn't find a solution, so i decided to start a new thread. Thank you all in advance |
3rd July 2018, 13:35 | #2 | |
I really should get out more.......
Rover 75 CDT Club Tourer Join Date: Nov 2006
Location: Milky Way
Posts: 2,388
Thanks: 105
Thanked 513 Times in 382 Posts
|
!
Quote:
Last edited by grivas; 3rd July 2018 at 13:36.. Reason: Spelling |
|
3rd July 2018, 14:55 | #3 | |
Avid contributor
Rover 75 Contemporary Saloon Join Date: Apr 2012
Location: Capitol
Posts: 116
Thanks: 37
Thanked 10 Times in 10 Posts
|
Quote:
I can do all these very fast, so i'll get back with the results. |
|
3rd July 2018, 16:21 | #4 |
Gets stuck in
R75 Connoisseur CDT (116PS) Saloon Auto; R75 Connoisseur CDT (116PS) Tourer Manual Join Date: Jan 2013
Location: Athlone, Ireland
Posts: 581
Thanks: 91
Thanked 75 Times in 58 Posts
|
|
3rd July 2018, 17:06 | #5 | |
Posted a thing or two
Rover 75 saloon, manual. Rover 75 Tourer, Auto. Join Date: Jan 2013
Location: Newry
Posts: 1,783
Thanks: 574
Thanked 443 Times in 371 Posts
|
Quote:
Are both cars the same from factory? Ie are both 115bhp or 130bhp? Or is the auto perhaps 115 and the manual 130 bhp. Has either one been remapped? Both of the above points alone may account for an appreciable difference. However, If you’ve had the auto car for a while, and are now noticing a decline in performance, that’s another issue, most of the suspects which you’ve already looked at.🤔 What maf did you purchase? Anything other than a proper Bosch one may be a waste of time. Are MAF readings “within spec”...sorry I don’t have figures to hand, but you should be able to get them on here somewhere. Sent from my iPhone using Tapatalk
__________________
2006 75 Contemporary SE diesel manual (#1) 2003 75T Connoisseur SE diesel auto (For Comfort) 2005 75 Connoisseur SE diesel auto (Marmite duotone ) 2006 75 Connoisseur SE diesel auto (The last one?) 2009 E220 (For a change) 2018 L200 (For Big & Heavy Things) 1976 W114 250 Manual (For Sundays) |
|
3rd July 2018, 17:40 | #6 | |||
Avid contributor
Rover 75 Contemporary Saloon Join Date: Apr 2012
Location: Capitol
Posts: 116
Thanks: 37
Thanked 10 Times in 10 Posts
|
Quote:
Quote:
Quote:
Those values are within the range (almost perfect). When we speak of MAF values, what i found on TOAF is that "Real air mass" values are equal for both cars, but "Required air mass" values are different. For example when revved to 3000RPM as a reference: Car with manual gearbox - MAF values: - Real air mass: 650 mg/hub AND Required air mass: 433 mg/hub Car with automatic gearbox - MAF values: - Real air mass: 670 mg/hub AND Required air mass: 961 mg/hub So, the Required air mass are 'very' different. What is Required air mass at least and is this a sign? Thanks again... |
|||
4th July 2018, 14:15 | #7 | |
I really should get out more.......
Rover 75 CDT Club Tourer Join Date: Nov 2006
Location: Milky Way
Posts: 2,388
Thanks: 105
Thanked 513 Times in 382 Posts
|
Quote:
How do you know the MAF sensor is a genuine Bosch sensor?. Also you could swap the MAF sensors between cars and then see?. |
|
4th July 2018, 14:40 | #8 |
MG ZT Join Date: Jan 2011
Location: Newcastle Upon Tyne
Posts: 20,151
Thanks: 3,565
Thanked 10,837 Times in 5,718 Posts
|
Look at the live data of the MAF while very gently increasing the revs from tickover.
If the mass airflow readings drop to <350 mg/stroke then increase the revs to over 2000 RPM briefly and then release the throttle pedal and allow the car to idle. Then note the MAF readings, do they recover within five seconds to circa 495mg/stroke, or does this take considerably longer? The off load figures you quote look to be well within spec, nigh on perfect in fact, so I suspect the EGR operation is the problem here By the way I always disable EGR operation before resorting to unplugging the MAF, because unplugging the MAF also disables EGR operation, so a completely perfect MAF sensor can be classed as poor, when in fact what is happening is the EGR sticking Brian |
4th July 2018, 15:49 | #9 | |
Avid contributor
Rover 75 Contemporary Saloon Join Date: Apr 2012
Location: Capitol
Posts: 116
Thanks: 37
Thanked 10 Times in 10 Posts
|
Quote:
I accidentally deleted previous message. I'll do the thing you mentioned. As well, how can i disable EGR operation you said? And how to repair EGR if that is the case? Thanks |
|
4th July 2018, 16:30 | #10 | |
MG ZT Join Date: Jan 2011
Location: Newcastle Upon Tyne
Posts: 20,151
Thanks: 3,565
Thanked 10,837 Times in 5,718 Posts
|
Quote:
Generally speaking failures of this type are caused by the carbon break of the pushrod which operates the valve, becoming clogged to the point it scores the guide tube inside the EGR. Cleaning the EGR may help matters, but simply unplugging the connector will suffice for testing purposes. So follow the vacuum hose back from the diaphragm on the EGR toward the engine, the actuator solenoid is connected to this Brian |
|
|
|