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1995-2002 Range Rover P38A
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336 Posts
Discussion Starter #1
Hi

Would anyone care to read and comment on the data in this file?

I would appreciate any advice, as I need to learn more about the values and gain some knowledge on what I am looking for and looking at :)

I have no idea what the values should be for a normal (4.6) RR so I do not know if these values are good or bad. I think there must be some incorrect values as the engine does not run as well as it should. It lacks power and does not accelerate as normal. The RR now cold starts ok but 10-15 seconds after starting it almost stalls, only the ECM seems to keep it going. After approx 30-40 seconds it starts to idle reasonably well and improves when it warms up.

Because of previous poor performance I have checked and since cleaned (with proper cleaner) the MAF and subsequently, based on other advice, reset the adaptive values. The idling problem above seems to have been a result of the clean/reset just mentioned.

Next Monday I will take the opportunity to test the RR with another MAF. This will at least confirm the state of my current MAF, which I believe to be ok. I don't really want to spend huge $$$ on a part that does not solve the RR's problem.

[attachment=0:wzg5h516]air&fuel 2 20091004.zip[/attachment:wzg5h516]

I am slowly gaining knowledge on the vagaries of the engine etc, so any help with this data will be of great assistance.

Thank you...

BTW During the creation of this csv file, I held the accelerator flat to the floor - the MAF readings were ~122. The engine would NOT rev any higher than 2500rpm. Any comments on this?
 

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Registered
1995-2002 Range Rover P38A
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336 Posts
Discussion Starter #3
Hi

Rich998a said:
The MAF is reading low at idle.
Thank you. Could you please qualify that a little? Does that mean the MAF is definitely faulty and needs replacing or is it just a low reading and the ECM will compensate?

Where could I find out more info on the various values in the csv file?
 

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Premium Member
2010-2012 Range Rover MkIII / L322
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4,635 Posts
You'll need to check, but I understood the MAF should be reading around 20-25 at idle. My MAF reads 16-18 at Idle with a 3 year old Genuine MAF.

Do you find that the gearbox kickdown doesn't always work when you floor it?
 

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517 Posts
If the MAF is failing and you do an adaption reset you can make things worse. The ECU will have slowly adapted with the MAF. If you then reset, the MAF can be so far out that the ECU will not be able to make such a big adaption. I recently had this on my Merc. Not running great - reset adaption values - really poor idle and acceleration, when tested the MAF was showing 1/2 the correct value at WOT.
Test your MAF using values given by AllyV8 in the link I have given you in your other post.
 

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1995-2002 Range Rover P38A
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336 Posts
Discussion Starter #6
Hi

Rich998a said:
You'll need to check, but I understood the MAF should be reading around 20-25 at idle. My MAF reads 16-18 at Idle with a 3 year old Genuine MAF.

Do you find that the gearbox kickdown doesn't always work when you floor it?
Yes, but that is probably because under normal driving conditions the engine just dies if I floor the accelerator. :)

While parked and under test with the RCL, the engine currently does not rev higher than 2500rpm if I floor it. The MAF reading goes up to ~122 at 2500rpm.

From what I have read within these current messages, it seems to me that the MAF is the problem.
 

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1995-2002 Range Rover P38A
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336 Posts
Discussion Starter #7
Hi
AMcK said:
If the MAF is failing and you do an adaption reset you can make things worse. The ECU will have slowly adapted with the MAF. If you then reset, the MAF can be so far out that the ECU will not be able to make such a big adaption.
Yes, so I found out :) I can confirm that from my recent experience :)
 
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