Fuel Trim Code

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TomH84
Joined: Sun 15 Dec, 2013 15:22
Posts: 113

  Z3 roadster 2.2i

Fuel Trim Code

Post by TomH84 »

I know this is a long shot but, thought I'd ask...

After an oil service, wash and wax, my Zed has rewarded me with a check engine light :head: :head:

The C-110 scanner code reads "fuel trim bank 1 permissible range exceeded." From memory, this code is often linked to intake/vacuum leaks, but also 02 sensors. Car runs perfectly. No obvious fault(s) apparent.

I've had a look at the hoses this pm, but don't see any obvious holes etc (last year I found a huge hole in the lower intake boot which I replaced). The small pipe from the F connector on the upper intake boot looks worn but is not cracked.

Any ideas of "where to start" with this...?

Every year I get a niggle like this! Damn all these electronic monitoring systems / check engine lights. On the MGB, there's none of this...

Cheers

Tom
2002 BMW Z3 2.2i 82k
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1971(K) MGB GT - the 'other' car
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colb
Joined: Sat 05 May, 2012 22:46
Posts: 690

  Z3 roadster 1.8 TU
Location: Newport South Wales UK

Re: Fuel Trim Code

Post by colb »

Frequent cause is a vacuum leak between the Maf and the intake or any of the other air hoses within the system. If visual checks don't reveal any holes best try a smoke test by blowing smoke under pressure into the intake after the Maf.
If that fails to show up any leaks then start suspecting the other things in the system, are the Exhaust sensors performing if you have some diagnostics to see what they are doing it may pinpoint where the fault is. Don't rule out a bad Maf, its the first sensor in a chain, it may be at fault and causing the other sensors to be receiving bad data hence the bad mixture.

Colb
Colb
1999 BMW 1.8 Z3
2003 BMW 2.5 Z4
1998 Honda Deauville NT650V
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TomH84
Joined: Sun 15 Dec, 2013 15:22
Posts: 113

  Z3 roadster 2.2i

Re: Fuel Trim Code

Post by TomH84 »

Cheers!

I'll a smoke test and see where that takes me. I had a go with some carb cleaner (works for the MG) but that didn't get me far. If I can't find any leaks, it does suggest a slow/failing MAF.

I pulled the data stream info this afternoon. This suggests "lean" condition on both banks when under part load. Now I think about it, this lean problem could actually be linked to an old/failing fuel filter or fuel pump. Hmm...

Bank 1 adaptive (idle) = 0.11 OK (0.2 max) See http://www.europeantransmissions.com/Bu ... ionBMW.pdf
Bank 2 adaptive (idle) = 0.13 OK (0.2 max)

Bank 1 multiplicative (under load) = 11.2% Limit exceeded (8%)
Bank 2 multiplicative (under load) = 9.3 % Limit exceeded (8%)

Thx again
2002 BMW Z3 2.2i 82k
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1971(K) MGB GT - the 'other' car
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colb
Joined: Sat 05 May, 2012 22:46
Posts: 690

  Z3 roadster 1.8 TU
Location: Newport South Wales UK

Re: Fuel Trim Code

Post by colb »

Your mention of the fuel filter may be relevant when I had problems with mine I went through everything in attempt to get it running right.
I did change out the filter and found it was the original filter of 1999 vintage, it had never been changed. Put a new one in but still had problems. Eventually ended up replacing the Lambda sensors and the Maf which put everything right, no problems since.
Used OEM parts after wasting cash on cheap pattern parts particularly the Maf replacement, always go for Bosch or Seimens, expensive but they do what they are supposed to do.
Colb
Colb
1999 BMW 1.8 Z3
2003 BMW 2.5 Z4
1998 Honda Deauville NT650V
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TomH84
Joined: Sun 15 Dec, 2013 15:22
Posts: 113

  Z3 roadster 2.2i

Re: Fuel Trim Code

Post by TomH84 »

New filter ordered. Let's see what that does to the fuel trim values...

Right, back to the darts!

Tom
2002 BMW Z3 2.2i 82k
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1971(K) MGB GT - the 'other' car
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