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Model specific boards => Golf mk4 => Topic started by: WadGTI on 08 October 2013, 23:46

Title: Fuel Trim Problem
Post by: WadGTI on 08 October 2013, 23:46
Hi folks,

Everytime I get rid of a fault another comes back in its place..really getting me down now  :sad:

Anyways, I have one fault only on the engine block which is perhaps good.
 
1 Fault Found:
17536 - Fuel Trim: Bank 1 (Mult): System too Lean
        P1128 - 35-10 - - - Intermittent

I have cleared the code (came back). done a TB reset (then cleared code) and has come back. The car does have power though and boosts. I also got a refurbed bosch MAf last week as I had MAF code too. Anyways I have took some readings on blocks 002 and 032 on VAGCOM tonight.

I won't post all off it as there lots, but the ones I think are important are -

 
Group A:   002         
   Idle speed   Engine load   Inj. period   Air mass in
TIME   700-820 rpm   15-25%   2.0 - 4.0 ms   2.0-4.5 g/s
STAMP    /min   %    ms    g/s
0   720   15.8   2.04   2.31
0.4   720   16.5   2.04   2.47
0.8   760   16.5   2.04   2.42
1.2   720   15.8   2.04   2.33
1.6   720   15.8   2.04   2.36


52.61   5080   108.3   14.28   107.72
53.11   5440   115   14.96   120.58
53.51   5760   124.1   16.32   136.06

From what I can tell from online is that 136 is about right for the AUQ (bhp x 0.8)

The 032 codes readings are strange though!. Everytime time stamp has the same value from start to finish.

Group A:   032   
   Idle O2 Adapt   Run O2 Adapt
TIME   -10-10%   -10-10%
STAMP   %   %
0   -2.1   21.1
0.4   -2.1   21.1
0.9   -2.1   21.1
1.31   -2.1   21.1
1.81   -2.1   21.1

At a guess, is my o2 sensor buggered?. These logs were taking with the fault code still stored and all readiness tests at passed. The car was overfueling for a while and thinking it had maybe damaged the sensor.

Thanks folks
Title: Re: Fuel Trim Problem
Post by: WadGTI on 09 October 2013, 12:18
Any suggestions guys as I can pick up the o2 sensor(s) today.

Thanks
Title: Re: Fuel Trim Problem
Post by: rio_gti on 09 October 2013, 13:36
any motorfactors but go bosch  :wink:
Title: Re: Fuel Trim Problem
Post by: WadGTI on 09 October 2013, 13:44
any motorfactors but go bosch  :wink:

Thanks Rio. Have been on ECP website and can get the bosch sensor for £72 all in which is a cracking price as VW and TPS wanting £140+ for it.

Just hoping that the above symptons point towards the 02 sensor as I have been spending too much money on it recently and fund are getting short.

THe timing belt fund is gone too lol  :grin:
Title: Re: Fuel Trim Problem
Post by: WadGTI on 10 October 2013, 12:28
One of my mates is going to test my emmisions after work.

Does any know if this will clearly point in the direction of the o2 sensor if its faulty?

Thanks
Liam
Title: Re: Fuel Trim Problem
Post by: WadGTI on 10 October 2013, 18:14
Ok....so I had the emissions tested and it passted everything. (this was with the fault code still stored and it was not in learn mode).

I took a run out just now and measured the following. Can anyone tell me whats going on here??

Sorry guys, I tried to edit this to make it more readable but it just aint doing it.

Group A:   032            Group B:   002            Group C:   033   
   Idle O2 AdaptRun O2 Adapt              Idle speed   Engine load   Inj. period   Air mass in      PreCat O2 Reg   PreCat O2 V
TIME   -10-10%   -10-10%           TIME   700-820 rpm   15-25%   2.0 - 4.0 ms   2.0-4.5 g/s   TIME   -10-10%   0-1V
STAMP   %   %         STAMP    /min   %    ms    g/s   STAMP   %    V
1.14   0.9   2.3                         0.34   760   15   2.04   2.25   0.72   -5.5   1.48
2.55   0.9   2.3                         1.65   720   15   2.04   2.22   2.15   0   1.56
3.76   0.9   2.3                         2.95   720   15   2.04   2.25   3.35   -6.3   1.58
4.96   0.9   2.3                         4.16   760   15   2.04   2.28   4.56   -6.3   1.5
6.18   0.9   2.3                         5.36   720   16.5   2.04   2.42   5.76   -0.8   1.56
7.59   0.9   2.3                         6.68   1120   30.1   3.74   5.61   7.17   0   1.58
8.88   0.9   2.3                         7.99   1320   41.4   5.78   12.33   8.48   10.2   1.22
10.1   0.9   2.3                         9.28   2120   39.8   5.44   17.03   9.7   15.6   1.54
11.3   0.9   2.3                         10.5   1600   51.9   7.14   17.97   10.9   3.9   1.66
12.51   0.9   2.3                         11.7   2040   33.8   4.08   8.39   12.1   10.2   1.54
13.81   0.9   2.3                         13.01   2000   12.8   0   5.36   13.41   0   4
15.03   0.9   2.3                         14.23   1960   25.6   4.42   10.89   14.63   0   0.74
16.23   0.9   2.3                         15.43   2000   12   1.7   4.89   15.83   0   1.54
17.44   0.9   2.3                         16.63   1880   13.5   0   5.14   17.04   0   4.2
18.74   0.9   2.3                         17.94   1760   19.5   3.4   6.81   18.34   0   0.42
19.95   0.9   2.3                         19.15   1800   36.8   4.42   13.17   19.55   8.6   1.6
21.15   0.9   2.3                         20.35   1960   18.8   2.38   5.67   20.75   2.3   1.34
22.46   0.9   2.3                         21.55   1920   36.1   5.1   15.25   21.97   7.8   1.6
23.66   0.9   2.3                         22.86   2360   71.4   10.54   36   23.26   20.3   1.7
25.09   0.9   2.3                         24.08   3200   84.2   11.9   52.53   24.59   21.1   1.58
26.38   0.9   2.3                         25.6   4480   99.2   14.28   84.44   26   17.2   1.16
27.6   0.9   2.3                         26.78   5440   109   14.62   114.61   27.2   5.5   0.92
28.9   0.9   2.3                         28   6360   112   17.68   133.11   28.42   0   0.04
30.21   0.9   2.3                         29.31   4440   13.5   0   9.44   29.81   0   4.14
31.42   0.9   2.3                         30.61   4560   12   0   9.44   31.01   0   4.18
32.72   0.9   2.3                         31.92   4040   12   0   9.53   32.32   0   4.22
 

Title: Re: Fuel Trim Problem
Post by: WadGTI on 10 October 2013, 18:42
I found this on vortex -

Block 033 - Pre-Cat Oxygen Sensor Control

 - Go to Block 033. The value in Field 1 represents the pre-cat oxygen sensor control. The value should fluctuate at least 2% in the -10 to +10% range.

My readings shoot above 20 as above.

Just to add here, there is no leaks in any part of the exhuast system, charge pipe looks good, From what i can tell/hear no vacc leaks (other that getting a smoke test which I am planning on doing shortly), the car has boost, pull very well. The o2 sensors have never been changed ever by the looks of them too.

It has just came to my that the SAI leaks or is loud either way when on (cold start). Could this act like a vaccum leak even when off?

Thanks
Title: Re: Fuel Trim Problem
Post by: WadGTI on 10 October 2013, 20:29
Some boost figures

Engine Speed   Engine Load   Spec. Boost   Actual Boost
700-6800 RPM   15-150%   990-1800 mbar   <=1800 mbar
 /min   %    mbar    mbar


30.89   4240   93.2   1630   1560
31.69   5000   107.5   1670   1590
32.68   5880   123.3   1630   1650
33.5   6480   115   1570   1590
34.31   5840   11.3   1020   1190
35.31   4640   12   1020   1060


From what I can tell, its boosting aorund 9 psi (ish) around 6k revs?
Title: Re: Fuel Trim Problem
Post by: Wazzzer on 12 October 2013, 12:17
system too lean is usually an air leak in after the MAF...

and yes it's hitting around 9psi. Is that with your foot flat to the floor?
Title: Re: Fuel Trim Problem
Post by: WadGTI on 14 October 2013, 00:10
system too lean is usually an air leak in after the MAF...

and yes it's hitting around 9psi. Is that with your foot flat to the floor?

Thanks Wazzer. Yeah your right.

I found 2 leaks  - pcv breather that goes into the tip  (the plastic extension on the pipe was torn at the seem) and one of the vac reservoir pipes that I blocked off for the n249 bypass was still leaking. - Used the spray bottle method and was surprised with the results lol

Picking up new breather tomorrow and the full n249 removal tomorrow. Hopefully will be air tight now and will get better maf readings :)

Only thing is, I'm not sure if I can run the following vac line (Manifold -> N112 -> CheckValve/SAI)??

My current vac setup is DV -> T Piece -> FPR/Manifold - Runs great and have no fulter - Good Noise too. Not really wanting to mess with this vac line as it works well in my view.

Yeah, 9 psi on WOT run.

Cheers
Title: Re: Fuel Trim Problem
Post by: WadGTI on 17 October 2013, 11:24
Hi Folks,
Bit of an update. The car is pulling very strong and idleing good. This has been compared to my mates 150 which he could not keep up with me.

However, a chap from the Vwvortext forum who has been looking at some logs for me, has advised I have a major timing pull (up to 12 @5k revs).

The car itself, feels great which is strange. My MAF is still pulling low readings (as of yesterday), but again there is pently of power.

So far –
2 vac leaks found and sorted, fuel filter changed, spark plugs check (very good condition) and gapped to 0.32, themrostat changed, coolant temp sendor changed and MAF.

The o2 sensor has yet to changed, but its giving a reading from VAGCOM and the car passed an emmisions test last week.

I am at a loss with this now .

The car is booked in tomorrow for a belt and pump change as it may have jumped a tooth, but not sure as unable to verifiy the timing. The car is now @ 124k and I assume it was last changed around 60k.

The car runs great, but I am still getting this timing pull!!. Can anyone advise why a MAF would give low readings (just over 100 g/s on WOT pull) and not come up with a fault code.

The car was scanned again yesterday and I have no fault codes.

Any feedback would be brill.
Thanks
Title: Re: Fuel Trim Problem
Post by: MoshiMoshi on 17 October 2013, 15:59
Hi folks,

Everytime I get rid of a fault another comes back in its place..really getting me down now  :sad:


Welcome to the club ;)
Title: Re: Fuel Trim Problem
Post by: Wazzzer on 19 October 2013, 11:05
Timing pull can be caused by high intake temperatures
Title: Re: Fuel Trim Problem
Post by: WadGTI on 19 October 2013, 11:44
Timing pull can be caused by high intake temperatures

Thanks Wazzer, from what I can tell, the air temp is good on the intake as per vagcom.

However, after doing some more reading, using standard 95 ron fuel can cause timing pull. I use 95.

The sticker on the fuel cap says 95/98. Over the years, I have more or less used vpower, but I tried it in the golf when I first got it, but it was knocking. Went back to 95 and knocking went away.

I doubt the car has anything but 95 over 124k mileage. Changed my fuel filter recently and I am contemplating giving vpower another try.

Can anyone give any insight into this as other info suggests it could take 400+ miles of the car to adapt from 95 to 99. I'm not sure if 400 miles of knocking would be safe?

At least one bit of good new...timing belt and pump was changed yesterday  :smiley: