Audi S3 EGT Problem

[IbanezDan51]

Hi all,

Hoping someone knowledgeable can chime in...


I thought I had a vac leak which was causing my idle to be a bit lumpy (varies by about 25-50rpm). Went through all the old pipes, deleted some of it even... made sure there is no leaks. When putting the car back together I forgot to plug the sensor back in and I thought I had cured the problem as the idle was steady.


Went out in the car and it ran OK apart from wide open throttle where it stuttered ran smooth ish. Realised I hadn't plugged the sensor back in I did so and immediately the annoying revs were back to varying.


Also had the car on the rollers a week ago and the car made stock power but it appears looking at logs of other cars to almost be lagging - which is why I went looking for vac leaks. It does appear to have no power down low. I have experience with exhaust leaks before which has caused this pre turbine but I have had a feel around when cold and can not feel any leaks.

Any help?

Thanks,
Dan

 

[<tuffty/>]

No fault codes? mapped? logged boost request vs actual (115)?

Laggy could be a number of things... weak actuator, tired turbo, pre-turbine exhaust leak (would be noticeable)

What are the fuel trims (032) saying?

Any logs from the dyno run?

Any other mods?

<tuffty/>

 

[IbanezDan51]

No fault codes? mapped? logged boost request vs actual (115)?

Laggy could be a number of things... weak actuator, tired turbo, pre-turbine exhaust leak (would be noticeable)

What are the fuel trims (032) saying?

Any logs from the dyno run?

Any other mods?

<tuffty/>

Fuel trims are ok I think, reads -0.6% idle and -3.9% partial.

i do have a log of a run up the road, do you have an email tufty? What are the best channels to log?

Car is completely standard apart from the pcv simplification, ran the same before this... Just got rid of a leak from the suction jet pump.

thanks,
Dan

 

[badger5]

logs?

 

[S3 Paul]

Ive only had one EGT issue...
I ignored it for a while...
Result? New head ,turbo and manifold ,
Get some logging done and let these lads take a look,

 

[IbanezDan51]

What parameters do you want me to log?

I logged the EGT temps and it seemed to be doing its job. Nothing sporadic although I am not sure what I am looking for...

Lambda sensor 1 at idle seems to be varying from +3% to -7%?

How do I attach any logs and which groups are best for me to log?

Dan

 

[IbanezDan51]

Aligned the TB and no difference. It's not their on cold start, only when it starts getting a little warm.

Also the boost is tailing off according to vag com of requested against actual. Can't make boost higher up.

Any clues? Will be servicing the car in the next few hundred miles.

 

[<tuffty/>]

Not without logs mate... boost tail off is normal on K04's... they are little turbos... you need to log airflow, boost requested vs actual and N75 duty to get a feel for whats going on there...

http://www.ross-tech.com/vag-com/m_blocks/

<tuffty/>

 

[IbanezDan51]

1.8L R4/5VT 0001

Group A: '115 Group B: '002
Engine Speed Engine Load Boost Pressure Boost Pressure Engine Speed Engine Load Injection Timing Mass Air Flow
TIME (G28) (specified) (actual) TIME (G28) Sensor (G70)
STAMP /min % mbar mbar STAMP /min % ms g/s
24.44 760 33.1 980 990 24.14 720 33.8 3.4 4.72
25.04 720 33.8 980 990 24.75 720 33.8 3.06 5.06
25.65 720 34.6 980 990 25.35 760 33.8 3.06 5.08
26.25 840 54.9 980 990 25.95 680 40.6 4.42 7.58
26.85 1000 60.2 980 1000 26.56 1000 58.6 5.44 11.69
27.47 1160 75.2 1080 1010 27.15 840 61.7 5.44 10.97
28.07 1800 73.7 990 1070 27.76 1440 77.4 7.14 23.06
28.67 2320 52.6 980 1140 28.37 2080 66.9 5.44 26.58
29.27 2040 14.3 980 1060 28.96 2320 30.1 2.04 6.25
29.88 1600 73.7 1290 1040 29.58 1600 37.6 5.44 25.19
30.48 1960 87.2 1350 1140 30.17 1800 78.9 7.48 28.92
31.09 2320 79.7 1120 1270 30.79 2160 88.7 7.82 36.97
31.69 2600 74.4 1060 1290 31.38 2440 75.2 6.46 34.94
32.3 2880 67.7 980 1300 31.99 2720 70.7 6.12 36.75
32.9 3040 44.4 980 1270 32.6 2960 66.2 6.12 38.5
33.49 2360 14.3 980 1080 33.2 2720 13.5 1.36 5.08
34.1 2120 70.7 1070 1070 33.79 2120 49.6 5.44 27.81
34.71 2280 94.7 1410 1200 34.4 2160 78.9 7.14 36.03
35.31 2480 119.5 1850 1450 35 2360 106 9.52 53
35.92 2720 148.9 1820 1790 35.61 2600 132.3 11.9 72.69
36.52 3040 155.6 1790 1880 36.22 2880 156.4 14.28 87.14
37.12 3360 149.6 1810 1810 36.82 3200 151.9 13.94 91.25
37.72 3680 152.6 1810 1820 37.42 3520 153.4 13.94 103.81
38.33 4000 151.9 1820 1830 38.03 3840 151.9 13.94 111.53
38.93 4280 154.1 1850 1820 38.63 4120 152.6 13.94 123.19
39.54 4600 156.4 1870 1830 39.23 4440 154.9 13.94 131.14
40.14 4880 157.1 1870 1810 39.84 4720 157.1 14.28 142.17
40.74 5160 156.4 1890 1810 40.44 5000 153.4 13.94 146.83
41.35 5440 156.4 1920 1860 41.04 5320 154.9 14.28 158.28
41.95 5720 160.9 1510 1870 41.65 5600 157.1 14.28 168.89
42.55 5120 11.3 980 1300 42.25 5560 19.5 1.36 9
43.16 4280 12.8 980 1080 42.85 4680 12.8 1.36 5.81
43.76 4200 11.3 980 1040 43.46 4200 12.8 0 8.81
44.36 4160 12 980 1020 44.06 4160 12 0 9.75
44.97 4080 12 980 1020 44.65 4120 12 0 9.69
45.57 4000 12 980 1020 45.27 4040 12 0 9.39
46.17 3920 12 980 1020 45.87 3960 12 0 9.44
46.78 3760 12 980 1020 46.47 3840 12 0 9.11
47.38 3600 12 980 1020 47.08 3720 12 0 8.75
47.97 3440 12.8 980 1020 47.67 3520 12 0 8.44
48.59 3280 12.8 980 1020 48.28 3360 12.8 0 8.42
49.18 3120 12.8 980 1020 48.89 3200 12.8 0 7.72
49.79 3120 17.3 980 1010 49.49 3120 12.8 2.04 7.81
50.4 3200 113.5 1700 1300 50.1 3120 85.7 8.16 58.5
51 3320 150.4 1780 1800 50.7 3280 142.1 12.58 100.5
51.6 3520 148.9 1770 1780 51.3 3440 148.1 13.6 96.69
52.21 3720 149.6 1780 1790 51.91 3600 149.6 13.6 103.56
52.81 3880 148.9 1800 1760 52.51 3800 148.9 13.6 108.33
53.41 4040 147.4 1810 1780 53.11 4000 149.6 13.6 114.28
54.02 4240 149.6 1820 1790 53.72 4160 148.9 13.6 119.83
54.62 4400 150.4 1840 1810 54.32 4320 149.6 13.6 125.53
55.22 4560 152.6 1860 1870 54.92 4480 153.4 13.94 132.47
55.83 4720 153.4 1860 1820 55.53 4680 153.4 13.94 135.78
56.43 4920 154.9 1860 1850 56.13 4800 154.1 13.94 140.56
57.03 5040 154.1 1880 1820 56.73 4960 153.4 13.94 145.28
57.64 5040 20.3 980 1690 57.34 5120 154.9 13.94 150.42
58.24 5000 12.8 980 1130 57.94 5080 12 1.36 3.78
58.85 4880 12 980 1050 58.54 4960 12 0 9.11
59.44 4680 12 980 1020 59.15 4760 12 0 10.81
60.05 4480 12 980 1010 59.75 4560 12 0 10.81
60.66 4280 12 980 1010 60.35 4360 12 0 10.64
61.26 4080 12 980 1020 60.96 4160 12.8 0 10.31
61.86 3840 12 980 1020 61.56 3960 12 0 9.81
62.47 3640 12 980 1020 62.16 3760 12 0 9.06
63.06 3440 12.8 980 1020 62.76 3560 12 0 8.47
63.66 3240 12.8 980 1020 63.37 3360 12.8 0 8.42
64.28 3040 12.8 980 1020 63.96 3160 12.8 0 7.81
64.88 2840 12.8 980 1020 64.58 2920 12.8 0 7.42
65.48 2600 12.8 980 1010 65.18 2720 12.8 0 6.92
66.09 2400 12.8 980 1010 65.77 2520 12.8 0 6.39



Log of actual boost vs required is above.

Is there a better way I can attach these logs?

I have some of EGT sensor and lambda too, cant find what group the N75 duty cycle is though?

 

[IbanezDan51]

Ah group 119!

Will log that on the way back from work also.

 

[<tuffty/>]

Do a snip tool or screen grab of the relevant section of data (only the run not all the stuff around it) and post the pic... thusly...

<tuffty/>

 

[IbanezDan51]

Do a snip tool or screen grab of the relevant section of data (only the run not all the stuff around it) and post the pic... thusly...

<tuffty/>

Hows this?



Thanks

 

[<tuffty/>]

Better... log blocks 003, 115 and 118 together

<tuffty/>

 

[IbanezDan51]

Better... log blocks 003, 115 and 118 together

<tuffty/>

Hows this?

Thanks for your help

 

[IbanezDan51]

Any clues? Can do some more logs tomorrow morning

 

[s3dave]

N75 seems sporadic?

 

[<tuffty/>]

Nothing leaping out based on that mate tbh... where does the stutter occur rpm wise? is it always when WOT?

What makes you think its lagging? its asking for around 0.8bar (around 12 psi which is std boost) and achieving it... spool wise looks like boost is coming in just after 2k rpm...

Plenty of timing in there and throttle stays open...

What are you comparing yours too?...

<tuffty/>

 

[IbanezDan51]

Nothing leaping out based on that mate tbh... where does the stutter occur rpm wise? is it always when WOT?

What makes you think its lagging? its asking for around 0.8bar (around 12 psi which is std boost) and achieving it... spool wise looks like boost is coming in just after 2k rpm...

Plenty of timing in there and throttle stays open...

What are you comparing yours too?...

<tuffty/>

Its mainly an idle problem but when on the rollers at R-Tech we compared the spool on mine to another (Leon BAM I think?) and it was laggy and didn't spool as quickly? Does feel like it has very little torque... maybe I have got to use to a V8..

I've checked every vac pipe now and replaced most of it but I still have this unsmooth idle - sometimes slightly worse than others. Perhaps I need to change the plugs and give it a good service. I will try to do it tomorrow and see if anything is better.

Dan

 

[IbanezDan51]

Well, gave her a service today (almost been 10k since previous..).

New plugs (NGK platinum) and my idle seems to be rock steady. Looking at plug 4 the spark might have been jumping a bit.

Will confirm if it's perfect over the next few days.

Thanks for your help all.
Dan

 

[IbanezDan51]

So after driving around in the car for awhile it seems the problem is still there.

I have ordered new fuel injector seals/pintels and filters and a new intake manifold gasket to see if it helps but knowing that the idle fuel trim is readin -0.6% I am guessing it is not a vacuum leak.

Could it be unmetered air caused by a split pre turbo in the intake pipe? Or would this cause the idle fuel trim to be worse than it is also?

I have been reading a bit into how the cam VVT system works and questioning this?

Any ideas appreciated.

I will get to the bottom of this!

Thanks,
Dan