VAG-Com logs for boost problem

[co004]

Hi All,

My car has been having boost problems whilst accerating. Basically the boost cuts in and out. I've done some block measuring in 3rd gear, could anyone shed any light on what they think the problem may be?

Saturday	28	February	2009	21:41:09								
06A 906 032 HN 		1.8L R4/5VT         0002										
												
	Group A:	003				Group B:	020				Group C:	 Not Running
		Idle speed	Air mass in	Throt Angle	Ignit Angle		Idle Stabilization	Idle Stabilization	Idle Stabilization	Idle Stabilization		
	TIME	700-820 rpm	2.0-4.5 g/s	0.2-4.0%	0-12 BTDC	TIME					TIME	
MARKER	STAMP	 /min	 g/s	%	 °BTDC	STAMP	 CF	 CF	 CF	 CF	STAMP	
	0.44	2160	42.19	99.2	18.8	0.84	0	0	0	0		
	1.24	2440	64.14	100	13.5	1.64	0	0	0	0		
	2.05	2840	92.94	99.6	5.3	2.55	0	0	0	0		
	2.97	3240	95.89	96.9	18	3.35	0	0	0	3		
	3.77	3600	47.86	22.7	27.8	4.17	0	0	0	3		
	4.68	3960	61.06	25.1	19.5	5.17	0	0	0	3		
	5.57	4320	133.33	29.4	9.8	5.97	0	0	3	2.3		
	6.38	4600	155.47	94.9	13.5	6.79	0	0	3	2.3		
	7.19	4880	106.33	88.2	24	7.59	0	3	3	2.3		
	7.99	5280	166.5	100	12.8	8.39	0	3	2.3	1.5		
	8.81	5520	171.61	99.2	12	9.3	0	0	0	0		
	9.7	4880	15.81	5.9	5.3	10.1	0	0	0	0		
	10.5	4240	8.69	6.3	3	10.9	0	0	0	0

Saturday	28	February	2009	21:47:24								
06A 906 032 HN 		1.8L R4/5VT         0002										
												
	Group A:	115				Group B:	031				Group C:	 Not Running
		Engine Speed	Engine Load	Spec. Boost	Actual Boost		Lambda Factor	Lambda Factor	Bin. Bits	Bin. Bits		
	TIME	700-6800 RPM	15-150%	990-1800 mbar	<=1800 mbar	TIME					TIME	
MARKER	STAMP	 /min	%	 mbar	 mbar	STAMP					STAMP	
	0.01	2280	90.2	1700	1190	0.4	0.98	1	        	        		
	0.8	2600	124.8	1700	1620	1.22	0.98	0.96	        	        		
	1.62	2960	168.4	1690	2140	2.11	0.96	0.95	        	        		
	2.51	3360	142.1	1630	1700	2.93	0.9	0.95	        	        		
	3.33	3720	104.5	1620	1320	3.84	0.92	0.95	        	        		
	4.32	4120	108.3	1650	1350	4.74	0.91	0.9	        	        		
	5.25	4560	112.8	1650	1720	5.73	0.86	0.81	        	        		
	6.14	4920	151.9	1650	2290	6.54	0.85	0.89	        	        		
	6.96	5280	160.9	1660	1930	7.44	0.78	0.81	        	        		
	7.85	5640	130.8	1470	1560	8.25	0.81	0.84

Saturday	28	February	2009	21:50:59								
06A 906 032 HN 		1.8L R4/5VT         0002										
												
	Group A:	118				Group B:	032				Group C:	 Not Running
		Engine Speed	Air Temp In	Boost Dut Cyc	Actual Boost		Idle O2 Adapt	Run O2 Adapt	 	 		
	TIME	700-6800 RPM	<=110 C	0-100% 	<=1800 mbar	TIME	-10-10%	-10-10%	 	 	TIME	
MARKER	STAMP	 /min	°C	%	 mbar	STAMP	%	%			STAMP	
	1.01	2800	20	51.4	1990	0.6	0.9	-6.3	        	        		
	1.81	3160	18	71.4	1360	1.4	0.9	-6.3	        	        		
	2.62	3560	20	0	1740	2.22	0.9	-6.3	        	        		
	3.44	3920	21	0	2350	3.02	0.9	-6.3	        	        		
	4.33	4280	21	36.9	2300	3.93	0.9	-6.3	        	        		
	5.13	4640	21	59.2	1940	4.73	0.9	-6.3	        	        		
	6.03	5000	24	65.9	1760	5.55	0.9	-6.3	        	        		
	6.94	5360	26	47.8	1360	6.44	0.9	-5.5

Many Thanks in advance...

 

[co004]

Looking at the Duty Cycle readings...

51.4
71.4
0
0
36.9
59.2
65.9
47.8

My foot was flat to the floor the whole time, am I right in thinking this is the N75 causing a problem?

Thanks
Chris

 

[DPJ]

Actual boost is way ahead of requested and it's surging.

Looking at the variation in fuel trim figures, I'd suggest you have a boost leak that appears under higher pressure. THe N75 looks like it's trying hard to regulate it - not at fault, I wouldn't think.

 

[co004]

Thanks Dave,

Is that likely to be a leak in a pipe or could it be another valve (ie. dump valve?)

 

[Damoegan]

More then likely a split hose mate.

Do you still have the stabdard DV on?

 

[DPJ]

You don't have a Bailey fitted, do you?

Could be either, I'm surprised you don't have a fault code from it. More likely to be a leak in a pipe, I think.

 

[Damoegan]

You don't have a Bailey fitted, do you?

Yep, when my Bailey was faulty I would either get too much boost or no boost.

 

[co004]

Thank you both, I'll check the pipes carefully as it still has the standard DV.

 

[DPJ]

Thank you both, I'll check the pipes carefully as it still has the standard DV.

It might be struggling to cope with the boost pressures being created.

 

[Damoegan]

It could be the dv then.

When checking the hoses check very carefully as the split could be very small and only appear under load.

Edit: Damn, you beat me again, Dave

 

[DPJ]

Good logs, by the way.

A little more towards the red line next time.

 

[co004]

Good logs, by the way.

A little more towards the red line next time.

Will remember that next time thanks.

 

[co004]

OK, Looking at the pipes, I'm not sure which ones would be most likely to be the culprit. I'm guessing its the ones before the turbo that I need to be checking most carefully but which ones are they?

Are there any that are a common problem?

 

[DPJ]

Maf>turbo>intercooler>throttlebody.

Also vac lines - those under the panel by the dipstick are prone.

 

[Damoegan]

OK, Looking at the pipes, I'm not sure which ones would be most likely to be the culprit. I'm guessing its the ones before the turbo that I need to be checking most carefully but which ones are they?

Are there any that are a common problem?

Check all intercooler piping, all vac lines from turbo and all vac lines roung the N249 & n112 valvs.

 

[fistic]

Hi guys.I have a surging problem. engin code is engine code. Max boost is around 1,2 bar. OEM hardware.
The isssue is: when the engine rotation goes reaches 5500 in 4th or 5th gear it starts surging. It is like it loosis ignition. It hangs for a second then strikes again and pulls like hell, then hangs again.

Can not fin out the couse. I have measured the car ona dyno maybe that explains something for you...but I cannot post attachments. Can someone help and post my attachment ?

 

[co004]

I bypassed the N249 a the weekend and this seems to have sorted it. I want to do some more runs before I confirm and do the original runs with VAG-COM plugged in again to compare, but it's looking good.

 

[co004]

Right, I had a problem on my Cupra with boost surging/cutting out. I replaced the DV with a Forge 007, didn't make a difference. At this point I was thinking it'd be a leak somewhere turbo side of the system.

Last weekend, not being able to find an obvious leak, I decided to do the N249 bypass as I thought it wouldn't hurt. Now this (I thought) fixed it. I was getting less boost but I expected that as I believe it was over boosting before and it was smooth.

I was getting dv chatter if I let off the throttle early but nothing higher up the range so this weekend I decided to redo the bypass with decent silicone piping as I'd used some shoddy fuel pipe type piping originally and wasn't convinced of it's integrity.

Now guess what! the surging is back! This doesn't make any sense to me now at all!

Any idea's anyone?

 

[DrLargePants]

Is there a guide for how to produce this ouput somewhere ? I have a similar issue...