O2 probe or MAF problem?

[tonipieleanu]

Did some research last night for the intermitent juddering a I get from time ti time and found this error with Vag-Com:

17521 Bank1-Sensor1 Internal Resistance too High (Intermitent)

Also, did a couple of power runs and my MAF readings ar peaking at 113g/s, which is a bit low for a stock 20VT.
The multiplicative fuel trim is also of with a value of 24! I'm running lean at high rpm


What sould I do first? O2 probe or the MAF?

Tuesday	8	July	2008	21:58:04								
06A 906 032 T  		1.8L R4/5VT         0003										

	Group A:	'003				Group B:	'115				Group C:	 Not Running
		Idle speed	Air mass in	Throt Angle	Ignit Angle		Engine Speed	Engine Load	Spec. Boost	Actual Boost		
	TIME	700-820 rpm	2.0-4.5 g/s	0.2-4.0%	0-12 BTDC	TIME	700-6800 RPM	15-150%	990-1800 mbar	<=1800 mbar	TIME	
MARKER	STAMP	 /min	 g/s	%	 °BTDC	STAMP	 /min	%	 mbar	 mbar	STAMP	

206.33	2160	26.69	100	24	206.73	2240	66.9	1880	1170
207.13	2360	37	100	19.5	207.53	2520	82	1880	1440
207.93	2640	49	100	12.8	208.33	2840	96.2	1830	1720
208.73	2960	56.67	100	8.3	209.13	3160	127.8	1770	1740
209.53	3280	61.94	100	9.8	209.93	3440	130.8	1720	1700
210.33	3600	68.25	100	12	210.73	3760	131.6	1730	1700
211.13	3880	73.81	100	12.8	211.53	4040	133.1	1750	1720
211.93	4160	78.31	100	12.8	212.33	4280	135.3	1730	1720
212.73	4440	86.47	100	15.8	213.11	4600	136.8	1720	1710
213.51	4720	91.92	100	15.8	213.93	4880	136.8	1720	1690
214.33	5000	97.17	100	16.5	214.73	5120	136.8	1730	1670
215.13	5280	103.14	100	15.8	215.53	5400	133.8	1730	1660
216.03	5520	107.83	100	17.3	216.43	5640	130.8	1700	1640
216.94	5800	113.83	100	16.5	217.34	5160	11.3	990	1320

Tuesday	8	July	2008	22:05:19							
06A 906 032 T  		1.8L R4/5VT         0003									

	Group A:	'004				Group B:	'120				Group C:
		Idle speed	ECM Voltage	Coolant Temp	Intake Temp		Engine Speed	Spec Load	Curr Load	ASR Status	
	TIME	700-820 rpm	12-15V	80-110 C	-48-110C	TIME	700-6800 RPM	0-399 Nm	0-260 Nm	active yes/no	TIME
MARKER	STAMP	 /min	 V	°C	°C	STAMP	 /min	 Nm	 Nm		STAMP

226.79	2360	13.51	96	50	226.28	2360	399.8	15.7	ASR OFF
227.59	2400	13.51	96	49	227.19	2360	399.8	13.7	ASR OFF
228.39	2600	13.44	96	48	227.99	2480	399.8	103.9	ASR OFF
229.19	2880	13.44	96	46	228.79	2720	399.8	149	ASR OFF
229.99	3240	13.51	96	45	229.59	3040	399.8	172.5	ASR OFF
230.79	3560	13.51	96	45	230.39	3400	399.8	180.3	ASR OFF
231.57	3840	13.44	96	45	231.17	3720	399.8	243	ASR OFF
232.37	4160	13.51	96	45	231.97	4000	399.8	248.9	ASR OFF
233.19	4440	13.51	96	47	232.77	4280	399.8	250.9	ASR OFF
233.98	4720	13.51	96	48	233.57	4560	399.8	250.9	ASR OFF
234.88	5000	13.51	96	50	234.48	4920	399.8	239.1	ASR OFF
235.79	5280	13.51	96	51	235.28	5160	399.8	241.1	ASR OFF
236.59	5560	13.44	96	53	236.19	5400	399.8	239.1	ASR OFF
237.38	5760	13.51	96	55	236.99	5640	399.8	231.3	ASR OFF

 

[DPJ]

You will run lean if the Maf is badly under-reading. New Maf required.

 

[tonipieleanu]

It's not badly under-reading It's 113g/s vs. ~140g/s for a stock 180bhp.

So, I should go for the MAF and not the lambda sensor?

 

[DPJ]

It's not badly under-reading It's 113g/s vs. ~140g/s for a stock 180bhp.

So, I should go for the MAF and not the lambda sensor?

20% under-reading is 'badly' in my book.

 

[tonipieleanu]

Could the MAF give me the lambda probe error?

The car is running pretty good in the lower gears around town. I get some juddering from time to time at WOT in the higher gears. Sometimes it's running rough even at idle.

Any other tests I can do to be sure it's the MAF and not the O2 probe?

 

[DPJ]

How will a faulty lambda sensor give you a low maf reading?

(The ecu calculates fuelling against the airflow the maf reads.........)

 

[VapourTrails]

i havent got a clue on how to read them but how do you know the RPM. If your hitting redline and the maf is showing 113 then id replace it as it should be reading around 130ish on standard and over 150 on a remapped 180ps

 

[VapourTrails]

Could the MAF give me the lambda probe error?

The car is running pretty good in the lower gears around town. I get some juddering from time to time at WOT in the higher gears. Sometimes it's running rough even at idle.

Any other tests I can do to be sure it's the MAF and not the O2 probe?

a faulty maf can show lambda faults. mine showed nothing and i was getting a maf reading of 90 at redline in 3rd gear.

 

[tonipieleanu]

How will a faulty lambda sensor give you a low maf reading?

(The ecu calculates fuelling against the airflow the maf reads.........)

It's the other way around: a faulty MAF can give bad lambda probe errors, or so I read somewere on vwvortex.

 

[VapourTrails]

It's the other way around: a faulty MAF can give bad lambda probe errors, or so I read somewere on vwvortex.

if your over or underfueling it the lamdba sensor will pick it up as to lean or to high readings. which normally happens when the maf goes as engine is being over fueled in error due to low readings etc... good sign is using fuel like there is no tomorrow.

 

[tonipieleanu]

I got that, but can this readings be interpretted by the ECU as a faulty lambda sensor?

I found some info on how to test the lambda probe with Vag-com. Will have a go later on tonight and see how it goes.

 

[DPJ]

............... which normally happens when the maf goes as engine is being over fueled in error due to low readings etc... good sign is using fuel like there is no tomorrow.

Sorry, you're wrong there.

low maf reading - ecu reads low airflow, ecu fuels to match ( =lower volume of fuel than really needed) - car runs LEAN.

When you have a boost leak, the car over-fuels.....

 

[VapourTrails]

cant be 100% but id say no as the low maf readings are direct from the maf and has nothing to do with the lamdba sensor readings.

 

[DPJ]

cant be 100% but id say no as the low maf readings are direct from the maf and has nothing to do with the lamdba sensor readings.

Is that a reply to my post?

 

[VapourTrails]

Sorry, you're wrong there.

low maf reading - ecu reads low airflow, ecu fuels to match ( =lower volume of fuel than really needed) - car runs LEAN.

When you have a boost leak, the car over-fuels.....

no that was a reply to the question above mine that posted as i was posting mine

yer my fingers where typing faster than my brain

mine was over fueling at high revs to compensate for low readings ie air was correct but too much fuel bogging it down and causing flooding etc.. but as this isnt the case here. ill keep my mouth shout

 

[VapourTrails]

duplicate entry