Knock Sensor....Help!

matylad · Feb 5, 2009

After a little help here guys. My sisters Leon Cupra 1.8T AUQ threw an engine diagnostic light a few weeks ago. Hooked it up to vagcom and the error code was something to with a knock sensor. Cleared the code and the light stayed out, however it was very stuttery on tick over. I initially thought that the stuttering could have been something to do with the dodgey supermarket 95 ron fuel she’d been using, it’s had a tank or 2 of optimax through it but no change, still stuttery. She’s just text me to say the light is back on. Is there anything I can log with the shareware version of vagcom that will tell me exactly what the fault is? My thoughts so far are either coil pack, spark plug, or a dodgy knock sensor.

Cheers, Matt.

DPJ · Feb 5, 2009

You should assume the car is running dangerously lean, until you can prove everything else is ok and it is a faulty knock sensor.

Needs logging / full diagnostics. There's got to be a reason its stuttery on tickover.

matylad · Feb 5, 2009

Thanks Dave. How would I do that though? I’m assuming logging a block or blocks?

Matt.

DPJ · Feb 5, 2009

I'd like to be seeing logs of
003 and 020 - to see MAF/CFs
115 and 031 - to see boost / af ratios
118 and 032 - to see duty cycle / fuel trims

(There are two knock sensors btw)

matylad · Feb 5, 2009

Right that’s great Dave, thanks. I am I right in thinking that I can’t log 115 with the shareware version? I’m assuming all these will have to be done in 4th gear 2k RPM up to redline (ish) ?

Matt.

DPJ · Feb 5, 2009

You can only log blocks 001-025 with a shareware version.

You really need a licenced version to sort this - or someone in your area.

matylad · Feb 5, 2009

I thought as much. I think I’ll buy the license and get it over and done with. I’ll get some logging done tomorrow afternoon and report back with the findings.

Thanks again really appreciate your help.

Matt.

DPJ · Feb 5, 2009

matylad said:
I thought as much. I think I’ll buy the license and get it over and done with. I’ll get some logging done tomorrow afternoon and report back with the findings.

Thanks again really appreciate your help.

Matt.

Keep us informed.

matylad · Feb 5, 2009

Will do. Just another quick question…… should I be logging 003 + 020, 115 + 031 and 118 + 032 at the same time e.g. 3 separate runs?

Matt.

DPJ · Feb 5, 2009

matylad said:
Will do. Just another quick question…… should I be logging 003 + 020, 115 + 031 and 118 + 032 at the same time e.g. 3 separate runs?

Matt.

matylad · Feb 7, 2009

Here we go logs for your viewing pleasure.....

Error codes are...

17544 - Fuel Trim: Bank 1 (Add): System too Lean
P1136 - 35-10 - - - Intermittent

16891 - Idle Control System RPM Higher than Expected.
P0507 - 35-10 - - - Intermittent

16712 - Knock Sensor 1 (G61): Signal too High
P0328 - 35-10 - - - Intermittent

Code:

	Group A:	'003				Group B:	'020			
		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				
Marker	STAMP	 /min	 g/s	%	 °BTDC	STAMP	 CF	 CF	 CF	 CF
										
	32.49	2000	43.5	100	10.5	31.99	0	0	0	0
	33.28	2160	56.56	100	4.5	32.88	0	0	0	3
	34.2	2400	66.44	100	6.8	33.7	0	0	0	3
	35	2600	73.86	100	8.3	34.6	0	0	0	2.3
	35.81	2800	78.22	100	9.8	35.4	0	0	0	2.3
	36.71	3000	80.61	100	12.8	36.31	0	0	0	1.5
	37.72	3280	87.67	100	12.8	37.22	0	0	0	1.5
	38.63	3520	90.56	100	15.8	38.13	0	0	0	1.5
	39.52	3720	95.89	100	16.5	39.12	0	0	0	0.8
	40.34	3880	101	100	17.3	39.94	0	0	0	0.8
	41.23	4120	105.75	100	17.3	40.74	0	0	0	0
	42.05	4280	108.86	100	17.3	41.65	0	0	0	0
	42.85	4480	115.78	100	17.3	42.45	0	0	0	0
	43.65	4640	120.58	100	17.3	43.25	0	0	0	0
	44.56	4840	127.86	100	17.3	44.07	0	0	0	0
	45.46	5040	129.11	100	18	45.06	0	0	0	0
	46.26	5240	139.39	99.6	18	45.86	0	0	0	0
	47.07	5400	142.69	99.6	18	46.67	0	0	0	0
	47.98	5560	145.33	100	18.8	47.49	0	0	0	0
	48.88	5720	147.72	100	19.5	48.38	0	0	0	0
	49.7	5880	152.17	100	19.5	49.3	0	0	0	0
	50.5	6000	149.67	100	21.8	50.08	0	0	0	0
	51.41	6120	150.67	100	21	50.9	0	0	0	0

Code:

	Group A:	'115				Group B:	'031			
		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				
Marker	STAMP	 /min	%	 mbar	 mbar	STAMP				
	10.86	1760	97	1620	1240	10.36	1.016	1	        	        
	11.66	1920	111.3	1690	1370	11.26	0.977	0.961	        	        
	12.48	2120	130.8	1710	1540	12.08	0.938	0.945	        	        
	13.28	2320	147.4	1700	1720	12.88	0.938	0.945	        	        
	14.08	2560	146.6	1690	1730	13.68	0.945	0.945	        	        
	14.99	2840	143.6	1680	1700	14.49	0.938	0.945	        	        
	15.9	3080	142.1	1660	1680	15.48	0.945	0.945	        	        
	16.7	3280	142.9	1620	1650	16.3	0.938	0.945	        	        
	17.5	3520	136.8	1600	1610	17.1	0.906	0.906	        	        
	18.41	3760	133.8	1610	1610	18.01	0.906	0.914	        	        
	19.32	3960	134.6	1630	1630	18.92	0.899	0.906	        	        
	20.22	4200	135.3	1640	1630	19.71	0.899	0.899	        	        
	21.03	4400	135.3	1640	1630	20.62	0.883	0.883	        	        
	21.83	4600	136.8	1630	1620	21.42	0.875	0.883	        	        
	22.84	4800	136.8	1640	1640	22.34	0.86	0.86	        	        
	23.75	5000	136.8	1640	1610	23.24	0.805	0.821	        	        
	24.54	5160	139.8	1640	1630	24.14	0.789	0.805	        	        
	25.35	5320	136.8	1650	1620	24.95	0.75	0.797	        	        
	26.17	5440	138.3	1660	1630	25.75	0.75	0.789	        	        
	27.05	5600	139.1	1650	1640	26.66	0.75	0.782	        	        
	27.98	5760	136.8	1630	1620	27.46	0.75	0.774	        	        
	28.76	5840	134.6	1610	1600	28.37	0.75	0.774	        	        
	29.57	5960	131.6	1580	1600	29.17	0.75	0.758	        	        
	30.39	6080	130.8	1580	1550	29.97	0.75	0.766

Code:

	Group A:	'118				Group B:	'032	
		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	-10.1	-10.1
Marker	STAMP	 /min	°C	%	 mbar	STAMP	%	%
	21.02	1880	16	95.3	1300	20.62	0.9	-0.8
	21.91	2040	16	95.3	1440	21.51	0.9	-0.8
	22.82	2240	16	76.9	1630	22.33	0.9	-0.8
	23.62	2480	17	64.3	1710	23.22	0.9	-0.8
	24.54	2680	17	60.8	1740	24.04	0.9	-0.8
	25.34	2880	18	58	1700	24.94	0.9	-0.8
	26.15	3120	18	57.3	1670	25.74	0.9	-0.8
	27.05	3320	18	55.3	1630	26.65	0.9	-0.8
	27.85	3520	20	54.1	1590	27.45	0.9	-0.8
	28.66	3720	21	54.5	1590	28.26	0.9	-0.8
	29.46	3880	21	55.7	1610	29.06	0.9	-0.8
	30.26	4080	23	57.3	1630	29.86	0.9	-0.8
	31.17	4280	24	57.6	1630	30.68	0.9	-0.8
	31.99	4480	24	58	1630	31.57	0.9	-0.8
	32.88	4680	26	58.4	1610	32.48	0.9	-0.8
	33.7	4840	27	59.2	1610	33.28	0.9	-0.8
	34.71	5040	29	60.8	1610	34.2	0.9	-0.8
	35.6	5240	30	62.4	1630	35.11	0.9	-0.8
	36.52	5440	31	64.3	1650	36.1	0.9	-0.8
	37.32	5560	32	64.3	1650	36.92	0.9	-0.8
	38.23	5760	33	63.9	1620	37.81	0.9	-0.8
	39.22	5920	34	63.9	1600	38.72	0.9	-0.8
	40.03	6000	36	63.5	1590	39.62	0.9	-0.8

The last column of 020 seems to have some strange numbers between 2160rpm and 3880rpm. What do we think?

Thanks, Matt.

matylad · Feb 9, 2009

Bumpty bump. Just in case the logs have been missed over the weekend.

matylad · Feb 9, 2009

Anybody

Really dont know what im looking for in the logs. Did I answer my own question with the correction factor on cylinder 4? :headhurt:

Matt.

DPJ · Feb 9, 2009

Sorry, I was away over the weekend.

Good logs, well done.

At first sight, everything looks ok for a standard car. (It's not remapped is it? )

Very slight correction factors on Cylinder 4 under load, but nothing to worry about - and certainly nothing to cause the Knock sensor code........

matylad · Feb 9, 2009

No worries Dave. Not bad for a first go then? The car is 100% standard nothing is after market, even the DV is standard! Not bad considering its done 96k!

What would you say is causing the knock sensor fault if you had to take a stab at it? Do you think it could be a bit of dodgy fuel? Maybe it is one of the knock sensors that goosed.

Thanks, Matt

DPJ · Feb 9, 2009

Knock sensor 1 could be faulty. Does the code come back virtually straight away if you clear it? They're a bugger to get at, tucked right under the inlet manifold. If you still get the fault, I'd be tempted to try cleaning it's electrical connector first. If replaced, they must be torqued up exactly to work properly.

Block 031 shows fuelling, actual then requested. It's doing what it's asked to, - it seems a little lean early on, but I must confess I don't recall seeing 031 for a standard car before.
Similarly, timing on block 003 seems quite advanced to me compared with a mapped car. :shrug:

The reasons for 17544 - Fuel Trim: Bank 1 (Add): System too Lean aren't jumping out at me, but you need to establish why. Did you clear the codes?

DPJ · Feb 9, 2009

17544

* Check Mass Air Flow (MAF) Sensor
* Check Fuel Pressure Regulator
* Check Fuel Pump
* Check Intake/Exhaust System for Leaks
* Check Secondary Air Injection for Leaks
* Check Vacuum Lines for Leaks

Your MAF looks ok to me. I'd be concentrating on the ones in bold. Is there any sign of oil being blown from the pipes under the cover near the dipstick?

matylad · Feb 9, 2009

I cleared the code when it first appeared and it took a couple of weeks to come back. I haven't cleared it since it reappeared.

Looking at the items in bold.....the secondary air pump sounds like a hoover and was hissing, the hissing is a relatively new noise! Could this be cause? I have the bolts etc to replace the rivets with just havent got round to doing it yet.

Matt.

DPJ · Feb 9, 2009

matylad said:
..........
Looking at the items in bold.....the secondary air pump sounds like a hoover and was hissing, the hissing is a relatively new noise! Could this be cause? I have the bolts etc to replace the rivets with just havent got round to doing it yet.

Matt.

I'm doubtful on that one causing lean......

matylad · Feb 9, 2009

Hmmm. This is going to be one of those PITA things to get sorted

So plan of attack....

Fix the secondary air pump, needs doing anyway.
Check the vacum pipes. Are these from the underside of the inlet mani upto the N249 and DV?
Try cleaning the electrical connections to the knock sensors.
Leaks on the intake system would have been picked up in the logs, wouldnt they?

Sound good? Anything else?

Cheers, Matt

Knock Sensor....Help!

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