Obd2 VR6 No Closed Loop? (Update P4, advice please)

[VRTrickster 0]

Ive been having a few rough running problems for a while now. This includes rough idle, very rich start up and slightly less mpg. I hooked up vagcom to take a look at measuring blocks as it doesnt show any faults. I noticed that the lambda values where high, rangeing from 10% to 20%? And there were no learnt values for idle and full throttle? Ive since replaced the lambda and have noticed a slight gain in mpg, but the readings are still similar? Ive now done about 200 miles since I disconnected the battery. Does anyone know what this could be, a faulty ecu perhaps? Thanks in advance for advice.

Edited February 23, 2011 by VRTrickster

[Kevin Bacon 5]

+10 to 20%, or - 10 to 20%?

 

Lambda is turned off at full throttle, so it won't 'learn' any values up there.

 

If the lambda is making adjustments in the measuring blocks, it's working OK. Although as much as 20% sounds too high. It's a standard engine I take it?

 

Is the MAF OK?

[VRTrickster 0]

Its modified as to my sig. I replaced the maf not so long ago with a bosch exchange unit from ecp. Maybe I should hook it up later and record what Ive got this evening so you could see what you think? Cheers.

[VRTrickster 0]

Right, I feel bit stupid now. I hooked it up this evening and it seems it has learnt some values. Ive taken some screen shots of before I started it, then just after and one up to temp. Also took one for the maf readings.

I was just wondering Kev. Could you please take a look over them and see if theres anything out of the ordinary, as you know a lot more about it than I do please. :notworthy:

 

Thanks

[Kevin Bacon 5]

Yep, all looks normal to me mate.

 

If you've replaced the lambda probe recently, perhaps give it some more time to adapt. Was it a genuine VW probe you used? I hope it wasn't a cheapy pattern!

[VRTrickster 0]

Yes it was Im afraid. Cant really stretch to a genuine one at the mo. It was £30 of fleabay, but it has got a years warranty. How much are the VW ones?

 

Thanks for looking over that for me kev, puts my mind at rest a bit. I still have a lumpy idle. Sort of pulsing if you get what I mean?

 

I dont know whether its to do with the Dougherty racing cams, light weight fly and stiffer mounts. What do you think?

 

Thanks again for you help.

[VRTrickster 0]

Oh, and also do I need to carry out basic settings on vagcom? I did reconnect the battery when the car had cooled a bit, should this affect things?

[VRTrickster 0]

Bump

[Kevin Bacon 5]

Yes it was Im afraid. Cant really stretch to a genuine one at the mo. It was £30 of fleabay, but it has got a years warranty. How much are the VW ones?

 

Thanks for looking over that for me kev, puts my mind at rest a bit. I still have a lumpy idle. Sort of pulsing if you get what I mean?

 

I dont know whether its to do with the Dougherty racing cams, light weight fly and stiffer mounts. What do you think?

 

Thanks again for you help.

 

I think that's part of your problem mate, the pattern lambda. I had a hunch about that didn't I? LOL! :D Why? Cause I've been there myself with OBD2 and iffy lambda probes.

 

Last time I bought a pukka OBD2 probe it was £70 + VAT from the stealer. I don't know how much they are these days, but honestly mate, it made the world of difference. Motronic is sensitive to probe conditon and brand, so if you can, I would stick a genuine one in.

 

I have SP 263 cams, 9lb flywheel and stiff mounts too chap. I haven't had any problems from those, but admitedly I do my own tuning so can soon correct any unhappiness at low rpms. I've found with those cams, fwheel and mounts the motor idles smoothest at 800rpm. Vince could raise the idle speed to that for you, but it would be part of a remap and rechip job though. That is the nuiscance of Motronic. The slightest change needed requires a day in the workshop.

 

I suspect at the standard idle speed + your cams, the overlap exhaust fumes could be diluting the air/fuel mix a little, causing a misfire. If you can be bothered, sticking the standard cams in would be a good test for that.

 

EDIT. I tell a lie. IIRC you can raise the idle speed with VAG COM in the throttle adaptation / basic settings screen by putting in a diferent HEX number. I can't remember the number for 800-850rpm though, but Vince will know.

[coullstar 0]

I got a replacement lambda recently and it was the Bosch OE part with correct connector for £70 delivered and it came the next day.

 

http://www.lambdapower.co.uk/

[VRTrickster 0]

Changing the idle does sound interesting. I'll have to take a look into that. I don't think I can be bothered to swap the cams back. I'll maybe give Vince a call on that one cheers kev.

 

I know what you mean about the probe, and I would normally go genuine but haven't got the funds at the moment. I will swap it for one as soon as I can though, especially if it causes problems.

 

coullstar, Thanks for the offer, I may take it off you but I'll see how much my dad might be able to get one threw Audi with staff discount. :)

[coullstar 0]

Im not selling one, just saying that you can get them cheaper and quicker from that place. Looks like I might need another one as well.... :brickwall:

[VRTrickster 0]

Oh yeah sorry. :oops:

 

I'll keep them in mind for a new one thanks.

[VRTrickster 0]

I'm really not happy now. After looking under the car today I noticed that a bolt had sheared off on the front engine mount bracket! This had caused the engine to drop. I don't know how long its been like that for, but that could be why I'm experiencing pulsing lumpy idle. It must have been causing a lot of stress to the rear mounts.

I've got to take the box out tomorrow to get the rest of the bolt out and I'm really looking forward to it! :brickwall:

[VRTrickster 0]

Right it seemed you were right kev. I ended up getting a couple of codes up for the lambda 00525 no signal intermittent and heating before cat, open short to ground. I took your advice and purchased a Bosch item off ebay for £68 delivered.

 

I fitted the new sensor over the weekend and the car seemed to drive a lot smoother. But after a a long drive to north London it started running like a bag of s**t and really lumpy idle! I hooked it up to vagcom and it threw the code 00525 O2 sensor short to ground. It is not giving any readings for the lambda also. I cleaned up all the connections on the loom plug but still nothing. I tested the voltage at the terminals whilst running and I got a 14v a 0.78v and IIRC 0.3 something. Do these sound familiar?

 

What can I do to test the lambda? Or could it just be the lambdas cur put?

 

Im really having a hate relationship with the car now! :mad2:

[VRTrickster 0]

Right it seemed you were right kev. I ended up getting a couple of codes up for the lambda 00525 no signal intermittent and heating before cat, open short to ground. I took your advice and purchased a Bosch item off ebay for £68 delivered.

 

I fitted the new sensor over the weekend and the car seemed to drive a lot smoother. But after a a long drive to north London it started running like a bag of s**t and really lumpy idle! I hooked it up to vagcom and it threw the code 00525 O2 sensor short to ground. It is not giving any readings for the lambda also. I cleaned up all the connections on the loom plug but still nothing. I tested the voltage at the terminals whilst running and I got a 14v a 0.78v and IIRC 0.3 something. Do these sound familiar?

 

What can I do to test the lambda? Or could it just be the lambdas cur put?

 

Im really having a hate relationship with the car now! :mad2:

 

Ive just read up about testing from the black signal wire. Ill run it up a see what Im getting there whilst connected.

[Kevin Bacon 5]

The lambda signal wire should give a voltage that constantly fluctuates from 0.1 to 0.9, after it's heated up. The lambda engages at 70 deg water temp, so probably just easier to watch the VAG-COM screen. If the lambda isn't working, the probe tends to stick at 0.45V permanently.

 

Remember to earth your meter on the chassis, not the lambda wiring.

 

Could potentially be a wiring fault but it could also be *another* dodgy lambda. OBD2 seems to be more sensitive to lambda quality than OBD1 and because it can adjust the fuelling more than OBD1 (+ / - 25%), you'll notice any wild lambda oscillations at lot more, hence the schitt running.

 

I know it's expensive, but personally I would bite the bullet and get the proper probe from the dealer, from the same model year as your OBD2 management.

 

As I mentioned before, I went through similar poo myself and only a genuine probe kept it happy for more than 10 minutes, but obviously give the wiring a thorough going over first.

[VRTrickster 0]

Right I've just had a looked at the wiring following this explanation on the bentley website.

 

http://tech.bentleypublishers.com/threa ... tstart=179

 

These are the results :

 

ECU Pin 20 to Lambda Pin 4 (0.6 Ohms)

 

ECU Pin 42 to Lambda Pin3 (0.5 Ohms)

 

ECU Pin 20 to Battery earth (infinite resistance)

 

So this concludes the wiring is ok, so I'm assuming its the Bosch lambda :( I've just sent the seller a message on ebay to get a replacement. There couldn't be a problem with the ECU could there?

[VRTrickster 0]

Just got my dad to price up a lambda from VW with discount, cos he works for Audi. And inclusive its £110!

 

Will testing the resistance from pins 20 and 42 tell me if theres a problem with the ECU?

 

Im going to swap the lambda back over to the after market one tomorrow to see if it registers on VAGCOM. Because at the moment there is nothing! Probably give the ECU pins a clean also. :?

[VRTrickster 0]

Feel like an idiot now. due to my heavy handedness I must of put a big dent in the side of the sensor that I found when I removed it today :(

 

I was supposed to use the ramp at the Audi dealer where my dad works. But I had I really heavy night and didnt get up till late, and had to struggle on the drive with not much visibility.

 

Thats £70 down the drain! I think Ill use the ramp next time when Ive saved enough money for the third new lambda! :mad2:

[Kevin Bacon 5]

Unlucky mate :(

 

£110 :shock: Fun me they've gone up in price a lot!

 

You're not far off an Innovate LC-1 wideband at that price. They have the uber reliable Bosch LSU 4.2 wideband probe as standard, aswell as a controller and AFR display. We used one of those to fuel Rob's (Heresites) Rotrexed VR and it worked perfectly. Instead of using the VAG probe, you just use the wideband and the signal from the LC-1. Nice and easy. You will need to drill out the lambda hole in your downpipe a litte though as widebands have a bigger tip.

 

Just an alternative mate if you're having troubles.

[VRTrickster 0]

Unlucky mate :(

 

 

Tell me about it. Ive just found one on ebay a guy is selling which he says is new and un used for £40. I've gone for this option as I can't afford £70 at the mo. I just hope it turns up all good.

 

Im driving it with the cheapo sensor back in at the mo, with no pre heating, so it runs like poo when cold!

[VRTrickster 0]

Fitted the third new lambda on Saturday, which was a Bosch item. I didnt disconnect battery till last night and carried out the basic setting procedure. After at least an hour and a half after re-connecting the battery it runs like a bag of s**t!

After my journey back from Egham to Brighton I plugged vag-com in. The old codes seemed to still be there so maybe I didnt leave the battery off for long enough? I went into measuring blocks and the lambda wasn't getting picked up at all! Cleared the codes and 00525 O2 sensor short to ground pops up again. Could this be because I didn't disconnect the battery for long enough? I think I need to test signal from the lambda plug whilst running and at the ecu end. This will surely tell me if the ecu is at fault?

Im really thinking about burning the car out at the minute! Any advice would be great.

[VRTrickster 0]

I just tested the lambda signal wire whilst running and cleaned the ecu pins. I was getting 0.6v constant when first started. When it warmed up a bit I got a reading of 0.0v to 0.2v fluctuating. So I should get a signal on vagcom if all the wiring is ok, which tested all good when I checked last week. :?

 

Im not getting any lambda readings what so ever. Would I see readings when cold on vagcom?

[VRTrickster 0]

bump