Fault error P0172 ISO9141 System to rich (Bank 1), revs and misfire

[Yaro]

Hi,

Did anyone come across this fault error. It came up once. After it has been erased ( a week ago) did not come so far. I heard it is intermittent.

Also, when i start engine from cold I can hear kind of like a misfire and revs fluctuate. I do not know if the kind of misfire persists as i drive a car.

Revs fluctuate as well when I bring the car to a stop. When I accelerate it a little they sort of recover. I have no warning lights on the dash.

It seems to me also that car drinks more fuel.

Much appreciate for any advice.

Cheers

Edited 10 September, 2010 by Yaro

[chicken_eyebrow]

http://wiki.ross-tech.com/wiki/index.php/16556/P0172

[bigbarnz]

Hi,

Did anyone come across this fault error. It came up once. After it has been erased ( a week ago) did not come so far. I heard it is intermittent.

Also, when i start engine from cold I can hear kind of like a misfire and revs fluctuate. I do not know if the kind of misfire persists as i drive a car.

Revs fluctuate as well when I bring the car to a stop. When I accelerate it a little they sort of recover. I have no warning lights on the dash.

It seems to me also that car drinks more fuel.

Much appreciate for any advice.

Cheers

sounds a bit like mine i dont know what it is yet tho

[Yaro]

http://wiki.ross-tech.com/wiki/index.php/16556/P0172

I looked at it before...

The thing is that I have a gas conversion on mine. So could rule out a few points. I am going to replace the MAF sensor and lambda as for revs. My hoses were checked a few times recently so I think they are still fine.

I shall see how it goes and let you know soon

CHeers

[ginandtonic]

The two things that made the most difference to my vRS were cleaning the MAF, and cleaning the throttle body. It was suffering from poor MPG, sluggish running, erratic idling (at one time the engine would almost stall when I pulled up at junctions). This was at about 80-90 K miles on the car.

Checking all the hoses and pipes for leaks is sensible (I did that), and cleaning the MAF improved the running and MPG a bit. But after I had the throttle body cleaned the car was transformed - the engine ran like new. I think the throttle plate gets a build up of muck which can stop it moving smoothly (or even make it stick at some points). Cleaning it thoroughly might make more difference than you expect.

Note: I had mine cleaned by a dealer. If you do it yourself be very careful with dismantling and re-assembly. You will need a VAG-COM to re-calibrate it after cleaning (although if you are careful not to remove certain connectors you may be able to avoid this - check out the archive of posts on here for guides on this).

[bigbarnz]

I looked at it before...

The thing is that I have a gas conversion on mine. So could rule out a few points. I am going to replace the MAF sensor and lambda as for revs. My hoses were checked a few times recently so I think they are still fine.

I shall see how it goes and let you know soon

CHeers

i was going to do that next but i dont want to spend a fortune on one if its not that, i cleaned mine but no difference. does your esp light flash sometimes when the power drops ?

[havoc924]

i was going to do that next but i dont want to spend a fortune on one if its not that, i cleaned mine but no difference. does your esp light flash sometimes when the power drops ?

I had a fault that sounds quite similar with an A4 tdi. It suffered a little throttle stick when it was cold and when driving sometimes.... intermissent fault but i did manage to cure it with a new engine temp sensor. to this date i dont know why that was causing the problem but for what it costs it might be worth a shot

good luck

[vwnutant]

ive got exactly the same probs on mine mk1 89k y reg , so is throttle an easy diy fix/clean

ant

[will_]

The thing is that I have a gas conversion on mine.

So do I. When I've had mixture too rich / too weak fault codes, it's been the LPG system not managing to apply the correct correction. If it's been on there a while, an LPG remap might cure it (my installer charged by £25 although I think this is pretty cheap) but mine turned out to be the gas ejectors sticking. A strip-down and clean (of the injectors) would quite possibly have fixed it but I was short on time and knowledge when it happened, and paid £150 to have the block of all four injectors replaced. The improvement in running was instant, although not perfect, as both the car's EMU and the LPG EMU took a while to adapt to the change.