Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[Dave C]

Hi,

Have 2001 2.6 V6 CD which has been showing its Emmisions warning light.

Did pedal test and codes 0170 and 0173 flashed, from info gathered of this forum i found them to be a problem with Banks 1 & 2 fuel trim malfunction.

Placed car into vaux specialist garage (amazing how many so called Vaux specalists do not know about the pedal test).

Here is what he wrote on the invoice:

Long term fuel trim out of range P0170, P0173.
Check mixture parameters via Tech 2 - Anomalous results.
Check ignition coils and spark plugs -#6 plug recess oil contaminated - renew ns cam cover gasket and inlet tract seals.
Fuel trimming anomalies during warm up still apparent, often resolving to good lamda switching and 0-1% fuel trim at operating temperature.
?fuel pressure 4.8 bar running 3.8 bar static-possibly high?
?all lambda sensor heater coils reported as being switched on at operating temp?
Call put in to vauxhall technical support.

I have had a good look around this forum and many people state that it could be a problem with the MAF sensor, however i have been informed the sensor is working fine and that he believes the issue could be to do with the fuel system, but at the moment he is not sure.

The ECU was reset and the light did not appear on, I have since driven to germany, the car drove great and it was not until over 340 miles into my drive did the emmisions warning light come on. Managed about 400 miles on a tank fuel of petrol, is this ok for a 2.6 V6?

Before i purchased the vehicle the dealer had replaced the whole exhaust from the cats back plus one lambda sensor, which one i am not sure. He also replaced the vehicle battery.

Anyone have any ideas, the specialist wants me to take it back when i am back from Germany as he wants to get to the cause. He had the vehicle for over two days but only charged me for the gaskest and O rings, labour for the leaking gasket repair and half for the electrical labour. All in all decent price for what he did.

[pauldmackay]

Common problem, do a search, it'll be the pre-cats getting tired on the exhaust, you have 2 cats on each bank. 

Well known issue, can be resolved by moving the lamdba sensors on the exhaust.  The car's emmission no doubt will still probably be fine and pass an MOT.

Not usually any need to change the downpipes themselves, the pre-cat helps with emission when the engine cold. 

[jonnycool]

Sorry, haven't been on the forum long, what do you do to the lambda sensors? I haven't heard this before

[pauldmackay]

Click here for a excellent explanation -

http://www.omegaowners.com/forum/YaBB.pl?num=1223977030

[jonnycool]

Not exactly light reading, but yes, an excellent article. Will have to read it again slowly. Thanks

[Dave C]

VXOMEGA, many thanks for the reply, I have read the attached post which has given me more info.
 
I am still not fully convinced about the pre-cats being the problem. On both occasions when the light has appeared it has been after an amount of miles have been driven before it appears, the latest being after 350 miles. Surely if the pre-cats were not working the light would of come on during start up and not near the end of my journey, furthermore i would have had a "cat efficiency" code in the ECU. I am still only showing the two fuel trim bank codes, which the warning light will only go out untill the codes are clear, please advise if i am wrong.

One thing i did forget to mention is that after the codes have been reset the engine seems to stutter but after driving about 50 meters becomes smooth again.
Even though the mechanic said the MAF sensor is working we did disconnect it for a night, the engine did seem to be a bit more responsive, do not know if this was true or maybe just myself thinking it. I have not had the best luck with cars so have become quite paraniod to every bump and knock i hear. 

[Kevin Wood]

The pre-cats don't normally cause a fuel trim malfunction such as this. What is happening is that the Lambda sensors are requiring a larger correction to the fuelling during some driving conditions than the ECU will allow.

I have seen several cars where a faulty MAF has caused this. The symptoms of rough running when the codes are reset reinforce this because resetting the codes also resets the long term fuel trim on this ECU, forcing it to rely on readings from the MAF until the fuel trim builds up again.

Having said that, first step is to make sure there are no intake air leaks or other simple issues which could cause the MAF to misread.

Where are you based? Anywhere hear one of us who has a tech 2?

Kevin

[kcl]

I had 0170 and 0173 a few years back and it was cured by changing the MAF. Also the mech told me that he had searched the same fault on a Vectra earlier and they had tried practically everything and it was the MAF also in that occasion.

[Dave C]

Kev,

I am at present out of the Uk in Germany until next month but will soon be moving to Aldershot, Hampshire which i believe is only up the road from yourself.

The mechanic i went to came highly recommended from family members and i know he has used the tech 2 on the car and checked for air leaks from the air intake back, but found none. Other than what i put on my initial post i cannot recall exactly what he said. What i can recal is that he believes the MAF to be working correctly and feels it is a fuel problem, however that is not a positive diagnoses and he is baffled. 

I just have a gut feeling that it is something simple like the MAF as the car is running good, no excessive fuel usage, just got about 300 miles on 3/4 of a tank, mainly motorway miles. Could the MAF just be dirty, therefore showing it is working but giving false readings? With the MAF disconnected i do believe the car was more responsive.

If the Emmisions light was not on then there would be no indication of a fault.

Furthermore in your opinion is it still ok to drive the car with the warning light on, do not want to fry my cats.

Dave

[Kevin Wood]

Hi Dave,

Aldershot is not far from me so if you've still got problems by then give me a shout and we'll have a look.

The MAF failures that I've seen have been subtle, in that the MAF just becomes less sensitive. It still gives a plausible reading and only when you compare it with a known good one to you realise it has been telling porkies.

I have tried cleaning them but achieved a 0% success rate, I'm afraid.

Having said that, we shouldn't jump to the conclusion that it is a faulty MAF.

Kevin

[Proz]

I had 0170 and 0173 a few years back and it was cured by changing the MAF. Also the mech told me that he had searched the same fault on a Vectra earlier and they had tried practically everything and it was the MAF also in that occasion.

Same here ..... new MAF and code was gone .... i had no code for maf but a new one cured it