Audi Question

[hexhamstu 9]

i'm not a member of an audi forum, so thought i may aswell ask here and hope for the best.

 

the problem is a flat spot in first between 3-5k revs and second seems quite slow for what it used to feel like.

 

the car is an audi a4 2.6 quattro. it has just had all the valves replaced after a cambelt tensioner went so it spent a couple of months sitting before the head came off. so i was wondering what could have gone wrong in this time.

 

i'm thinking fuel filter? do they have air flow meters?

[jonD6B 0]

I assume these engines are self timing through the ECU?

[hexhamstu 9]

beats me, it had a cam belt so? you saying the timing could be out?

its my brothers car and i went down to the garage that did the work with him today, they plugged theyre computer into it and it said nothing was wrong. then they denied it as there fault that it was running like this.

[j-16 1]

beats me, it had a cam belt so? you saying the timing could be out?

its my brothers car and i went down to the garage that did the work with him today, they plugged theyre computer into it and it said nothing was wrong. then they denied it as there fault that it was running like this.

 

 

If the battery is disconnected this will clear the fault codes, or the garage can clear them with their vag-com so this doesn't prove anything. Only after driving from cold to warm for a good few miles will the fault codes be recorded again by the ecu. Get them checked at another garage - costs about £25 to get a diagnostic scan done but this will not show mechanical fault apart from misfire.

 

Audi use a variation of the air flow meter call MAF which measures air mass to control fueling. I know this is a common Audi weak point as is the cooland temp sensor and coil packs (on s3 anyhow). These parts are all cheap to replace and can be done by yourself but just get a diagnostic done first to check the fault codes before you waste your money.

 

I would imagine a sensor contact has decayed while the car was unused or needs new plugs, maybe could try an injector cleaner in the fuel? Or stop using crap Supermarket fuel.

 

If the battery is disconnected this will clear the fault codes, or the garage can clear them with their vag-com so this doesn't prove anything. Only after driving from cold to warm for a good few miles will the fault codes be recorded again by the ecu. Get them checked at another garage - costs about £25 to get a diagnostic scan done but this will not show mechanical fault apart from misfire.

 

Audi use a variation of the air flow meter call MAF which measures air mass to control fueling. I know this is a common Audi weak point as is the cooland temp sensor and coil packs (on s3 anyhow). These parts are all cheap to replace and can be done by yourself but just get a diagnostic done first to check the fault codes before you waste your money.

 

I would imagine a sensor contact has decayed while the car was unused or needs new plugs, maybe could try an injector cleaner in the fuel? Or stop using crap Supermarket fuel.

 

 

By the way can i ask how much the cam chain tensioner job cost as i think my S3 needs this at the minute. I've been quoted £1200 for a recon head!

Edited May 24, 2006 by j-16

[pugrallye 0]

If the battery is disconnected this will clear the fault codes

rubbish, this isnt a peugeot

your first port of call for flat spots is an air mass meter, around £90 mark, VAG cars eat them, and rarely show up as a fault, need to log into measuring blocks screen 4 to check its readings. to be honest sounds like your timing is out....... very hard engines to time up correctly without correct locking tools (would check this first)

 

oh and cam chain tensioners on a 1.8 T arent an easy job is it throwing up faults on the cam sensor?

Edited May 24, 2006 by pugrallye

[Owain1602 0]

generaly if timing was quite a bit out on specific pulleys then it will show fault codes along the lines of Cam to crank sensors out of sync so you can put a scope on these two sensors and see where the reference marks are in relation to each other. but i dont really think this will be your problem, again i suspect air mass meter as if its been standing for a while then the wire gets contaminated fairly easy with things the initial burn out heat will not burn off, they are not really servicable items some people say you can clean them with carb cleaner and they might work better but I personally have never found this any help.

 

If there is a garage by you that uses VAG-COM then they can perform quite a good test on the AMM. What they can do is take the car down the road and in VAG COM there is a measuring block showing ammount of air inducted in Grams per second. They then should floor the car in 2nd gear and let it pull all the way almost to the limiter, at this sort of engine speed you are looking for 80% of the car's horsepower of Grams being inducted per second.

 

So if you have 100bhp then at the limiter you want 80% of that is grams so a working AMM would show you around 80g/s flowing in to the engine.

 

Bosch KTS has guite a good test on AMMs too but where a lot of people go wrong with this test it they perform it in the workshop with the car at stand still becuase maybe they cant take their KTS with them down the road, then the test is not the same with the car not moving. What I do is take the KTS becuase we're fortunate enough the have a KTS 650, graph Nominal air flow against Actual air flow and Engine rpm. The curves should increase with each other but dont be fooled as your actual air flow will NEVER be the same as nominal value.

 

But the garage you take it to should be able to sort it if they have any idea. Hope any of this gives you some idea.

[pugrallye 0]

any garage that uses VAG com need shooting

use proper 5051 equipment, and you can measure air mass reading solely at idle, and will give you a perfectly good reading to tell whether is on its way out or not, telling people to rev their vehicle to the limiter considering it may be out a tooth on the crank is NOT advisable! and a phase 1 a4 engine management system will not tell you if timing is out slightly

Edited May 24, 2006 by pugrallye

[Owain1602 0]

you can easily get a scope pattern off the crank and cam sensor and see wether the reference marks co-incide. I agree the limiter test is not the best to perform as throwing on a new AMM will take less than 5 minutes but it seems the car has been revved anyway for someone to know the flat spot is between 3-5K rpm. Why do you say anyone using VAG COM needs to be shot?its a great piece of kit for £200 absolutely great value for money.

I also work for a VAG/BMW/PORSCHE/MERC specialist, we're part of the Bosch network.

[pugrallye 0]

because its an aftermarket interface system with known failure points, and would not trust it with any car running a CAN bus especailly considering the engine ECU is linked with airbag module

[hexhamstu 9]

its now popping from the exhaust, so its over fueling, its my brothers car so no plugs have been taken out to inspect them or anything. im gonna have a look over it tomorrow hes booked it in at the audi garage but i dont want him wasting his money.

 

so this MAF will the audi garage have one i can borrow to test or is it a specialist part to each car, like AFMs? im guessing yes?

 

"By the way can i ask how much the cam chain tensioner job cost as i think my S3 needs this at the minute. I've been quoted £1200 for a recon head!"

 

i am not sure, he paid in excess of 1k for all the valves replacing, and the water pump etc.

Edited May 25, 2006 by hexhamstu

[Owain1602 0]

VAG COM is the only way some places can view certain data without having to have the 5051, so for £200 there is no doubt that is a very worthwile purchase and comes in very useful in the shop. what are its known failure points?

 

the audi place will probably have the AMM for your car but generaly if it is a dealership they will not allow you just to try one on as generally they dont want to help people to sort out their car them selfes.

[pugrallye 0]

Air mass meter francised dealerships will stock, and its an exchange item, price ranges from £90 to £170 depending on which part it is, as they are model specific, as long as its not a special order item, i cant see why they wouldnt refund it if its not required as long as you have a good story

 

I have heard and dealt with one or two cases of VAG com wiping flash memory from engine ECU's, and setting off crash signals in airbag system, neither of which are pretty outcomes!

Edited May 25, 2006 by pugrallye

[Owain1602 0]

I suppose they could wipe soft coding from ECUs if you are in the Re-code section and the computer thats used to connect VAG COM to the car crashes then you could loose the codes maybe but if you print the coding and ecu details whilst connected then it wont be any problem re-coding the ECU, even if you dont have the coding they can be worked out quite easily using ElsaWin.

 

Any yes, if you are dealing with the Air Bag section and you dont do what is tells you on the screen, such as not switch ignition off and leave till VAG COM tells you to switch it back on. You might trigger off an air bag controller. But not if you do as you should.

[pugrallye 0]

wasnt on about simple baud rate coding, was on about the ignition map, lol

[Owain1602 0]

rubbish, the ignition map is not on the eeprom part of a chip so no modifications can be made regardless of software or hardware. maybe it could damage the memory but we;ve been using it for ages and have not had 1 problem with it. I take it at face value, but remember at the end of the day it can crash as all software can but a computer will only do what people tell it to.

[Owain1602 0]

anyway, dont really matter about us, i hope you get the car sorted but AMM can cause all sorts of weird problems.

[hexhamstu 9]

well his car is a 2.6 quattro manufactured on 31st of dec 1995, audi dont have a MAF part number listed for this car, the guy at the VW garage couldnt find it, so phoned audi with the VIN number for the car and was told this. f***ing idiots. suposedly the car wasnt produced for very long so the parts cd is incomplete. GSF said the same. useless c*nts. we're gonna take it off and take it to the audi garage see what they can come up with

[pugrallye 0]

thats about right, lol quite a rare beast now those cars, strange its not on ETKA though unless they have started removing older models?

 

 

Oh and please dont try and patronise owain, have been doing this for many many years, and actually only specialising in VAG cars, and fully authorised to carry out warranty work, which not many independants have the ability to do, I have nothing to gain, by what I have said, just know exactly how cars come in, and what people/ other garages have done to them (another classic is the shorting of the brakelight switch by a garage to be unnamed, which resulted in a blown engine management system, dash panel and abs module) . I am pleased you get on with the interface system, tend to find its more marketed for the enthusiast rather than the professional, oh and piccy of RS4 in my workshop posted a while ago was said victim of ECU data damage lol.

Edited May 26, 2006 by pugrallye

[RHULPUG 0]

I sold my 1996 2.6 A4 Quattro back in february, and seem to remember the dealership being very helpful when they diagnosed a faulty air mass meter too. The problem is, as some people have already said, the car engine wasn't made for very long, and replaced with the 2.4(if I'm right), which was the same performance but more economical.

I'd advise him to get rid of it, I found them boring, very lacking in performance for such a big engine and drastic fuel economy. They can be picked up for around a grand now too!

[hexhamstu 9]

well it turns out his hasnt got a MAF i took all the breather pipes off and theres nothing attached to them apart from some oil breather pipes and what im guessing is an ignition module.

i told him not to buy it in the first place. and he thinks my car buying advice is crap anyway because i like french unreliable hatchbacks.

 

hes gonna take it into the audi garage, so hopefully they'll sort it out without over charging him to much.