Running problem with a 7a

[mrtat2k9]

not tryed maff coz i dont have anuther but i have tryed port and woudnt folt code come up with a knock sensors thanks

rob

[mcandmar]

Maf is a definite possibility. They are quite robust in a 7A as they have a tiny sensor unlike an S2 maf that has an element like a light bulb. May be no harm to pull it out and blast it with carb cleaner, all you have to do is remove the two screws and slide the sensor out of the body.

Cant see it being knock sensors, as above the engine will run fine, just down on power. I have never seen knock errors logged, infact only time i've ever seen anything logged in the 7A its been a hard fault, or a sensor unplugged.

Another possibility is low fuel pressure, can you confirm the fuel pump relay is working as it should. It should run for ~5 seconds with ignition on, then switched on again when the engine is started.

[mrtat2k9]

ok cleaned the maf and still no change are there any tests i can do on the maf. as regard to fuel pumps nearly new only thing i can think of with that is the filter blocked thanks

rob

[mcandmar]

Not sure if this will tell you anything but heres a brief guide from the Bentley manual.

-Leave MAF connected and peel back rubber boot to expose connectors
-Connect multimeter to PIN 2 & 4 and measure volts (2v range), switch ignition on and it should be between 1.0-1.5volts. With ignition off it should be between .3 and 1.1 volts.

There is also a lot of faff about testing the wiring resistance between the MAF and ECU, each pin should have less than .5ohms. And a note saying to ONLY to use gold plated connector terminals if replacing them.

[mrtat2k9]

i will cheque tomorrow but if its not in the rang then does that means it ******d

[mcandmar]

By the book yes, i think its all from the Audi service manuals, if in doubt sell the customer a new one.

[mrtat2k9]

ok thanks i will have a try and sort it out tomorrow

[Mikes2]

You haven't got the fuel feed and return lines reversed have you ?

[mrtat2k9]

i will admit it seams like its only started since i replaced the fuel pipes but im sure i havent thank you

rob

[mrtat2k9]

ok did a test it was about 2.5 volts so i turned the screew down si i git 1.50 volt but it wnt idea

[mcandmar]

I wouldn't be so quick to mess with the MAF adjustment, to set it up properly you need a CO meter. Some info i posted in another thread..

http://www.s2forum.com/forum/showpost.php?p=404839&postcount=18

So your saying it will start but not idle? Will it rev cleanly or is that problem still there to? If so i'd put the maf adjustment back where it was for the time being.

[mrtat2k9]

ok the problem was still there but i found some thing out when i tryed a diffrent air filter when i put it all back together i for got to connect the maf back it started fine and will rev ok but just keeps stoping

[Sleeper_Avant]

if it revs ok with MAF disconected then its not fuel pump or lines connected incorrect.

you need to check the MAF or swop with one that hasnt been molested with a screwdriver in the adjustment hole fella!

you clearly havent got an emissions analyzer so..........
1 remove and clean the spark plugs.
2 take car out and drive it how you would......
3 upon returning turn engine off imedietly and remove 1 spark plug and check colour of the tip.

white = lean
black = fuel rich
tan/brown = perfect

report back, or gimme a ring/text on 7563 799 485

you MUST be running fresh fuel, clean air filter and obviously make sure the fuel lines are NOT crushed or badly curroded as this makes a huge difference!

Sean.

[mrtat2k9]

hi thanks all for helping i think iv sorted it now i borrowed a maf of a mate put it on runs better no then it has ever done. i think im in need of a new maf dont serpose any one knows how much they are for audi do they. thank you all for your help to start of with i would never have thort it was the maf so thank you all.

rob

[mcandmar]

Glad you got it sorted