Audi 7A problems

[Nuno Cristiano]

Hi friends,

I have here a Audi Coupé Quattro with 7A of a friend but i have problem with engine.

So, car in low water temp are OK! After um push engine after 4500rpm car go to safe mode and sound in exhaust changes to thicker.

If i turn off key and turn on car go OK but after 4500rpm is same problem.

If i turn ON engine and put driver wish 100% from 1000rpm to high revs car go OK ( in first gear ) to 5000rpm and after it go to safe mode.

- I saw that old mechanic have first knock sensor put in wrong place and i put in right place. Car use 2 Knocks and i replace from other car.

- I measured fuel pump pressure and in high load car does 4.2bar ( is OK ).

- I clean 2 VR´s sensors from Flywheel and same problem.

- I saw engine point and all OK.

- I measure Oil Pressure and all OK. I have fear that lifters had high pressure oil and valves not closer but is OK!

- I put VEMS standAlone that i do in pass to my Quattro and car go better but not with original power of 7A engine.

- I removed plugs and have color white ( Lean AFR )...

- I replace other injectors of other friend and same problem.

- When car go in safe mode car does flames in exhaust when i put driver with 100% and 0% ... 100% and 0 %... seems to me that the ignition is off point when go to Safe Mode


Anyone have same experience?

[mcandmar]

Faulty MAF sensor?

[Ryss]

You seem to have covered a lot of the likely potential problems.

Check Fuel filter. Fuel rail pressure and maybe try colder plugs. I had a problem (7A) with detonation (would cause limp mode) and solved this with colder plugs and octane booster.

[simon20vq]

O2 sensor sending lean signal maybe

[Error404]

have you pulled the codes?

[Nuno Cristiano]

I bought new O2 sensor BERU. Original O2 had problems and i saw with scope and not had signal variation 0~1v.

I measure fuel pressure in tank and all OK.

I too tested other MAF sensor and same problem.

About plug if i remember well car use group 6. Not sure.

Originally i think is 5 not sure too.

About codes i not tested sorry.

Never like blinking code.

Anyone have other idea?

[nicka90q]

Pull codes. It will at least tell you where to look.
Check throttle potentiometer it can crack from heat and it is a common failure.
On this page you have a lot of problems described. http://www.20v.org/indexb4.html

[Nuno Cristiano]

Pull codes. It will at least tell you where to look.
Check throttle potentiometer it can crack from heat and it is a common failure.
On this page you have a lot of problems described. http://www.20v.org/indexb4.html

Thank you but i tested with VEMS ECU and read 0~100% drivers wish and read right CLT temperature.

[nicka90q]

Then ECU is broken.
Test engine with other stock ECU and if all works good than you will know the problem

[tscheel]

I guess this means that you have checket the timing?

- I saw engine point and all OK.

Sounds like a jumped timing belt to me (i'm no mechanic).

I have a functioning ECU from the late version 7A (4 plugs) if you are interested.

[simon20vq]

temp sender on the back of the head, cost about 9 quid worth replacing as this can cause all kinds of issues if broken.

[Error404]

I would not bother doing anything else until you have check the codes, it is too easy all you need is an LED and some wire. Otherwise you are working blind, this can go on forever with electronics!
I still think you have an issue with the knock sensor(s).

[4WheelDrifter]

I would not bother doing anything else until you have check the codes, it is too easy all you need is an LED and some wire. Otherwise you are working blind, this can go on forever with electronics!
I still think you have an issue with the knock sensor(s).

Or you could slowly replace each part of the car one at a time until you find the fault. That method should work eventually. How much time and money do you have?