No power !

[ben4866]

I'm having trouble with my AGU which seems flat as a fart. It doesn't seem to be boosting and has no power until above 3k rpm and even then its still rubbish really. There is just NO torque.
Ive just done a boost leak test and system holds 15psi without any leaks and all vacuum lines are new. I briefly bypassed N75 to to see if turbo works ok and it was a totally different car to drive, could here the turbo spool around 2k and car pulled very strong.
My problem is VAG COM shows no faults at all and with no boost or vac leaks I guess it must be the ECU deciding not to demand boost ? Due to a sensor ? But no fault codes !
Any help greatly appreciated.

 

[ben4866]

Oh and I fitted a brand new N75f a couple of weeks ago.
Anyone got any ideas ?

 

[Broken Byzan]

Probably faulty wiring to the N75, did changing the N75 make any difference at all?

 

[ben4866]

To be honest no I don't think it did.

 

[makster1978]

how do you bybass n75?? having same issues disconnected sensor from n75 and made no difference to performace

 

[<tuffty/>]

how do you bybass n75?? having same issues disconnected sensor from n75 and made no difference to performace

You don't bypass the N75... its the boost control valve

Disconnecting the N75 electrically will not improve performance as it will force the turbo to run actuator pressure

<tuffty/>

 

[makster1978]

had the car on diognostics came up with fault codes for temp sender and maf so changed them both also changed n75 for peace of mind the car does run a little better but still no boost above 3000rpm driving slowly in the gears its fine, as soon as I floar the pedal acceleration picks up nicely till 3000rpm then the car holds back juddering then a few pops coming from the air filter area,any ideas guys, no error codes now really frustrating

 

[<tuffty/>]

Without logging on a dyno then not really... could be a MAF or ignition amplifier issue...

Have you had it smoke tested?

<tuffty/>

 

[makster1978]

thought about the smoke test I will mention it when I ring vag specialist Monday to book in,i guess it needs the top software to look it over,were abouts would I find the maf amplifier

 

[makster1978]

tuffty I read that maf disconnected can improve performance if its goosed does this apply to 1999 a3 1.8t I read one of your threads depending on engine code this can be the case but not sure what my engine code is if you can shed some light on this cheers

 

[makster1978]

ok after I changed the temp sensor the code keeps re appearing 16500 all the wires seem fine,i also have a new code 65535 fan module,it says on rosstech this code can also mean accelerator sensor may of failed ie the reason why my pedals so flat,could anybody tell me were to find the accelerator sensor mnes pre facelift agr.thanks

 

[makster1978]

update on my car,vag.com have had it for 4 days I have had the coolant sensor changed and now the fault hasent returned but still have no power past 3k revs,vag have done a smoke test and no leaks, tried a new maf new ignition control module and n75 then noticed a bad pipe going to fuel pump replaced that still no joy,there going to replace crankshaft sensor with a original but I replaced this recently which stopped it cutting out but still getting the poping sound from the air box when floored,no fault codes,really frustrated now I can sence the towel getting thrown in

 

[makster1978]

can anyone tell me if its possible my fuel preasure regulator could be at fault would this throw a code up

 

[<tuffty/>]

can anyone tell me if its possible my fuel preasure regulator could be at fault would this throw a code up

What code?

<tuffty/>

 

[makster1978]

no codes on the engine now so looking into other things it could be

 

[<tuffty/>]

Ah sorry... misread the post... the FPR itself can't throw up a code but if it was faulty (which pretty much never happens) then you might get an adaption fault code... the FPR has been known to get blocked from rotting rubber in the fuel lines and will increase the fuel pressure ending up in a fuel system too rich code...

As for disconnecting the MAF... yours is an AGU engine code being a 99 A3? if thats the case the engine pretty much won't run if its disconnected...

AGU's do more or less everything from MAF readings so if the MAF is under reading then it could cause issues

<tuffty/>

 

[makster1978]

thanks for the reply tuffty, vagcom my local specialsts tried a new maf, I have wrote further back in this post what they did,they had it a while, it seemed to me they were dodging spending to much time on the car and fed me sh**t,they said they cleaned the throttle body I will find out if this is true Saturday when I take it off myself,in 2 weeks I will of owned the car a year and its had this problem from day one,but did buy a spares repair and as the car revs perfect in neutral I wasent to know of this problem I am having while driving,i had It trailered back,when I disconnect the maf the car completely cuts out,only when I disconnect n75 It will run slightly better ie It will take longer than usual for the car to go into idle mode and does seem a lot faster,i replaced the n75 but made no difference,