Running Problems

[valjo]

Hi!

I have mine ecu chiped by s2central.net. Car is audi s2 aby.
Now i have some problems, car wont go as it should, boost only 1.2. In 6 gear i get sometimes 1.3 but then boost quickly drop to 1.2.
I have new n75, new DV, new sparks, 100% no boost leak.
I have checked pot, g69, intake temperatur sensor, all fine
If i put old original ecu into car it works fine, overboost is ok (1,15-1.2)......
Any ideas and suggestions what should be wrong?
thanks

[waad_uk]

I would be interested to see what happens here as those are the boost figures I get with my homefried ABY. Mine has always boosted a touch low, and the homefries did push the boost up a shade (about 0.2 bar)

[S2central.net]

@Valjo - you have been running for a while with no problems.

At full load (say in 4th or higher up a hill from 30mph) you should see 1.3-1.4bar. Don't forget that ambient air pressure has to be accounted for... As the ECU is programmed to set absolute boost pressure.

If your altitude sensor or throttle pot are playing up then you may not see full boost. BY the sounds of things they may be ok if standard max boost is alright.

IF you are certain that you are absolutely airtight then maybe the MAP sensor within the modified ECU is faulty / inaccurate at those boost levels. Needs an ECU breakout box to test that unfort.

Have you checked all the other general things like spark plugs being tight, coil packs / HT in good condition with good earth strap ? What about cylinder compression and the PCV system ? Is the wastegate in good condition ?

Only other to suggest is try another MAF at the airbox - if yours is faulty / inaccurate at high flow levels then it will send bad signals to ECU.

Its just odd that it used to be fine then recently something went bad... I myself had to change MAF recently cause of high boost and misfire problems.

[Animal Mother]

Am I correct in thinking that standard boost is up to 1.1 to 1.2 bar max (my car reads 1.9-2.1 inc. atmospheric on UrS6 dash gauge)?

If so, what should it boost to max with the homefry?

I will eventually get a more accurate digi gauge.

[S2central.net]

@Animal - In the UrS4/S6 that digital guage shows ABSOLUTE pressure ie the sum of ambient pressure (nominally ~1 bar) and boost pressure.

So you are seeing about 0.9-1.1 max boost, which is about right for stock. After the upgrade you'll be seeing about 2.2-2.4 on that guage depending on load, ambient conditions, interplanetary orbit patterns etc etc

PS - Missed the stupid postie a few mins ago - gotta trundle down to depot to fetch your ECU - I hate it when that happens. Wish they'd knock the firkin door properly !

[Animal Mother]

@Animal - In the UrS4/S6 that digital guage shows ABSOLUTE pressure ie the sum of ambient pressure (nominally ~1 bar) and boost pressure.

So you are seeing about 0.9-1.1 max boost, which is about right for stock. After the upgrade you'll be seeing about 2.2-2.4 on that guage depending on load, ambient conditions, interplanetary orbit patterns etc etc

PS - Missed the stupid postie a few mins ago - gotta trundle down to depot to fetch your ECU - I hate it when that happens. Wish they'd knock the firkin door properly !

Cool. Does boost increase depending on colour of car (seeing as red ones are faster)?

Hope postie doesn't start playing footie with the parcel like they do around here!

How long does it actually take you to fettle the ECU? Hours, minutes?
Do you replace/upgrade any parts or just reprogram?

[Ross]

Cool. Does boost increase depending on colour of car (seeing as red ones are faster)?

'fraid not, my car's a deeper shade of red granted, but my homefries was seeing generally 1.3bar. It didn't actually feel that quick in honesty, compared to the homefries on my coupe that was always 1.5 on the button - and that was green! That was ABY vs. 3B tho, not sure if that makes a difference.

@Paul, what kinda figures should one see at the redline stock vs homefried? As I was always aware the avant would still give a good push to the redline, even if the midrange was down compared to the coupe...

[S2central.net]

On the redline - its about 0.8bar - about as much puff as the K24 can handle up there.

[Crawford_S2]

Interesting thread, i am running a homefry too as you know paul and i developed running issues recently. i am sure they are unrelated to the ECU as it was fine for a while on the homefry before. What should i see in Psi on my vdo retrofit jobbie, fitted it as i started to get issues and was seeing slightly more boost when it was ferkin about than now when it seems to be running well and pulling strongly.

Replaced the lambda, maf, fuel pump, filter and regulator. cleaned the WGFV which is fairly new, the throttle body and the ISV. Also tested the throttle pot as per s2central guidelines and seems ok if anything the resistance at WOT is a little low (2900)

ECU is doing its job fine though, trouble with these beasties is its like the ex wife, only takes a slight thing to send them mental

[valjo]

If your altitude sensor or throttle pot are playing up then you may not see full boost. BY the sounds of things they may be ok if standard max boost is alright.

IF you are certain that you are absolutely airtight then maybe the MAP sensor within the modified ECU is faulty / inaccurate at those boost levels. Needs an ECU breakout box to test that unfort.

Have you checked all the other general things like spark plugs being tight, coil packs / HT in good condition with good earth strap ? What about cylinder compression and the PCV system ? Is the wastegate in good condition ?

Only other to suggest is try another MAF at the airbox - if yours is faulty / inaccurate at high flow levels then it will send bad signals to ECU.

Its just odd that it used to be fine then recently something went bad... I myself had to change MAF recently cause of high boost and misfire problems.

spark plugs connectros are one year old and without any cracks!
how could i test WG -i checked diaphragma and there is no leaks to see- ?
several times i got error: 00537 Oxygen Sensor Control Limit exceeded, only with chip (i have replaced lambda)
engine was rebuild 3 years ago and is in top condition
well maf is about 5-6 years old, and i have cleaned it but no differences....
thanks for help

[valjo]

On the redline - its about 0.8bar - about as much puff as the K24 can handle up there.

i get those boost at redline with homefries......


i am also almost sure that problem is not chip......

[Animal Mother]

'fraid not, my car's a deeper shade of red granted, but my homefries was seeing generally 1.3bar. It didn't actually feel that quick in honesty, compared to the homefries on my coupe that was always 1.5 on the button - and that was green!

My car is green too, so should be alright then.

[S2central.net]

Its not the chips - there's somewhere between 50-60 cars running around the world with those fitted.

WHats your fuel pressure like - and state of the injectors ?

Sure you aint got a boost or exhaust leak - either of those can cause lambda / adaptation woes. What fuel you running in Slovenia out of interest ?

[valjo]

Its not the chips - there's somewhere between 50-60 cars running around the world with those fitted.

WHats your fuel pressure like - and state of the injectors ?

Sure you aint got a boost or exhaust leak - either of those can cause lambda / adaptation woes. What fuel you running in Slovenia out of interest ?

we have 98 or 100 octain fuel there, so i am almost sure fuel is ok.
yes according to those lambda error i should check injectors, fuel presure and leaks-will do that next week.
But could those error cause low boost? with original ecu i have no problems and none ecu errors..
thanks

[Knight Rider S4]

[QUOTE=S2central.net;265844

IF you are certain that you are absolutely airtight then maybe the MAP sensor within the modified ECU is faulty / inaccurate at those boost levels. Needs an ECU breakout box to test that unfort.

.[/QUOTE]

I would be checking this first as if the car is running fine on standard ECU the fault must lie here

I would just buy another MAP sensor and install

Cheers