Test MAF?

[S2tuner]

KayGee: yes, Motronic does adapt, however, it can't adapt right to having the wrong MAF with the wrong output curve programmed in the chip, this is what I meant....

Rich's logs showed 230g/s peak with 1.5 bar boost on RS4 turbos. It makes no sense. I've tuned an AGB engine with RS4 turbos on it and we had solid 290-310g/s on the stock MAF. The reason is because an RS4 MAF has a larger diameter housing, so when for instance 200g/s go through it, the output signal will only mean 170 g/s (ballpark numbers for the example here) to the ECU that thinks a stock MAF is still fitted...

HTH,

Mihnea

[KayGee]

Arghh, gotcha re adaption. Think we were at crossed purposes. My thinking was it took 600 miles to go out of spec and start mis behaving not that the adaption mean't it would tune itself to work with the RS4 MAF. Took 600 miles to untune itself.

Totally agree on the MAF readings mine at Std produced 225g/s.

[S2tuner]

Agreed then KayGee

Okay, I saw Rich's logs and this confirms what I was saying. The juddering he's getting are lean running spots where O2 sensor voltage drops down to almost 0v. This is because the ECU thinks there isn't as much air going through the engine as there actually is, and thus it leans the mixture out accordingly. It basically does its job, and it also confirms to disbelievers that the ECU doesn't care about the MAP sensor's output for fuelling.


Rich, get the stock MAF back on ASAP if you don't want to ruin your engine, lean running can burn holes through your pistons and/or melt exhaust valves. IMHO, the EGT sensor fault codes you're getting could well be due only to lean running that means too high EGTs.

Hope this helps,

Mihnea

[rweir]

Rich, get the stock MAF back on ASAP if you don't want to ruin your engine, lean running can burn holes through your pistons and/or melt exhaust valves. IMHO, the EGT sensor fault codes you're getting could well be due only to lean running that means too high EGTs.

Hope this helps,

Mihnea

Yes, does help, thanks guys.

So, is ok to drive the car, but not too boost it, basicly take it easy for the drive down to London (From Glasgow) to this garage and let them put my old MAF back on?

rich

[S2tuner]

Ouch, from Glasgow? Jesus. Try avoiding WOT as much as possible then, yes, and you should be ok.

HTH,

Mihnea

[JonnyX]

Totally agree with Mihnea, you need to scale the MAF readings appropriately or use proportionally
sized injectors. (i.e. so you inject a proportional amount of unmetered fuel to the amount of
unmetered air you are putting in). If you use proportionally sized injectors to match the increase
in MAF cross sectional area then the adaptation limits of the ECU can handle the rest. Although a
proper remap is the more robust solution. It would be useful
to see your long term fuel trim though (block 31). Did you say you have RS4 injectors on the car
but have an RS4 IM to go on? Are you sure? RS4 injectors won't fit a stock S4 IM without adapters
AFAIK. A 5 bar FPR may help but you would need to do the calculations.

How do people who have the RS4 IM get the ports to match the S4 head? My understanding is
that the RS4 ports are much bigger and there isn't enough material to safely port the S4 head?

Cheers,

Jon

[rweir]

I do not know why I did not do this before, but anyway, disconnected the MAF, and guess what? All working perfectly.

I am going to get my old MAF put on for just now.

The car is on its way to the garage. At the moment it has SKN injectors, which are RS4 like I believe. The garage are going to fit RS4 injectors along with the intake manifold etc etc, so I believe they can then just put in a modified RS4 chip (450bhp one). Is this acceptable Mihnea? Or is a custom map the best way to go with this?

Cheers
Rich

[Imolavirus]

i doubt that using a modified RS4 chip is going to be the easiest route, only becuase the RS4 has a larger throttle body and different intake cams than the S4.

[S2tuner]

Exactly my point. Plus a modified RS4 chip needs an RS4 ECU, which doesn't work straight in Rich's car...

Mihnea

i doubt that using a modified RS4 chip is going to be the easiest route, only becuase the RS4 has a larger throttle body and different intake cams than the S4.

[rweir]

Exactly my point. Plus a modified RS4 chip needs an RS4 ECU, which doesn't work straight in Rich's car...

Mihnea

i doubt that using a modified RS4 chip is going to be the easiest route, only becuase the RS4 has a larger throttle body and different intake cams than the S4.

The latest is that it is going to cost too much for me to get all the RS4 injectors, intake manifold and fitting.

I think I will just put my old MAF back on and run it like that until I can get meet up with you Mihnea and get a custom map done....

Should I possibly replace the two EGT (G235 and G236), as these are coming up with the errors I reported at the start of this thread?

rich

[JonnyX]

The EGT errors are more likely due to the fact that you are running lean. I would actually be
a little concerned if I was you as it sounds like you have been running the car outside of the
limits in which the ME7.1 can protect you from damage. If you run the old (S4) maf you
may still have a problem, depends on the flow rate and fuel pressure of the injectors
you are using relative to stock s4 injectors. Best thing is to get a custom remap or make
sure that your injector flow rates are proportional to the amount of air you are metering.

Long term fuel trim is block 32 (not 31 as I mentioned earlier in the thread, thats o2 voltages).
It might be worth clearing fault codes (which clears the learned values in 32) and running
around for a bit with your stock MAF. block 32 should give you an idea of what your fuel
trims looks like. It's not a substitute for a wideband meter though.