NefMoto

Hello everyone!

The problem is that our RS4 B5 is running so rich as rear bumper gets black after few pulls and it smells very gasoline like@idle ;)

It also has very unfriendly L/100km figures, almost 25L+ per 100km when cruising at 100km/h.

Checked our MAF / O2 readings with VAG.COM  , then compared to friends RS4 B5 readings  and  this is what we came up with:

MAF readings @idle@90C – both cars have the same readings  ~4.5 g/s , so it seems MAF sensor is in working condition.

IAT readings @idle@90C – both cars have the same readings  ~40C , so it seems IAT sensor is in working condition.

Here comes the nightmare:

Pre cat o2 readings @idle@90C (our car) = 0.815 - 0.87V , never goes lower than 0.8V (too damn rich);

Pre cat o2 readings @idle@90C (friend’s car) = fluctuates between 0.1V-0.6V (normal situation for narrow band o2 sensor showing stoich air-fuel I suppose)

Group 033 O2 sensor  Diag status readings @idle@90C (our car) = 0% , never ever changes.

Group 033 O2 sensor Diag status readings @idle@90C (friend’s car) = fluctuates between -2.3% and 0.8%

Group 078 Air mass (g/s) sec.air.inj.   @idle@90C (our car) = -100% , never ever changes.

Group 078 Air mass (g/s) sec.air.inj.   @idle@90C (friend’s car) = -3.1% , never ever changes.

Thermostat and CLT sensor were replaced with OEM new ones few weeks ago.

Engine does not throw any “fuel trim too rich” or “o2 sensor problem” codes, everything is clean even after driving 200km+ trip….

All the coil plugs are black and dirty after inspection.

Haven’t checked  the fuel pressure in the rail (as it’s too time consuming to install T-fitting with gauge), but have never heard of FPR’s to go bad. I could replace it with other 4BAR FPR for testing purposes.

Any suggestions?

P.S. Please don’t blame tune as our car was running great (10l/100km cruiser) with exactly the same tune before.

What are your LTFT's in group 032? Are you sure you have the same injectors as your friend's car? I would also switch O2 sensors to make sure.

O2 precat replaced yesterday, still same o2 readings. I have bigger injection, but the car was dyno tuned and had great mpg figures. Will check 032 readings. Any other suggestions?

So your tuning this car with no wideband and only VCDS?

You need to figure out why lambda regulation isn't active.

Get ME7L working.

No,  the car was dyno tuned with wb lambda of course and the car behave fine last few years with 560hp/780nm and great mpg figures. I am no expert in ME7 but it seems that something has failed and asking for ECU to be on the rich side even at 90c....

I am pretty 032 Ltft was 0 even driving 300km with putnu touching Code erase.  The engine is not giving any errors btw.

Get ME7L setup and then it shouldn't be too hard to diagnose.

I'm thinking target lambda != 1

EGTs possibly.

+1, since i disabled mine I always keep forgetting about them...

who did the tune? I've seen files lately that zero the error classes but leave regulation in place :(

Software was done by Turbotec (Finland) I suppose.
 
Ok, EGT's. Thing is the car was tuned with 630cc Siemens injectors (~790cc if running with stock 4BAR FPR), FMIC, RS6 turbos with larger compressor wheels and resonators in place of cats. Everything was running silky smooth after that! Software is software, flashed parameters can't change after time ;)
 
Now there are cats (larger than stock of course) in 3" downpipes , even larger turbos and custom ex. manifolds with larger dia runners. Larger ex. manifold runners and larger turbos can't make more back pressure, they could only reduce it. Cats in place of resonators could make more back pressure in theory. 
But I am pretty sure that this fuel mixture problem was even before the last upgrade.
 
BTW, post cat O2 sensors show approx 0.43V (might be they are disabled in software as that was our wish to remove MIL after replacing original cats with resonators).
 
But then - if they are stock narrow band EGT sensors (measuring EGT only after 945C), and VAG.COM shows that EGT's are not exceeding 945C, then how can we talk about EGT's then?
 
What about Secondary air injection showing -100%? What if N80 or other valve  in vacuum system has failed? Can they influence the mixture so radically?
 
Thanks in advance for everyone  sharing their opinion!
 
Krists

EGTs are probably fine then


Maybe. S4s don't run SAI.. maybe some RS4 tuners can pipe up here.

Trims?

I've had the same problem last year (also RS4), there it was the coolant temperature sensor which measured too cold conditions. Therefore the engine (thought it) was in "heat up" phase and therefore very rich.
In case the lambda value is much higher than it target you would have an error (in case sensors are OK). So for me it looks as if the current real lambda is rich as expected from the ECU. that could be linked to a wrong engine temperature measurement...
I have changed the sensor and then life was lean again...
maybe worth to check...

BR
Greg

OP says "Thermostat and CLT sensor were replaced with OEM new ones few weeks ago" but I agree that is a common culprit.

A log would be informative at this point.

Recently did 10 timing jobs out of them 3 thermostats failed after a week (stuck open) my part supplier said there's a bad oem distributor which they stopped from sourcing not sure if this effects over seas

Hello everyone!

 

I am still fighting with rich mixture problem. The problem is that I live about 1000 km’s away from my tuner. Few days ago I received a modified rom file from my chiptuner and have to find a way to burn it on the ECU.

I don’t have much experience in flashing ME7 ecu and the car is daily driver, therefore I need to make sure about the following:

1.       Yesterday I tried to read my 2001 RS4 551K ECU with e-bay dongle and it did successfully read 1024 kb’s. In fact, it did read the flash memory even if I changed memory layouts from 29F800BT to 29F800BB and 29F800 (unfortunately I didn’t open the ECU case to make sure which AMD flash chip I have).
2.       The last tune (which had rich mixture idle/cruise problem) was previously read from the ECU with other kind of software.  Don’t know which one,  the raw format wasn’t bin but it was then exported to bin file and sent to the chiptuner.
3.       My chiptuner modified this bin file and sent the file back (should include corrected cheksum). As he said, the software had o2 sensors correction disabled for some reason.
4.       Both bins (modified bin and bin I read with the nefmoto software ) have the same size -  1024 kb’s. Both files have been checked for correct checksums.
5.       I opened both files with Winols and tuner pro software and at the first glance they both seem right in main boost / fuel maps (I did not investigate all modified maps of course).

Gathering all the above, the main question is – does it matter which ECU flashing/reading interface has been used to read the ECU and flash the modified bin back to the ECU if source and modified files have the same raw bin format with the same size?

I could of course send the nefmoto bin file to the chiptuner for mods or copy-paste all the modified maps to the nefmoto file, but is it really necessary ?

Can I identify AMD flash chip and correct memory layout without opening the ECU?

If the car doesn’t start with the modified file, will there be the possibility to flash back the last bin file I read with Nefmoto software without benchflashing?

Does 1024kb’s BIN file means that the flash memory chip has been read 100% (all the IMMO code info etc.) and could be used for BDM or OBD bench flashing  to other 551K ECU if something goes completely wrong?

 

No. Don't flash unless you have a bench harness to recover in boot mode.
No.