Rs4 running rich

B6/7 S4/RS4
#1

My car seems to be running rich. When I accelerate really hard I get dark smoke. I’m jhm tuned, exhaust, & piggies. Car has 107k recent carbon cleaning and I just replaced oil separator, one injector that failed in the wide open position. I’ll be doing spark plugs and coils tomorrow just to be safe and start firing the parts cannon in the most obvious directon.

My big question here is what parameters does this car tune the fuel curve from? I’d imagine the ecu samples data as you drive and can adjust itself accordingly within a small variation from the fuel curve programmed in the software… So two of the main things I can think of that would directly relate to fueling would be o2 sensor and maf values? Should I attempt to clean the maf and change out the apparently original 107,000 mile old oxygen sensors? I’m grasping at straws here and planned to do new o2 sensors when I do my downpipes and clutch & flywheel in the spring. Just looking for direction.

#2

Is it rich all the time or just in the first few min of the car starting and running.

If you had a fuel injector stay open there is a chance that your cars ECU is in limp mode still and setting the car on a fixed path to fueling.

The colder the weather the more the fuel system will be working to compensate.

To directly answer. Your 02 sensors and your MAF control fuel.

#3

Mine’s always run rich like that, before and after the JHM tune. I’ve also tried new O2 sensors, MAF, spark plugs, high pressure fuel pumps, fuel filter, and a new PCV valve. It still does it. Even my mom who was following me today made a point to tell me that my car was smoking when I would take off quick, but only then, didn’t do it under normal acceleration. But this is always been the case, especially if I’ve really been babying the car for a while, the next time I floor it and let the revs get up over 5k, I’ll leave a trail of smoke so bad I can barely see the car behind me.

So in the end, I can say for certain that parts I’ve replaced haven’t made a single bit of difference. The next thing I want to try is getting my injectors cleaned and flow matched to see if it helps any, and I may even replace the water temp sensor for the hell of it.

#4

Brian, are your piggies completely catless or just the precats gutted? This can have a drastic effect on what you see coming out the exhaust obviously. My B7 S4 which had no cats would always have a little smoke on initial hard acceleration until the ECU adjusted throughout a WOT pull. From experience with this platform and others, I’d say that is pretty normal on a tuned car with a more free flowing exhaust.

If I were you I’d still send off all my injectors to get tested and flow matched. I think someone here just recently did that. It won’t hurt the problem and will likely make the car run better,

This would have no effect on a Rich condition, but I didn’t see you mention the fuel filter filter, that is something you should also probably address too.

#5

Sorry, yes I did the fuel filter the second week I owned the car. Thanks for the input guys. I appreciate it and don’t feel so alone anymore.

#6

Well new plugs and some drive time and I had a smoke free drive. She’s running great again. I’m sure I’ll still get the cold start smoke and raw fuel smell but I can live with that.

#7

I never came back here to update, but a few months after this post I had an injector fail and stick wide open. Since changing the bad injector I no longer get the dark colored smoke. I also took the opportunity to replace the oil separator when everything was apart as well as a carbon cleaning. The carbon build up in 7k miles was pretty bad. I had just done a carbon cleaning in July. It seemed like it had all come back fyi.

#8

Glad you got your issue fixed.

I get the carbon buildup really quickly too. The PCV/oil separator is just not efficient enough and recirculates a large amount of oil vapor back into the intake. I’m hoping replacing the stock oil separator unit with a high-efficiency aftermarket option will help alleviate the excessive amount of carbon buildup. People have tried aftermarket oil separators in the past, but I’m not convinced the ones they tried were sufficient for the job.

#9

Must have been your jhm tune.

#10

Thanks for comming back for the update. So that is two bad injectors in one year. Have you pulled the other injectors out to look at them or have them tested

#11

FWP! never answered my question about that before and I wasn’t even trying to be rude.

Yeah, it would be a great idea to take all the injectors out to have them flow matched/rebuilt.

#12

I plan to pull all of them and send them out for cleaning and balancing. Once I can have the car down for a few days.

#13

Great idea. We are seeing more and more out of range injectors in the FSI cars. That can lead to a lot of long term issues

#14

Sorry, what was the question? I must have missed it.

#15

So you had pinging with the old PCV valve and the fuel injectors were not working correctly. Are you still going to blame the tune? It is a fair question and not meant as an attack.

#16

PCV valve wouldn’t have affected it, and while maybe the injectors would have, I still think it had a lot to do with temperatures. It only pinged when my dash said it was 105 or hotter outside (the hotter it got, the more it pinged), and when I looked at the logs, the car was trying to pull as much timing as it could up to the 16 degree max, and it would ping beyond that. After they got me a revised tune, those knock retard numbers went down to a max of about 10 degrees getting pulled when it was really hot out, and only about 2 or 4 degrees of retard at night when it was much cooler, but I stopped hearing the pinging. It was still doing it at throttle tip-in at high revs if I was driving “aggressively” and I never got Jake to respond on that. I will have to see how it acts once it gets hot outside again.