gregt909

Hi, I had my car dyno'd today and they had to back off because it was running extremely lean. The tech said it was up to 13 A/F at 4600 rpm. He said it should be 12 maximum. Have any other Roushcharger folks has this problem? I'm going to call Roush on Monday but I thought I would check with folks as well

Driver72

You didn't get your car "tuned" when the Roush supercharger was installed?

did a dealer install it? If so, I'd contact them then, they need to tune it better.
13:1 seems a bit lean, but I wouldn't think it was "dangerously" lean that they couldn't
run the dyno for you.

did the dyno shop offer to adjust it via a tune?

hawgman

For a SCed car, 13 is pretty lean. You want to be in the mid 11s. If a dealer installed the SC, I would definitely take it back to them. If a HP shop installed it or you installed it with the supplied Roush tune ( or sent Roush the PCM for tuning ) then I would be on the horn to Roush first thing Monday morning.

gregt909

Exactly, Roush did the tune and the tech was very informative about a superchaged A/F ration vs. a N/A A/F ratio. He said a S/C engine should hit 12 max. I will be calling Roush on Monday to get it straightened out, Hopefully.
I would think that Roush would be concered concidering they are warrantying my engine. We'll see, I'll let you know.

chevykiller

Hawg is on the money. Did you ever have it dynoed before since the install? Specifically, did the a/f change or it is just now you are discovering it?

Airborneflyguy

the saleen SC has the same issue with it's canned tune. Look into 39# injectors and a good dyno tune.

Is it through the whole powerband or the top end? if top end then bigger injectors should solve the problem. If it;s throughout the power band it's all tune.

gregt909

This is the first time it's been dyno'd so I assume it's always been like this. The Roush actually come with larger injectors so I'm pretty sure it's the tune. The A/F looks to be pretty steady all the way through the power band. Hopefully I didn't do any damage by driving it as long as I did with it running so lean.

gregt909

Well, after 3 days at the dealer and numorous phone calls to Roush they concluded there's nothing wrong with my car?? The dealer doesn't have the ability to check the A/F ratio so I'm not sure they have come to this conclusion. I guess I will be going yet another dyno shop to have them check it. According to Roush there is only one tune for the Mustang. I wonder if the fuel pump could be the issue??

chevykiller

I don't know but either way you could try a BAP. With your power leve, that would be all you need anyway with your stock pump. The fact your numbers are in the 13 range doesn't mean your losing fuel, it proabably is just the tune. Either way, get a dyno and post back the chart and then we'll know for sure if it's a fuel issue or not. I'm guessing it's just the tune itself cause you said the a/f is steady.
Good luck.

Mark

CrazyHorse0217

Let me know where you go to get dyno'd, and maybe I could go to the same place. Then we would have a good comparison, even though I have the automatic.

Is Roush telling you that a 13:1 mix is OK, or are they telling you the dyno results are wrong?

Does anyone know if, after the warranty period with Roush, you can completely override their tune? From what I have heard so far, I'm not sure Roush has made that possible without "breaking" their code.