UrS4

Hey guys, I need your opinions,

I just went and had my baby dynoed. My mods are in my sig. My current tuner is Fred at Evoperformance.com. Just before putting it on the dyno I reflashed the 93 octane tune. I did two runs pretty much back to back. The car was fully warmed up and the temp in the shop was around 60+ degrees.



Guys I need some help.
The power was 284whp and 296wtrq on a Dynojet. That seems good for only having the JLTII CAI and the 4.10s hurt the trq a little. The problem is the A/F ratio was always above 14 and got as high as 14.8 with an average around 14.5. The shop I had this done at said that is too lean and that in this cooler weather it should be around 13.6 with it dropping to about 13.2 in 90+ weather. He said for every 10 degrees F the car will richen it up 0.1 on the A/F.

I agreed to have him dyno tune it later in the week. I asked what could make it run so lean since this easy mod should be bread and better for a shop like Evo? He thinks it is all in the tuning. I suggested a dirty MAF sensor, what do you guys think, could this solve the lean problem? I am going to clean the MAF and have them do some more baseline runs before I go ahead with the new tuning. These guys that own the dyno shop seem cool and will give me two new tunes so I will still have the 93 octane tune from Fred to compare if I can get this A/F under control.

What should my numbers be and how will the A/F affect it and what A/F should I be at?

Thanks everyone.

Blazing Saddles

Yeah, that certanly is lean. I've found my sweet spot is 13.2 I have an AEM A/F gauge and adjust mine to the weather.

UrS4

Is the high A/F due to the tune or could it be from something else like a dirty MAF sensor, or a faulty A/F sensor at the shop?

DoctorQ

Here's some informative a/f information I found posted on another board...

http://forums.bradbarnett.net/showpo...6&postcount=81

hawgman

My money is on the tune being the culpret.

UrS4

Well I pulled the MAF sensor to clean it and it was nearly clean as a whistle. There was a slight bit of film/grime towards the mounting side and when I sprayed it clean there wasn't any staining on the towel.

To DoctorQ thanks for the post it was very helpful and informative. The only thing I am not sure about is if those A/F ratios are measured at the tailpipe or in from of the cats. Everyone tells me that it will be leaner at the tailpipe. But I don't know how much different it will be, 0.1-0.5?

scramblr

You've probably already done this, or hopefully will, but you should send the graph to Evo and have them take a look at the tune. May just need some adjusting and they should be able to do that with no problem.

UrS4

Scrambler,

I haven't yet and honestly I don't know if I will. I have been emailing Evo asking about newer tunes and I haven't gotten a reply at all and it has been a full week. Whenever I have emailed Brenspeed or other tuners, mustang parts dealers (Steeda), they have responded within one day. I don't mean to bag on Fred, but I think all this success and his new focus on getting his GT500 into the 9s in the quarter has made him forget about the bread and butter GT guys that made his business grow.

But at this point scrambler I don't know if it is the best use of my time and money to deal with Fred anymore regarding mail order 'custom' tunes. If I send him the dyno sheet, if he ever gets back to me, and I have to reflash my car back to stock, send him the handheld which I am sure I will pay the shipping, wait for him to put a new tune in or adjust the old one which he may charge me for too, then wait for him to ship it and then put the tune in and then what? Since the A/F was off to begin with, I will be going back to the dyno to double check the A/F because I am paranoid about Freds tunes and mail order tunes for that matter now. All that time and money will be more than just going back to the dyno and having two new tunes put in that are guaranteed safe for only another 190 bucks.

06GT4RAD

I have not done business with EVO but in his defense of not returning your email it is after all Thanksgiving weekend.

Also where were you taking these readings? It sound to me like you were doing it at the tailpipe in which case the A/F mixture would have gone past the cats and that could have cleaned it up quite a bit. In my understandings the A/F ratio are to be taken prior to the cats.


Richard

BigDave

If you can get a custom dyno tune for $190, I would go with that over any mail-order tune.