cfr865

I really don't think its vendor bashing if there is a problem with a vendors tune that has been proven on a dyno, to be lean ect. I think we should all be informed. I for one don't want to harm my engine because a "vendors " tune is protentially Harmful!!!!!!!!!!!!!!!!!!!, Then when the customer that had the problem tries to contact them they don't even respond. Maybe that vendor deserves to be bashed back into reality.

rygenstormlocke

Justin put up a good post on what could cause a lean condition regardless of tune. He said one common scenario was a re-oiled air filter that actually gets oil on the maf sensor and causes an issue. He said its always good practice to clean the maf sensor after an oil change. Don't quote me on it exactly though. I need to go dig up the email with his response in it.

wmtheflash

After reading that post I was a little curious about my A/F ratio on my canned SCT 93 octane tune. I'm going to need to some help reading the results, though.

Procedure: I drove the car for a short distance to warm it up, then started data logging prior to merging onto the interstate. I accelerate from about 20 to 60 mph, going from around 600 rpm to almost 5,600 rpm, so I got a good range.

Results:

I made sure to long any variation of the Long Term and Short Term Fuel Trims, along with throttle position to make sure I hit wide open throttle. In any case, all of the fuel trims came out at a constant .747. I also logged the Knock Sensor 1 and Knock Sensor 2 and they were consistently 0 throughout the procedure. Woohoo! No knock!

Now, here's where I need some help. It's my understanding that I need to multiple .747 by 14.64 (or 14.7, not sure!) to get the A/F ratio. Is this correct? If so, then mine is 10.9. Is my logic right?

I know, I know, it's not as accurate as measuring it at the tail pipe. However, I think it's telling me that the system is running rich for safety, which is what you'd expect from a canned tune. No surprises at all, I'm very happy.

I also noticed that the my Steeda Intake with AEM filter is working just fine and is supplying much more air than the system is demanding.

I have an SCT Strategy Flash running 1.14 firmware with a 9415A version 12. Vehicle is a 2006 GT with an automatic transmission.

By the way, data logging on the XCAL2 is really easy. I generated the graph without the aid of a laptop. The device itself will hold 90 seconds of data and log up to 20 parameters at once.

[IMG]local://upfiles/37741/532327B44F0E40439F081468FD5E4D09.jpg[/IMG]

28HopUp

For the experienced tuners to chime in, I'd like to ask if a tailpipe sniffer even gives accurate A/F ratios? Professional racers will fab up their exhaust with bungs in the pipe(s) for the A/F sensor(s), which can be located post-head, pre-cat, post-cat, and even farther back. Granted, most of us will not modify our exhaust to allow for that. But will a tailpipe sensor give reliable results? Just because there's a lean reading at the tailpipe doesn't necessarily mean the tune is lean. The A/F ratio DOES change as it exits the exhaust (which I confirmed with a VERY experienced tuner who is not a sponsor here).

I'd love for some experienced tuners to post in here with their thoughts about the accuracy of tailpipe sniffers.

jerjan

First of all, I'm not an expert. I have done some tuning in the past, I was always told that the most accurate readings need to be taken as close to the engine as possible IE: either right after the exhaust manifold or just past the header collector. That is why the factory 02 bungs are placed there. Taking the readings farther back can lead to potential incorrect readings. Especially as fuel can continue to burn in the cats and in the tailpipes and mufflers. Taking readings in those areas tell you what has happened after all the variables. Thats not exactly what you want. You want to know what just happened in the engine, not what happened after it passed through a bunch of components.

jerjan

So, does a tailpipe sniffer give accurate results. Probably not, as it can't tell you what happened before the exhaust gases passed through your entire exhaust system. It only reads what's left of the gases after the fact.

rygenstormlocke

I've read the tailpipe sensor can be up to one point off on the actual reading. On my car, PH installed a bung before the headers, in one of the turbo pipes for a accurate reading.

zcat

Well this really throws a curve. My fuel ratio was deemed lean a couple weeks ago by the dyno tuner when we did some pulls. I had readings in the upper 12's to mid 13's from about 4000 to redline with the mixture reading leaner as rpms raised and based on those readings I have been talking to Whipple about a new reflash. Could these readings be correct or could I be pretty much right on the money - damn it, just when you think your on the right track you see something like this and it makes sense! I do wish the tune was easier to break into - it acts like a stock Ford tune & you cannot modify it with a diablosport[]

Daniel60

All this lean talk and I'm still running the dog **** out of mine and with almost 37 , 000 miles and I have the same mean running ape I have had always.

[IMG]local://upfiles/11318/3A0F15C1CE874E99BC27320C00EC6802.jpg[/IMG]

zcat

You might get away with that on a NA motor, but when you force feed, you can blow holes in pistons by running lean rather easily[:@]