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-   -   Sniper Tune Question (https://forums.maxperformanceinc.com/forums/showthread.php?t=860995)

Formula8 08-22-2022 12:24 PM

Sniper Tune Question
 
Noob question but I am considering having my Sniper tuned through an email tuner. I have a few hundred miles of self tuning (fuel only) under my belt now and the car runs probably better than it ever has. I just want to make sure I understand the point of the tune.

I am going to try and getting the timing control up and running this weekend. After being tuned, what am I doing with things like the target AF's and timing targets. Wouldn't the Sniper try to adjust from the "optimized" mail order tune back towards the targets I set or when the mail order tune is installed, are those reset? Or disabled?

JLMounce 08-22-2022 12:55 PM

I'm not saying that a mail order tune is bad, but is there a reason that you think a mail order tune would by default be better than what you've achieved yourself through the driving and tweaking process? Especially if the car is running better than it ever has.

As far as the mail order tune goes, you're going to be overwriting the tune you have in the system now, so even if the learn function is still active it will be attempting to achieve the commanded inputs for the new tune. It's not going to try and drift to the inputs you currently have in the system. If you get the tune and you like it a lot, I would recommend turning off the learn functions in the system. That locks out or limits your long term trim movement and you typically rely on your short term trims for adjustments due to weather and altitude changes. You do however have to them be mindful of making any changes to the car that could effect the tune. From engine part changes to even driveline changes like a rear-end gear change.

If this car was late model mustang, camaro, challenger etc where everyone is working with the same parts and the same engines, mail order tuning can be great because they are derived from tunes that the companies have developed on a dyno and through road testing. It's hard to go completely wrong as a result. For a traditional Pontiac that won't have a plethora of tunes out there, I'd be a little more hesitant. If you don't trust your own skills and tuning, I would actually suggest spending a little extra and having it tuned locally by a competent tuner on a dyno and on the road.

Formulajones 08-23-2022 09:37 AM

Used to be a lot of guys doing mail order tunes back when I was fooling with LS stuff. Like JLmounce mentioned, with most of those cars being so equal it seemed to work well enough at the time. I can't even imagine a mail order tune on a 60 year old classic car that has 100 different variables changed from the next classic car, and so on. I would think you'd really have to be present and live for things to be spot on. It really is specific to each car. Most likely you would be mailing datalogs back and forth along with your tune while he made small tweaks to try. It could turn into a pretty long process.

As far as target AFR's you've set verses someone else's tune, more likely than not the new tune would have it's own set of target AFR's with it's own learn and fuel trim limits set. The question would be "Is that going to be right for your engine?"

As JL mentioned, once you have a good base fuel table nailed down it's usually best to dummy down the learn feature and just leave the closed loop comp (short term correction) active to a reasonable amount so it's able to make small fuel changes for changing conditions without making big changes to the learn table (long term fuel)

As an example, you can pick certain areas of the fuel curve to allow closed loop compensation to make those small adjustments at any amount you desire. For instance I tend to leave it at 50% adding fuel only in the WOT areas like 80 KPA and above but not able to pull out fuel, maybe 10%, while the rest of the table might be 10% + or -

I do this because I've already had a fuel pump failure that was getting weak. At WOT fuel pressure was dropping dangerously low, but the Sniper was compensating trying to add as much fuel as it could. Dad noticed fuel pressure low as I set up the Sniper to flash yellow below a certain PSI. Thankfully the close loop comp added the necessary fuel to at least try to keep it at the commanded 12.8 AFR. This at least kept the engine safe at WOT but didn't corrupt the learn table because I had the learn turned down.
If closed loop comp would have been turned way down in those areas, the engine would have went dangerously lean and I couldn't be sure dad would have seen it in time before some sort of damage occurred.

This type of tuning or thought process can also be beneficial when the 02 sensor dies. Also always a good idea, once you have a good base fuel table, to have an open loop tune saved on the SD card when you suspect you're having an 02 issue. You can at least drive the car back home that way.

Formula8 09-07-2022 12:10 AM

Just updating. I got the car up and running with the Hyperspark. I took the opportunity to clean up the wiring to the MSD, add capacitors on both the Sniper and MSD and completely shield (with grounds) most all of the sensor wiring. I ended up building a
conservative custom timing map, used the wizard for fuel and will just get some miles on it to build its own fuel map for now. I only have about 10 miles on it at this point but without a doubt, the car runs better than it ever has.

Formulajones 09-07-2022 11:26 AM

Quote:

Originally Posted by Formula8 (Post 6370435)
Just updating. I got the car up and running with the Hyperspark. I took the opportunity to clean up the wiring to the MSD, add capacitors on both the Sniper and MSD and completely shield (with grounds) most all of the sensor wiring. I ended up building a
conservative custom timing map, used the wizard for fuel and will just get some miles on it to build its own fuel map for now. I only have about 10 miles on it at this point but without a doubt, the car runs better than it ever has.

Out of curiosity, are you still using the billet MSD and just locked it out for timing control?

I have one here I'm contemplating doing that very thing rather than buying a new holley distributor. I just hate to remove a perfectly good working USA made MSD distributor (bought it 25 years ago when they were still in Texas) vs installing what is probably something from ching chong now.

Formula8 09-07-2022 05:22 PM

I actually had a Mallory magnetic trigger dist. and MSD6AL on the car. To simplify things when I installed the Sniper, I took out the MSD6AL and started the Sniper on fuel only with the Mallory distributor. What I did here is swapped out the Mallory for Holley's Hyperspark distributor and kept my existing MSD6AL rather than using the Hyperspark unit for exactly the reasons you mentioned.

I have slightly more faith in my 8 year old and known to work MSD box than any current box sold by Holley which I have never used. I at least feel better with the overpriced capacitors on both the MSD and Sniper that I have done everything I can to extend the life of both.


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