Okay yall so I just got in my Xcal2, for my 2003 GT. I got it with two tunes (87 and 93 octanes). I had a tank of 87 so I went ahead and flashed it for that tune. She ran like a sonofabitch, and I knew that with 93 gas and the tune i'd see an even greater improvement. So, after the tank emptied out, I flashed the 93 tune (sitting at the pump at the gas station). Then I filled her up a full tank of 93. I started her up and took off, to find this problem:

When I free rev (no load) the engine sounds fine...clean and smooth. (Mind you I kept it under 3k as a safeguard). However, once I started driving, I noticed that when I got on the gas a little, a funny sound came from the engine. I honestly don't know to describe it. The sound reminded me of my crappy automatic tranny noises from my other mustang. By the way this car is a manual so don't get any ideas lol...It's obviously from the engine, and it's obviously because of the tune...I immediately stopped and flashed back to the 87 octane tune and the car ran fine. (How nice, a full tank of 93 and I'm on an 87 tune...damnit!)

SO, do you guys have any idea what the cause for this noise could be? That's not what I imagined pinging/detonation to sound like, but then again I have never heard it before, and I don't know what to expect. Maybe I didn't give the fuel system enough time to pump pure 93 gas to the engine? (Meaning maybe it still had 87 running through) That might sound silly, but I want to try it again in the morning now that I've been running it on 93 for several miles. By the way how bad is it to run a car tuned for 87 on 93 gas? I assume you're not supposed to...

Or maybe the tune is just plain wrong? Hope I didn't possibly hurt the engine already...probably not eh.

Anyway, any ideas!? Thanks for your time.

 

theres nothing wrong with running a higher octane on a tune that requires less octane. its just bad when its the other way around.

dont know what to tell you about the other stuff

 

The tune is probably funky. Put your stock tune back on and send it back in. Or have your tuner send you a new tune. You might have been hearing some detonation. See on those tunes timing is advanced and i've known a few people to put to much timing on a mail order tune on accident. You didnt hurt your motor but like I said switch back to your stock for now. To you figure out what the tuner did.

 

Wow thanks for the quick replies at 3 in the morning guys.

I put it back to the custom 87 tune for now. I'll be damned if I send it back in...I don't play the shipping/waiting games. I bought it from AM so should I contact them or should I contact someone at SCT?

 

Call in they have your tune on file so they should be able to look at it from there. All they need is the serial number on your xcal. If i'm correct talk to Nick he should still be the tuner over at AM. You can also PM him through here he is The Fox Body Authority. He's a nice guy he'll be sure to check it out for you.

https://mustangboards.com/members/th...authority.html

You could go through SCT to look at it but you would have to upload it and they take awhile to get to you.

 

Thanks bro I just pm'd him.

 

Hold the phone. If you filled the car at the pump with a fresh tank of 8=93 right after running 87 and then put on the 93 octane tune, you WILL get detonation. You need to drive that car around for a while to allow your fuel lines to clear out before switching over to the 93 octane tune. I would say a good 20 to 50 miles. Trust me.

Now, if the sound is something else besides detonation, I don't know what to tell you. Detonation will sound like muffled marbles in a can.

 

Never had to when I switch and never heard detonation hell i'll even spray. He had a problem with the 87 octane when he had 87 already in the tank already. It sounds like too much timing on each tuned to me which would make sense since his car runs fine when he has his 87 octane tune on but has 93 in the tank.

 

The car ran amazingly when I had 87 in the tank and had the 87 tune. It's also running strong when I had the 93 in the tank and have the 87 tune. It was just when I put 93 in the tank, and put on the 93 tune that the problem occured. I've driven it a good half tank now with the 93 gas so in the morning I'm gonna try the 93 tune again to see how it runs. This ish makes me nervous as hell...who knows if you're hurting the engine....ever? geesh.

 

A little knock or ping and you should be fine. Sounds like you stopped it right away anyway. Keep in mnd that none of us can hear what you are hearing so we are making asumptions.

I bet when you make the switch to the 93 octane tune that you will not hearing anything wrong in the morning. Hey, at least you know your timing is advanced.

 

Well guys I put the 93 tune back on after running half a tank of 93 through in order to completely clear out the 87, and she's runnin fine.

And I also played with the dual stage rev limiter. Holy CRAP that's cool.

Thanks for the help everyone. Time for some dyno action.

 

Great!

 

Oh crap, it looks like I lied. I drove it around for a bit and thought it sounded fine. Then later on during the drive home I noticed the sound I had heard earlier, or at least I think I did! It was pretty subtle, and it sounded like muffled marbles in a can, so sheeeeit. I put the 87 tune back on and I'm leaving it like that till I discuss the problem with someone at AM. I drove it hard this time, I damn well may have hurt the engine. What the ****.

 

Don't worry about hurting the motor. You should be fine. Ona stock motor running n/a, It takes a lot of knock to cause a problem. If you want peace of mind, pull a plug and take a look at it. Bad detonation will damage the spark plug.

AM uses very well-known and proven tunes. You need to have realistic expectations of a mail-order tune. Among other things, with the 93 octane tune, they advance the timing. But, that assumes that your a/f is normal to begin with and that your fuel quality is good. Things like how much Ethanol is in your fuel affect things too. Also, any intake or exhaust mods you have may have lean you up a bit which means you can't run as much timing advance.

If you get some knock with the high octane tune, they may just need to pull out some timing. There is a certain amount of guess work with a mail order tune.

 

What he said...


it's hard to get mail order tunes that are exact, dyno tune ftw.