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Piggyback vs Flash tune

Posted: Thu Oct 18, 2018 3:31 pm
by texanbrit
I keep seeing marketing for piggybacks for these cars, and they irritate me. I understand that it's largely a me problem, but the reasons they state that piggybacks are better are mostly wrong.

Flash tunes cause CELs:
Most check engine lights are caused by hardware issues not software; but typically piggyback tuners cause more CELs than flash tunes because:
- they add more physical connections to the car
- they intercept the signal that the ECU is generating causing a disconnect between what the ECU is expecting and what the car does
- the ECU is constantly in learning mode and can adapt in a negative way to some piggybacks/driving styles

Don't worry about State inspections
This is nonsense. No flash tune ever made someone fail a state inspection.

Other challenges with piggybacks include not being able to deal with the odd torque curves that are programmed into the 500T, and all the new 2018 turbo models. As well as not being able to adapt to additional aftermarket upgrades, down-pipes, intakes etc.

Where are piggybacks good?
If you have a warranty it is nice to be able to remove the piggyback before you take it to the dealership. Of course if the issue is the piggyback it will make it difficult for them to diagnose the problem but hey, at least you won't have to listen to the invalid warranty speech. Plus if you breakdown and get towed it might be difficult to get the piggyback off before the dealer sees it.

Anyway I've vented, so should be mentally healthy for a few minutes. Am I wrong here? Discuss.....

Re: Piggyback vs Flash tune

Posted: Thu Oct 18, 2018 5:18 pm
by operamatt
Piggy Backs are better in every way and you know it. Only downside is the box tuner weighs your car down by alittle less than a pound. Who’s paying you?

Re: Piggyback vs Flash tune

Posted: Thu Oct 18, 2018 5:24 pm
by retrophit
A flash tune is like being single on a Saturday. A piggyback is like being married.

Re: Piggyback vs Flash tune

Posted: Thu Oct 18, 2018 5:26 pm
by operamatt
retrophit wrote: Thu Oct 18, 2018 5:24 pm A flash tune is like being single on a Saturday. A piggyback is like being married.
but.... i like being married :/

Re: Piggyback vs Flash tune

Posted: Thu Oct 18, 2018 9:55 pm
by texanbrit
operamatt wrote: Thu Oct 18, 2018 5:18 pm Piggy Backs are better in every way and you know it. Only downside is the box tuner weighs your car down by alittle less than a pound. Who’s paying you?
I thought of another benefit, you can see it. Can't see a flash tune, so how do you really know?!?

Nobody pays me; apparently I'm really bad at this.

Re: Piggyback vs Flash tune

Posted: Thu Oct 18, 2018 9:59 pm
by NGEN
He’s responding to a post on the blue forum. You will see it easily as that particular vendor focuses heavily on marketing their piggyback. There are benefits to both for sure but don’t believe all the negativity that is being stated about flash tunes from that same vendor.

Re: Piggyback vs Flash tune

Posted: Thu Oct 18, 2018 10:52 pm
by MadFiat
texanbrit wrote: Thu Oct 18, 2018 9:55 pm
operamatt wrote: Thu Oct 18, 2018 5:18 pm Piggy Backs are better in every way and you know it. Only downside is the box tuner weighs your car down by alittle less than a pound. Who’s paying you?
I thought of another benefit, you can see it. Can't see a flash tune, so how do you really know?!?

Nobody pays me; apparently I'm really bad at this.
Believe me, the dealer knows. I have paid that price.

Re: Piggyback vs Flash tune

Posted: Fri Oct 19, 2018 8:42 am
by retrophit
I’ve said this before: BMW can detect piggybacks and I wouldn’t be surprised if FCA can too. Of course, the stakes are higher on expensive BMW engines.

Re: Piggyback vs Flash tune

Posted: Fri Oct 19, 2018 1:16 pm
by MadFiat
As far as detecting piggybacks, that depends. There are clues, but as far as I know on a Fiat ECU no definitive method of detecting, unless you leave physical evidence... such as for example a piece of velcro and a clean spot on the front of your fusebox.... Certain PCM error codes can suggest a piggyback may have been present, however, most of those can be fully erased. There are some permanent statistics you can't erase, such as over rev counters, etc.. but nothing regarding boost or MAP sensor readings.

Usually when a dealer tells you can can "Detect a piggyback" they're bluffing or guessing, or going off of physical evidence such as you buggered the plugs, left the mounting brackets, or have mods that normally go with a piggyback... For example, nobody's going to have a catless downpipe, aftermarket intercooler and expensive coils and intake... without also having sort of piggyback or tune.

Now, I can't speak for what a BMW PCM can do... but with Fiat? Bluffing or guessing. When I took my car in for PCM repair, I had no way around the fact that it had a dozen flashes showing on the counter... However they guessed at what that meant. The service advisor claimed I had an aftermarket MAP Sensor which was causing my issue... which as everyone here knows, you don't replace the MAP Sensor on a 500. He was guessing based on prior knowledge. On an SRT-4, you had to upgrade the MAP sensor if you were going over 18psi of boost, as it couldn't read spikes or values over 20psi. So he merely guessed that I had replaced my MAP sensor. He also knew I'd had an exhaust because the bolts on the downpipe had evidence of being removed/replaced recently... which that part was true. They have their ways.

But detecting the piggyback outright? Nahhh.. Not if you are careful.

Re: Piggyback vs Flash tune

Posted: Fri Oct 19, 2018 8:19 pm
by ice445
Piggybacks are trash purely because they can't alter stock fueling. Given how lean the engine already is (the engineers optimized it for fuel economy and emissions at part throttle), you're basically asking for things to break. At least with a good tune they add a bunch of fuel to make up for the shit they do. That way only horrible timing curves that don't account for sweltering IAT's are going to cause any damage.