Has your car ever forgotten its tune?

[Ted B]

ok now i got this info from ATI (procharger) after my trans took a poo, i upgraded....took about a month to get the trans clutch/flywheely bars so it sat for about a month with no batt connected. Now i have all kinds of hesitation like not getting enough fuel or misfires out the wazoo, and yes my plugs are a little old looking, and yes one of them has a small piece of ceramic missing (hopeing to god it happened outside of the engine as i re-gapped them 6 months ago, and yes i have a brand new set of TR-6s arriving tomorrow. All that being said is it possible that my car forgot its tune and reverted to the stock mach 1 tune? Have any of you heard of a car losing its tune ECU modules were pretty simple back in 03 programming was mostly stored on EPROMS that once written usually would hold the info for years unless over written or the eprom was zapped.

Just wanted to see if anyone had heard of this before as I have not.

 

[01yellercobra]

Nope. I'm pretty sure it can't happen. Otherwise stock cars would need to be reflashed all the time. It's probably just a coincidence on the timing. A cracked plug can cause all kinds of issues.

 

[Ted B]

@slo984now you were half right possibly maybe kinda. Brand new motorcraft AIC and set of TR-6s gapped to .028" and she runs like new, sorta, but now runs like a stock mach 1...maybe there is some merit in a tune gone missing.

 

[TK1299]

My 93 recently developed a low idle and driveability sucks a little. Also it stalls sometimes now when the RPM’s drop. I keep thinking I need a retune, so yes I believe for reasons unknown to me I think it forgot the tune.

 

[01yellercobra]

I've been tuning since 2007ish. I've never had a car "forget" it's tune. If the car isn't running right you need to make sure all the mechanics are good. If you're running a chip make sure its seated fully. I'm assuming you're not running the stock MAF and injectors. If it reverted back to a stock tune with aftermarket MAF and injectors it wouldn't even run like a stock Mach.

 

[01yellercobra]

My 93 recently developed a low idle and driveability sucks a little. Also it stalls sometimes now when the RPM’s drop. I keep thinking I need a retune, so yes I believe for reasons unknown to me I think it forgot the tune.

I'd bet something is on its way out or wore out. Probably something simple too.

 

[TK1299]

I'd bet something is on its way out or wore out. Probably something simple too.

You’re probably correct. That’s the joy of owning a foxbody

 

[Ted B]

Im going to be digging back into my vacuum system tonite to see if i can find a leak...the new plugs looks like they had a white deposits on it which means the car is running lean, so i think i'll start at the damn fuel pressure rail sensor i've been told they are garbage and tend to leak.

 

[04sleeper]

Think of "Flash Tunes" as "Flash Drives" Do you loose the information if you unplug it? No. It's flash memory.

Unless something mechanical changes, the car will run the same. Check elsewhere and I bet you will find your issue.

 

[decipha]

If for any reason the tune does get corrupted some kind of way be it a failed flash rom or faulty ecu its very easy to determine.

Simply turn the key on and u will hear the fuel pump prime and shut off. On return style fuel systems if the ecu isnt functioning correctly the pump still stay running and will not shut off. On a Returnless fuel system if the ecu is not functioning correctly the pump will not prime at all on key on.

 

[Ted B]

@decipha thanks man that's a good piece of info i didn't know, I'm an electrical engineer and I know the ECU stores its base tune on a NON VOLATILE single burn EPROM, thus unless the chip is damaged it can never return to stock. the tune, is actually flashed to a 2nd EPROM that is used for OEM upgrades to firmware, and or aftermarket tunes. If the ECU goes to look for the ECU firmware and cannot find it on the first secondary chip it will default to the primary chip. SO its possible, but EPROMS are solid state, old school and i've worked with them for years and unless you get a bad batch from china they are usually good forever.

But i have a returnless system on my 4v as i have the pressure regulator unit, I actually prime the fuel pump 2 times before starting, but i am indeed hearing the fuel pump prime and shut off for each turn of the key to acc so that's a good sign.

Rando question tho i adjusted the butterfly screw on my tb when i had the bad AIC installed and unplugged to allow the car to idle properly when cold, if its shut it has no way of getting air thus stalls right away. Now that I have a new AIC should I set it back to full close? I know the fuel rail regulator runs off of vacuum and at idle should be around 5psia (9 psi in vacuum), when WOT it should be ZERO on a NA car, and with a boosted car + whatever boost you are running increasing the fuel pressure 1psi per 1lb of boost. The secondary reason i opened the butterfly a bit was to stop having a pressure build up on the inlet side of the TB because that causes a slight pressure agest the plate and gives you the feeling of a jump in throttle when you crack the throttle to go.

 

[Ted B]

@04sleeper you are probably right even though i think I have good vacuum i really have a hard time beliving that when the car ran like crap with bad plugs and a bad AIC now that those are new it runs better with no or less boost. It really feels like top end is dead so im thinking its either not telling the pump to supply more fuel, because of vacuum, or some other stupid thing. I may bust out my arduino and just log the analog voltage during a run to see what kind of numbers im getting I will have to do some digging on the voltage range but should be a 0-5V signal then its simple math to find out the duty cycle.

 

[decipha]

fair warning, based on what you've stated I assumed you have an 03 mach1 with a blower

if thats the case and you had leaned fouled plugs chances are youve hurt the engine. This is assuming is a stock high compression hyper/powdered mach1/marauder engine.

those are extremely fragile engines and it doesn't take much at all to hurt them when they are boosted.

Most likely from what your describing your fuel pump is weak. If its a stock engine it would be best to rebuild it and forge it now before something lets loose and does more costly damage.

 

[Ted B]

@decipha I will give you a NOD on that...however im going to have to shelve the car for that. I believe and when i get a new fuel rail pressure regulator i will see if i'm correct I believe the pump is ok, however the sensor is jacked and thus not sending signal to send fuel at the right time. If that's not the case i'm bringing it back to the dealer i bought it from they are going to eat a diagnostic cost and see if they can find a problem. NO promises on helping me pay for it, but at least they can do a better job with the right tools to inspect, test and look for faulty parts, or damaged internals via a borescope.

 

[MG0h3]

My 93 recently developed a low idle and driveability sucks a little. Also it stalls sometimes now when the RPM’s drop. I keep thinking I need a retune, so yes I believe for reasons unknown to me I think it forgot the tune.

Did you have a dead battery recently?

The ecms in that era were "dumb"

Anytime the batt is dead or unhooked you need to do an idle relearn. At operating temp start adding loads in ; lights, fan, stereo, Ac,...eventually having every accessory possible on. Let the car idle for 1 min or so between each addition acc.

Throttle body cleaning can help as well.

Sent from my SM-G950U using the svtperformance.com mobile app

 

[Ted B]

@MG0h3 Yes you are 100% correct, I do that everytime I have the battery unplugged for more than 10 mins. However The problem is deeper than that for sure, the ECU relearning is not going to stop my car from making boost or my fuel rails not deliver fuel...I think my issue is fuel related, and IDK if its a bad sensor or vacuum leak, or god forbid a bad cyl...ill know more this coming friday hopefully.

 

[MG0h3]

@MG0h3 Yes you are 100% correct, I do that everytime I have the battery unplugged for more than 10 mins. However The problem is deeper than that for sure, the ECU relearning is not going to stop my car from making boost or my fuel rails not deliver fuel...I think my issue is fuel related, and IDK if its a bad sensor or vacuum leak, or god forbid a bad cyl...ill know more this coming friday hopefully.

Copy that. Was throwing that out there for TK

Sent from my SM-G950U using the svtperformance.com mobile app

 

[TK1299]

Did you have a dead battery recently?

The ecms in that era were "dumb"

Anytime the batt is dead or unhooked you need to do an idle relearn. At operating temp start adding loads in ; lights, fan, stereo, Ac,...eventually having every accessory possible on. Let the car idle for 1 min or so between each addition acc.

Throttle body cleaning can help as well.

Sent from my SM-G950U using the svtperformance.com mobile app

I did recently change the battery. I’ll try what you suggested, thanks broseph

 

[cj428mach]

Did you have a dead battery recently?

The ecms in that era were "dumb"

Anytime the batt is dead or unhooked you need to do an idle relearn. At operating temp start adding loads in ; lights, fan, stereo, Ac,...eventually having every accessory possible on. Let the car idle for 1 min or so between each addition acc.

Throttle body cleaning can help as well.

Sent from my SM-G950U using the svtperformance.com mobile app

decipha would be able to give more input than anyone but the old fox ecms have capacitors and other electronics that more than likely are failing at this age. Its getting tough to find fox ecms in good shape at all anymore. Thats why i ditched my A9L for a megasquirt plug and play.

 

[gt347mustang]

It's funny when a car starts acting up first thing people blame is the tune.