New to 5.0's

[74delta]

Hey everyone new here and just picked up a mustang. I've always been a fire bird guy and wanted to try something new and picked up a 95 gt very m5. The car has some modifications like full shorty headers back, trick flow intake, CAI. I noticed some pinging and a rough idle when it would get to around 180 degrees so I looked into timing and it was set at 17 degrees base timing. After researching on this site I saw factory was 10 so I followed the procedure and set it at that and did a base idle reset. Low and behold the car idling seemed much happier but was noticeably less peppy. The previous owner told me he always ran 93 octane and figured that was just because the 17 degrees of base timing so after I set it at 10 I tried throwing 10 gallons of 87 in it. The car at 10 degrees of timing running 93 might be the slowest car I've ever driven. Runs/idle great but has the power of a 3 cylinder geo metro. Should I bump the timing up to say 14 and run premium and see if it pings or is there something im missing? Its crazy the power loss but again runs well.

 

[74delta]

Pics of the car

 

[RAU03MACH]

around 14 is the sweet spot

and welcome

 

[shovel]

Probably something else wrong with it if it's slow, these are classic cars at this point so they're not going to win any races against anybody's new M3 but they moved fine when new.

It's about impossible to reverse engineer random previous owners' modifications, might be a good idea to go through it piece by piece.

 

[74delta]

Probably something else wrong with it if it's slow, these are classic cars at this point so they're not going to win any races against anybody's new M3 but they moved fine when new.

It's about impossible to reverse engineer random previous owners' modifications, might be a good idea to go through it piece by piece.

Ill say the bump from 17 degrees to 10 degrees was a noticeable difference and then once I got a couple blocks from putting the 87 octane in it got worse. I just never would think it would be that dramatic. Im going to adjust the timing back up a bit and see how it reacts and throw some octane booster and top it off with 93 octane and see where that gets me.

 

[badass98svt]

As mentioned above, 14-15 is the sweet spot

 

[96blak54]

Try unplugging the mass air flow (MAF) sensor and then give the car a drive. If the engine runs better, focus your attention to the maf. Maybe cleaning?

Your car has alot of goodies and dont appear to be stock parts. Not a bad thing,but like Shovel stated above, youll be better off to adventure each component to ensure correct function.

 

[74delta]

Try unplugging the mass air flow (MAF) sensor and then give the car a drive. If the engine runs better, focus your attention to the maf. Maybe cleaning?

Your car has alot of goodies and dont appear to be stock parts. Not a bad thing,but like Shovel stated above, youll be better off to adventure each component to ensure correct function.

I didn't think of doing that. Will it just throw it in a stock map safe mode? The only thing I changed was timing and fuel type so didn't start looking into other things yet.

 

[96blak54]

Into a default mode, yes! Its a simple test. Should run a little fat on fuel, but like stated, if it runs alot better you will know where to focus attention too.

 

[74delta]

So im dumb and never noticed when I had the battery unhooked to do some work when I hooked it back up my positive had a crappy connection and I was losing voltage. Must have been misfiring under load due to the ignition not having enough power. Fixed my connections and it is back to the type of slow I noticed after moving to 10 degrees and nothing to do with the 87 octane fuel. Now to put as much timing back into I can without it pinging and running 93 this weekend.

 

[RAU03MACH]

These cars tend to like around 14 with some mods anything that is modded heads cam intakes that match may require a tune

 

[74delta]

My car only has a few bolt ons. Full exhaust including headers(02s still in), trick flow burner intake, CAI, TB, McLeod clutch, aluminum flywheel and driveshaft. I have a set of cobra injectors but left the stocks in for now.

 

[b1pig]

looking at what has been said so far....
Stock injectors on an engine with mods that makes it more efficient at moving air? The old 302s use older fuel metering. Unless someone altered it or installed an aftermarket ECU, the computer assumes the engine is completely stock. So timing, fueling and such are all based on that. Its not a self learning like a Holley system.

Lean is mean, but too mean will ping.


As said, fattening that mixture up would also be my first move.
I'm so lucky my car was dang near completely stock when I got it. Hope you get it figured out.

 

[74delta]

looking at what has been said so far....
Stock injectors on an engine with mods that makes it more efficient at moving air? The old 302s use older fuel metering. Unless someone altered it or installed an aftermarket ECU, the computer assumes the engine is completely stock. So timing, fueling and such are all based on that. Its not a self learning like a Holley system.

Lean is mean, but too mean will ping.


As said, fattening that mixture up would also be my first move.
I'm so lucky my car was dang near completely stock when I got it. Hope you get it figured out.

As far as I know it hasn't been tuned but I have a few more upgrades id like to do before I drop the money on bringing it to a dyno shop. I installed a set of 3.73s yesterday and im thinking I might throw a cam in it or save up for a set of aftermarket heads/cam kit. I dunno yet.

 

[shovel]

If you're going to spend any money at all on the car don't bash your head against the wall trying to work with the original ECU. Put a modern ECU in it with widebands and speed density, you'll thank me later.

 

[74delta]

Ya im debating that. I come from the world of ls swapped older gm cars and have run a few holley terminator setups.

 

[b1pig]

think of it like this.... the oem ecu in our cars are like tuning a Nintendo. Even if you could, you'd have a hard time finding both a person and a tool capable of the job.

Personally if it were my money, I'd get into a Holley setup. I'm honestly about to have this problem myself, but for the interim, I'll probably slip in larger injectors... but that will be a band-aid till I can afford a new ECU.