trinydex

iTrader: (12)

all these people keep talking about this and this happened and the car pulled timing... how do you know it's happening. does it sound like something? feel like something?

i ask because i'm lucky enough to have a unocal 76 that sells race gas (100 octane) on my way to visiting my mom in pasadena (station is the one on the corner right when the 110 ends in pasadena, they have one 100 octane pump on the left side of the station). i went in yesterday and i put two gallons in a pretty much empty tank and then filled the rest up with premium. i kind of wanted to see if i could get like... 93 or 4 outta this type of mix and see what the east coast people run. it's gonna sound pretty cooky but i really think it made a difference, it seemed to pull harder and boost felt better at lower rpms. but i could just be imagining everything.

so is it possible that the crappy gas i get all the time (have to get all the time) is causing the car to always be pulling timing and the little race gas i did run made some difference?

SpecVSpeed

iTrader: (2)

I recently did the same thing.....I live up in Agoura Hills, and there is a 76 that sells the 100 octane race gas. Last weekend I filled up with 4 gallons of 100 and around 10 of the 91. I do think I can feel a difference, but I do think some of it is mental as well..... I feel like the car is smoother in the low end and pulls a little stronger as the boost tapers off in the top end of the rev range.
As far as what it would feel like if the ECU was pulling timing, I dont think I can answer your question. Most likely a slight loss of power on the top end but Im not sure. Im just trying to decide wether it is worth it to drop the extra bucks to make a 94 or 95 octane mix every time I fill up.

webguy330i

iTrader: (17)

Depends on how severe the timing 'pull' is.

If it's a lot, you will have basically NO ability to accelerate and you will feel a very strange and strong vibration throughout the car (in particular through the steering wheel) when you attempt to open the throttle. At steady throttle it will be much the same, just a lighter vibration. Generally this one is called by the ecu throwing a p030x code.

A little timing pull due to poor combustion or knock feels like a sudden loss of power but it does not persist like the above situation.

Buckkaaaa!!

iTrader: (2)

sounds like you're on california gas =D

lil'evil_evo

iTrader: (17)

If your car pulls timing a little here and there is it really bad for your car?

nebolic

iTrader: (1)

if the car is pulling timing you'll hear ticking noise, or rather a faint tick. I know because I have experienced it first hand. You'll feel a slight hesitation in power.

Nebo

bishiboy

iTrader: (10)

The EVO ECU is a great computer.
By pulling timing it is saving your engine from detonation, which will destroy it.
Most often, when timing is pulled, it is around 4000-6500 rpms, It feels like the power is building then there are some "stare-steps" in power, like dips.
The knock sensor is very sensitive, so even valave train noise can cause timing to be pulled.
Running 93 octane or above is the best insurance. Us 91 octane guys have to tune our cars for the decrease in octane, by adding more fuel, cutting boost and or decreasng timing advance. Some alternative methods help too, water injection, propane injection, anything to help cool charge air or increase octane.

lil'evil_evo

iTrader: (17)

^ That clears some stuff up thanks.

trinydex

iTrader: (12)

wow you can propane inject to lower engine temps? does that mean you can methan inject too? cuz that's top fuel right?

propellerhead

iTrader: (3)

Err, no. You're thinking of nitro-methane versus methane gas.

marksae

iTrader: (12)

Have you ever done a pull when your car is warming up and notice that it pulls harder than when doing the same pull after your car is fully warmed up? This is how it feels when your ECU is pulling your timing.

If the EVO ECU is similar to the DSM ECU, which it should be, you'll get an extra degree of timing advance if your air intake temps are below 84F, and another degree if your coolant temps are under 210F. This is probably what causes the power difference in the scenario I mentioned above.