Threw a check engine light no auto reset at 140 mph+

[NotGnu]

Ok, obviously I can't go to the dealer and have them troubleshoot throwing P300 misfire codes at +140 MPH.
And frankly, this go cart is a little scary at that speed.
I caught air.

 

[Sam4]

f^ck them. hit the fuel cut off.

 

[D1JL]

I always thought the car was restricted to a max of 138 mph.
Unless you have the PCM reset this may be normal.

 

[SteveS]

Usually P0300 is something you need to jump on and fix. But that's when you've been doing normal driving. Getting air at 140+ wouldn't be in the normal parameters for the Fiesta ST. Insufficient fuel delivery, spark plug problems, all kinds of things could have resulted in the misfires that caused the code.

As long as the engine didn't overrev or run lean and burn things, it has probably survived. But if it did overrev, there could have been valve damage, the timing belt could have jumped, a piston burned, etc.

 

[NotGnu]

It runs fine now. When it misfired, I let it coast down to where i could shift into third and hit the gas w/o a misfire.
I was a fool for taking it that fast. I was checking to see if there was a 120 mph governor like my Acura TL.
I bought this car from a dealer. 1 owner car. But it has so many after market parts that look professionally done. No doubt in my mind this car had at least a level 1 tune.
I'm cash poor now. I def. need to take this to a tuner shop and get it dyno'd.
It def. faster than stock.
I love this car. So under rated. It always brings a smile to my face.

 

[FiestaSTdude]

I always thought the car was restricted to a max of 138 mph.
Unless you have the PCM reset this may be normal.

I’ve always read that it’s 130mph, which I’ve confirmed by testing. Also to me it doesn’t feel like a limiter, it feels like the engine just can’t push the car any faster.

 

[Sam4]

I’ve always read that it’s 130mph, which I’ve confirmed by testing. Also to me it doesn’t feel like a limiter, it feels like the engine just can’t push the car any faster.

Yeah - but you're on a dirt road with steelies!!

 

[D1JL]

I’ve always read that it’s 130mph, which I’ve confirmed by testing.

My bad, 130mph is correct.
Most cars are limited by the tires that they are originally supplied with.

From infoweb:
In the past, before computers onboard, things like horsepower, gear ratio and all that made the difference. Now, what limits almost almost all vehicles is the computer. In addition cars may not exceed the sustained speed rating of the tire. Ex. S=112mph. H=130mph V=155mph then all the WZ and such with no limits so then drag and power becomes the factor.

 

[NotGnu]

I always thought the car was restricted to a max of 138 mph.
Unless you have the PCM reset this may be normal.

If that is true, then I bought this car w/ a tune. I'm pretty sure that it has a tune.

 

[NotGnu]

I’ve always read that it’s 130mph, which I’ve confirmed by testing. Also to me it doesn’t feel like a limiter, it feels like the engine just can’t push the car any faster.

Well, I can attest to the fact that the engine can.

 

[FiestaSTdude]

Well, I can attest to the fact that the engine can.

Are you tuned though? I’m thinking that with a tune, you could definitely go faster since there’s no limiter to hold you back.

 

[CreepyOldMan]

I can confirm that the car can easily hit 140mph+. I did it a couple weeks back and didn't even realize it until I looked down at the speedo and saw it was over 140mph. I have an S280 pushing over 280whp though.

 

[Mega ST]

150+ is easily achievable on E30 and stock turbo. Much more stable at that speed lowered and proper alignment. Being SWB and designed for quick turn, it's not ideal for high speeds.

 

[esp_martin]

150+ is easily achievable on E30 and stock turbo. Much more stable at that speed lowered and proper alignment. Being SWB and designed for quick turn, it's not ideal for high speeds.

yeah a quick side by side comparison of cars built for speed and cars built to be quick, you can tell where the FiST squarely lands.

to me, the FiST (i dare say) feels dangerous to drive at 130mph+ on publicly maintained roads without proper suspension and aero improvements. but that's just my opinion.

 

[CreepyOldMan]

yeah a quick side by side comparison of cars built for speed and cars built to be quick, you can tell where the FiST squarely lands.

to me, the FiST (i dare say) feels dangerous to drive at 130mph+ on publicly maintained roads without proper suspension and aero improvements. but that's just my opinion.

I agree, but since I've got it dialed in on coilovers, aligned, and outfitted with Falken Azenis RT660 it's much more confidence inspiring. Not sure how much my front splitter, side skirts, and rear splitter are contributing but I was definitely surprised by how stable it was at 140mph+. That's why I was unaware of just how fast I was going until I peeked the speedo.