There are two fuel cutoffs on the stock 87 GM bin for my car.

One fuel cutoff is related to engine speed. Fuel cutoff is set at 10031rpm.

The other one is fuel cutoff at vehicle speed of 255mph.

Do these fuel cutoffs actual function in the ECM????

If I want to safeguard my engine, if I set fuel cutoff at 6,200rpm, will this actually happen???

Has anyone actually tried this????

TIA
Doc

 

Yess they both work. I played with them both and in both MPH and RPM the engine stopped receiving fuel at the values I set.

 

Thanks for the response.

Well, if they work, then I think it is a good idea to set these fuel cutoff values at some reasonable value to safe guard our engines.

I think that for me with my tranny shifting at 5300rpm, that 6000rpm would be good. And 150mph for top speed.

Why did GM elect to not use these functions in '87?
They are used in my '99 SS.

Doc

 

That's 12 years doc, lots of things changed. You could say..."why did GM elect to install a smaller cam in 86 compared to 85?" Doesn't make sence does it! Besides, the newer fuel cut off I think isn't as harsh (stop all fuel) on the engine. I could be wrong though. Maybe it is the same, then you gotta ask, why did GM install the highway mode yet never use it? Lots of why did questions, that's the fun part of eprom burning. Find the special options and enable, play, tweak em till your car runs the way you like it.
Does anybody know if the 7747 or 8746 has a rev limiter? I never spent the time reading each line of the 210 page hack document!