pmturner

I have a 87 C4 with a 4+3 trans. and a HYpertech PROM put in 8 -10 yrs. and suddenly got a Code 33 diagnostic. It began with a sluggish start with low initial RPMs then would idle roughly at 1300 RPM. I started it today and it ran fine without a error code. I drove long enough to get up to normal operating temperatures, shut it off to get gas and then it wouldn't start, it would crank but not fire. I finally got it to start by giving it a lot of gas to get ignition. Gingerly drove it home. I'll replace the MAF relays and check the wiring to them. My MAF has been modified approx. 10 yrs ago with screens removed along with a airfoil deflector upstream. What do you think is causing this intermittent unreliable problem? Thanks, Paul T.

aklim

https://www.corvetteforum.com/forums...86-please.html

Not sure why you did it but I'd go back to stock instead of HyperJUNK.

Without analysis of the ECM, it might be hard to say if the hacks you put in were running on the ragged edge of adjustment and suddenly it does meet the ideal condition for a problem or whether there is failure. I suspect you will have to try it as though it were stock and see what happens.