D&S 85 IROC

I've replace all the spark plug wires, spark plugs cap rotor coil and the engine still has a miss. Any body have any idea's?

jonarotz

iTrader: (26)

Next in line would be fuel injectors. Before I would drop the cash on a new set I would do a compression test on all cylinders to make sure there aren't any other issues.

tony_cogliandro

iTrader: (3)

that is like asking what makes a human being sick.
take it to a dyno and run it there.
if you have a smog station around you can run it on that equipment to see what is off and that might tell you where it is.
if the miss is standard, for the same cylinder you will get an idea where to look.
if it is not the same cylinder maybe you have a short in a wire that jumps to ground - but not with a standard timing.

jonarotz

iTrader: (26)

The really dyno isn't going to tell you more than you already know. You know it misses, it might tell you that you are lean or rich but that's about it. Start with the basics. Compression test, if everything check out good I would start looking at the injectors. How bad is the miss? Do you have any vacuum leaks? What is the fuel pressure? Look at the easy stuff first. I would hate to see you spend money on dyno tests and whatever else and still not know any more then you do already.

D&S 85 IROC

Well the miss comes and goes. I have a adjustable regulator and it set at 50lbs, new 19lb injectors. No vacuum leaks I plug up all the vac ports. I think the next thing I'm going to do is a leakage test on the cyl's.
The car does have a hypertech chip in th ecm.
85 iroc 305 58MM throttle body 87 MSD distrubtor (small cap)external coil

jonarotz

iTrader: (26)

Your chip might be off and causing some of your issues. Is it set up for the larger throttlebody and higher fuel pressure?

1TUF92Z

When does the miss occur? Idle? Cruise? Acceleration? WOT? Gotta give us more info.