thirdtimesthecharm

So I installed new coils the other day in an attempt to help the surging at steady throttle cruising, rough idle, and excessive backfiring at low RPM engine breaking.

...if you haven't guessed yet i drive an SE.

Anyway, none of these symptoms were aided, but a new one appeared. Now, mostly when the engines under load, it feels like one rotor stops making power. If I back off the throttle to the threshold of engine breaking, the problem sometimes fixes itself.

I cant give the injector wiring harness a wiggle at idle to check for a short, because the condition doesn't exist at idle.

If you took the time to read all that, thanks. any ideas?

Edit: i have new plugs, wires, dist. cap, new fuel filter in hand.

Eriks85Rx7

maybe you have a sticking seal?

RotorMotorDriver

iTrader: (1)

Not to sound dismal, but thats exactly how my Dads -SE ran right before the motor died. He finally started it one day and it was idling to warm up and one rotor just stopped working and it started shaking like a paint mixer. Pulled the plugs, and one rotor housing just made a whirling sound, no compression poofs.

However, it could also be an igniter problem, or a pickup in the dizzy thats causing spark to stop, thus your loss of power from one rotor seemingly. In fact it would be total loss of either leading or trailing spark temporarily however, but I'm sure the loss of power would feel large either way.

~T.J.

thirdtimesthecharm

Yea, it a bad loss. I was between leading ignitor due to the loss's severity, or my injector wiring harness, which i gave a good wiggle before coming back from work today and the problem occured less frequently on my drive.

TPS adjustment was also called to my my attention by RXNos1200.

i got a road trip tomorrow so looks like i better get busy!

Edit: are the GM HEI igntiors a direct replacement or are modifications required. What year/model do they come off of?

thirdtimesthecharm

TPS adjusted... problem still occuring

RotorMotorDriver

iTrader: (1)

Does the problem occur if you rev the motor stationary? As in while in neutral?

Basically, what Im getting at is if there is a way to run a spark checking device on it where you can actually see it. So if it does it while stationary, have someone rev it up to the point of it doing it, and you be ready with a timing light or inline spark checker on one of the wires. Then just go through and see if they are all sparking when you have this problem. That would (to me anyway) separate ignition from fuel problem.

If it doesnt do it at an idle just revving, you might try putting the rear on jack stands with the front blocked and try driving it in gear in place to do the same thing. See if you can get it that way. Maybe its the motor torquing back and forth causing a short in your injector harness like you said.

~T.J.

EDIT: Then again, if it was the harness shorting from the motor torque, you would think at and idle if you wiggled it you could get SOMETHING from it...

thirdtimesthecharm

Right, my biggest headache is separating ignition problems from fuel.

I HAVE gotten the condition to happen while revving with the clutch in once, but that was once in... oh about 100 times by now. I just bought the GM igniter for fifteen bucks at autozone for my leading coil. If that doesn't solve the problem then its down to the injector wiring harness.

I will not give in to defeat!

PS: anyone know if I can use the GM as a direct replacement for the J-109 without Any additional wiring? Any writeups?

RotorMotorDriver

iTrader: (1)

Heres a write up. Good luck getting it going!

https://www.rx7club.com/showthread.php?t=654192


~T.J.