My KA has developed an annoying habbit of stumbling after it starts. Once its fired it will stumble its way down to around 500rpm then ever so slowly work its way back to either 700 or 1000rpm depending on if I have AC on or not @ the time.

My thoughts are it could either be my Coolant Temp sensor...or my TPS. What do you think??

Either way...it does seem to work fine after it finds proper idle. It doesnt bog or stumble once i'm under way. There are times where it seems numb performance wise, but i write that off to it being a KA...

Thanks for you input fellas, in advance.

-Royce

 

That orange wire didn't fix it?
I was really hoping it would.

Does it stumble for a few seconds or we talking minutes?
Does it do it every single time you start the car, without fail?
Does the amount of time in between shut off and start up seem to make a difference?
Do you have to touch the throttle to get it to behave, or does it eventually sort itself out?
Does hitting the gas make a difference, does it immediately stop the stumble or does it go back to stumbling?

If it only does it after it has sat for several hours. (IE long enough too cool off almost completely) then that supports the coolant temp being bad.

If touching the throttle solves the problem, then that supports the TPS being the problem. Even if it isn't the core problem, doesn't hurt to adjust it. they can read differently after so much time/use/vibration/heat. Some run better closer to .50, others run better closer to .40. others won't run at anything other than .45.

If it only lasts for a few seconds, that would make me think that it is a fueling problem. Maybe the pump isn't pumping quite enough to build up the pressure fast enough. Maybe the FPR is stuck open. Try pulling the vacuum off of the FPR to see if that makes a difference.
does the fuel pump prime for more than just a couple of seconds when you hit the key? If it is a quick little bbrrrrbp. and that's it, then the relay could be the problem and isn't letting the pump run long enough when it cycles on and off.

typically, electrical things get worse when they get hot, which makes me think that it doesn't have anything to do with the coil, wires, plugs, CAS/dizzy.

 

Well...

Empire, im just getting a chance to split the column open today. Looking for that orange wire...but dont see it right off hand. I'm going to google up the wiring of the ignition to see if i can track down the wire that would signal the injectors to do their "all open burst" @ start. I think that would make it start hard...not so much with the stumbling issue. I will take care of wiring that up before I introduce any other variables.

i'll keep ya posted.

Thanks,

-Royce

 

I could have sworn it was orange... maybe I've got my wires mixed up...
it is an extra wire on the ignition switch.
Its been a while since I've been in there, but if i can remember it right, there are two wires you need to actually start the car, and two you need for it to run. there is an extra wire that is on the "start" circuit. I thought it was orange. but I could be totally wrong about the colors.
From what I remember, if you look at the back of the ignition, it should be pretty obvious what wires are part of what key positions. But I could be getting other cars mixed up

don't ask why I've seen the back of enough ignition switches to get them confused.
even when I explain it, it still doesn't sound good. lol.

 

I took a chance in getting a new ignition switch. Advance had one for $30 and for giggles I grabbed a Temp collant sensor too. Starting much better and no stumbling. There is a reason why it was put together that way I guess. I'll keep ya posted if ant thing stupid developes again...thanks!