Possible ignition/timing issue. Dies when idles down when warmed up.

[BajaBugBoy]

Hey guys I've got a 91 Festy, all stock with the 1.3L. I apologize if this is posted somewhere else and I didn't find the info I needed; maybe someone else with better forum navigating skills could easily find something about this.

So I recently tried installing a tachometer by running the green (signal) wire soldered inline with the negative wire off the ignition coil (yellow/green wire I think?), black/ground to the post that holds the wiper arm motor to the firewall (it grounds the wiper motor itself so I assumed it should be a fine ground for this) and I was trying to find a good switched power source under the hood. I found a wire that was hanging loose in the engine bay with a female spade bit already attached, and it had switched power. Perfect! So I thought. I plugged it all in, and the engine seemed to drop its idle a few hundred RPM when I plugged in the power source, and the previously tested good tach was flashing all digits very faintly. It took me a minute or two to realize that the power source I had chosen was probably a timing freeze circuit that you ground out when setting the timing so it doesn't move around. Now, the tach doesn't work at all, and when it's hot and/or the engine warms up, it stalls when I let off the throttle from an RPM somewhere over probably 1K. The tach is still hooked to ground and signal, but not power. Sorry for the extensive backstory, but now my question is;

Could I have damaged some kind of ignition circuit by plugging the tach into that plug? Would that be causing the engine stall when throttle letoff? Or is it more likely that I just have an issue with the solder point in the negative wire of the coil, like too much resistance?

Any advice would be appreciated!

[bravekozak]

What color was the loose wire that was hanging in the engine bay?
The tach reads the pulses from the negative terminal of the ignition coil (yellow/green stripe).

[BajaBugBoy]

The wire hanging loose was yellow/green. It had a brownish plastic plug type female spade connector on the end that looked factory. Yeah, I know it reads from the negative side of the coil. I spliced the green signal wire from the tach to the yellow/green wire from the ignition coil. I'm pretty sure that's the negative side of the ignition coil, because when I test ran the tach spliced into that coil wire, and the red/black wires to the respective terminals of the battery, it worked fine, and the engine ran normal.

[FestYboy]

I hope you weren't previously aware of the filtered tach signal wire that is already in the cluster harness, and decided to do the above instead... Also, did you take the time to verify that the switched power source you used was fused properly for the new load?

[BajaBugBoy]

I was not aware of said signal wire. Where does that wire let out? Maybe I'll just re-run my wires and go that route. And no I didn't, I didn't really know what that power source was except that it was switched like I needed. In hindsight yes this was a very botched job as I was short on time and it didn't go as I'd anticipated. I'm less worried about getting the tach hooked up and more about making sure I can figure out why it's stalling out. I can go through and check/set timing and start troubleshooting a list of different things that I could think of but I'm looking for someone who might know if what I've done has altered/damaged something in particular that they can point me in the direction of.

[FestYboy]

I'll verify, but I suspect that you pulled power from a 12v signal wire from the ECU... If that's the case, you're looking at a new ECU. Again, I need to verify.

[BajaBugBoy]

Ahahawesome. Please do verify. If it's something I need to go into the ECU and repair I'm capable of doing that as well, I would just need to know what I'm looking for. I'm skeptical though because it seems to run just fine still, it just dies out when idling down after disengaging clutch. Also, if you could link whatever resource you're looking into that might be helpful as well.

Thanks FestY

[FestYboy]

I'll be using a factory EVTM to verify. Do this in the meantime: when the engine is cold, allow the engine rpms to stabilize, then pull the IAC plug to freeze the stepper motor in an open position. This may help your stalling at idle when warm issue for the time being.

[BajaBugBoy]

I'm in no real need to get by, I've got two other rides to get me by. :car: :car: If I end up needing it though I'll definitely go for that. Thanks for the info.

[Rick the Quick]

Hey Festyboy, if I read you correctly my '91 L has a tach signal wire in the cluster harness? Do you happen to know the color? Also can anyone recommend a decent aftermarket tach. I don't want to spend $400 but I don't want to buy a piece of junk either. I imagine they are almost all made in China. Since putting the B6ME in the daily driver / back up car I have developed a serious heavy foot. I am curious of my revs when running it hard. Does anyone know the safe rpm limit on a single cam, 16 valve, Kia built B6ME? What do you think Ryal?
Sorry if I hijacked the thread.

[FestYboy]

I'll have to get back to you on the wire color, but as for the b6-me, I would imagine 74-7600 rpm would be safe if the fuel system can keep up. Otherwise, keep it under 7k.

[Rick the Quick]

Wow that's a lot of rpms. I don't need to be in the 7K+ neighborhood fending off a land barge on the street. Perhaps the fuel system is the limiter. I am running the stock fuel pump with B3 injectors and the performance is very impressive. It's been so much fun pushing 'er hard that the tach seems like a usable accessory so I am glad I came across this thread. Thank you for your reply FestYboy. I will take you up on the color of the tach feed wire on my '91L if you or anyone happens to know. Also if anyone can recommend a decent aftermarket tach that doesn't cost an arm and a leg.

[WmWatt]

There are Festiva instrument panels with the tachometer included. Maybe you could post a query in the buy and sell forum?

[Rick the Quick]

Thanks WmWatt, don't ask me why I didn't think of that. I had one in my now deceased '88. When I went to the towing yard to get the stereo system out I should have grabbed the cluster. That was before I knew about this forum. At the time I was banged up pretty bad and didn't imagine I would be driving a Festiva again. Now I got a '93 with a B6T going in it and a '91 with a B6ME. I guess the collision in the '88 caused me brain damage. Ha ha ha.

[BajaBugBoy]

So Festy, have you found anything on what I might have done with that power source under the hood? Sorry to sound needy, I know I said that I'm in no rush, I just don't want this thread to get turned around into a thread soley about tachometers. Thanks again.