Okay, I've had my 93 LHD single turbo for a few years now. I was only able to start the car a couple times when I first got it and drove it once, but the engine was toast so I rebuilt the engine myself about a year ago and have been slowly restoring Aloy (what I named her) to get back on the road. Aloy came with a microtech lt9c and LS1 coils and I've been able to start her up multiple times and let idle for long periods while I've made adjustments in the microtech maps on my laptop. I've driven around the block once.

The issue I am having is I've never been able to smooth out the idle. It hiccups often. I can quickly rev to 2000-2500rpm and it sounds good, but if I very slowly rev it up it will struggle. Injectors have been cleaned and flow tested. I've messed with adding and taking away fuel and inputting maps from the forum from similar setups as mine.

So, I got my hands on a timing light because I haven't been able to find any vacuum leaks and am running out of ideas. Vacuum sits at 15 and will jump to 17 at times at 950-1000rpm idle. I hooked up the timing light to the front rotor on the trailing plug wire, pointed it at the trigger wheel (stock) and pulled the trigger hoping to see the little 20° notch in the wheel, but it wasn't there. It was on the other side. Like 180°. Okay... So I attached the light to the rear trailing plug wire and checked the timing again and there was the notch. Right where it should be. Isn't rotor 1 trailing supposed to be at 20° not rotor 2? Am I wrong? Are my trailing wires switched?

I'm starting to get confused. The microtech static timing is set to 0. Does anyone here have any thoughts?

 

You have to "lock timing" to set base timing with a light. I'm not sure how that process works with a Mircotech but hopefully that gets you on the right track.

 

Here's what the microtech manual has to say, but since there's no physical way of adjusting an FD's timing
I feel like I have something mixed up because why would rotor 1 timing be 180 degrees off. Unless my trigger wheel is from a different car maybe?

 

Has the ecu ever been tuned to the car?

Also, FYI, there is a Microtech sub-forum here:
https://www.rx7club.com/microtech-111/
Not very active but...

 

I'd imagine it was tuned to the car. Whether it was by a professional tuner or not I don't know. It probably was a looong time ago. I know the ECU is set up for an S6 FD because there's faint sharpie that says S6 on the back of it. All I've done is taken a map that I found from a member on here that seems to work well.

I appreciate the sub forum link! I've searched quite a bit of Microtech subs. I know it's a dying breed of ECU, but I feel like I could get the car going at least until I can upgrade to haltech or something. The timing mark being that far off just really got me scratching my head.

 

I assume that you have checked the trigger wheel is not too wobbly? Have you also checked the gap between the triggers and the crank angle sensors.

Are you running the stock coils? Have you checked all of them?

They may show spark, but the spark could be weak.

Also is your coil harness hooked up in the correct order.

The S6 coil harness had a bit of a complicated grounding circuit.

Some of the grounding wires could be damaged?

Has someone actually plugged a S8 version col harness into your set up?

Or worse plugged in a S8 coil set into the car with the coils mounted in a different order than the S6?:

 

It sounds to me like the trailing coils may be connected to the wrong ECU outputs, or the ECU trailing coil outputs might be configured wrong in software if that's possible. Have you tried the timing light on the leading coil(s)? Even if the leading timing is not exactly -20 BTDC, you should be able to see if it's firing near the factory timing mark or 180 degrees off. I'm not familiar with Microtech, but If it were my car, I might run without the trailing coils and check if the misfire clears up. I would try to avoid running the engine with the trailing coils firing at the wrong angle, I've heard that is very likely to hurt the engine.

 

Hey Redbul!
Hey scotty305! Trigger wheel seems to be straight and the gap I would say is a couple mm from the CAS I'm running LS1 coils. I've had to replace T1 coil a couple times from it burning up. I eventually got new LS1 pigtails/connections because the old ones were in bad shape and I re-grounded that part of the harness (which also has the ECU main ground wire) to go straight to battery negative. I think that helped with the coil going bad. Spark seems to be good. I was so certain I had the coil harness in the right order from going over it so many times, but I went out to the garage yesterday to take another look at it I'm pretty sure my trailing coils were mixed. Unplugged everything, triple checked everything, plugged everything back, triple checked before trying to crank it over.. and it did start up right away. I had to return the timing light, but I'll get it back and check timing again. I really hope I didn't mess anything up by running it with trailing firing in the wrong order.

I'll report back when I get that timing light!

 

The chart on the lower half of the pages gives the firing order. You might try to find the same chart in the USDM FSM (Section F?).

Something to keep in mind is that the leading plugs are set up to fire at the same time everytime. This is often not well understood or explained. In effect each "fuel charge" to each face, in turn, receives three sparks. Each charge gets two sparks from the leading plug. What happens when the trailing plugs are out of phase might be a bit difficult to get your mind around. At what position of the rotor face is the charge getting the spark from an out of phase trailing plug.

 

Here is the English version from the 1993 Service Highlights manual. It is interesting to note that the chart divides the ignition cycle into four phases (not three as you might assume). This is important to help understand what phase each face is in when spark is happening..

 

The top of those charts may be helpful. From the perspective of the ignition coils, the factory setup uses a 'wasted spark' dual-post coil which fires the leading spark plugs every 180 degrees which is twice as often as needed. If checking the factory leading spark plug wires with a timing light, both the front and rear leading spark plug wires will fire near the factory mark and also 180 degrees away from it. The leading spark is useful when it happens at TDC, which is the top-right diagram. The leading spark is less useful at 180 degrees before TDC, which is the top-left diagram. The leading spark is just igniting the already-burned mixture that is exiting the exhaust. Firing the trailing spark 180 degrees too early (when the other rotor's trailing spark should be firing) would be bad, since the combustion would begin far too early while the chamber is still getting smaller. If this happens at high load, you might see damaged seals or dented rotors.

I think the dual-post leading coil was for cost savings not performance, because it wasn't retained with the RX8 setup and most people claim they gain power or eliminate high-load misfires when replacing the single wasted-spark leading coil with individual coils that fire once per 360 degrees.

With a Microtech ECU, it's likely that the car has individual front and rear leading coils and not the factory wasted-spark dual-pole setup. Either way, it's important to understand how to check timing and also important to check with the light on each of the four spark plug wires. Since the factory trigger wheel has 12 teeth, you can add a second mark 6 teeth away from the factory mark for checking the rear coils. The second mark doesn't have to be perfect, but you can use it to double-check that the rear trailing coil is firing near that mark (not near the front mark) and also make sure the trailing coil is firing later than the leading coil. Try advancing or retarding the ignition timing in the ECU software to get a feel for which direction the timing light moves when the timing is advanced or retarded. The trailing coil should always be firing later (less advanced, more retarded) than the leading coil.