NewRXr

I've been trying to restore full power to a '85 GSL-SE that I purchased recently. I've made some progress and restored smoothness and drivability but the main problem, lack of full power, still persists. At this point I'm starting to think the problem is a weak or erratic spark experienced under high loads.

The car starts easily, runs excellent in the low end and makes decent torque. At WOT the power starts to fade and I can hear a series of "puts" starting when the power goes away. If I use a stock leading coil the power fades at ~4500 but with a MSD Blaster coil it holds until ~5700 before the puts start and the power falls off. The coils are firing and the rotors, cap, and wires are in decent shape. Timing is stock. TPS is in adjustment. New plugs and fuel filter. I've just restored my secondary ports, they work now but only seem to have worsened the condition. The O2 sensor looks ratty and is an unknown. I haven't checked fuel pressure at WOT either.

I'm a professional mechanic with knowledge, skills and equipment. I have access to a hand held ignition scope that I can hook up and observe while driving the car. The thing is that while I am very knowledgeable on internal combustion I am still a rotary novice. I'm not sure the best method I should use to go about observing the ignition waveforms that would make the most sence.

Since the scope is designed around piston engines how should I set it up for the rotary? If I use it in distributor igintion mode, I will only be able to observe one coil and it's plugs at a time, leading or trailing. Then I could go either 2 or 6 cylinder to view all of the plug firings for that coil. If I use its DIS harness and tap directly onto each plug wire I could see all of them at once. But the question is how would I set up the scope to keep track of the wave forms? I'm thinking I should use the DIS harness and set it up as a four cylinder engine. Then I should see two leading waveforms and two trailing. But the scope looks for a positive and negative firing to number cylinders so I don't know what's going to happen.

Is there anyone with rotary scoping experience in the house that can shed some light here before I have to learn the hard way?

Vernon

black_sunshine

Scoping a rotary is just like any other engine out there Set it up as a 4-cyl DIS system. You'll only be able to see 3 waveforms; two for the trailing and one for the leading (leading fires batch). Honestly, I would just set it up in oscilliscope mode (if it has just a generic mode for analog/digital circuits) and probe the signals coming from the CAS (checks the hall-effect sensors). Then I'd probe the coils' input signals (checks the computer's interpretation of the CAS's signal). I'd also log a graph of that O2 sensor and see what it's telling the computer; I'd bet it's leaning-out up top.

From my experience, if it's loosing power up-top, that usually translates into lack of fuel; replace that fuel pump if the waveforms are correct.

Syonyk

New fuel filter - have you cleaned the low pressure in the tank as well? Just a thought.

-=Russ=-

NewRXr

I'm open to any suggestions Russ, what exactly do you mean? Is it a filter or a pump you're talking about.

Vernon

NewRXr

Black Sunshine, I didn't see your post when I first reconnected to this post. Thanks for your insight, this saved me a lot of time. I had not realized that the leading coil on my '85 13B was batch firing the plugs, I always assumed the two rotors were timed opposite each other. I'm not familiar with the term CAS yet but I have an oscillioscope also, I figured that if I found any ignition waveform problems I would be doing something like this next.

Vernon

rotarygod

iTrader: (1)

Vernon, I Pm'd you. Give me a call this week and let me look at it. I know your car better than you do!

Fred

NewRXr

He he, yeah I know Fred, I've just been to busy to know when I'll be looking at it or not so I do it in spurts. I read a lot of your posts though. Doing a search for "Igninition Scope" pulled up your 6-cycle 3.8 liter thesis. very interesting and helpful to me. Now I understand to eccentric shaft to rotor relationship and this engines power characteristics much better. The tip on tuning for displacement was eye opening.

I'll probably give you a call if I've tried the tips I get and still can't get it. I was kind of waiting to call you when I needed to turbocharge an RX-8. LOL I've got my GF thinking about trading in her Firehawk for one. Gotta have at least 350 HP for that weight or what's the point? I'm spoiled on 12 second street cars.

Vernon

hugues

maybe this can help you somewhat (for 2nd gen) ...

http://www.teamfc3s.org/info/articles/demystifying.html

hugues-

Wargasm

The article above is good, check it out...

I've done some ignition troubleshooting on my 1993 car, and if you monitor the signals going to the coils on an oscilloscope you should see equal height repeating blips for each trailing coil that look the same... then for the leading coil, you should see pretty much the same thing, but twice as fast.

Sorry but I don't know much about the 1st gens...

Trailing 1 or Trailing 2

......|......|......|......|......

Leading

...|...|...|...|...|...|...

rotarygod

iTrader: (1)

The GSL-SE does not have wasted spark so both patterns would look the same.

Syonyk

There's the high pressure fuel filter that most people think of when they change the filter. It's in the fuel line, between the fuel pump & the engine.

There's *also* a "pre-filter" in the gas tank, attached to the fuel pump. Pull up the carpet in the back, access the fuel pump through the obvious portal, and there *should* be a filter in the tank, attached to the intake side of the fuel pump. If that filter is clogged, it can cause problems as well.

If it is clogged, you might want to look at flushing out the gas tank to remove the random crap floating around, or you'll probably be cleaning that filter annoyingly often.

-=Russ=-

NewRXr

Thanks for the tip on the floorpan access, I would have actually dropped the tank first and then see it. I'm to used to domestic fuel pump swaps, I forget to think Asian on this car. LOL

Vernon

rotarygod

iTrader: (1)

Vernon, when you cleaned the aux port system so that it functions again, did you remove the intake manifold and the sleeves to clean them or did you just check to see they rotate properly? The reason I ask is because I am wondering if the sleeves are in upside down. When you install the sleeves in the engine, the opening should default facing down. This is how they are in the closed position. I know Dave had them out before but even he isn't 100% sure he installed them correctly. If you removed them and just went by how he had them installed, if he made a mistake, you copied it. I'd make sure these are installed correctly. It doesn't matter if they turn at this point. If they turn they are still only rotating to another closed position.

They generally open in the 3800-4000 rpm range. If they didn't open up, you would definitely start to bog down pretty quickly above this point. Now the problem is twofold. The first is that you lack the proper intake port timing and airflow to make power. The second part of the problem would be that the ecu is still sending enough fuel into the engine for properly working ports. Now you have an overly rich condition.

This sounds like the most likely candidate to me and would be the very first thing I would try. When my fuel filter was clogged, the car would sputter everywhere under full throttle regardless of rpm. It may not be a bad idea to change the filter anyways just to be safe.

NewRXr

Fred, I did take them completely out and clean everything up. I remember that the slots on the acutator shaft slots had a big end and a small end, and that each secondary valve's spline was made the same. Now that I think about it I didn't actually get a mirror and flashlight out and check inside the intake ports to see where they were, but only because the parts would only line up one way. I made sure to have them lined up with the slots correctly so that the intake would go on without jamming against them. Dave had them correct because when I cut the Tie-Wraps off one the idle went wacky and after both were cut the idle was smoother than it had ever been. Low end torque improved etc. Then once I got them fixed up the cutting out got a little worse, as if the extra flow only makes it miss sooner and worse, so I think it's correct. I'm definately sure enough that I'm not taking it apart again-LOL.

In this case one of the actuator assemblys wasn't sealing completely at its intake manifold flange, exhaust pressure was blowing out between the flanges. The port valves had been "wired" open for so long that they were stiff and required cleaning to free them up again. Then after careful resealing and assembly I could almost get them to open on free revs, I could help them open with my fingers with the engine revved up, a true load rev would open them no problem.

I'll have it on the scope soon, and also check fuel pressure under WOT. I brought the scope home but I spent this evening fixing a loose throttle stop dampener that cause my idle to sky-rocket upto 4500 by the time I made my 8 mile trip to the house yesterday. This had me severly P.O.ed because I thought it was something much worse after all the intake work I had just completed. It took me a few minutes to find that. Then I had to repair a loose front valance because I caught it on a parking space curb and backed up. Note to self: JACKA$$.

Vernon

NewRXr

****UPDATE****

I found cut off switches wired into each coil power circut and located near the front seat posts. The job was crappy, no solder, only crimp connects, and smaller gauge wires. At about 7 feet for each circut the voltage drop at the coils was inevitable. This crap has now been removed and new eyelets have been soldered onto the factory wires that now connect directly to the coils again. I think the "jumper" was installed by someone else who didn't know about the kill switches when one was accidently tripped and that coil went dead. With the jumper both coils were being fed from one poorly wired power supply circuit.

The ignition switch was always a little off, it would stop cranking when turned all the way. It had a "crank" sweet spot. Friday it started killing the igniton circuts when the key was released from crank to run. I had to hold it just off of crank to stay running. Luckily I had an 85 switch extra laying around for about a year now. I used it. This problem and potential cause of other woes is gone.

While the car runs better still, the problem is still there.

Now for the findings on the scope, I have a problem in the distributor. So far I've been checking the leading ignition. The primary coil firing is messed up. Instead of a clean swithing wave it is messy, and every tenth or so firing the primary wave is fuzzy as all get out. When one of these "fuzzy" primary switches takes place the motor skips. The primary voltage is very high, at about 450 Volts, but the messy waves are hanidicapping the secondary voltages. They actually drop under load, the opposite of what I'm used to. The secondary spark will peak at about 20 KV right off idle at WOT then drop to about 12.5 KV and as low as 9 KV on the miss. Obviously I'm blowing out my spark at high RPM loads with these messed up primary signals preventing a clean secondary spark.

I can get a reman distributor for $125 but I'm on a budget, so I have a question.

QUESTION:
Can I swap the distributor over from my good running '81 12A? I think the advance mechanisims would have to be swapped to retain the proper timing curves but other than that will they swap? I think they do but I'm not sure so I ask. I'm quite the whiz at recalibrating old Ford timing curves in those distributors so I know what to expect. I just don't know for certain that it will fit and function in the 13B.

Thanks for any help here.
Vernon.

NewRXr

NEVERMIND:

It was due to a MSD Blaster coil being used on the stock ignitor without a balast resistor. I put the scope on the trailing side just to see what was up. It was clean and working well, it has a stock coil because the MSD coil I had on there for a short while shorted from tower to ground. It was a junkyard find so I tossed it without grief.

I had just read in the "No more Ignitors" post that one of the guys was told by MSD techs that we shouldn't run Blaster coils without a balast resistor because their lower resistance might draw to much current for the stock ignitors and cause problems with them. So I pulled the original Diamond coil out and put it in place of the MSD Blaster on the Leading igntion. This made the ignitor fire clean and steady. The secondary spark is stronger and stable at high RPMs.

Well now the car runs strong upto 6000 RPM, not as strong as I would like though. At 6000 the popping comes back. Now that I know the ignition is working properly I'm going to turn my attention back to the fuel. I'm going to flush the injectors tommorrow. This car will be fast or I'll blow it the HELL UP! LOL