I've spent the last couple of months trying to bring an 88 Turbo II back to life. After having the gas tank cleaned, new fuel pump, spark plugs, and fixing all the vacuum leaks I could find, it fired up first try. It was on jack stands while I changed brake and clutch fluid, and I would start it and let it run for 15-20 minutes each time.

The other day, I put the car back on the ground, aired up the tires and tried to start it. Suddenly it's getting no spark from either coil. I'm assuming that both coils didn't coincidentally go bad at the exact same time, but I am an RX-7 n00b and was hoping for some help.

I've tried searching around for a wiring diagram and a way to check the coils but haven't had much luck. Any help is appreciated.

 

W/key to on measure for battery voltage on the Black/Yellow wire at either coil. It should be 12 volts.

 

Both coils are getting the full 12+ volts.

 

What made you realize the coils weren't firing?

 

One day it decided not to start, so I pulled the plugs and cranked it over with the plugs grounded on the engine pull tabs. None of the 4 plugs would produce a spark.

 

If you have any of the emission solenoids they each have a two wire plug to them where one wire is Black/White. W/key to on check for battery voltage on this wire. This wire also powers up the ECU, which an unpowered ECU could be one of the many possible causes for your problem.

 

Where are the solenoids located? That will be the next thing I check.

 

There will be four or five of them each with a tape colored spot on them on the driver side of the engine. The solenoids are part of what is called the "rat's nest" due to the overabundance of hoses (metal and rubber).

 

OK, so I found the solenoids, but I can't reach the plugs to unplug one and test it. There is a green 3-prong plug on the solenoid harness that doesn't go to anything, so I checked voltage there and only got ~.2 volts.

I located the ECU in the FSM, but I can't figure out how to get it out, or how to test it once it's out. Sorry for all the n00b questions.

 

On an S4 the emission solenoid plugs would be on the driver side of the engine and they are black w/a round colored spot (spot is made of adhesive tape) on them such as blue,yellow,orange etc. They each have two wires to them and small vacuum hoses connected to them where the back of the plug should more than readily accessible. Just stick the red meter lead into the back of the plug where the B/W wire is and the black meter lead on a suitable ground such as the alternator casing or negative battery terminal and w/key to on it should measure 12 volts.

 

I found the plugs with no problem, but I don't have enough room to get a meter lead down there. I'll try again though.

After I check the solenoids, what will the results tell me? If there is no power, is the ECU bad? If there is power, the coils could be bad?

 

Not all of the solenoids face the same direction at least they don't on mine so some of the electrical plugs face outward (these are the ones which are accessible) and some face inward towards the engine. All you need to do is check one of the B/W wires.

If there is by chance no power then the ECU will not be powered up. Pin 3I (smallest ECU plug top row far left and the wire is B/W) would read 12 volts w/key to on. You back probe the wire in the plug so the ECU stays put. When measuring for voltage at the ECU you use the ECU mounting bolts (as there are two to choose from in the front of the ECU) for the meter ground source.

 

check the engine fuse in the cabin at your left foot kick panel.

 

He mentioned that both coils were receiving power via the B/Y wire so that means the Main relay is working which means that the Engine fuse is good.

 

Thank you for all the help. I'll try to check the solenoids tomorrow when it warms back up a little.

How do you get to the ecu? It looks like you pull up the carpet and it should be right there, does that sound about right?

 

Ask yourself this common question: Does my tach needle make small bounces when I crank the engine over?

If the tach needle makes tiny movements when cranking the engine over........at least the trail coil assy's are firing the sparkplug for trail.

 

There is a silver metal protective plate which covers the ECU. The plate has four nuts that fasten it into place, two in front and two towards the upper back.

 

Neither coil is getting spark, that was the first thing I checked.

 

Welll, there's checking for spark and ....there's checking for spark. I'd suggest with all plugs on where they belong........turn the engine over with the starter and watch the tach needle.

IF the tach needle did not bump........then pull the small, white in color, two wire plug off the Lead coil assy. Check for batt voltage on the black/yellow..which I think you've already proven is there. Then put your meter on the OTHER wire in the two wire plug and with key ON, slowly turn the engine over by hand. The meter should show 0 vdc as you turn the engine over by hand and then show approx 5vdc as the engine is turned over by hand and it should keep repeating this cycle as you slowly turn the engine over by hand.

IF the voltage does as described above..........then the ECU is sending out the Trigger signal to the coil assy. If you don't see the zero to five vdc EVER then something is causing the ECU to not do it's job of sending out a trigger signal. That can be addressed by somebody later.

 

I guess I'll try this after I check voltage at the emission solenoids. If it's warm enough tomorrow I'll check everything and post up the results.

 

http://qik.com/video/32006682

If you look at that video and stare at the tach needle as he carnks the engine over with the starter, you'll see the movement of the tach needle which in turn indicates the trail sparkplugs firing.

Just FYI and nothing more or less. Clarifying what I meant by tach needle bumps when starting.

 

Didn't have a lot of free time today, so all I got to do was turn it over and look for the tach jumps. Tach needle didn't move at all, so I'm assuming it's an ecu problem. I'll try to check the solenoid voltage tomorrow.

 

I know it's been awhile but I finally had time to mess with it tonight. I got the ecu out but I couldn't find a wiring diagram so I didn't know what wires to check. Does anyone have a link to a turbo II wiring diagram?

 

http://foxed.ca/foxed/index.php?page...nual#secondgen

 

I looked through the diagrams in the link posted. It gave me connector views and wire colors, but I couldn't find where it said what wire is what. Does anyone know which wire is the power to the ecu, and which one is the spark signal output? I'll just use the body as the ground.