I just got my first rx7 - a 91 convertible, non-turbo of course, and I purchased it not running in hopes of fixing it and learning in the meantime. Heres what I've found. The car turns over, but won't fire up. I haven't done a compression test, but when I pulled a plug from each cylinder, you definitely hear a rythmic and even pulse of air pressure. I know it's getting fuel as the plug had some on them, and you can smell it after trying to start. I also tried "deflooding" it to see if this is the problem. Plug wires are quite new looking, and I put in new plugs just to be safe. I tried to get the plugs to spark outside the combustion chamber, and apparently theres no spark on any of the plugs. I've check the coil packs and the crank angle sensor with a DMM, and the resistence measurements are in spec according to the Haynes manual. I've also just replaced the battery and battery terminals. Any suggestions on where to look next? Thanks!



Kirk

 

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I had a similar problem with an 86na. we r&r'd the engine with a motor that was running in the donor car, got the car to run for about 20 seconds after the replacement and then nothing. The symptoms were identical to yours. Long story short, it was a bad MAF, finally diagnosed through error codes on a snap op tester. If you can find a runninig car, swap the maf and see if that is it, it takes about 10 minutes. Hope that is it (but it probably won't be!!!)

 

Didn't know a bad MAF would cause the car not to spark at all. I'll check into that and see if that is maybe the problem. Other than that, I was hoping it wasn't the ECU as I believe the other post is suggesting to check. Thanks for the help so far.



Kirk

 

spark works something like this.



1. power: battery ->ignition switch -> main relay -> 12v @coils



2. signal: crank angle sensor = rpm signal -> ecu -> coils -> plug wires -> plugs

 

Just double checked the power scheme you above. No ignition = no power at coils. When I flipped to ignition, coils have 12.4V DC, so power is good. Crank angle sensor and coils are supposedly good through the haynes manual resistance test. Plugs are brand new. This leaves ECU and wires. Wires are NGK and look to be fairly new. What kind of resistance should they have through them for these motors?

 

I've also spent the day checking grounds between the battery and various ground points on the car. Everything is good at this point. The computer module on the drivers side is also getting 12.4V DC.

 

spark plugs?

 

Spark plugs are brand new standard NGK. I checked ground at the plugs between the negative battery terminal, and they are all grounding properly. I've also torn the passanger kick panel off today to get to the ECU. Smelled a little damp under there, which probably isn't good. Is there anything I can test to check the ECU with just a DMM? It's a N353 model.

 

I've stopped working on the car for today, but think I am getting spark now. I was cranking the motor for a while with the gas pedal floored to cut the fuel, and after I while I would get a slight chug from the motor like it wanted to start. Once or twice I got a pop from the muffler, and also a cloud of smoke. Now I'm wondering if its bad to the flooding again? Battery is almost dead though. I'll have to wait till tomorrow. Thanks for all the help so far.