Wav

What's the cause? and how common is it on a tuned turbo'd rotary>?

I have a 94 FD3S and is tuned with an apexi pfc on the std twins, running approx. 1bar boost with WI and cool intakes due to a v-mount set up. afr's never go above 11.5 on WOT.

The car now does not start, even though it was only used a few hours earlier, compression is low on a 65k mile engine, but it has never failed to start when cold, although it has only just started to have problems starting from hot, but only very occasionally. And the rotors give even pulses on each face, so it hasn't thrown a tip.

It has spark, it has fuel, it is NOT flooded and the crank angle sensors hae the correct resistance. So what's the problem? could the compression drop that much that it simply will not start?

It does try to start, i.e. it combusts a little, but if you open the throttle it stop and once the starter is switch off it'll die almost straight away.

What do you guys think? any suggestions will be appreciated

Thanks in advance,

Paul

Howard Coleman

iTrader: (6)

unfortunately your motor appears to exhibit all of the signs of very low compression. since you say all of the pops are equal it would probably be worn apex seals. you appear to have the proper pieces to lengthen engine life w a decent IC, a PFC and WI but maybe before the mods were in place the engine got a bit hot or the lube wasn't there etc. my guess is that your apex seals will need replacement along w a new set of side seals, gapped at .02 and the usual water and oil seals. your housings may or may not need replacement.

an easy way to get it running is to put a switch into the fuel circuit and turn it off and start cranking. it should start and then just switch the fuel on. once started it should run o k. you can generally do this for a few thousand miles before the motor gives up.

you might do a compression check...

good luck,
howard coleman

Wav

Thanks for your reply Howard.

Yeah I think the low compression is the cause, using a std piston comp tester it now reads 5bar on the rear rotor and just a tad less than 4 bar on the front rotor, obviously this is with the engine cold. Will try to tow start it this evening and will let you guys know how I get on.

Cheers,

Paul

Wav

I tried to TOW start the car today and it still will not go. The engine will combust and will stay at a constant 2k rpm in 2nd at 20mph tow speed, but it will not rev at all and once you put it in neutral the car will just die. If it does just have low compression it would still tow start right?

I now think it could be an electrical problem as the car did get very wet on the drive before it went dead.


Does anyone have any ideas?

Cheers,

Paul

Howard Coleman

iTrader: (6)

you should do a compression test... perhaps compression is not the problem and then you can get on as to whether it is elec or fuel.

howard coleman

Wav

Less than 4 bar average for the front rotor trio and bang on 5 bar average for the rear rotor trio. This was done with a std comp tester and I have no access to a mazda comp tester at this present time.

Could it really be that low on compression that it just doesn't want to start?, even with a tow!

Cheers,

Paul