While doing some drag racing and auto-x yesterday (119.5mph 1/4mile terminal with a little T04E 57trim) the car lost power and then refused to start and I cant figure out what hell is wrong...

AFRs and oil/water temps and pressures were on the money, but a slight miss appeared so headed to the pits.
First thing I noticed was my pre-comp WI jet had came out, giving the engine zero water- not good!
Removed and swapped over the plugs (the ones I removed looked ok btw) and it wouldnt start without a push start, and at high revs it made a horrendous metal on metal screeching sound from somewhere so we shut it off.
Bit later on as we needed to get it home we push started it again (incredibly hard to even push start) and I drove it around the paddock- It was missing heavily but was still drivable, it boosted, no smoke, just about idled, but it was very wrong and could hear a knocking noise at idle too.
After realising it was drivable and presuming the damage was done I drove it 100 miles home in a mix of rush hour city traffic and 70mph open roads, and realised above 5000rpm the miss cleared up and it seemingly had full power and full 1.5bar boost all the way to 8000rpm?!
Got home, and it was still knocking like mad at idle and missing like hell at low revs, but got there fine.

Oil and water temps were normal, oil pressure is normal, no exhaust smoke, no oil or water has been used, nothing.

Missing without any bad temps, smokes, or pressures, or fluid use sounds electronic.
But the knocking and earlier screeching are clearly mechanical.
The fact it started at the same time as the pre-comp jet falling out sounds mechanical.
The lack of starting ability and missfire could be mechanical or electronic.
The fact it took an 8000rpm and 1.5bar boost beating and didnt get any worse and didnt seem down on power at high revs dont sound like a mechanical problem either.
But that doesnt explain the noises.

Im confused as hell, has anyone got any idea?!

 

have u pulled the plugs and spun the engine over to see what the compression sounds like? u may have lost/broke an apex seal. either way sounds like it's rebuild time.

 

Thats what I'll do once I get in from work Michael, and I agree, im expecting the worst.

But the way most things are acting normally and at 5000rpm+ power seems (on the road at least, so purely seat of the pants) no slower than before, seems odd.

I'll report back once I have a listen!

 

Right, did the noise test, an both sound the same, and regular, so unless both are down to one tip, which I doubt considering I was driving it still, or my ears are terrible, then it didnt help me.

Plug colours were interesting though...?!

Rear rotor, black and rich and normal really...


Front rotor, orange, almost, well, rusty...


These plugs had done 100 miles, and were installed new AFTER the problem first started.

Did seem, under 5k anyhow, like it was only running on 1 or 1 and a bit rotors. Or maybe both, but not well.

Will a compression tester with a normal piston engine comp tester tell me anything? As I got one of them...

 

I had something similar happen to a fb I used to own. I hear a terrible high pitched scratching type noise. I was about 5 miles from home and it was 2am. It drove home okay but had no power when I would step on the gas pedal. After pulling the engine apart. My omp had failed and the rear rotor dug itself into the rear plate. Check compression it sure does sound like it might be rebuild time. Good Luck bro.

 

Yeah, the noise, which stopped and didnt come back, sure as **** sounded like a rotor spinning round and round while scraping on metal!

Will I be able to get any kind of worthwhile result with a normal piston compression tester? As I understand rotary ones are different?

 

Did a compression test using a normal piston tester.

Cold engine of course as it wont start.

Both rotors got approx 5bar.

With the button pressed held in to watch the gauge bump up and down like they say works with rotors, well, didnt tell me much as gauge moved so fast, but it bouced up and down to about 2-3bar over and over on both rotors, but so fast I couldnt be sure.

Does that tell anyone anything?

 

yeah that's too low. had to find conversions for bar to psi.

http://www.sensorsone.co.uk/pressure...h2o-fth2o.html

 

i wouldnt say low yet... pull the schreader valve out of the comp tester then check the bounces and are they all even pulses or 2 high 1 low or something like that... that valve in there will give you lower numbers do it again with the schreader out and not pushing the pressure release.

z

 

Did it without the valve, inconclusive, and the woosh test sounded fine too.
5bar = 72psi, and for a dead cold engine thats not bad. Poor if warm, but wasnt.

Anyhow, things have got even stranger now...

My brother was over from Canada and out of random interest I decided to show him the car was fooked, and oddly, it started!
Sounded lumpy and low, but it started?! Stopped and started it about 10 times and it fired up and idled every time, hot or cold- It would barely start even with a push start before.

We did a spark test-
Pull off the leading plug leads and it idles worse, but each rotor sounded the same, like they was running as healthily as each other.
Pulled off the trailing plug leads, and despite them sparking strongly, it had zero effect on idle- Do they do nothing at idle then?

The amount of missfire and so on varied randomly as was running too, better and worse, which seemed at odds with mechanical issues too.

Pulled off MAP sensor and FPR pipes and that affected idle as expected, so its neither them at fault.

The plug leads thing, showing both engines acting identically well/badly, plus the general behaviour of the car when it acting like this, suggests its not the engine now?!

Im going to change the fuel filter next and see if that makes any difference, but overall, im confused as ****.

BUT if its not mechanical, thats awesome.

I jus cant see how it can be, as the likelyhood of BOTH rotors being as damaged as each other that you cannot physically tell one from the other when testing them by pulling plug leads, is pretty damn remote, surely?

 

Heres a vid I did about an hour ago that might help diagnose. Best off watching it in HD as its clearer then.

Ignore how difficult it was to start, it had an empty tank id just filled with a jerry can, you can hear when it finally gets fuel as you hear the whirring of the pump.

Can hear the whirr at 7sec then it immediately fires up.

YouTube - So... My RX7s engine isnt healthy, but is this rotor tips or non-mechanical...?

Can see the boost gauge fluttering, and the vac seems low to me, but it only flutters by about 0.1 of a bar at most.
Can hear the engine sounding like a slight miss as i hold the revs, never used to ever sound like that.

Read the description of the video for a low-down of my findings, or lack of, so far.

 

you have a dead seal, it is easily apparent in that evened out dead spot sound during cranking.

sorry, try to clamp the water injection line better next time. i'm sure that is what caused it to pop.

 

Karack- You do have a point, unfortunately.

If it helps you hear whatever more clearly, here are some better ones I just did with the plugs out...

Front rotor-
YouTube - Woosh testing the front rotor on my RX7....

Rear rotor-
YouTube - Woosh testing the rear rotor on my RX7...

Both rotors-
YouTube - Its a rotary steam engine.... All plugs out woosh test.