Hello all I'll start off by stating I have read a numerous number of threads about the rx8 hot start problems and so far have not found a problem that has corrected my issue

Changed spark plugs wires all 4 coils done decarb cat working properly do have a bad o2 sensor going to replace in a few days new battery new starter

Problem hot start like all others starts normal when cold won't start when hot but will start hot if I roll start it not that makes no since to me if it were a compression problem shouldn't it not start when hot when I roll start it? It doesn't hesitate at all when rolling it I haven't noticed any power loss. Was thinking maybe a possible leaking injector or the bad o2 sensor downstream is flooding it? don't have a the proper tester for compression on a rotary read I can use a piston one if I remove the air release valve on it and watch closely for the 3 sides of the rotor not sure if this works or not

Any thoughts would be appreciated thanks again

 

Yes, you can often roll-start a low compression engine that won't start on the starter. The roll start effectively has a 'cranking' RPM significantly higher than the starter is turning it, since even a 5mph 1st gear roll is around 700rpm, vs a 200-300rpm starter.


Get a proper compression test.

 

Ah well didn't think of that I shall then know of any good sites to get the proper compression tester?

Also think it would be wise to start pre mix my fuel maybe little extra oil would help seal better I run 91 non ethanol gas

 

The added oil from premix would be, at best, a bandaid. But, might help short term.

Is 91 the highest octane you can get?

 

93 and 95 are the next highest ones before race fuel at 101 and 110

 

Going to do compression tests tomorrow and see what she pulls in