I have a 2005 Rx-8 with 200k miles one the chassis. My original motor went out at 174k miles. Rebuilt and bridge ported the existing motor, I have 25k miles on it. It ran like a champ until last week. After a nice long drive I came to a stop light and the car stalled and would not restart. I searched the forums for all possible reasons and fixes and she still will not restart. I have a new starter, spark plugs , BHR coils, new battery and I replaced my crank sensor because I picked up a error code on the COBB saying it had low performance issues. My alternator tested good, I cleaned me MAFS it was a little dirty. My K&N air filter is clean. My fuel pump is fairly new.

Does our car have a turn over switch just incase you flip the car over it would kill the main systems? I ask because after I visited my buddy I had to go on the side shoulder which was at a steep angle to avoid a accident in the road. After I came off the shoulder and drove back onto the road , I came to the next stop light and the car shut off and would not restart. Does anybody know if the 8 has this function.

Weird thing if I push start my car , the car will come on and drive fine. Other than that the car will crank and crank without turning over. Any ideas guys?

 

Anybody?

 

Bump start it fires, Crank and it doesn't

If I am understanding this correctly, sounds like an electrical issue.

When you bump start you are in the run mode, seems when you turn to crank the car the run mode loses power and either is not sending fuel or spark.

Pull a plug and see if it sparks when you crank.

If it was a rollover safety switch it would cut fuel, IRCC I do not believe we have a roll safety switch but if we did it would be on the fuel pump

 

Thanks ,ill pull a plug to see if it sparks. I even sprayed starter fluid into the throttle body and it still did not crank. Before I attempted to use starter fluid to turn her over , I noticed the smell of gas coming through the tail pipes. So I am assuming the fuel pump is working.

Thanks for the suggestion.

 

you sir are the proud owner of a blown apex seal.

 

Sounds like a loss of compression to me. Assuming you are getting fuel and ignition. All that time time trying to hit 10,000RPM takes it's toll.

 

I was thinking the same thing 9k.

Shady possible... Before my old motor went dead, every time a apex seal blown , it would make a sound of a shot gun going off. This time around no shot gun sound. Car was running fine , no symptoms leading up till last Thursday. Always started hot or cold.

 

More like bridge port went and took ur whole engine with it, check compression first,

Why u b port for a street car anyway? You do know that it kills ur engine faster rite?

 

Wanted something different. Fortunately my 8 is my third car, more of a toy than a daily driver. I retired it from daily driver use last year when I rebuilt the motor and did the bridge port. Still though , having a car down is frustrating.

Carbon and 9k , I pulled the plug , she is getting spark.

Compression test tomorrow.

But if it was compression, wouldn't the car drive really horrible, have no power? I can push start the car rather easily and she drives fine in all the gears, it when you come to a stop, she will idle for 10 sec then the car dies , she shuts off and if you try to crank her over she just continiously cranks without turning over.

When my old motor was going out at 170k miles and when the 2nd apex seal blew,it was a noticable difference in the way the car drove ,took forver to start, even push starting was a task, it was very weak, couldn't go past 7k rpms without the car falling on its face. Major stumbling issues. When the 3rd apex seal went the car didnt even crank. Almost like the rotor was hung hung up on broken apex seal debri.

 

Depends on how low compression is, the starter may not be able to spin the car fast enough. about 250-300 RPM max. When you bump start it spins much faster and could result it it being able to start.

Im unfortunately leaning towards compression.

If it is, do a good tear down thread, I think we would all be interested in what happened

 

I am starting to think the same about the compression issue. The Cobb AP shows the starter or motor spinning at 280-310 rpms on start up.

If I have to tear it down I assume the housings are ok with 25k miles on them, before this happen , I did not detect any motor vibration like the last motor. The old housings had serious chaffing on the lower and upper housings. The irons where still good, and was to spec thankfully.

Yessir Carbon I'll take good pics of everything.

 

Any major exhaust porting, or just bridgeport?

 

If you can bump start it, it's either the bridge or a vacuum leak.

 

Carbon, no exhaust porting.

Yeah its bridged. Sorry for not updating, not going to be able to do a compression test till tomorrow. Been super busy.

But I did this, I was told to disconnect the MAFS and try to start it. You know when I did that the car almost started. It would crank over then suddenly shut off. Do you guys think a bad MAFS is the culprit or do still think its compression?

I ordered a MAFS just incase its not compression. Also what are good compression numbers for the front and rear?

 

Would through a CEL is it was a MAF problem.

 

Yes but the CEL never came on when it was disconnected either. So what gives?

 

Any RX-8 will start and often idle fine with the MAF disconnected until you touch the throttle and then it will stall out. Faulty MAFS are very rare and when they do fail, 99% of the time you get a code.

 

Compression is a sliding scale depending on RPM.

 

Back in september user Perigosa was having idling issues and we got together, turned out she had a bad MAF. No CEL at all. It would start up and drive fine, but let the rpms drop below 1k and it would stall. Figured it out by swapping mine in, if you know anyone nearby with an 8 OP, try swapping it. Can't hurt

 

CliffJumper I will have to try that.

I did the compression test, 102 for the front rotor, 98 for the rear rotor. She is on the low side as I know 120 is the standard. A buddy came over and we rechecked everything and even disconnected the ecu and reconnected it back to the wiring harness.

For a min or two she was not giving off spark, so we made the BHR system was grounded properly and rechecked the connectors. That seemed to work.

We fired her up and this time around was a little more promising than last time, I could get only get the car to crank. This go around, the car cranked and was puffing out smoke out the tail pipes, the car fired up twice then shut off. Its acting like its flooded. Trying to crank her over so much we killed the battery, went to get my jumper cables , only to realize I left them in my other car that my wife took.

Long story short, I'll pick up my batttery from being charged after work , I'll put the battery back in today and see what happens.

 

Your doing it wrong.

 

What am I doing wrong?

 

Those compression #'s are not even close to right.

 

There was another scale underneath that went from 0-10. Is that the scale I should have been looking at? If so the front rotor read 8 and the rear 7.5 ish.

I don't understand why my readings are wrong, please explain im confused.

 

8.2-8.5 is a perfect engine, but it is also dependent on the RPM 200-300.

both of those numbers are needed.