I've been experiencing hot start issues and was concerned that it was my new motor from Gotham. But after talking to Steve Kan I'm not so worried about the motor.
However, I removed the turbo (RX6) and about an ounce of oil poured out the compressor outlet. Thus, the turbo seals are shot.
I then removed the exh. manifold and checked all 6 apex seals by look and feel. All were perfectly fine - no scatches, knicks, or cracks.
So my question is, could the bad turbo be causing my problem with hot starts?
I've never heard of it but it is the only thing that is wrong.

 

Usually hto start issues are more to do with a dying primary igntion coil.

 

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/wont-stay-running-when-warmed-up-600003/
this is the thread that I describe my problem
I got the idle figured out, it was just off from summer driving and had to be adjusted for the cold weather
so it idles fine now and does not die on its own but still won't start when its hot

 

really?? that is the first I've heard of this
I did a search for hot start issues and all I came up with was "do a compression test - your motor is blown"

so the leading coil going bad is a possible cause also?
thanks for the input

 

I have read material from Mazda that states the PRC solenoid cuts off vacuum to the fuel pressure regulator to prevent hot start problems. This happens, according to page F-111 of my 1994 factory manual, when ALL of the following conditions are present:

1) fuel thermosensor indicates above 50°C
2) engine coolant temperature sensor indicates above 70°C
3) throttle is opened less than 30%
4) either neutral or clutch switch is closed (indicating idle condition to PCME)

If 1) - 4) are all true, then the PRC solenoid is activated (which removes vacuum from FPR, raising fuel pressure) for approximately 90 seconds during and after engine startup.

This is supposed to minimize vapor lock in the fuel system. (Frankly, I don't see how, but anyway that's their party line.)

 

No, the turbo has absolutely nothing to do with startup.

Generaly, hot start problems are a result of borderline/weak compression, or slow cranking rpm.

It can also be too much or too little cranking injector pulsewidth, or even less likely, an ignition problem.

 

yeah, I saw all the info on the FPR solenoid, but since I don't have one and haven't had one for a few years, I pretty much ruled that out

 

thanks for the input on the turbo
the cranking pulsewidth is interesting, I'll have to get ahold of a datalogit
although less likely, the coils are worth considering

as stated, I have ruled out low compression for now since talking to Steve about the condition of the engine and its running characteristics

 

Do a compression test. Is your motor ported? I've seen many instances where a motor was ported and the time wasn't taken to make sure all the metal shavings and debris from the porting/polishing process was properly cleaned up. This stuff will cause alot of initial wear when the motor is started, possible damage the turbo, and result in a weak motor right from the start. It happens very often when people take short cuts such and leaving the stationary gears in place when porting. Alot of crap can get trapped in there and find its way into the oiling system and motor. Check your oil for debris as well. Other causes may be a failing oil metering pump and lack of premix in a motor with 3mm seals. How are the injectors? Did you replace or clean/rebuild them?

 

the motor is a Gotham stage2 (streetport) w/3mm seals
it was bought right after it was broken in and tuned by Steve
I have faith that no debris or short cuts were included in the rebuild

I discussed a failing OMP with Steve - checked VMOP on commander and checked out good
the motor included new SS lines also
Steve did recommend premix for now until I get this figured out

the injectors were cleaned and balanced by RC - 1300cc on sec. and 550cc on pri.

I will drain the oil and check for unusual metal debris though, thanks

 

BTW, the motor has less than 3k miles on it

 

I could have sworn there was a pretty large discussion about burnt out primary coils, especially if your running an ign amp, last year on how it causes hard start issues after the enigne warms up.

 

I'll see if I can find it
I did add an ign amp (msd 6al) when I installed the new motor

 

So ohm out the coils. There is a spec inm the mazda book.