NoPistons -Mazda Rx7 & Rx8 Rotary Forum

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-   3rd Generation Specific (https://www.nopistons.com/3rd-generation-specific-18/)
-   -   High Rpm Miss (https://www.nopistons.com/3rd-generation-specific-18/high-rpm-miss-26026/)

FDnutt 10-03-2003 09:43 AM

I need some suggestions.......I have a high RPM, high load miss. My 3rd gen is cutting out for a split second around 5500 rpms when under boost. I have checked the volt. to the fuel pump and it is getting 12.4 V so I don't think it is fuel cut. It is almost like it stops firing for half a second and then kicks back in. I have checked duty cycle on the injectors and they are not maxed out. Anyone with any ideas???? Here are my related mods:



EFI PMS

Full non-seq

Open Exh.

Manual boost adj. (running 11.5 to 12.5 boost)

open intake

Walbro fuel pump



https://www.nopistons.com/forums/pub...1047683664.gif

vosko 10-03-2003 10:02 AM

you are hitting fuel cut

FDnutt 10-03-2003 10:15 AM

If I am hitting fuel cut why does the voltage to the fuel pump stay the same? Does the ECU cut the pulse to the injectors and and not the power to the fuel pump? If that is the case, how can I fix it??



Thanks

jspecracer7 10-03-2003 10:49 AM

fuel cut as in your ECU is reading higher than normal boost and cutting fuel to the engine.



What ECU are you running? Stock with the PMS as a piggy back?

vosko 10-03-2003 10:53 AM

it doesn't cut the fuel pump it just tells the injectors not to fire. it is so you don't blow the engine.... i personally don't like the PMS system.... played with it once and was not impressed

tcb100 10-03-2003 11:19 AM

A frequent cause of the fuel cut problem with the PMS is the knock sensor. It gave me fits too until PFS relocated the sensor higher off the engine. Problem totally went away. The sensor must interpret all sorts of engine compartment noise as "knock".

vosko 10-03-2003 11:24 AM

i was gonna say that but i didn't know the PMS did anything with it

FDnutt 10-03-2003 01:07 PM

OK, that's the second time I have heard of someone moving the knock sensor. I have thought about trying it, just worried about the safty factor. I guess I will move it and if I pop the motor, o well I wanted to do some port work anyway. Will make for a nice winter project https://www.nopistons.com/forums/pub...#>/biggrin.png


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