Hey,

So I purchased a Mazda Protege 2002 Hatchback manual that had a blown head gasket, I replaced that and surfaced the head, no issues there.

However, now when it starts it starts up fine, idles at 1200ish then eases down to about 500-600 rpm but as it sits there after a while it starts misfiring and eventually dies, if i take it for a drive i have NO power if im in a higher gear and under load, it jumps and coughs like it's completely missing something in the combustion side of things.

SO FAR:
I've replaced:
Fuel pump,
Fuel filter
Fuel Pressure Regulator (the pressure is good at 30-36 psi as per spec and doesnt jump around even during loss of power)
Head Gasket
Ignition packs
spark plugs
Valve cover gasket
intake tube between Mass Airflow Sensor and intake manifold


I've checked:
Mass airflow sensor (readings are within the specs 0.8 - 2.2v at idle)
Throttle Position sensor (reading within the specs of CTP 0.1 - 1.1v and WOT 3.0-4.6v)
Looked for vacuum leaks found nothing


The EGR has been removed previously, From what i can tell it's blocked off but will pull the intake to confirm.

Any ideas or help would be MUCH appreciated as im currenly defeated, i dont know why it wont stay running.

Cheers,

 

Has it been scanned for fault codes?

Have you tested & monitored fuel pressure?

 

I havnt got a OBD scanner and cant get it to one so that's unfortunatly a no, hoping to rely on peoples knowledge.

Yes i've tested and monitored fuel pressure even under load and it holds steady.

 

What pressure reading did you get?

 

Have you confirmed the cambelt is correctly timed up?

 

Fuel pressure is sitting strong between 30-36 as stated in the manual, Even when reved or under load.

and yes the cambelt is correctly timed, as it was a direct swap that i did myself and tested to make sure it was still timed after several rotations both from the timing belt marks and the timing marks on the cams and crank for TDC

The car starts up and idles perfectly, but once it heats up or has load put on, it misses and cant keep up.

 

These engine do suffer from Cam position sensors dying when hot.

 

Now that it's had a few heat cycles, you need to go back and retorque everything especially the head and manifold bolts. I would also do a compression check.

 

Is there any way to test or check the Cam sensor?
I've got a cheap OBDII on it's way to check any codes too.

I'll do a compression test and see what that says, but if it's running fine on start up, shouldnt the compression be fine?

 

Compression test was 110 PSI on cylinder 1, 3 & 4 number 2 was at 90.

after checking the manual and min should be 145, can any of you confirm if the PSI on your proteges are similar at 110?
I've also put in some Compression restore oil additive.

My OBD2 doesnt connect to the vehicle as it is an Australian version that didnt come with OBD2, it has the Mazda 17pin OBD1 looking connecter,
I have tried connecting the wires and i can get power to my OBD2 device but no connection to the ECU, I followed this post (https://forscan.org/forum/viewtopic.php?f=4&t=5)