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Help Diagnose The Problem...

huddy

By huddy,
in Engines & Forced Induction

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huddy Veteran

huddy

Posted
Posted

Problem - car is breaking down / missing above 4500, 5000 ish under load.

Engine - RB24DET, GT3076r, Power FC.

What i found initially - water in the valley with coilpacks (not good!)

What we did to try and fix the problem:

- soaked up all the water.

- sprayed a bit of rp7 on coil packs as they didn't appear to be that wet.

- changed 6 x spark plugs all round.

went out and tested and still had same problems.

so we:

- changed 6 x coilpacks

- went out test with normal boost of about 22psi and low boost of 1 bar.

still had same problems, exactly the same symptoms.

we then:

- checked timing and swapped CAS

went out again, still had same problems...

People that were on the sidelines said that sometimes it seemed to clear up a little bit, and then be back worse than ever.

My thoughts:

- electrical / wiring problem.

It hasn't ever had symptoms like this before even with the coilpacks (standard) / spark plugs (BCPR6ES gapped 0.7 - changed after every track meet). The igniter is securely fixed, and if it was this my thoughts are that it would be a more constant missing (it is not present on free revving the engine).

Can anyone shed some light / help brainstorm?

cheers

-Matt

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tridentt150v Grand Master

tridentt150v

Posted
Posted

First you have to find out if it is electrical or fuel!

Can you isolate the miss to one cylinder [hard when it doesn't happen 'off load']. Can you swap coil loom?

How's the fuel pump, filter, fpr, injectors? If it only happens under load [and you've swapped out the plugs and coils] then could be fuel.

Oh, and what was the water from, washing? If its coolant, head gasket or some such for sure!

huddy Veteran

huddy

Posted
  • Author
Posted

water was from the vented bonnet... good to keep heat out, but crap for wet weather...

i'm going to have a closer look tomorrow, paying special attention to the wiring - coil loom / to the injectors / AFM... will also check all the vacuum hoses - if all goes well i'll start it up again to check it idles fine, but this wont tell me anything until i get it on the dyno to get some load/boost into it. Once on the dyno will try to isolate to a cylinder...

...so if you can just throwing things out there for me to check that'd be great

thanks again

-Matt

huddy Veteran

huddy

Posted
  • Author
Posted

what i found: the O2 sensor plug/connector had melted and was disconnected... could this be a problem?

other things i did to try and fix problem:

-tightened plug to ecu (it was not loose though)

-checked connectors on coilpacks, injecotrs, igniter, AFM - all appeared in working order

-change oil/oil filter/fuel filter (general maintenance)

-checked vaccum hoses/connections - all appeared ok

-check cooler piping (possible leak on boost??) - all sealed and tight

any other things? it's been suggested it may be an 'earthing' problem - can anyone specify what earth's in specific (ie where are they on the loom)

the car idles / rev's perfectly, i haven't had it on the dyno yet so i can't get it onto load/boost...

ANY OTHER IDEAS???

many thanks

-Matt

paulr33 Grand Master

paulr33

Posted
Posted

02's wont be used when the car is under load so discount that idea, howver is the plug was shorting out, this wont be good for the ECU - so confirm that

theres a known misfire bug with BNR32 and PFC users, its in the FAQ, have a read of that it might give you some ideas on where to look

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