Help Diagnose The Problem...

[huddy]

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

[tridentt150v]

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!

[Amec]

have you done a boost leak test to eliminate that?

[huddy]

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]

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]

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

[huddy]

thanks for some clarity paul - your FAQ is not working atm though

[paulr33]

oh its been broken since the forum upgrade

they must have made some changes to apache

it should come back soon

[GTR-Ben]

Could have a slightly damaged valve? only becoming a problem at peak load?

[huddy]

i did read that in another thread... but with it being inconsistant... eg one time it cleared up i am not so sure...

please continue with more ideas