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Fridge_repair_man

Manual conversion gone wrong

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Hey guys

trying to get some advice for where to go with problem solving on my stagea, its one of the dreaded 08/97 built cars that have an ecu they ran for only one month apparently.

pretty much the problem is the car is idle hunting badly running rich and rarely but sometimes stalling at idle and then under power it will stutter and cut out untill i clutch out taking load off.

The previous owner had it manual swapped from an auto and the issues started from there as i found from the mechanic who serviced it.

if someone could help with a pin out sheet or advice on which ecu to go with or if theres. Something i should replace i would much appreciate it. 

Edited by Fridge_repair_man

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The most common ecu is the OV300 followed by the OV 301 so I take it you have an OV310? The problems you descibe are unlikely to be the fault of the ecu or the manual conversion as cars usually run fine with the auto ecu. I will attach a pinout which you could check against your ecu. if you really want to ditch the ecu you could fit a Link which would give you the tune-ability you will need if you are going to go for more power (bigger turbo, injectors etc).

Pinouts WGC34_Series_1_-_STAGEA_RB25DET_Auto_ECU_ translated.xls

R34 Pinouts with wire colours.ods

Pinouts R34_ecu.pdf

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4 minutes ago, KiwiRS4T said:

The most common ecu is the OV300 followed by the OV 301 so I take it you have an OV310? The problems you descibe are unlikely to be the fault of the ecu or the manual conversion as cars usually run fine with the auto ecu. I will attach a pinout which you could check against your ecu. if you really want to ditch the ecu you could fit a Link which would give you the tune-ability you will need if you are going to go for more power (bigger turbo, injectors etc).

Pinouts WGC34_Series_1_-_STAGEA_RB25DET_Auto_ECU_ translated.xls

R34 Pinouts with wire colours.ods

Pinouts R34_ecu.pdf

If not the ecu pins what would you suggest i look at, ive replaced alot of thing  and im running out of ideas

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Try this;

https://www.sau.com.au/forums/topic/110431-diy-aac-valve-cleaning-idle-reset/

clean the afm and check the wiring and plug

replace the fuel filter

check fuel pressure ...new pump?

check that the CAS turns smoothly

I presume you have replaced the plugs and cleaned and possibly insulated the coils

New air filter

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I agree it's unlikely to be the ECU that is the issue, although not impossible....what would be pretty much impossible is finding another one of those bloody ECUs to swap in.  As you've probably seen elsewhere my stagea is the same month and had troubles when I swapped to an aftermarket ECU because pin outs were different to the ones before and after.

I'm assuming the car is reasonably stock other than the manual conversion.  Having an auto ECU in a manual converted car will not cause an issue on it's own, the main difference is the atuo ECU has logic to cut timing when the auto is shifting for smoother shifts. Since you have a manual now the ECU never gets that signal so that function is not used.

The other thing about the auto ECU is that it might be less tolerant to mods, and that could be part of your issue depending on mods.  In earlier series like r32 and r33 the ECU was more accepting of extra boost/airflow, but in the later series (and I found this ECU in particular) was really unhappy even with boost at 10psi instead of 7 even on the standard turbo. Basically the map had a really narrow band where it runs at sensible air fuel ratios, and it goes mega rich and retards the timing heaps outside that with the intent of protecting the engine from whatever went wrong to take it off that narrow path.  Very rich running in particular can cause misfires alone, and can quickly foul spark plugs which will increase the issue.

So....if you are unmodified, check the usual skyline/stagea stuff like Bobby has posted above.

* Most likely reason for running rough and idle and stalling is an air leak in the intake after the air flow meter and before the inlet valves, or a dead or dying AFM. A good mechanic can do a smoke test to check and it would be a good idea to swap for another AFM and see if that helps

* Maybe run it on a dyno somewhere with monitoring of fuel pressure because by this age could be fuel filter, injectors clogged or leaking, fuel pump dying/losing flow at high pressure

* Coil packs / spark plugs / spark plug gap. Start by replacing with new plugs gapped to 0.8mm instead of standard. If that helps there is a problem in the ignition system so consider new coils or check the coil pack wiring and earth

* Have a compression test done, there could be a mechanical problem in the engine.

If the car is modified or running higher boost you need to get it on a dyno and find out if it is a rich running problem, and if so plan for an aftermarket ECU and some added expense getting wiring modified somewhat.  Sorry I don't have a wiring diagram or details of what was changed in my car, it was more than 10 years ago now. I know there were coil and air con issues but can't remember details.

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