Hi all, right then here we go!! CAR IS MY99 STI

My engine is really hard to start and is cutting out after fitting 20g / 550cc injectors and manifold spacers. Injectors have been set up and mapping side of things has been checked by ZEN performance (thank you Paul). adjusting the fuelling makes no difference to it!

i have tried a few things such like, adding extra earth cable to manifold, cam shaft sensor, checked and cleaned all connections, adjust TPS switch, fuel pressure, injector o rings, checked all turbo hoses for leaks, coolant sensor, MAF sensor

also when the fans cut in the engine starts hunting and missing in till it cuts out. (if you open the throttle it makes no difference as it does not respond to anything)

if i got the car to start it would run fine until last night, but since then it has started to get worse and worse as it does not idle now

ok things i am going to try next.....

new power fc ecu
idle valve
new plugs (long shot i know)
crankshaft sensor (but i think paul cheaked this but we was pushed for time)

if anyone else can think of anything it could be or has come across something like this before please take the time to reply via pm or post it on here as this is really starting to get to me

mark

 

has the wiring for the fans been checked, along the bottom of the rad??.............the loom ruiuns very close to the manifold and had a few cars where this has not been secured properly causing all sorts off earthing issues once the loom has started to melt.........

alyn

 

i cant say i have seen any signs of damage, but i will look and confirm this!

more ideas the better, that’s what I say
thanks for the help

 

anymore idears anyone

 

Have you checked what the battery voltage is doing during the fans cutting in? If voltage is being lost, battery will show it for sure and could explain why she starts to cut as the alternator would be working OT with the extra load of the fans...

 

right then i have found where the problem is.... i will do my best to explain this!

engine will not start with the alternator plugged in (3 pin plug) but if i disconnect it will run fine

after playing around with my power probe on it i have found that the blue wire in the three pin plug is at fault some where or what it goes to is. the reason i say this is because if i earth out the blue wire it only lets the alternator charge at 12.5v but it starts fine!! but if i take away the earth it starts charging at 14.4v but the engine starts to die and idles really bad (but then some times runs fine and charges fine ). i have fitted a new alternator and its still the same so i need to find out where that blue wire goes or what it goes to! i think it must go to a voltage controller somewhere for the charging system?? i have found a few links on here to wiring diagrams but they are for the 2 pin alternators systems

so if somewhere has a wiring diagram for a my99 sti or p1 modal that would be great or if anyone knows where that blue wire goes that would be also great.

cheers
mark

 

have you got a full 3 wires in the plug or just 2 because if there is three then chances are it's the type where the ecu decides when to let the alternator charge.

 

yeah it has three wires in the plug, so i am thinking the blue wire goes to a controller, an the controller switchs it to earth to make the alt charge. ??

oh i have tried tracking the wire back to the ecu but i cant find it

 

I can't tell you the wire colours, but i can tell you the wire codes and where they go to. You should be able to tell which the blue is from process of elimination.

3 pin generator,

W = Heavy wire to battery pos via 80amp fuse.

L = engine control module via connector 19. (sti models only).

LR = Battery pos via fuse number 3 (10amp) via connector 3.

BW = Charge warning light (in combination meter) via connectors 13 & 8. Socket on instrument panel = B1. This should be neg when engine is off, switching to pos when the engine is started/or alternator is spun to extinguish the warning light.

The feed to the oppisite side of the warning light comes from fuse number 13 via connector 14. The socket on the instrument panel = C7. This should be switched pos.

Hope this helps.

 

thanks for that

ok i have now found the wire at the ecu. so what we are saying is that the alt will not charge intill the ecu switchs the earth.

i just cant see how this is fault can stop the car from starting! something must be back feeding

anybody know what else is on that circuit that could cause such a fault??

 

Is it possible that the injector flow has been corrected at 12V but not at 14.4V, so the modified (correct) value for your new injectors is available when the system is at 12V, but once you get away from that (cranking, low voltage with fans on etc) that its using the old injector flow rate and running too rich. (Injector characteristics are mapped againt battery voltage)?

Just a thought!

Simon

 

good idear but no, as i've tried that adding fuel or taking it away makes no odds

 

Right then today i have been on the phone to a local subaru garage and they say they have never come across this before! One chap who works there has even rang me back an confirmed that they have never seen something like this before!! even with his 26 years of working for subaru.. (don’t look good does it lol)

so just so we all know... i have changed

ecu
alternator
battery (dont really no why but hay was worth ago)
iac valve
cam sensor
crank sensor
coil pack
plugs (needed doing anyway)
coolant temp (had a spare)
maf (also had a spare)
going back to 440's and the map for them

So doing all that was a waste of time

Tonight after work i thought right you little fu**ker i'm going to fix you! but guess what i didn’t!

but these where my findings....

get car to start and let run (needs a little help to idle) in till it gets hot and then as soon as the fan's kick in it starts running like a turd and cuts out!

next stage was to remove the polly belt and then test it again.

car started first time and the idle was spot on 900rpm then the fans cut in and out with no ill effect on the engine.

next step is to buy a straight jacket as this is sending me potty!!

 

so after doing the belt test above it can only point now to something else as it wouldn’t of started and ran if it was a wiring issue with the alternator as the ecu was trying to cut it in and make it charge

so it looks like something on the car does not mind 12v but as soon as it get 14volts it wants to shut down and stop working


i think this thread should be moved to projects section

 

Have you checked the wiring to the ISCV and TPS?

ISTR the factory earthing points aren't the best. Is there a chance that anything off the engine - ECU/fans etc. isn't earthing properly?

Only other suggestion is to pull all non-essential fuses and see if that makes a difference....


J.

 

guys i am still having nightmare with this problem.

i just cant see how the car can run fine at 12v but at 14v it dont like starting or running!

due to having this problem with the car i have not really driven it much, so tonight i thought i would open the old girl up and see what see makes of 1.3bar of boost but to my suprise the car still only got to 0.8bar

great so now i have 2 problems with the car!

could the two faults be related, anyone?

 

thought i would did this old post up and see if we have any fresh idears

i have now sorted the boost problem and have put some miles on it now.

in the end i didnt find the fault with the starting/ fan problem, but i found away around it. ( put in a extra battery cable which goes to the battery direct from the alternator)

i know its fixed it but its not right and i'm not happy with having to cheat my way around the fault

so i am going to re-start my mission to find the fault!!

i would say its high resistance within one of the main cables or connections, but i have had all new power leads lol

so this is what ive tried...

power leads
clean all earths
relays (engine bay ones)
new battery
ecu (had spare)
alternator
iac valve (had spare)
cam sensor
crank sensor
coil pack (had spare)
plugs (needed doing anyway)
coolant temp (had a spare)
maf (also had a spare)
going back to 440's and the map for them

i'm now just going to slowly work my way though the rest of the possible things it could over the winter.

but if anyone has and ideas then let me know

mark