millwrx

iTrader: (1)

hi,i have a 94 plate wrx import and over the past week has developed a running fault,the car starts from hot or cold perfect,idles perfect,go's up through the gears and comes on boost fine and holds perfect at 1.3bar with on fault.now for the fault,when yon hold the revs at about 1600rpm there is a slight misfire which seems to stay till about 3200rpm{hot or cold}have also noticed that my air/fuel ratio meter is reading max richness,car runs alot of mods,blitz id3 boost controller,apex fuel computer{only moniters}full decat,equel length headers,440cc injectors,hks filter,uprated fuel pump,says it has a mines ecu chip but have never cracked it open to see,later/bigger sti top mount intercooler,sti bottom end{rebuilt by me 7 months ago}.have rang a few specialists but to no a vale.have replaced the maf,spark plugs{ngk}3 of the coils are new and have tried a different one on the fouth,have disconected the 02 sensor to see if that cured it but that didnt work.no air leaks,even carried out a compression check which was fine,no faults logged in the ecu check.hope someone can help as i am running out of ideas!

millwrx

iTrader: (1)

anyone any ideas please???????????????????????????????????????????? ????

Jolly Green Monster

iTrader: (4)

instant reaction

you have 440 injectors on a 380injector map with an uprated pump on the standard fuel pressure regulator.. it is over powering the standard fuel pressure regulator and running very rich at that rpm.. once on boost it is using more of the fuel and so not able to over power the fuel pressure reg and the increase boost over standard needs more fuel anyway, but I expect it is still rich.

The mines ecu runs very agresive timing, not surprized it needs a rebuild previously.

perhaps worth considering having it mapped properly for the mods, imho.

Simon

Delboy2

The last WRX I saw with an uprated fuel pump with 440's(Standard Injectors are 380cc) on a standard fuel pressure regulator was running 'dog rich' on the wideband and had a very similar problem to what you are experiencing. The ECU needs to be set to run with the bigger injectors and it would be wise to fit an uprated FPR. As already stated - the Mines Chip runs alot more ignition advance than the specific map for your car (which is setup for running on Jap Fuel 100RON) so with this chip fitted I too wouldnt be surprised if this added to the demise of your last engine so a remap would also be advisable.

Cheers

millwrx

iTrader: (1)

[QUOTE=Delboy2]The last WRX I saw with an uprated fuel pump with 440's(Standard Injectors are 380cc) on a standard fuel pressure regulator was running 'dog rich' on the wideband and had a very similar problem to what you are experiencing. The ECU needs to be set to run with the bigger injectors and it would be wise to fit an uprated FPR. As already stated - the Mines Chip runs alot more ignition advance than the specific map for your car (which is setup for running on Jap Fuel 100RON) so with this chip fitted I too wouldnt be surprised if this added to the demise of your last engine so a remap would also be advisable.

found out today that the connection for my air/fuel gauge on the ecu end was at fault which was giving me the rich reading as it is now fine and working like it should.still have the slight misfire.i have fitted over the past week mind 2 new sti engine mounts and a group n gearbox mount from roger clark motorsport which are alot stiffer than my old ones so perhaps this misfire has always been there due to the map it use's and i have never felt it before?cus the car apart from this slight misfire is perfect to drive.the engine was rebuilt cus it was getting on abit not cus it blew up or anything.my fuel pressure on the standard pressure reg is 3 bar if i remember right which i have been told is correct.any more ideas????????????????????????????????????????

Delboy2

Yes the std fuel pressure is ~3bar at atmospheric pressure - the standard fuel injectors on your car are 380cc's as said above and you have 440cc's fitted, has the ecu been mapped to accomodate these? If it hasn't it will run much richer than normal.

Cheers

millwrx

iTrader: (1)

hi,yes can see wot you are saying but these have been in for some time and this fault only started last week.

Jolly Green Monster

iTrader: (4)

instant reaction

you have 440 injectors on a 380injector map with an uprated pump on the standard fuel pressure regulator.. it is over powering the standard fuel pressure regulator and running very rich at that rpm.. once on boost it is using more of the fuel and so not able to over power the fuel pressure reg and the increase boost over standard needs more fuel anyway, but I expect it is still rich.

The mines ecu runs very agresive timing, not surprized it needs a rebuild previously.

perhaps worth considering having it mapped properly for the mods, imho.

Simon

millwrx

iTrader: (1)

my air/fuel gauge now i have fixed the bad connection says that the fueling at that rpm is fine and not running rich at all.the missfire sounds more eletrical to me because of the sudden miss,to listen to it you would think its a coilpack on the way out.

Jolly Green Monster

iTrader: (4)

or it has fouled the plugs because it is running rich.

millwrx

iTrader: (1)

no the plugs are perfect,well afer checking all that i could i have ended up taking it to powerstation to see if they can find out wots wrong,fingers crossed!

ScoobyDawg

Hi mate

I would appear to have the same problem with a JDM 1998 WRX TypeR.
Performs well unless I slow down to between 2000-3200 rpm and slowly ease the power back on, following traffic, and then it splutters farts ****s and I have to boot it.

Would u let us know what your problem is when you find out.

Cheers M8

Dawg

scooby-tc

iTrader: (2)

I had similar problems on my 98 type r immediatly after fitting uprated fuel pump.After JGM remapped it it ran like a dream,still sounds to me like a fuelling issue,definately recommend a remap before this engine goes pop

millwrx

iTrader: (1)

hi,yes will let you no when i get it back,

millwrx

iTrader: (1)

well it was checked over by power station and no fault was found.the viberation at that rev range is to do with the much harder new engine and gearbox mounts that i fitted.

rexabusa

engine mounts cause your car to misfire

millwrx

iTrader: (1)

no,the mounts cus they are alot stiffer cause the car to vibrate at that rev range which lead me to belive it had a slight miss.