boost cut ???
 

hey guys i have just finished my first conversion with stock rs donk with a tdo5h, 99 tmic, bosch coil pack, 02 sti tbe.

so whats happening is when i get to around 3000-3500rpm i come onto boost around about 5psi then get to 4000-4500rpm on 10psi and it will either loose power or completly cut out like the car has stalled so i obviously pull the clutch in at this point and back off. ???

and whats weird as it will boost perfect 10psi for first 5mins then start to do what i have explained anybody got any ideas of whats happening ????

cheerz,james

[url]http://www.perth-wrx.com/vb/mechanicals/42484-limiter.html[/url]

Check your spark plug gap (0.8mm) and check fuel pressure and fuel filter.

Also clean the AFM and reset the ECU.

What fuel pump is in it?

hey guys cheerz for your replys

i have gapped the plugs, changed airflow meter, reset ecu

and iam running the walbro 255 fuel pump.

how can i check the fuel pressure ?

cheerz,james

well ive but new plugs in gapped to 0.8

but then i discovered 1 of my leads has a slice and has taken the rubber coating of will this effect it at all ? im gonna to change it but dont see how i little bit of the coating is my problem.

cheerz,james

still got this problem anyone else got any ideas ?

cheers,james

How are you controlling boost?

i have had it just straight wastegate to comp , have used stock boost controller, but now im using a mbc turbsmart T running wastegate pressure.

all have done the same thing it boosts fine untill the car has been driving 5-10 mins then it hesitates really bad or just cuts out at around 3500 rpm

cheerz,james

Is the factory MAP sensor still plumbed in properly? (along with the pressure exchange solenoid)
Is the stock boost solenoid still plugged in electricly?

It sound like the typical Rs Lib limp mode.

Sounds liek a fueling issue possibly then. Get Doug to check it out.

[QUOTE=Rossco;570917]Is the factory MAP sensor still plumbed in properly? (along with the pressure exchange solenoid)
Is the stock boost solenoid still plugged in electricly?

It sound like the typical Rs Lib limp mode.[/QUOTE]

hey yes all plugged in and yes the stock boost soleniod is stil electricly plugged in but nothing else connected on it.

im thinking of putting my power fc i just bought in and wiping the tune to stock pfc tune is it okay to do this ??

and will it be better for the engine ??

Try to read the ecu's error codes first. There's a write up on here that I did ages ago. Search for "ecu reset" or "ecu code read" or similar.

Find out if it's going into limp mode.

[QUOTE=Rossco;570930]Try to read the ecu's error codes first. There's a write up on here that I did ages ago. Search for "ecu reset" or "ecu code read" or similar.

Find out if it's going into limp mode.[/QUOTE]

i have already done the ecu reset and tried checking for codes i will go and try again but if i get no codes im going to try install the pfc on the base tune and see how it goes, next ill probly look at coils and fuel setup.

cheerz,james

My old RS did drive. Drove ok, got hot, would run like utter shit. '

Ended up being fuel pump

well i just did the a code check and im getting 23 just kept repeating 23 so thats the afm i will change it and see how it goes.

and i just put a new fuel pump in but im thinking it mite be the filter or injectors.

cheerz,james

swapped afm, reset ecu but still getting code 23 ??

Code 23 on obd1 is pressure sensor (map) is it not.... I'm on iPhone & can't check.

[QUOTE=Rossco;570961]Code 23 on obd1 is pressure sensor (map) is it not.... I'm on iPhone & can't check.[/QUOTE]

by your thread it said the below.

23 Mass air flow sensor

but both afm are known working ?? they couldnt of just karked it in 3 months of sitting on a shelf could they ?

cheerz,james

23 is definitely Air Flow Meter.
You need to take it to a workshop so they can check the circuits and data.
Subaru Wangara will sort you out.

map or maf, you got to make sure which one. otherwise drop by my workshop n I will plug in the carman diagnostic and chk for u foc.

[QUOTE=69terra69;570963]by your thread it said the below.

23 Mass air flow sensor

but both afm are known working ?? they couldnt of just karked it in 3 months of sitting on a shelf could they ?

cheerz,james[/QUOTE]

It's definitely mass air flow, I have the workshop manual in front of me, code 23 is Mass Air Flow

Check that your MAP sensor is seeing boost.

If you stay under 5 Psi and rev past 4500 does it still breakdown?

ive just spent the last 2 hours or so starring at my engine bay going over every little thing i could see, and i spotted on 1 of the plugs to 1 of the coils was missing abit of insulation so i taped it up went for a drive, and it boosted fine to 9-10 psi.

still had a small hesitation but no where near as bad as before so it has marginally fixed the problem.

so now im gonna try bump the boost upto 14-15psi and see what happens.

cheerz,james

swap all the ignition leads out.

[QUOTE=tuna;571065]swap all the ignition leads out.[/QUOTE]

was going to do this as asap im actually considering renewing my whole ignition and fuel system as its near on 20 year old stuff.

hopefully this sorts my problem as im trying to get my car working all sweet so i can put my power fc in i just purchased and get a tune.

cheerz,james

If you have a fault code its there for a reason. Unless someone has inadvertently unplugged the AFM while the ignition was turned on.
It may be the ignitor more so then the coil and leads.
You really need to check fuel pressure as stated above, if you can have a gauge on when it cuts out, might eliminate the fuel system.
It may also be the crank sensor.
Does it have to be warmed up before it starts playing up?

[QUOTE=johnvk7;571111]If you have a fault code its there for a reason. Unless someone has inadvertently unplugged the AFM while the ignition was turned on.
It may be the ignitor more so then the coil and leads.
You really need to check fuel pressure as stated above, if you can have a gauge on when it cuts out, might eliminate the fuel system.
It may also be the crank sensor.
Does it have to be warmed up before it starts playing up?[/QUOTE]

yes it does only do it once its warmed up, i will check fuel pressure as soon as i can get my hands on a gauge.

cheerz,james

got a set of leads from my old motor that you can have if you like, early wrx motor, coil pack in the centre.
I'm guessing they would be the same? :)

Do not use the PFC first.

1) PFC requires fuzzy logic setup including runing the aircon n lights so the self learn function on it is complete.

2) If it is a new PFC, the standard map is set very rich so you can tune safely. Not recommended to replace factory ecu if not tuned.

3) If the PFC is used, you will not know what tune is in it. injector corrections and duty will be very different

--- did you chg the maf off a working car? did you try cleaning the maf with contact cleaner?

--- what boost meter or instrument are you using to gauge the boost pressure? use a secondary boost reference to be sure that the vehicle is not overboosting.

--- any leaks down the up-pipe and manifold. might affect the O2 sensor which will then cause the ecu to counter the leak by making the engine run rich. This can then foul the plugs. Is it blowing black smoke out of the exhaust?

--- you said it improved when u found one faulty lead. did you chg the whole lead set? chging one while the other 3 are just as bad might not solve the problem.

--- a few guys here pointed to fuel. A faulty fuel pump will cause cut-off and eventually you will not be able to run the the engine. So chk the fuel pump. Also chg the fuel filter, could be clogged. Faulty injectors or clogged injectors are are, but u'll be very unlucky if it was.

Just go back to the basics:

1) You have a chk light --- really I will be looking at the maf --- but u said you changed it so was it a new one or one off another car of the same model that you were sure was working on it?

2) You need fuel, spark and compression to run the engine properly. So check these areas individually.

3) Also was timing affected in anyway before this happened?

Good luck with the problem solving. Will love to know what it was.




[QUOTE=69terra69;570927]im thinking of putting my power fc i just bought in and wiping the tune to stock pfc tune is it okay to do this ??

and will it be better for the engine ??[/QUOTE]

RS should have coil on plug.
Alot of people do the bosch coil conversion as they are known for failure. There is however a DIY guide somewhere on RSLC to retro fit the coils from a bugeye? to the RS engine.

thanks mate this should keep me goin all day tommoro checking everything listed and i will update you how it goes.

[COLOR="Red"]--- did you chg the maf off a working car? did you try cleaning the maf with contact cleaner?[/COLOR]

i am sure the afm i changed with is working unless it karked it from sitting for 3 months.

[COLOR="Red"]--- few guys here pointed to fuel. A faulty fuel pump will cause cut-off and eventually you will not be able to run the the engine. So chk the fuel pump. Also chg the fuel filter, could be clogged. Faulty injectors or clogged injectors are are, but u'll be very unlucky if it was.[/COLOR]

im sure the fuel pump is fine its brand new.i do have another fuel filter i can chuck in.

[COLOR="Red"]--- any leaks down the up-pipe and manifold. might affect the O2 sensor which will then cause the ecu to counter the leak by making the engine run rich. This can then foul the plugs. Is it blowing black smoke out of the exhaust?[/COLOR]

i dont think the up pipe is leaking but if i remeber correctly when i changed plugs the other day the 2 closet to the fire wall were very black.

had a wrex come in the other day with a fuel pump problem similar to what you are saying here. We chged the pump and fuel filter and off she went.

Also please take note that 8 out of 10 walbro fuel pumps sold in Perth are fake. I am not going to point my fingers at which retailer, but you can PM me and let me know where you got your pump from.

Before you continue, find a mate with the same car and plug that afm in to see if it works fine. Won't want to do all the checks and find out it is the AFM.

Also check for leaks on the manifold and uppipe and around the turbo. You will see a very obvious black around the pipe or connection where the leak is.

also, now that you have changed the plugs, remove them again, and take a look once more. Then use a wire brush and brush them clean n chuck them back in and let me know the condition of the plugs.

Also you could do this, remove each lead and plug a spark plug into it and put the spark plug tip against a conductive metal part on the engine. Get a friend to crank the engine over and you stand over the engine and see if it sparks. BE VERY SURE TO INSULATE YOUR HANDS WITH RUBBER GLOVES while doing this.


If you dont see any spark, the plug or lead is faulty. If you see a very weak spark compared to the others, same thing.

OT - but always amazed at the help and information that comes from this forum. :)

well today i am pretty sure i have fixed the problem as of now, i have taken it for a drive maybe around 40mins up and down the gears as much as i could and it seemed to boost fine on 10psi. well over 5 mins where it wasnt boosting before.

so one of the first things i did was too change the fuel filter, then i heat shrunk the wires going to the coils as i suspected they were arcing out on the manifold from the exposed wire.

i also sprayed every connection with contact cleaner.

then i found that stupidly i forgot to put the gasket in between my dump and the turbo housing as there was alot of black splatter everywhere.

this was all i done then as i said i took it for a drive and it seems fine, but after the long drive i seen smoke coming from the bonnet so i had a look and it looks like it might be when i spilt power steering fluid all over the headers.

how long will this take to burn off ?

as if its not the power steering fluid it might be a leaking rocker cover.

thanks for all your help hopfully it is fixed and doesnt play up in the next couple days

Well done! If you spilt power steering fluid, it will take maybe half an hour to an hr to burn off.

I have seen rocker covers leak so bad that smoke actually continually rise through the bonnet. Check your oil level over the next few days as well and monitor that leak if that is the cause of the smoking.

Keep us updated.

[QUOTE=mao;571575]Well done! If you spilt power steering fluid, it will take maybe half an hour to an hr to burn off.

I have seen rocker covers leak so bad that smoke actually continually rise through the bonnet. Check your oil level over the next few days as well and monitor that leak if that is the cause of the smoking.

Keep us updated.[/QUOTE]

ok i will monitor my oil as its still doing it so im thinking it could be my rocker cover.

and to my surprise my car started hesitating on boost on the way home from work today grrrr.

so now im on the hunt for a new afm to suit RS liberty or wrx to suit.

cheerz,james