Hi,

Ok, with my other thread(s) pointing at the fuel pump I'm going to change it, the question is if I go for a 255l Walbro/scoobyworx etc will it need mapping in? What's the best option for my 08 Hatch STi that won't need mapping, other than OEM (as I guess they're not cheap)

TIA

Ian

 

you will be fine fitting an uprated pump bud. no mapping required.

 

Mapping isnt a necessity in most cases but and this is important, if the car has been mapped to an old pump that is tired and struggling then the fuel trim will have been changed to push the tired pump at full chat to compensate for it not been at its best. Then it will over fuel with a new more powerful pump.

 

Hi Darrell,

It's not mapped (yet) totally factory stock, I'm just trying to chase down what might be causing my problems. Have replaced the plugs and 2 injectors and still no luck so I'm going to replace the pump as it's a cheap option on the list of things to try

Will the stock map cope ok in your opinion?

Cheers,

Ian

 

As long as it hasn't been mapped to a weak pump yes :-)

 

Have it mapped/the original map checked anyway - might prevent the dreaded 'detted/fractured ringlands' from occuring if the engine/map is standard.

Mick

 

Cheers Mick, that's the plan in the near future (once the warranty has run out )

 

Hi Ian

What car you have and what issue you have ?

OE Fuel pump is I think 175LPH and upgraded is 255LPH,I would recommend at least get car check'd by yours mapper or get car on RR,where will or can tell you if car is running rich or lean

With larger pump I would suspect you will be running bit rich

And agree with Mick too about the get car mapped,will worth it

Hope this help

Thanks,Jura

 

Hi Jura,

It's a 08 Hatch STi and my tales of woe are listed here: https://www.scoobynet.com/general-te...-the-cold.html

I'm probably going to get it mapped next month now, once the pump is in and the other 2 injectors.

I'm trying to keep the other thread updated as I change things for future reference.

 

Hi Ian

Those yours issues are I would suspect are map related and seen few threads on this on US forums on this,usually mapper will change Fuel pump duty cycle to 70-100%

Yours injectors I would suspect are fine and yours fuel pump is OK too,should be enough for yours next mods

I would speak with yours mapper first and then decide,if its worthwhile to change all this

Hope this help

Thanks,Jura

 

The pump will need changing before mapping, an uprated pump will over fuel the engine on boost in the open loop areas. A std pump is inadequate for anything other than a very mild tune of a std car

Your hesitation problem will not be fuel related, you may have cracked piston ring lands causing the ecu to pull ignition in the rpm area you mention in other threads, it could take 20 degrees of retard easily which would cause the engine to run very roughly and not have any power.

Disconnecting the battery will reset the ecu and it takes time for the ecu to recognise the problem again which is why it feels better for a while.

get a leak down test and compression test done I suggest.

There is one other possibility, it could be suffering from "phantom knock" syndrome, if so you will never see any codes and nothing can be changed to fix it, the only way to sort that is to modify the way the knock sensor is mounted BUT that can only be done in conjunction with a mapper as the ecu must still be allowed to react to genuine knock

not an easy one, changing injectors will do nothing its nothing related to the injectors

cheers

bob

 

Maybe a daft question? Why are you not getting the problem fixed under warranty?

 

@Bob Rawle, what is your thoughts on mild tune, filter , sports cat and full exhaust?

 

Sorry I didn't expand that. Aftermarket warranty, I bought the car second hand last year. The warranty won't pay unless something is broken and at the moment you can't say that as the car does run.

@Bob the pump will be done just prior to you seeing it S4U in Feb/March (spoke to Rick yesterday). Len has already done a compression test and all cylinders were 150. When it's on the RR will you be able to tell if that amount of retardation is present in the map prior to tuning?