Hello there,

I've got a Gems ecu in my '99 wrx and we can't get the idle mapping right.

It needs to be very rich to make it run right. When we decrease the fuel mapping it stalls. What else can we try to get this right ?

The rest of the mapping goes fine and it runs well (about 390hp on the engine at 1.4bar).

The car has the following mods;

- 2.5 closed deck engine
- Forged ROSS pistons
- Forged connecting rods
- Sti bearings
- HKS FMIC
- HKS SSQV
- HKS Garret Turbo (GT 2835)
- 740 cc injectors
- Extra cold spark plugs
- Invidia Downpipe
- Invidia Middenpipe
- Varex backbox
- Apexi AVC-R Boostcontroler
- Lambda-Link
- Knock-Link
and some more stuff

Thanks in advance

Derk

 

fairly usual to have to leave the idle richer on the GEMS, firstly rescale the fuel map so you have the minimum increments in the fuel cells.. (you will need to double check the whole fuel map is still correct after this)
You should retard the timing off flat in the areas the idle may touch and get the fuel cells the same also.. but you are likely on that setup to need to run it at at least 13:1AFR to keep it stable.

it can be a nightmare where you spend ages altering stuff and just nearly get it perfect and make one last little alteration and it throws the whole lot out again.. lol

Simon

 

Hi Simon,

Thanks for the info, we'll use your tips to get it right.

My mapper usually works with autronic and as far as I know i'm the only subaru driver using Gems over here, so it's hard to get it mapped right. Luckely he's one of few that want to try and figure out the Gems system. Using the help program we found out about the rescaling . We needed to because at the higher rev ranges it wouldn't open the injectors long enough.

I've had Steve Simpson over here ones a few years ago, but after that I had a head gasket leak and other problems and needed a rebuilt, so the mapping had to be changed again. Having Steve come over here every time isn't cheap. He did tell me that the Gems system has to be treated diverently then other systems as it's in some ways not very logical.

Derk

 

if you can learn to map a gems well then everything else is easy in life

 

Roger that

Derk