terryb

I'm lookig at a potential new purchase that has a GEMS ECU fitted. I noted on the test drive that the idling was erratic when first started (it needed revs to prevent it stalling). This sympton only lasted a short time and it would idle normally after 10s or so.

Is this a common symptom associated with GEMS?

Cheers

Terry

stockcar

would suggest the cold start is not quite right, not generally a "fault" just simply slightly out of calibration....................

alyn

911

a friend of mine had GEMS mapped by Steve S on his Sti RAV3 and his was really bad when cold.
Graham.

terryb

thanks guys

stockcar

Graham, would suggest its simply not "finalised"................

we do a lot of these - both from scratch and re-maps, and although you can have a good guesstimate for the set-up from cold - its only after doing a couple of cold fires that you can be sure its sussed...............

the biggest problem is if someone wants it back same day, as they arrive hot and then you can't do a "cold start" to check, obviously...............

alyn

Johnny50

I had the same issues with my Gems..

You get used to it.

Kael

You mean GEMS is meant to idle?!?!?

Johnny50

Think you pay extra for that.

terryb

I think I get the picture now..

Kael

Putting this as politically as I can....

Fantastic ecu, shame about the 'choosen' mapper shall we say?

Johnny50

Hmm...

911

I think that the GEMS is a competition orientated ECU and as such is not full of road manners.
Other end perhaps is the Apexi Fc I have that is great on my road/hill climb car.
Even that is a touch hesitant on starting, but great when warm.

There is a compromise whenever you modify a road car.

Graham.

Scoobyslammed

My Gems on MY98 Sti type R is spot on... runs near perfect... was mapped by Steve Simpson...On a cold start it will fire straight away with no throttle then stall, 2nd time will fire straight away and idle properly... so if it don't start 1st time, will always fire 2nd time...
Only hope he does as good job when the 2.5 is in and up and running???

stockcar

thats a bit of a fallacy Graham, pretty much all of the impreza versions have full cold start/ idle control simply need to be calibrated properly..........

think most problems occur when a car is "mapped" in a couple of hours and then left at that, you need to try at least one proper cold start the following day to refine this area because its obviously not feasible when the car is red hot

some people fit, map and leave the same day so its very difficult to get this last area completely perfect

alyn

Kael

Agree 100% with Alyn.

911

Ok, give-in. Just witnessed it so many times on Carman's RA.
Graham

powercrazed

I have a GEMS fitted to my 94wrx. Never, ever fires first turn (even if you leave it a few seconds to prime the pump) but always starts second turn. It doesn't always idle perfect but its ok 75% of the time.

Nathan

AlanG

Well he's done a couple of 2.5's i know of...results will all depend on spec and condition of engine

tath

Mais non, i've got a PFC mapped by a certain scotsman that starts and idles better when cold than my standard ecu

911

Exactly.
I will have the PFC mapped again by The Scottish Wizzard early next year from the start, so maybe that will sort the 'unique' cold idle issue I have.
Other than that it is a 'gem' of a system....
Sorry, Graham

Scoobyslammed

Quote:Well he's done a couple of 2.5's i know of...results will all depend on spec and condition of engine
Engine work is being done by Teg sport, mapping by Steve... spec as follows...
2.5 block with uprated pistons and rods, modded oil pump... hks headers and down pipe all wrapped...620 injectors, copies of the wrc cams, head work, fmic, gems ecu... and then what ever Teg decide turbo wise... at the moment i've got a sti 8 one on... was £800 new last year, but teg are doing another one for around £1200... dunno what it is though? But my turbo is on its limits... so the only way is up? Anti-lag too...can't think of owt else at the moment...
Fingers crossed i'm hoping for some good power/torque figures....

AlanG

Doesn't sound too disimilar a spec to mine at the moment.
Should get good torque depending on what turbo they recommend

When you hoping to get it mapped?

Scoobyslammed

Just doing the final saving and getting the parts together... it should be going to Teg sport early next year... (jan/feb)... for the engine rebuild... once running in period is over it will be mapped...
All this because my 2litre block developed a noisy bottom end bearing...
While its apart may aswell upgarde!!!
Was running high 300bhp atleast before my misfourtune... previous owner spent a bomb on it...