Jay_bee

iTrader: (1)

Im currently running an Apexi on a MY99 STi and Im considering getting a GEMs ecu as I have the option of doing a P/X with my Apexi plus some cash (for a very reasonable price).

Mods at the moment are: Apexi induction & induction heat shield (by AndrewC), newage TMIC, full decat, Walbro 255 fuel pump, Apexi PFC, Sard Racing radiator, uprated oil pump, lightened flywheel & Exedy organic clutch

I've done some searches and spoken to a couple of people but Im getting real mixed views.

The options are keep the Apexi and get an AVCR & 3 port boost solenoid or swap the Apexi + a few hundred quid (price of the AVCR) for the GEMs

From my limited research (and knowledge) the pros & cons of the GEMS over the Apexi from what I can tell are:

Pros:
Get rid of the MAF
Mappable boost (& more control over the solenoid duty cycle?)
Charge temp sensor to adjust ignition (when charge temps go up)
Switchable map
(Antilag as a toy but its not really useable day to day and with my current turbo)

Cons:
Crap at starting
Doesnt idle
Hack into wiring harness
The charge temp thing is great when its hot but when its cold (like in winter) will be more likely to overboost (if originally mapped in summer) as it "could" be mapped leaner when its warm?


HELP!!!

Neilo

i woudlnt bother, the APexi im fairly sure can be mapped without MAF too, and im sure you can have switchable maps on them too? for the limited gain id stick with what youve got....

911

Friend had Gems on his RA.
What you hear is correct in his experience.
Run the Apexi and have it mapped by an expert. (Andy F in my case)

The Fixer

Stick with what you already have, fit the APEXi boost control kit (& APEXi solenoid) or an AVCR with its APEXI solenoid.

Not much to be gained really by swapping as it will cost you extra to swap and then it will cost you extra to get the GEMS remapped to suit your car. If your desperate to get rid of the MAF then Andy Forrest sells a MAF delete type kit but I suspect with the level of mods you are running there will be no need to get rid of the MAF at this time.

Conrad

Jay_bee

iTrader: (1)

Thanks for the replies.

I can switch maps on my Apexi, if I plug my laptop in an load a new map, not exactly "switchable", but I get where you're coming from.

With regards to future mods, I will be finishing off uprating the fuelling with a SX fuel reg and bigger injectors (prob 740's), sorting out a bigger turbo (poss a Garret of some variety), tubular headers & uppipe, Samco inlet (they're the main bits that are planned.. apart from the rebuild when it goes pop LOL).

So Im not sure if that'll have any bearing on things?

With regards to the MAF delete, thats about £200 plus a remap i think?

The bottom line is I can basically get a Gems for the same money as an AVCR.

When I originally had it mapped (by Andy) it was suggested the Apexi boost control kit was really more suited to older cars.

SO... its get the AVCR and solenoid then?

911

Think so.
I'm running a 2 litre with AndyF 20g + supporting mods mapped to 407 x 380 on a stock MAF and a 3 port sol.(Optimax = NF)

Jay_bee

iTrader: (1)

Nice figures, whats the lag like on the 20g?

I actually had collected all the parts listed above (except I had a TD05/06
20g that I bought off Steven Darley not a Garret but its been suggested by a friend a Garret might be the way forward) about 3 months ago but sold them all before I put them on the car because I was going to sell the car... I've since changed my mind as I couldnt bear to get rid

So now I've got to start collecting all over again

Anyone got an AVCR for sale

terryb

I run a GEMS and can report no poor cold-starting issues nor any real idling issues.

I think though the worst thing could be the fuel economy as apparently it runs closed loop all the time (or so I've been told)

I think if I had the choice of which one to go for from the beginning then it would be Apexi

Davey P

iTrader: (1)

Stick with the Apexi. If you have got the commander then you can switch maps using that.

gazza19800sti1

gems is far better anti lag for a start , switchable too , more complex yes maybe but if you know what your doin gems can be amazing .if not would be a right problem ... ..my question is why dont raly cars use apexis then ????????? especially as throttle responce matters so much ...?
apexi are bang per buck , and have produced amazing performance . but i mybe old fashioned but dont you get what you pay for .. and yes cold start can e a prob but can be sorted , if i had anoter option the only other way i would go is autronic

gazza19800sti1

sorry keyboard bad spilt lager on it last night.
gazza

911

No anti lag with Apexi (or at least the one i have)
Apexi is £700 inc mapping.

GEMS/MOTEC etc all more $$ as they are very focused ecu's, but for a road car? I have an FC on my hill climb/road car (in that order)

Yes, you do get what you pay for, and a £700 Apexi is great for the purpose of road car not rally/track car.

Andy F runs (2 x ) Apexi on his 9 sec 1/4 miler.

As to 20g lagg? Yes it does a bit if you are lazy. Keep it in the sweet rev range and you won't notice it, but let it off the boil and it will lagg.

Mine hits 1.5 bar at about 3800, so that is the bottom number when pressing on. Keep it running between 4000 to 7500 (Sti remember!) and the car is fab.
Mind you, would like to bolt a 2.5 with forged internals to it...

Graham.

jaytc2003

iTrader: (1)

how do you do that????


what software do you use?

Jay_bee

iTrader: (1)

Well, I havent a clue how you can possibly switch maps using the Commander as there isnt a facilty to save an alternative map to it as its only and interface with the ecu, theres no storage space, well, I certainly cant on mine anyway.

At the moment, I dont use the software (which is the FC Datalogit) as I dont know enough to tinker safely... yet

http://www.fc-datalogit.co.nz/

From what I do know its just a case of doing a map, say for race fuel and saving a copy of it just as you would any other document on your pc. Then when you want to use it, connect your laptop to the ecu and select the saved map off your desktop and bobs your uncle (i think?).

Im trying to learn a bit more about it.

No theres def no antilag option on the Apexi and in reality, yes its a nice toy to have but its not right to use it on public roads and I dont fancy shelling out of a new turbo every 20K miles so Im going to stick with the Apexi and go for the AVC-R

Graham, with regards to a 2.5 conversion, I've considered that for mine but its been mentioned to me that with mine being a Type R (close ratio box) do you think it would be worth it as from my understanding the 2.5 doesnt like to rev (like the STi engines should do to 7500 - 8250) as its all about low down torque?

AndrewC

Jeff - haven't we been here before?

Give me a ring or email me if you want to talk about it.

Andrew...

Jay_bee

iTrader: (1)

We never looked at a Gems before Andrew... but I havent heard from you for ages so I dont like to impose, plus thought you'd be mega busy with the mafsim stuff

I'll drop you a line

911

2.5?Forged internals should give a better max rev point.
With such an engine a new box with ppg gears allows a 'UK' ratio set.
Graham.

Jolly Green Monster

iTrader: (4)

You cannot switch maps with the PFC or the GEMs, the GEMs switch just removes some ignition.. it doesn't switch to another ecu map.
You can with the PFC have 4 boost settings and switch on the commander or remove timing from the whole map with a couple of key presses therefore getting the same thing as you do with the GEMs.

Unless you fit a different idle valve to allow more air to flow and/or jack the throttle open the GEMs antilag is not true antilag and just used to pop and bang for show which you can achieve on the PFC anyway.

Rally cars don't use Apexi as the removal of the MAF sensor is wrongly or rightly deemed to be attractive to them and the GEMs was around before PFC really took off and has been followed aim lessly since, with also the "you get what you pay for" idea being followed rather than actually analysising what you actually get. Plus the main UK dealer in GEMs runs a rally car which brings it to the attention of anyone doing rallying.

Boost is slightly more controllable on the GEMs in that it is RPM based control but purely on the duty cycle rather than an actual boost target but when set up correctly does work well. AVC-R is more controllable with gear dependant duty increase of decrease allowing different boost in each gear or the same boost reached etc and allows monitoring and peak display etc.. but is useable with both PFC and GEMs.

PFC on the 99 STi has a charge temp sensor too.

Already mentions antislag and switchable map

Most of the cons you mention are down to the mapping, if it is mapped comprehensively then there should be no starting / idling problems, the wiring if hacked about way to much on the installations I have seen and agree it is an issue.

MAF can be removed with the PFC too now.

Simon

Jay_bee

iTrader: (1)

Thanks Simon,

Funnily enough, I've just been having a chat with Andrew about the charge temp sensor on the Apexi and he said the same thing but I was under the impression that yes there is an air temp sensor but not one that will adjust the timing depending on what the temp is?

Im aware of the 4 boost settings/targets on the Apexi and that you can increase/decrease timing across the whole map but its not quite the same as having a dedicated map for certain situations, and with regards to the switchable map on the Gems (or not as the case may be), I stand corrected

Not that it makes any difference to me as Im not particularly interested in the funtion but I wasnt aware there was an antilag type facility on the PFC ?

Jolly Green Monster

iTrader: (4)

You can set it up to retard the timing and/or increase the fuelling on intake temp..

You can inject fuel on a closed throttle and retard the timing to make it pop and bang on overrun which is what 99% of the GEMs are set up to do only anyway.

Simon

Jay_bee

iTrader: (1)

Thanks again Simon

Im popping round to Andrew's next week sometime (assuming his diary allows it ).

Jeff

Davey P

iTrader: (1)

My friend has a Apexi Power FC Commander and ECU. He can switch between a low and high boost map. I have seen this with my very own eyes.

stockcar

most of the issues surrounding idle and poor cold starting are down to the individual 'mapping' of the car and not due to the software or hardware of the GEMS................we personally have a track/rally car that due to work constraints can sit for months at a time and fires up first try every time, idles as a factory car and does what it should!!
have plenty of customers with these on and no issues either........................

alyn

Jolly Green Monster

iTrader: (4)

you can change the boost yes.. but it only alters the target boost and the boost duty cycle.. the actual ecu map is not switched.

Simon

Jay_bee

iTrader: (1)

Simon,

You mention that the PFC for the 99 has a charge temp sensor. Which sensor does it use for this funtion or will I need to get an additional sensor and plumb it in?

Incidentally, where does the sensor actually go, into the intercooler in the same fashion as a Gems?

And if you dont mind me asking, where is the setting for this? (Im sure Andrew will know but Im just curious)

Jeff

Jolly Green Monster

iTrader: (4)

it is there already.. in the air intake pipe near the air filter.

Settings are set up via datalogit or similar software by the mapper.

Simon

Jay_bee

iTrader: (1)

I thought it might be that one, at the moment, mine's just "kicking about" near the induction kit.

Do you think it would be sensible to relocate it into the intercooler so its actually monitoring the charge temp?

As for the Mapper, AndrewC will be doing it this time

Jolly Green Monster

iTrader: (4)

I would position it so it measures the air entering the air filter.

Excellent.. mapped properly rather than the current shambles.

Simon

Jay_bee

iTrader: (1)

Have you heard where I've just had it mapped or something?

Jolly Green Monster

iTrader: (4)

I think it is pretty obvious as they obviously tried to sell you a GEMs..