I've a 96 V3 sti which has had a lot of engine work done by a previous owner and its running 390 bhp on a GEMS ECU. Does anyone know if this supposed to run without the MAF. It seems to have no effect whether the MAF is connected or not. However I still have the lumpy idle and sometimes poor cold starting which seems to be a trait of the GEMS. Thanks.

 

Yeah im 99% sure its mafless

 

hi I also run gems on my V5 RA and wood be interested in see if this is right, as the last owner sent a lot of money on the car why buy gems and not simtec? or can u update the software on a gems to a later version to run mafless thanks for the help guys

 

 

Yeah I am considering switching to Simtec myself. I don't know a great deal about the GEMS but rightly or wrongly the MAF has no effect on my car!

 

Yes the Gems runs Mafless

Banny

 

Thanks for the help going to unplug the maf what symptoms am i looking for running with it unpluged?

 

The car should run no problem with the maf disconnected.

Banny

 

Benji and poo () - you both may as well remove the MAF tube and any other unrequired associated paraphernalia, and simply have the cone filter (assuming it has a cone?) fixed directly to the turbo intake pipe, for a shortened and less restrictive airflow path, etc.

 

Might be worth checking whether the GEMS on the cars concerned are using an inlet air temperature sensor in the MAF unit before running with them disconnected as a matter of course.

Similarly if the cars have been mapped with elements of the OE intake in place, recommending that these bits be removed and replaced possibly isn't the safest advice, even with a speed density ECU.

 

The sti v3 has a seperate air inlet temp sensor, it is not built into the maf sensor like the MY99/00 cars.

Banny

 

Cool, thanks Banny.

 

Thanks for your help guys. Am I right in thinking that you can also set up anti-lag on GEMs???

I still think i'm going to end up going down the Simtec route though eventually.

 

Is it lumpy when you drive on low and part throttle like under 2500 revs?. It might be the antilag thats doing this. Do you have a switch in the car to turn it on/off?

 

No, no switch unfortunately. I'm pretty sure I haven't got the anti-lag option. It can be a pig sometimes when starting from cold and just a bit lumpy when trying to crawl along in traffic. Once you are on an open road its great! I've heard that the poor cold start and lumpy idle are a GEMS trait and they are great for rally cars not so good for the road.

 

I think the GEMS are liked by rally prep specialists TEG Sport (Town End Garages?)

 

Gems does not use the MAF it uses a MAP sensor. This is connected to two of the wires cut from the MAF loom to connect to the ECU. I have had a GEMS on my bug for nearly 6 years and love it. Yes on a cold morning it is a pig to start, when I was up in Scotland anything below 8 centigrade was a sod but could be done, any lower and 15 mins work to re-fit oe ecu and get it warmed up. I know run a lovely 400 bhp which is lovely in town or on open road. Mine is looked after by Steve Simpson at TEG Sport but also Scoobyclinic do GEMS as well.

 

great help guys but why is my maf still connected? and can i just replace it all with a samco hose and pull it all out? sti v5 99/00

 

If the maf is plugged in I'd be tempted to leave it unless the wires have been cut further down and connected to a temp sensor or like someone else suggested it might be taking temp from maf sensor?. In the gems software there are options for maf or map so not sure how your car is set up (don't know a great lot about mapping). Its prop. best to get someone to plug it in find out if it needs that sensor. You can ugrade firmware on gems for later versions think its about £80.

 

i will be looking deeper into this and i post my results