Hello.
I installed the PPG dogbox with speedo gear suplied with it along with AEM standalone and an STI cluster into my WRX. and now i have mystery with speedo. When the car cold it works fine but when it gets warmed up, especially driving highway it is starting to do crazy things. my speedo on the cluster jumps a little around in speeds, sometimes it drops to 0 while crusing. sometimes its jumps like from 40 to 60 mph. Especially when I acc hard it is start to jump like crazy. And sometimes it can wor fine for half an hour and then start to do that again. On the other hand I have AVC-R apexi in the car and speedo in there doing crazy stuff too. some times it shoots top speed like 900kph , sometimes it jumps from 50 to 70 to 40 to 90 and so on when i am crusing at constant speed. and someimes it works just fine. and it in not conected to speedo on the cluster. I mean if the cluster speedo shows fine speed the avc-r may go crazy and on the other hand when avc-r is fine the speedo can do that. Any ideas PLEASE?
I already tried to replace the cluster back to wrx - didn't help. I replaced the tranny speedo sensor to a new one - no help either. So my only options are AEM and speedo gear with dogbox. what you think it can be? maybe something else?
Thank you.

Or an electrical/grounding issue...

where is grounding inside the car is? I checked all the grounds in the engine bay but where else i need to check?
Thsank you.

I had this same problem when I installed my EMS. It seems to be a common problem with these computers(I've seen it in a NSX and a Supra as well). All I had to do was to secure some of my grounds a little better and the speedo went back to normal. You may want to try giving the EMS some more heat shielding and insulating it from the stock ecu bracket. Many people have reported problems with the EMS when the case is grounding out. I would try pulling the EMS out and putting it on the carpet with everything still hooked up to test and see if you still have the problem. My 2 cents.
-Hill
Agile Automotive Performance
www.agileauto.com

Yes I had the grounding problems before. but i tied all the grounds and it went back fine. maybe i need to find some grounds inside the car? do you know of any?
Can you ell me which grounds located where so I could check them better?