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Old 07-03-2006, 01:53 PM   #1
Scooby Specialist
Member#: 100671
Join Date: Nov 2005
Chapter/Region: NWIC
Location: South King County
2004 WRX

Default Boost Spiking Using After Changing Maps with Cobb AP (kind of long)

First off, i have searched and have learned many things about boost spiking and the reasons why it happens, but still cant really find anything with the same as my problem.

Car Info: 04 with VF34, Sti Pinks, 255 fp, TurboXS TBE, HKS BOV, and i was running on the Cobbs AP VF34 Map, also running 18psi boost.

Before last night i had never accounted this huge of Boost Spike!

Well i was changing my base map with the ap becuase i only had it set on stage 1, but i was running the vf34 map on the realtime map. And while trying to do this i keep coming up with errors: Voltage too Low (its not), cannot connect to ECU. So I figured it was just the diagport cable (i heard these go out somtimes) So i figured i'll just pick a new one up in the next couple of days.

After all this me and the gf were going out for the night and i like to step on it a little coming out on the 50mph road i come out on. well it boosts up faster then ever and hits 20 psi, so i thought oh a little boost spike, happens sometimes. but then it drops all the way down to 10psi and stays there. This was all in second gear. Third gear does the same. BUT I DID NOT THROW A CODE!

Ok.... So here are the possibilities it might be and why i do/dont think its them.

1. HKS BOV - some people say that a atsmopheric BOV can cause this. I have had this on the car for over 5 months and no problems.

2. Leaking hose somewhere - I've checked over and over. tightened things and still nothing.

3. No Cat = no back pressure - i dont know if this is true but i have had the TBE on for about a month and no problems as of now.

4. Need to get my wastegate open up more - again no problems as of now with it.

5. Screwed up ECU - This is my theory just because it seems weird that happened right after messing with the AP. I did notice that i did have the radio on while trying to change the base map (dumb mistake)... But i heard if you screw up the ECU with the Cobb AP you wouldn't be able to start the car.

6. Stuck in Stage 1 on Cobb AP - I dont think that this matters but does it? Since i never got it changed did it just reset itself to the base map after the errors?

Car still Drives fine just as long as i dont get high into boost. Also i have noticed it is running a lot more rich, more and bigger backfires and smells a little bit more. Kinda poor at the moment so taking it to a shop is really the last option.

Any advice/ideas would be appreciated! Thanks!
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