Here's the deal:

When my evo's at idle and the boost gauge is reading vacuum, most of the time it wags about 1-2 mm up and down, but whenever I apply any gas it responds exactly how you would expect it too. If it didn't firm up with boost, one might think that the needle was loose, but its not. The guage is T-ed in correctly according to the forum how-to's, also.

Do you guys have this too? If it's normal with evos, I'm cool, but a mechanic I know said it might indicate a valvetrain issue.

Opinions? I'd really appreciate your help with this!




BTW, my mods include:

BR 3" turbo back w/cat delete (O2 fixed)
BR upper IC piping & mini Batt. kit
BR intake & pipe kit
Walbro 255 lph FP
BR MBC @ 20.5 psi
Dynoflashed for 93 octane
Exedy twin disc
B&M short throw
Greddy TT
Autometer boost gauge (column mounted)

 

try to do a search next time been talked about a lot. here read thru this thread twards the end should be what ur looking for. sounds like you possably T'd into the fuel rail off of the vacume hose thats all the way on the passanger side.. not the best place because it changes preasure think like the 2nd and thrid page has some pictures on it their is one with red drawing on it its a good place their is a better place but the good place works perfectly fine and ur probably close to it.


https://www.evolutionm.net/forums/sh...ad.php?t=98250

 

Chinto, thanks for the link to the thread, you'll probably recognize this pic!



This is where I'm tapped in at, do you think vacuum flux from this location is common? It's that "needle-wagging" at vacuum that's got me worried.

 

i recognized that picture...i should have put a copyright on it...

anyhow its possible the location you took, that its getting a bleedover from somewhere else.

I dont know, thats my guess.

 

haha if thats where ur tapped ur tapped at the right spot.. umm.. possably try a diff boost guage if you can get ur hands on one


( fyi its blackevovii's engin thats all dirty ) i had to clean it for him so he took the damn pic so i could help people.. ( and yes i did clean it )

any way if ur getting spikes or movements from taping their you possably have a leak some where but id try a diff boost guage first normaly easier then hunting down a hole or leak in vacumelines.

 

mine does the same, but only started worse after cams, your fine.

 

Thanks for not suing me for using the pic -- HAHAHA! Anyway, I really appreciate your responses!

Lucky for me, I've got a new set of Defi D gauges at the house (including boost) ready to go in my new Craighardy panel soon --- that could be the ticket! I'll give the boost gauge swap a shot, and hopefully that will address the issue.

Thanks again fellas!

 

Thanks 93civEJ1, that's good to know (especially as I'm about to go with 264's). Much appreciated!