EVO GTA RPM Drop

[NiteWalker]

Hi Guys,
I'm new in this forum and perhaps sifu sifu here can give me some advise on my issue. I owned an evo 7.5 gta and lately getting a very strange problem which is the RPM drop tremendously to 500 and bounce back when i'm pushed and released the gas while i'm driving. The event only happend when i push released the gas at 2500-2800 rpm especially when stopping and moving between speed bump and up hill. The issue happened right after replace the faulty OS2 sensor. No faulty code, no error was detected by using the Autoland Scan device. Tried turn off BOV, replaced throttle body, MAF sensor and even install the HKS EiDS (Electronic Idle Stabilizer) is doesn't help at all result the same. Any idea? What the possible cause of this issue?

Spec as the following:
Stock ECU
Evo8 downpipe
HKS Fliter
HKS BOV
Greddy Boost Controller
Apexi Timer and Boost Meeter
Pivot Speed Limiter
RallyArt Exhaust

 

[egiewan]

Happened to me before bro....go to your workshop, check if there is any vacuum hoses loose or not connected properly to the intake manifold area. When I got my GTA, I was having the same problem till recently when I top overhauled my car...my mech told me there is one unused vacuum slot not connected to anything. It should be closed but I think the previous owner left it out. Once the hole was covered, the problem was gone! Anything, update me here k? :-)

 

[NiteWalker]

Hi Egiewa, thanks for the advise will rush to my mech tomorrow to get them check all hoses. Will update you later.

cheers.

 

[egiewan]

No problem bro....make sure you check throughly. There are some hidden vacuum slots under the intake if I'm not mistaken. If your regular mech cant solve it, maybe you can pay a visit to mine in Setapak, KL.

 

[NiteWalker]

Bro, can you send me your workshop address or contact nos in case my mech can't handle it i can arrange to drop by your buddy shop immediately. Can't stand with the dropping anymore very annoying need to get rid of it. Or you can text me the info @ 0193255958.