Strange misfire....

[joesfj40]

Evening everyone,

Currently my daily driver 96 4Runner V6 3.4 Supercharged 5 speed manual. Whats going on with it has me stumped... A very slight misfire that only happens from what I can tell in 5th gear at 2900-3000RPM. I have 0 codes and also 0 pending codes, for about 3000 miles now i've noticed this going on. As far as what i've done to being the process of elimination in trying to locate this issue is, clean throttle body, clean MAF, replace denso spark plugs and denso wires...


Next plan is to replace the fuel filter just for giggles? Along get a compression on all cylinders.
No signs of head gasket problems...
New motor has 50k on it.
Full wide open throttle is just fine, cruising in town is fine, and cruising at 65mph is fine but that 2900-3000 freeway speed is a very slight tiny misfire.

Any ideas?

 

[Mudder]

Is your timing set right?

 

[Kris]

I've heard that the bypass valve on the back of the super charger can go bad.

To me it sounds like a boost leak. Here me out.
At WOT (lots of skinny pedal) the fueling system is able to keep up - unless you have a 7th injector, the 3.4 fuel system is barely able to keep up.
At light throttle and little load, you aren't building any boost and, thus, not experiencing a boost leak.
However, at freeway speeds (70-75+?) medium throttle and medium load require a small amount of boost. Which, if i'm correct, is then leaked to the atmosphere.

How did the plugs you removed look?

 

[Kris]

P.S. This seems like a neat thread.
The 3.4L TRD Supercharger Thread - Toyota 4Runner Forum - Largest 4Runner Forum

Have not read through this one, but maybe it'll help:
Bypass Actuator on 3.4 TRD supercharger slow to close? - YotaTech Forums