R3T cyclical hiss

[Anomaly]

Have you looked / felt around the exhaust side to make sure it's not an exhaust leak?

Yea, it's not. It’s comin' from the top/ intake side of the engine.

 

[Gregger]

If I remember, one of the fellows had a cracked throttle body boot. The rubber was torn by the clamp at that location (too tight). I did a search but couldn't find the post. Did you check on Tune ECU to see if your vacuum readings were similar between cylinders and/or low overall (I can't remember if a low reading below 600 usually means low vacuum)?

Another way to check for a leak is to use a bit of acetylene from an oxy/ace torch. I've found many vacuum leaks with this method in the automotive field as a mechanic. Engine revs up right away. You have to make sure the intake inlets (throttle bodies) aren't picking up the acetylene fumes giving a false vacuum leak indication. Hard part is getting the acetylene...

 

[Tripps]

If I remember, one of the fellows had a cracked throttle body boot. The rubber was torn by the clamp at that location (too tight). I did a search but couldn't find the post. Did you check on Tune ECU to see if your vacuum readings were similar between cylinders and/or low overall (I can't remember if a low reading below 600 usually means low vacuum)?

Another way to check for a leak is to use a bit of acetylene from an oxy/ace torch. I've found many vacuum leaks with this method in the automotive field as a mechanic. Engine revs up right away. You have to make sure the intake inlets (throttle bodies) aren't picking up the acetylene fumes giving a false vacuum leak indication. Hard part is getting the acetylene...

Carb cleaner works too.

 

[Anomaly]

If I remember, one of the fellows had a cracked throttle body boot.

Ha, at least I now have a part name. Scope came this mornin' (4am) so I plugged it up to charge and I'll check it out once I get home. Smoke helped a lot to narrot it down to a specific area, but didn't see the actual leak yet, just the vicinity.

 

[Stillserving]

Only issue with carb cleaner is nowadays there is so much plastic and paint everywhere, gotta watch where you spray that stuff. Old days, not so many worries...

 

[Gerald]

If I remember, one of the fellows had a cracked throttle body boot. The rubber was torn by the clamp at that location (too tight). I did a search but couldn't find the post. Did you check on Tune ECU to see if your vacuum readings were similar between cylinders and/or low overall (I can't remember if a low reading below 600 usually means low vacuum)?

Another way to check for a leak is to use a bit of acetylene from an oxy/ace torch. I've found many vacuum leaks with this method in the automotive field as a mechanic. Engine revs up right away. You have to make sure the intake inlets (throttle bodies) aren't picking up the acetylene fumes giving a false vacuum leak indication. Hard part is getting the acetylene...

Pump squirt can with gas or lacquer thinner, does fine in a small, localized area. Need to check that uncovered connection doesn't have a hose somewhere close that came off and is not getting supplied with vacuum. Seems like I remember a hose on that and not a cap.

 

[Anomaly]

Yea

If I remember, one of the fellows had a cracked throttle body boot. The rubber was torn by the clamp at that location (too tight).

Leaked a bit of propane, and could just find the issue is between the two rear cylinders (#2 & #3 maybe? No idea the numbering). Still was never able to pinpoint it. My best guess is that it's the throttle body adapters. I'll check with the dealer tomorrow see if they're available. If not ebay. Not gonna wait around on a 20wk backorder.

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Now, just gotta figure out how to remove the throttle bodies. I'm fairly mechanically inclined, but I'm accident prone so hopefully I won't break anythin' gettin' these out.

Oh, and yea, the cylinder pressure is off.

 

[TURBO200R4]

Cyl numbers is 1 in the front
2 in the middle
And #3 in the rear
There is three hoses attached to the base inside and at the otherside there is a nipple on each throttle body.
A backfire can blow any of these off
And sometimes the hose just split
Possible leak on the injector orings.

 

[Anomaly]

Ok, I think I've finally found it. The clamp ring on the throttle body adapter of cylinder 2 is off by like 1/4". The clamp on cylinder 1 is loose as well. I can't see it at all, but I can feel it. The clamp for cylinder 1 is *relatively" accessible, but man cylinder 2 is hard to get to. I haven't been able to get my fingers on the screw clamp yet. But being that the front of the throttle bodies can pivot off the intake 1/4 of an inch, I think the leak is from loose clamps on the throttle body adapters. Gonna fool around a bit more tryin', but I may end up takin' it to the dealer. Unfortunately, I know when I'm out of my depth. If this was a simple hose or somethin' I'd be good, but I'm not super handy.

 

[Anomaly]

Alright was sick for a few days and ended up in the ER so pardon the late response.

Turns out it was the throttle body adapter on cylinder 2. The boot/afapter had come loose and was being sucked into the throttlebodies creating a small gap and the air leak. Wasn't really confortable unmounting the throttle bodies, but I had a friend as an extra set of hands and we got it.

Thanks for the help diagnosing the problem guys!