streetzlegend

iTrader: (8)

On 3.5s with FWD manifolds, which cylinder usually runs leanest? Where you guys recommend I put a probe?

I remember seeing a good article talking about the best placement, mentioning that if you get temp from a single cylinder it wont be very accurate since it picks up pulses and not a constant flow, so its better to put it on a bank instead (such as one leg of the ypipe, perhaps the leg that includes the leanst cylinder). what yall think?

Nealoc187

iTrader: (23)

About 1-2" down the primary, on the hottest cyl. I'm not sure what cylinder runs the hottest though. You could install 6 EGTs like they do in planes, and monitor each cylinder lol.

When I melted pistons on my VQ30, it was the front center, and front driver's side that melted - take that for what it's worth. Maybe those are the hottest, but maybe it was just luck of the draw as far as which ones I melted when I overboosted.

Which cylinders did you crack ring lands in and/or blow the head gasket on? If you can figure out some consistency with which cylinders people are having problems with, I'd say that's a pretty safe bet as to what cylinders run the hottest on our cars.

edit: the other two times i had problems with a VQ, once it was the rear driver's side cyl, and once it was the front passenger and front driver's side cyl. not much consistency there. i bet you can find some more data if you search other people's blown HG or cracked ring land posts.

maxmaxima91

varying injector flow can change this to so that kinda makes it more complex.. i vote 6 probes.

streetzlegend

iTrader: (8)

Yeah, for sure im not going to put 6 probe$. For my head gasket on the 3.0, both gaskets were had on all cylinders lol, and for the ring lands, i never took it apart so im not sure. For the bad 3.5 I got, the cylinder that threw a rod was rear driver driver side like Neal. One closes to the throttle body.