should I go with a smaller throttle body?

Im ultimately trying to make more low-end torque for towing. Its an LQ9 with a comps cam 202/212 .507 lift 116 LS. besides having some idle issues which I think is caused by the guy before me drilling a hole in throttle plate. cant get it to idle less that 725 with IAC at 0. stop is all the way down... but I digress. I know back in the carb days we'd go 2 barrel when we wanted to make lower end torque, so Im thinking the trottle body would have the same effect. thought and any idea how to calculate this?

if you look at this log.. its pretty big. I was just gathering data. found I needed to pull a little timing out.


Attachment 94435
Attachment 94436

Should have probably mentioned other than cam and springs its an all-stock motor with cathedral port heads.

what are you pulling/towing? is there a goal or budget in mind, or??

I?m planning on pulling a 13kmax 5th wheel. I don?t want add boost and would prefer to line this swap out first before making too big of changes. Just trying to get more out of it. An O5 lq9 was rated at 380 ft lbs. I was hoping for 410 at the flywheel at about 3500 rpm.

Fix all the fueling first before worrying about pulling timing. The very positive fuel trims need work first, then figure out timing. Whatever happened to your VE table is a mystery to me, that is something horrible looking. Being lean and the throttle body issue go hand and hand. If it's fighting the fueling you will never get it to idle right or drive right.

The stock throttle body is what you should keep, it best fits the stock intake manifold and going smaller is a step backwards. I would weld the drilled hole shut or get a new throttle body though. There should be no reason to have the hole drilled in it with such a small camshaft.

I also see it has larger injectors based on the tune file, make sure that data is correct and that fuel pressure is steady around 58psi.

You can easily plug the TB hole with a piece of lead shot.

AH Crap.. the VE table. I copied that from the original tune the guy gave me. I have a closer one (in theory).
Thanks, I will check the fuel pressure and the injectors. Probably part of the problem. as for the throttle body I got it with the motor, but that was before this cam swap.

so I pulled the injector. Its 12594512 which is 36 lbs (I think) and factory calls for 26, .. so as long as they match in the tune. 36 and 36 or 26 and 26 I should be ok.. right? As for fuel pressure, I'm going to have get my gauge, that I can't find right off.