I hooked up my OBD2 scanner to my g35.

I was surprised to see that the throttle only opens up 85% at WOT. WTF is going on?

I tried this with both the engine on and off

Is there a way to make the throttle open fully?


Thanks,

Andrew

 

Somewhere I read that if the throttle body open all the way at 100% that there was an possibility of it sticking or staying open, has anyone else heard of this?

 

I read somewhere here that you don't get 100% untill a ECU "reflash" by someone like Technosquare.

After a search I found This

 

Sorry about the misinformation but, you were right Texasscout. Either way, there is no problem with his car being that the throttle open up only 85%, it's designed that way from the factory.

 

You must measure [with a manometer] the pressure differential across the throttle plate [plenum vs tube in front of TB] to determine what minor effect throttle plate position has on the plenum pressure at WOT.

Remember outside atmospheric pressure is what fill the plenum and subsequently the runner and cylinders.

A short cut is to just measure plenum pressure [how much lower it is than outside barometeric] at WOT...........the 20" HG at idle/cruise decreases to 1-1.5"...............1" HG= 28.92/29.92 represents 0.335 or 3.3% pressure drop.

When you bench flow a head, the industry standard is 28" water column or 1.0 psi loss from 14.7 psi or 6.8% total loss thru air filter, maf, hoses, TB, plenum, runners, valves into the cylinder.

Some engines like early Q45 actually open beyond 100% [parallel] to avoid this phenomenon 85-90-95-100-105-110-115 ----WOT position pretty meaningless as most engines have oversized throttle body.

What's important is whether the ecu understand that 85% .............IS WOT!

 

Wow. I wish you'd post more often We need more people like you in here.

 

I am wondering if the additional 15% opening can give anymore to the engine.

Is the throttle body already big enough for this engine so that opening up more than 85% won't provide an more flow? if not, there may be additional airflow available by opening the throttle a bit more.

 

If your throttle body becomes gummed up with carbon and the throttle body opens to 90-degrees (or 100% as some state) there is a potentially HUGE problem waiting to happen.

(The best I can remember from the explaination I received, 2nd hand, from a Nissan Engineer)...

When the car is at WOT, the ECU is NOT reading the data sent via the O2 sensors, rather it reverts to a fuel map for wide open throttle. This allows the car to get lean (or possibly rich depending on the mods you've added) for a period of time until the throttle body begins to close. If the throttle body gets stuck in the open position due to carbon build up, the plate inside of the throttle body could stick in the open position and the car could run dangerously lean for too long and then BOOM!

 

With all the Gs out here running with TS ECU (and there are MANY) don’t you think we would have heard about problems by now (if they existed)?...

 

NO! Most people will have the TB's cleaned at the dealership or just do it themselves. It takes a while (like 50,000-100,000 miles) for a TB to get to a point where it will get dirty enough to get "stuck". I'd say in another 2 or so years we'll start hearing about people with the TS ECU reflash having problems with engines blown *IF* they don't clean out their TB's when they should.

 

Where can I find more info (Preferably from Nissan) about properly cleaning the TB?

 

When the ECU goes into open loop it doesn't read the throttle plate but the "pedal" since we have drive by wire. The throttle sticking open would have little or no effect. What is being said would be correct if we had a throttle cable and the ecu took the tps signal for throttle input.

 

When you do get a TS falsh for 100% open TB . The ECU will still say 85% open on an OBDII . I started to wonder if TS flashed it in there..but they did and it just doesnt read that way

 

I think the point of my origianl post has been lost.

What I really wanted to know is if there is a power beneift gained by being able to open the throttle an additional 15%.

Is the 85% throttle opening somewhat choking the intake side of the engine??? Maybe our throttle bodies are amply large enough and opening the throttle more doesn't provide any more power !?!?!?!??!

 

I would opine that this could happen at 1% throttle or 85% throttle opening as well; this is not necessarily tied to the 100% (presumably 90 degrees) opening IMHO.

Since the throttle is controlled by a motor, could the 85% be to minimise the "lag" between lifting the throttle and closing of the blades? (basically to provide "crisper" throttle response)

My Trailblazer has a drive-by-wire throttle as well, and it is noticably slower to react than the Nissan product.

The size of the TB being large enough to support higher HP levels, I doubt on a lightly-modded NA car one would see any measurable gains from this alone. I doubt the 15% is choking the motor either.....