Cheap and Easy Throttle Response Mods

[ccreddell]

I'll try to set some things straight here, even if no one is interested. It's true on most TBI trucks that flipping the air cleaner lid delivers gains you can feel. But there is a reason for it, and the reason it works so well is because most TBI air cleaners have the heat riser stuck closed. Whether the stove pipe is still there or not, 9 times out of 10, the flapper valve is always closed. I completely gutted mine, sealed up the hole and reinstalled it without the muffler and now I have the same airflow (or better) than a flipped lid, plus I'm getting cold air from the fender. The stock TBI can only flow so much through those 2 little holes and the stock air cleaner ducting to the fender can more than handle it. An open element has no advantage because you still can only flow the amount the throttle body can flow, and because you're sucking air from the engine compartment-even at speed the air coming in through the radiator is a hundred degrees higher than ambient. Hot air isn't as dense, so you flow less than if you get the air before the radiator heats it up.

 

[superdave]

Good call on that valve in the air cleaner. I hadn't thought about that one.

To the OP. Nobody is busting your chops. You get opinions on message boards. "Cold air intakes" is a topic of discussion that arises here frequently. Many people mistake more noise for more performance. It's still whatever floats your boat. The spring you added is changing the pedal feel and not really the response. Again, whatever floats your boat. I would add on that though to make sure you aren't doing something that may cause the throttle to hang open.

 

[Big D]

yea that spring Idea, not a good idea.

 

[Roger Stephenson]

Do you have objective data to support your assertion that the stock 'stovepipe' flows like **** at low RPM? Or any objective data at all to show what your engine requires at even 3000 rpm for airflow?

Factory air inlets that draw from in front of the radiator core support gives cool air to the engine at all operating conditions.

I did the 'flip the lid' on my '95 K2500 a week or two ago and will state that the seat of the pants feel supports that the engine is breathing much better and is making more power. I bought the K&N cold air package for my '88 C1500 and believe that this mod achieves much the same power gain. I only did the lid flip as a quick test to see what happened but I will be leaving it. Would I rather have cold air induction, yes but this is a zero dollar investment. I followed this up by having true dual exhausts fitted, and I didn't really feel much difference with that 2.25 pipes and mufflers.

 

[CoolDude1975]

The objective data is that I don't have to press the firm ass gas pedal halfway down anymore to get the ****** to move. Now I barely gotta touch it and it gets down. I don't know what sort of vibe I let off on forums but no one ever takes me seriously which is kinda funny and ok as well.

I posted this for any fella with a stock truck wanting more t response cause if I'd have known how much it helps I would have done this much sooner. But now this will only be remembered as 'that one weirdo with the open filter and reverse spring.'

And that's okay too. I'm absolutely happy with my damn-near-free driveablility mod.

Who gives a **** what those dudes are saying, you don't need anyone's approval or thoughts on it when you know for a fact that it's worked for you. You've actually given me a few ideas on some things to do on my Yukon. Keep up the great work brother!

 

[Jorge6.5]

I'll try to set some things straight here, even if no one is interested. It's true on most TBI trucks that flipping the air cleaner lid delivers gains you can feel. But there is a reason for it, and the reason it works so well is because most TBI air cleaners have the heat riser stuck closed. Whether the stove pipe is still there or not, 9 times out of 10, the flapper valve is always closed. I completely gutted mine, sealed up the hole and reinstalled it without the muffler and now I have the same airflow (or better) than a flipped lid, plus I'm getting cold air from the fender. The stock TBI can only flow so much through those 2 little holes and the stock air cleaner ducting to the fender can more than handle it. An open element has no advantage because you still can only flow the amount the throttle body can flow, and because you're sucking air from the engine compartment-even at speed the air coming in through the radiator is a hundred degrees higher than ambient. Hot air isn't as dense, so you flow less than if you get the air before the radiator heats it up.

Nailed it!

 

[Rock Hard Concrete]

Well improving the petal feel directly improves throttle response. Distance traveled is only half of the equation. How many pounds of force you have to physically push the pedal is the other half.

My buddy did just the spring on his 4.3 yesterday after I showed him mine and he is very happy with it and like myself was kicking himself for not thinking of it earlier.

Honestly though the open element filter is getting most flack the spring is 85% of what makes this mod so great. There isn't even close to enough tension to hold the throttle open the spring is actually relatively weak but makes the pedal especially light in the first quarter of throttle movement.

 

[michael hurd]

Pedal feel has nothing to do with throttle response. Less than zero percent. Throttle response depends on volumetric efficiency, dynamic engine compression ratio, the type of fuel delivery system, ( carb / electronic injection ) camshaft profile, exhaust, and ignition timing, not to mention the capability of the processor in an electronic injection system.


If it's too stiff, perhaps a visit to the gym may be in order. Seriously. Remember, you are stepping on a pedal with a linkage and cable, not at all like DBW with zero feedback. Having driven some of these trucks while fairly new, stiffness was a non-issue.

 

[Supercharged111]

I'll try to set some things straight here, even if no one is interested. It's true on most TBI trucks that flipping the air cleaner lid delivers gains you can feel. But there is a reason for it, and the reason it works so well is because most TBI air cleaners have the heat riser stuck closed. Whether the stove pipe is still there or not, 9 times out of 10, the flapper valve is always closed. I completely gutted mine, sealed up the hole and reinstalled it without the muffler and now I have the same airflow (or better) than a flipped lid, plus I'm getting cold air from the fender. The stock TBI can only flow so much through those 2 little holes and the stock air cleaner ducting to the fender can more than handle it. An open element has no advantage because you still can only flow the amount the throttle body can flow, and because you're sucking air from the engine compartment-even at speed the air coming in through the radiator is a hundred degrees higher than ambient. Hot air isn't as dense, so you flow less than if you get the air before the radiator heats it up.

IIRC I just removed my flapper spring on the valve, that seemed to keep it open. That and the choked down silencer tube. Electric fan also helped. OP make sure you have 12.5+ psi of fuel pressure. Bumping timing helps too. You are sucking some seriously hot air now, I remember logging with/without the lid on my 98 and I was shocked at the difference.

 

[Tzfbird]

IMO, yes air temp plays a role but not to throttle response however less restriction would including less restriction everywhere from air entering the filter housing to leaving the exhaust.

On my 1990 GMC I noticed that there is no intake air temp sensor. The ECM can not modify the AFR based on intake air temps and the engine would run rich(slower response) if taking in hot air. Example: 100 degree air might have enough oxygen to burn 1.25g of fuel in a 350ci engine except that 1.5g was injected resulting in wasted fuel and a rich condition reducing engine performance.
Likewise could run lean(generally faster response) from cold air.
Example: 50 degree air could have enough oxygen to burn 1.75g of fuel in the same engine but the same 1.5g was injected resulting in a lean condition which is also not good.
Granted these examples are exaggerated but the idea is there. This points to the ECM tune being a catch-all and programmed to run in a variety of conditions only based on coolant temperature which is not optimal for either power or fuel economy.

Like Hurd said, response has a lot to do with engine build. TBI is a very slow system and the ECM reacts based on readings taken from sensors maybe 2-3 times a second. New vehicles are way faster resulting in better response. TBI is a happy and robust medium between carb and OBDII style fuel injection. The cams used in the late 80s/early 90s are terrible and designed to increase fuel economy by keeping the engine at low speeds.