Any downside to modding the throttle body?

[austinado16]

Getting in the mood to "rebuild" the throttle body. I've seen the mods of:
-removing the raised "rim" from around each of the venturi's
-install an adjustable fuel pressure regulator
-install a fuel pressure gauge at the TB
-install a spacer block between the injector pod housing and the TB housing

Any drawbacks to any of these? Does removing the the "rim" and raising the injectors create any sort of lean running issues, or does the computer compensate just by the fact that it's reading/adjusting mixture based on the input from the oxygen sensor?

Are any kits for doing this work any better than others?

I'm chasing a very slight random miss at hot idle and I've got no intake leaks at the IM or TB base, and the EGR is new. PCV is new as of last week. All tune related parts are new, as in, less than a year, and all AC-Delco.

I don't think the TB has ever been touched, so that's why I'd like to give it some love.

 

[Jims86]

Getting in the mood to "rebuild" the throttle body. I've seen the mods of:
-removing the raised "rim" from around each of the venturi's
-install an adjustable fuel pressure regulator
-install a fuel pressure gauge at the TB
-install a spacer block between the injector pod housing and the TB housing

Any drawbacks to any of these? Does removing the the "rim" and raising the injectors create any sort of lean running issues, or does the computer compensate just by the fact that it's reading/adjusting mixture based on the input from the oxygen sensor?

Are any kits for doing this work any better than others?

I'm chasing a very slight random miss at hot idle and I've got no intake leaks at the IM or TB base, and the EGR is new. PCV is new as of last week. All tune related parts are new, as in, less than a year, and all AC-Delco.

I don't think the TB has ever been touched, so that's why I'd like to give it some love.

Maybe the injector pod spacer, but you wont notice much from the mods. None of it will effect the way it runs, everything is based on Vac, coolant temp, and o2.
Have you filled the crank case with propane ro check the underside of the manifold?

 

[austinado16]

Mmm....no, I've never even heard of doing that. That would suck to have a perforated/cracked underside. But it ran like this with the stock manifold on it too, so I'm thinking this Edelbrock is okay.

Re; the pod spacer. Are you saying it's worth doing, or that it might cause an issue?

Is the coolant temp sensor always being "listened to," or is it basically an on/off switch for closed loop function.....or maybe both?

 

[Jims86]

Mmm....no, I've never even heard of doing that. That would suck to have a perforated/cracked underside. But it ran like this with the stock manifold on it too, so I'm thinking this Edelbrock is okay.

Re; the pod spacer. Are you saying it's worth doing, or that it might cause an issue?

Is the coolant temp sensor always being "listened to," or is it basically an on/off switch for closed loop function.....or maybe both?

Its the only way to check for under manifold vacuum leaks. Plug off both pcv ports, take out the dipstick, and stick a rubber line from a propane source on the dipstick tube, and turn it on while the engine is running.
The pod spacer letsmore air by, but its not enough to feel it in the seat of your pants.
You would be better off porting the manifold, and getting your TBI Base ported to 2" with the 454 throttle blades....which brings you from around 430 cfm to about 740(not exactly sure on those numbers, but they are close.)
Coolant sensor is constantly monitored, o2 is ignored until it gets up to around 600 degrees.

 

[austinado16]

Thanks. Wasn't sure how the CTS worked. On the German stuff, the CTS controls how much fuel is delivered during warm-up, until say, 180*F, at which point it's no longer really doing anything other than saying, "The coolant is above X temp, so start listening to the o2 sensor from now on."

Is that how the CTS is functioning in this American Iron? Sorry for all the Q's, I'm still behind the learning curve on this GM stuff.

Ordered a pod spacer for about $15 shipped on ebay. Then ordered a rebuild kit, adjustable regulator, pressure gauge and adapter from CFM. That should be enough to get me a good basic rebuild and be able to dial in the fuel pressure, as well as keep an eye on it in the future.

Thinking about replacing the IAC, but so far, I'm being told that AC-Delco version is NLA. So far, it just looks like aftermarket stuff is available.

 

[Jims86]

Thanks. Wasn't sure how the CTS worked. On the German stuff, the CTS controls how much fuel is delivered during warm-up, until say, 180*F, at which point it's no longer really doing anything other than saying, "The coolant is above X temp, so start listening to the o2 sensor from now on."

Is that how the CTS is functioning in this American Iron? Sorry for all the Q's, I'm still behind the learning curve on this GM stuff.

Ordered a pod spacer for about $15 shipped on ebay. Then ordered a rebuild kit, adjustable regulator, pressure gauge and adapter from CFM. That should be enough to get me a good basic rebuild and be able to dial in the fuel pressure, as well as keep an eye on it in the future.

Thinking about replacing the IAC, but so far, I'm being told that AC-Delco version is NLA. So far, it just looks like aftermarket stuff is available.

If AC is NLA, airtex/wells is good quality. NAPA should have them under their name....they will tell you who makes the part for them. Example:NAPA gold filters=WIX

In fact, just found it on rock auto, airtex/wells part #2H1037 $40 ....But test yours first, ground the test connector, and turn the key on for 30 seconds, and look down into the IAC passage to make sure it closes. the big thing is when they carbon up from the blowby that evaprates bak into the throttle body while the engine is off.

 

[austinado16]

Yeah the local NAPA has "theirs" (didn't ask brand because I was trying to find AC) for $38ish and I've got a shopping cart on RockAuto with the one you found, plus an AC ignition switch (mine rotates w/o the key) and a couple other parts.

Can you explain the IAC test better? You mention grounding a test connector. Not sure what you're talking about.

 

[Jims86]

Yeah the local NAPA has "theirs" (didn't ask brand because I was trying to find AC) for $38ish and I've got a shopping cart on RockAuto with the one you found, plus an AC ignition switch (mine rotates w/o the key) and a couple other parts.

Can you explain the IAC test better? You mention grounding a test connector. Not sure what you're talking about.

Sure. If you have ever used the "paper clip" method to pull trouble codes, this is also the way to close the IAC for re setting the throttle blades(Idle)
By jumping diagnostic ports A and B with a paper clip, and turn the ignition to on for 30 seconds, this should completely close the IAC.

Unplug the IAC after it is confirmed closed( you will see the nose of it in the IAC cavity)then take the paper clip out, start the engine(already at Op temp.)and set the idle in gear to 500 rpm, 525-550 for older engines, then turn the engine off.

plug the IAC back in.
disconnect the battery for 15 seconds(to re set the ECM)
re connect battery, start engine.
you have set the idle to factory specs, drive it around so the ECM can re learn everything, and it should smooth out after a few trips.

 

[austinado16]

Thanks! Wasn't there a sticky about how to get and read the codes w/o a scanner. I can't find it for the life of me.

 

[RetroC10Sport]

http://www.obd-codes.com/faq/read-gm-2-digit-obd-codes-free.php

http://www.gmsquarebody.com/forum/showthread.php?t=6844

 

[austinado16]

Thank you sir!

Quote:
How to read the codes:
Ground terminals A and B (see diagram below) with the ignition "ON" and engine not running. The system will enter the diagnostic mode. In this mode, the computer will display a Code 12, three consecutive times, by flashing the "CHECK ENGINE", "SERVICE ENGINE SOON" or "MALFUNCTION INDICATOR LAMP" or light. A Code 12 consists of one flash, a short pause, then two flashes in rapid succession. After Code 12 is displayed, any stored trouble codes will be displayed by flashing the "CHECK ENGINE", "SERVICE ENGINE SOON" or "MALFUNCTION INDICATOR LAMP" light. All codes are displayed 3 times each then a code 12 will repeat. In the diagnostic mode, the computer will also energize all computer controlled relays and solenoids.

Read more at: http://www.obd-codes.com/faq/read-gm-2-digit-obd-codes-free.php
Copyright © OBD-Codes.com

 

[austinado16]

The kit from CFM finally arrived today so I climbed into the engine compartment and had at it.

Right now I'm not feeling the love for the CFM stuff. I ordered a rebuild kit, the adjustable regulator, and the pressure gauge with adaptor that's supposed to take the place of the outlet fitting on the throttle body and allow the pressure gauge to live there. I also ordered the 1/4" pod spacer, but it came from a seller on ebay for quite a bit less money and I got it 2 days, not 10, like all this CFM stuff.

The regulator has a big (red) thumb-wheel that winds up sticking out the bottom of the regulator and it hits the vac fitting that's there. Hey, you think they could make that thumb-wheel 1/8th inch smaller in diameter? Nope, they expect you to bend the fitting. What happens when you bend a steel fitting? They F*cking break. Mine didn't snap off, but it does have a thin white line, like if I'd moved it a fraction further, I'd be screwed right now.

The fitting for the pressure gauge had a bunch of metal shavings inside it from where they drilled and tapped 2 1/8NPT holes for the gauge. Nice craftsmanship. It appears to be threaded with the wrong pitch, because the fitting on the truck's fuel line will not thread into it. Yet the original fitting and the truck's fuel line fitting thread together nicely with just my fingers. Feels like the CFM piece is threaded SAE, and the truck is metric? Or vise-versa. Gonna call them in the morning and see what the deal is.

The other thing that's grating me (and seems so typical with modified stuff like this) is that the CFM fitting is really long. The truck's return line is bent steel tubing, so I'm doubting I'm going to be able to use the CFM piece anyway, because it's going to be too hard to get the truck's tubing to cooperate. It was bad enough modding the fuel lines when I installed the Edelbrock manifold.

So it's back together for now and runs "normally." I can't comment on whether it's running better or different because I can't see and set the fuel pressure.