I know the throttle body heater is there to help with icing but Yellow will probably stay home in the winter from now on. So there shouldn't be any problem deleting it. Is there anything I'm missing? Yellow is stock 2.8.
Some people might say it will ice up summer or winter, but considering how it gets bypassed when the thermostat opens, any heating from it will be negligible compared to the heat conducted by the metal all around, and having the exhaust directly below. I removed mine over 1000kms ago, driven cold mornings and hot afternoons, with no issues whatsoever, I found one of the little rubber hoses on the thermostat housing was just long enough to stretch and connect to where the other was, therefore no need to plug the holes, it just bypasses the thermostat with a 3" tube instead of about 5 feet and the throttle body.
Some people might say it will ice up summer or winter, but considering how it gets bypassed when the thermostat opens, any heating from it will be negligible compared to the heat conducted by the metal all around, and having the exhaust directly below. I removed mine over 1000kms ago, driven cold mornings and hot afternoons, with no issues whatsoever, I found one of the little rubber hoses on the thermostat housing was just long enough to stretch and connect to where the other was, therefore no need to plug the holes, it just bypasses the thermostat with a 3" tube instead of about 5 feet and the throttle body.
My thoughts exactly. I've had side draft SU's ice up way back when and it's shocking to open the bonnet and see 2 giant snowballs. I agree, I'm sure the 2.8 throttle body gets warm enough and those tubes are just in the way. One could go so far as to modify the T-Stat housing and eliminate the little nipples.
I removed the TB heating lines about ten years ago on my Formula. I drive it year round in a temperate climate on the coast that does occasionally experience sub-freezing temperatures along with high humidity, and have had zero issues with icing of the TB. I connected the two nipples on the thermostat housing the same way as mentioned earlier.
Cool. I plan to replace all the original cooling system hoses ( some looking pretty swollen ) so the throttle body heater will disappear then. The little bypass tube is easy enough.
if you keep the egr installed (but no vaccum) it syncs a bit of heat Into the throttle body. but the coolant is definitely redundant and just to keep it around a certain temp range but just like the cold start injector it is certainly not required
If you're concerned about keeping it looking stock, you can keep the steel lines attached, and just by-pass the lines where they connect.
I leave mine connected, and I'm in South Florida... but honestly, unless I lived in Canada or Alaska, it probably doesn't do much.
No need to look stock, I'm more interested in cleaning it up. A sports car shouldn't have anything on it that doesn't make it go. And, those tubes add at least a few ounces of dead weight !! https://www.fiero.nl/forum/icons/icon7.gif
if you keep the egr installed (but no vaccum) it syncs a bit of heat Into the throttle body. but the coolant is definitely redundant and just to keep it around a certain temp range but just like the cold start injector it is certainly not required
Why would you have an EGR with no vacuum line? Yeah, you do need a cold start injector. I think you mentioned once that you have to crank a long time to get started. Could that be the problem?
Never believed that the throttle body heater lines did much good. Few if any vehicles use such a scheme, an engine compartment is hot to begin with and the throttle body sits near the exhaust crossover pipe. I've always removed the lines, put plugs in the tb, capped the connections at the water neck and have had no issues.
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
[This message has been edited by Dennis LaGrua (edited 08-31-2024).]
Never believed that the throttle body heater lines did much good. Few if any vehicles use such a scheme, an engine compartment is hot to begin with and the throttle body sits near the exhaust crossover pipe. I've always removed the lines, put plugs in the tb, capped the connections at the water neck and have had no issues.
Are there similar cars from that era that use coolant lines on the throttle body or intake? It seems like it's just a slightly newer version of the "ThermAC" if you will... but I don't think I've ever seen anything like that on other older cars that I've owned before.
On my old VWs, there's a thermostatically controlled "flap" that allows air to pass through the cooling fins on the cyl heads. But I suppose that's not really the same either, as that's just more like a thermostat controlling the temperature of what would be the coolant (if you will).
I have to wonder if the same guy who designed the tubes for the evaporative canister did the TB heater lines. Who ever it was had a thing for fancy looking long tubes.
Everybody talks about the throttle body icing, while thinking about carbs icing. What they are not taking into account (and I expect I may be opening a can of worms, here) is that carbs have to deal with the added effect of evaporative cooling from the fuel. The V6 throttle body is dry. There is no fuel to evaporate.
I took off my lines, years ago. Made it so much easier to get to the distributor and other stuff.
Why would you have an EGR with no vacuum line? Yeah, you do need a cold start injector. I think you mentioned once that you have to crank a long time to get started. Could that be the problem?
It was an example of how to do an egr delete yellow. just leaving everything installed but giving the egr no vaccum and removing the egr solenoid by the thermostat.my long crank was caused by a few leaky gaskets I've since replaced and the csi only working when warm (no idea why it just did that and I've since replaced the sensor and verified the wiring so no idea)
Everybody talks about the throttle body icing, while thinking about carbs icing. What they are not taking into account (and I expect I may be opening a can of worms, here) is that carbs have to deal with the added effect of evaporative cooling from the fuel. The V6 throttle body is dry. There is no fuel to evaporate.
I took off my lines, years ago. Made it so much easier to get to the distributor and other stuff.
I feel silly for missing that. Thank you. Yeah when you think about how a refrigerator works.... Ice box throttle bodies.
One does have to wonder what were they thinking? I think it's because some engineer at GM just liked tubes. That wouldn't surprise me at all. Or someone High Up heard stories of dangerous throttle body snow balls that strand grand mothers on cold foggy nights !!!
"Make sure they get heaters on the throttle bodies." "OK boss."
Cost wise, It would add a couple of operations on the assembly line and create one more possible supply chain issue. Complicate repair, complicate service manual drawings and part numbering ....... Can O Worms.
On the contrary, it seems to me that everybody has mentioned that the 2.8's TB doesn't ice up. Yes, keeping in mind that no atomizing of gasoline is taking place in the 2.8's TB, the installation of the factory heater tubes appears to be rather unnecessary.
I remember years ago watching ice form on the Rochester carburetors of whatever Chevy I happened to own at the time. It was like having a mini refrigeration unit sitting atop of the intake manifold.
[This message has been edited by Patrick (edited 09-01-2024).]
On the contrary, it seems to me that everybody has mentioned that the 2.8's TB doesn't ice up. Yes, keeping in mind that no atomizing of gasoline is taking place in the 2.8's TB, the installation of the factory heater tubes appears to be rather unnecessary.
I remember years ago watching ice form on the Rochester carburetors of whatever Chevy I happened to own at the time. It was like having a mini refrigeration unit sitting atop of the intake manifold.
This thread had me thinking earlier today when I was working on the car with my daughter. The A/C lines run right along the fuel lines for the 4 cyl / Iron Duke Fiero. I was wondering if it would make any difference in engine efficiency if I wrapped the pressure fuel line next to the pressure line from the A/C compressor... haha... it would cool the fuel line and provide some cool fuel into the TBI unit. Perfect for icing... and that's when I changed my mind.
I remember years ago watching ice form on the Rochester carburetors of whatever Chevy I happened to own at the time. It was like having a mini refrigeration unit sitting atop of the intake manifold.
Yeah, chill your bear on the Rochester and roast a weenie the manifold. Yeah. I wonder if anybody ever did it?
I suspect you meant beer. It would be rather difficult to convince a bear to climb into the engine bay!
The frost on the carbs was usually a short term phenomena (on my SBC and BBC engines), as eventually the exhaust crossover incorporated into the intake manifold (for this very purpose) would heat up the carburetor enough to eliminate the frost.
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Originally posted by Yellow-88:
...and roast a weenie the manifold. Yeah. I wonder if anybody ever did it?
Wrapping meat in aluminum foil and cooking it on the engine during a long drive is not an unheard of practice!
To me, the throttle body 'heater' is actually a coolant supply and return loop which can help in cold conditions as everyone mentioned.
But nobody mentioned about circulating coolant in the throttle body and perhaps prevents overheating too?
And warming the intake air, I believe this is part of "maintaining optimal operating temperatures" and "reducing emissions by ensuring complete combustion of the fuel-air mixture" in the early era of multi-point injection.
And yes, I agree that these coolant lines are a pain to work around the distributor!
My two cents....
------------------ Original Owner of a Silver '88 GT Under 'Production Refurbishment' @ 136k Miles
Never believed that the throttle body heater lines did much good. Few if any vehicles use such a scheme,
quote
Originally posted by 82-T/A [At Work]:
Are there similar cars from that era that use coolant lines on the throttle body or intake?
Lots of cars used throttle body coolant lines; the 2.8 and 3.1 MPFI engines and 3100 and 3400 SFI engines all do but so do V8s at least as far back as the tuned port era. The LT1 engines have them and I think the LS engines do but I am not certain. Other manufacturers use them also.
Some people delete them for the 0.0002 HP that might be gained by having a cooler and denser stream of incoming air.
I tend to think the system on the Fiero is noticeably complicated because of the need to route the coolant to the "rear" of the engine, because that is where the throttle body is.
Originally posted by css9450: Lots of cars used throttle body coolant lines; the 2.8 and 3.1 MPFI engines and 3100 and 3400 SFI engines all do but so do V8s at least as far back as the tuned port era. The LT1 engines have them and I think the LS engines do but I am not certain. Other manufacturers use them also.
Some people delete them for the 0.0002 HP that might be gained by having a cooler and denser stream of incoming air.
I tend to think the system on the Fiero is noticeably complicated because of the need to route the coolant to the "rear" of the engine, because that is where the throttle body is.
After posting this, it occurred to me that the Iron Duke has this as well. Coolant passes through the intake manifold as well, simply for the purpose of warming up the air and preventing that as well. I plan to leave it on mine, simply because... why not?
But I wanted to comment on your "noticeably complicated" part. The one positive to this, is that with all of these extra tubes and hoses... going back and forth, etc... for the heater core, intake heating, and the threshold coolant lines... that's a LOT of extra coolant. A properly running Fiero (that hasn't been modified or messed with), should really never overheat. I remember my 87 Fiero in its prime. Almost totally stock... just hogged out exhaust manifolds and 1.52:1 roller rockers... and in ~80 degree Florida weather, I'd have it idling in the shade, and with the 180 degree thermostat (I know, changing that out to 195), it would sit at the 1/4 mark, and the fan would never come on. It would just sit there, nice and cool...
I should know this, but I wonder how the coolant capacity of the Fiero compares to say, a Chevy Corsica from the same year with the same engine?
After posting this, it occurred to me that the Iron Duke has this as well. Coolant passes through the intake manifold as well, simply for the purpose of warming up the air and preventing that as well. I plan to leave it on mine, simply because... why not?
IMO, we're talking apples and oranges here. The 2.5 has TBI, whereas the 2.8 does not. With the injector located in the TB of the 2.5, atomization of fuel is taking place within this TB... and therefore freezing up of the 2.5's TB is a very real concern if warming measures are not taken.
IMO, we're talking apples and oranges here. The 2.5 has TBI, whereas the 2.8 does not. With the injector located in the TB of the 2.5, atomization of fuel is taking place within this TB... and therefore freezing up of the 2.5's TB is a very real concern if warming measures are not taken.
I assume the freezing up doesn't come from the fuel (as it doesn't freeze at normal freezing temperatures) and more to do with the water vapor possibly freezing as a result of the venturi-effect (insert correct science here)?
I assume the freezing up doesn't come from the fuel (as it doesn't freeze at normal freezing temperatures) and more to do with the water vapor possibly freezing as a result of the venturi-effect (insert correct science here)?
Don't be so quick to dismiss the effects of fuel atomization on carburetor (and/or TBI) icing.
Carb ice forms because the pressure drop in the venturi causes the air to "cool," and draw heat away from the surrounding metal of the carburetor venturi. Ice then can begin collecting on the cooled carburetor throat. This is the same principle that makes your refrigerator or air conditioner work.
Meanwhile, fuel being drawn through the fuel discharge nozzle into the airflow atomizes into very fine droplets that evaporate easily. When the fuel changes from a finely atomized liquid to a vapor it, too, cools—stripping more heat from the surrounding metal.
The result is that the carburetor's internal temperature may drop below freezing, even on a warm day. If the ambient air contains sufficient moisture (which can be the case even in seemingly dry air), frost (carburetor ice) can form on the inside of the carburetor.
[This message has been edited by Patrick (edited 09-03-2024).]
Originally posted by 82-T/A [At Work]: This thread had me thinking earlier today when I was working on the car with my daughter. The A/C lines run right along the fuel lines for the 4 cyl / Iron Duke Fiero. I was wondering if it would make any difference in engine efficiency if I wrapped the pressure fuel line next to the pressure line from the A/C compressor... haha... it would cool the fuel line and provide some cool fuel into the TBI unit. Perfect for icing... and that's when I changed my mind.
Would cooler fuel increase the rate of evaporative cooling? Or maybe just cool the body a bit? At what point along the air flow is the fuel injected on the TBI? Is there a venturi in it? I forgot.
On the V6 - the first time I needed to remove the coolant lines, I left them off. They just complicate the engine bay and get in the way. It's hard to imagine they add much capacity to the system, or improve the cooling capacity much, but I can accept that as a minor plus. But really if I thought I had a problem in that regard I'd just upgrade the radiator.
I first tried blocking the lines with rubber caps - but the caps weren't strong enough and in a week it was leaking. A short bypass hose connecting the 2 points worked fine, that's how I left it.
Theorizing some more - these lines could be a minor negative for the ECM's performance. The ECM wants to know the air temperature in the manifold, but the sensor isn't there. The sensor is in the air cleaner housing - upstream of the throttle. The coolant lines in the throttle body and the EGR heat both add variables that would hurt the repeatable accuracy of the ECM's "estimate" of what the Manifold air temperature actually is.
Presumably GM tried to account for this when they dialed in the tune, but they're working with limited information and a limited computer. For someone doing a custom tune, removing both of those variable heat sources could be seen as an advantage.
Originally posted by Patrick: Don't be so quick to dismiss the effects of fuel atomization on carburetor (and/or TBI) icing.
I didn't mean to suggest that the fuel wasn't a contributing factor in the cooling process... it has the same cooling effect as alcohol on a wound. I simply meant that it's not the fuel itself that is freezing, but the water vapor in the ambient air. There's a word for this, but I cannot remember.
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Originally posted by Yellow-88: Would cooler fuel increase the rate of evaporative cooling? Or maybe just cool the body a bit? At what point along the air flow is the fuel injected on the TBI? Is there a venturi in it? I forgot.
Well, every liquid transfers heat. Obviously not the transfer of coldness, but the shedding of heat. The injector on the TBI Fieros sits directly above the throttle body, and injects directly into it vertically as the air passes around it.
This is a picture of a Holley TBI replacement unit for the 2.5 Fiero (and CFI F-bodies and Corvettes). It's 95% identical to the stock one in the Fiero, it just has a larger bore and throttle plate. Otherwise, it's intentionally designed to be identical. It was just the first image that came up.
On the contrary, it seems to me that everybody has mentioned that the 2.8's TB doesn't ice up.
Over the years, I've seen lots of threads/posts, that seem to say that we (people who remove the tubes) are all going to die in grinding crashes caused by iced up throttle bodies. Just seems to be the way of things, here. You know how we get.
Don't even get me started on EGR...
[This message has been edited by Raydar (edited 09-04-2024).]
Why would you have an EGR with no vacuum line? Yeah, you do need a cold start injector. I think you mentioned once that you have to crank a long time to get started. Could that be the problem?
I had been experiencing long start times. Unplugged the cold start injector, and now it starts within moments. I think mine may be putting too much fuel into the intake.
Thank you for the enlightenment. Now I get it. The TBI unit is basically a carburetor with its fuel injected instead of being sucked out of the bowl. Carburetors rapidly evaporate fuel thus sheading heat, cooling the TB. There is no evaporation in the MPI throttle body so it won't get any cooler than the air coming in. Apparently the parameters needed to grow TB snowballs are pretty narrow because I ran multiple side draft carbs for many years often in what seemed like ideal conditions but only saw TB snowballs once. That day was just above freezing and very humid. I was running about half throttle for a hour steady. Yeah, the throttle sticks and could cause problems but the snowballs melt pretty quick.
So ..... I'm loosing the heat tubes on Yellow because they do nothing but just get in the way.
IMHO, GM included the water lines to eliminate the possibility of icing simply due to the possibility that the icing could occur under some very specific set of conditions. The cars were warrantied by GM, and sold all over the country.
Are the lines needed under most circumstances? Probably not. Will some cars that have had the lines removed experience the icing problem? Maybe, maybe not. Will the modification void the warranty? I think we all know the answer to that!
IMHO, GM included the water lines to eliminate the possibility of icing simply due to the possibility that the icing could occur under some very specific set of conditions.
Something about pressurized humid air moving through a narrow orifice can cause icing. I probably really should look into the science behind it, but I remember when I had a job inspecting pile-driving jobs (I had to count however many blows per foot) the pile-driving hammer would constantly develop frost and chunks of ice where the compressed air was exhausted out of it. Even on 90-degree days in the middle of summer. It was the craziest thing I ever saw.
