what is a throttle body bypass mod?

[the fat bastid]

the ss guys always talk about thier tbb mod.
i always thought you wouldn't want to by pass the throttle but hey, what do i know :D

this ebay auction doesnt seem to help any...

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=2430417733&category=33558

"bypassing the coolant line" is a little vauge..dont you need that for a reason?

[RF Overlord]

fat:

One word on the above-mentioned product: JUNK

...more words: SCAM and RIPOFF

They even admit this product "is manufactured by the same company that manufactured the IATR chip", a 29-cent resistor, that they called a "chip" which was added in place of the intake air temperature sensor to supposedly fool the motor into thinking it was getting colder air, and thereby produce more power (!!!)...they sold it for various amounts up to $10...it did NOTHING...neither will this...interesting how they claim the same HP increase for this product as for their bogus "chip": 10-15 HP...also of interest is the fact that the EXACT SAME part fits every fuel injected engine ever made:

"...with this kit being universal, you can also swap out the TBB and install it on a second car or truck."

Personally, I'd rather spend my money on an "O" pipe...check out KaleCo Auto (http://www.kalecoauto.com/perf.htm) for their extensive list of goodies for your car...

[01 Interceptor]

The TB bypass is a free mod on the 94-96 B-Bodies(Caprice/Impala SS/Roadmaster/Fleetwood). As we all know hot coolant going through the TB will cause the air to heat up. While this may be negligible during highway speeds, it can be significant during low speed and stop-n-go situations. It took all of 5 minutes to do with a set of pliers and a box cutter.

I do not know if this method would be possible on the MM as I do not know how the coolant is routed. Is it even routed through the TB? That would be my first question. If not, then no worries...if so, can you just bypass it by removing the hoses from each end and joining those together?

As far as needing the coolant to go through the TB, from the SS guys who helped me with this mod, the consensus is that it is really only needed in extremely cold climates. So my suggestion is: do not attempt this mod if you drive your car in extremely cold climates(i.e. an NE winter).

[cyclone03]

The coolent By-pass on the TB always looked like a source of extra intake heat.But it's not.The EGR runs into the intake the coolent line actually does help cool the TB.
Now it you block the egr off then the coolent will raise the intake temp. some.

[TripleTransAm]

I've always read that this coolant feed to the throttle bodies was to prevent throttle blade icing on really cold days.

As for the 4.6l DOHC, I don't see any references to coolant feed to our throttle bodies, in the "upper manifold removal" section. And I don't believe any coolant flows through the upper intake manifold, so.....

However, I do see something odd... reference to disconnecting PCV coolant hoses. WTF? Might actually result in the same effect: PCV gases on their way to the throttle body might get warmed up with coolant at this part, and then the warmed gasses blast the throttle body and keep it warm? I suppose this method would excuse us from having to warm up the ENTIRE throttle body for nothing... hey, could be, they did put a lot of thought into the Marauder intake system after all.

I'll have a closer look tomorrow when I pull the car out, but if this is the case, then the throttle body bypass mod is even easier than most other cars: just disconnect both coolant hoses, and insert a fitting between both, completely bypassing the PCV line (not the PCV valve, from what the diagram seems to indicate, but rather the intake side).

My honest opinion: probably not worth the hassle to do, power-wise.

[MitchB]

What do you consider to be 'really cold'? Throttle body icing is most likely at high humidity at temperatures between 40 and 50 degrees.

Mitch

I've always read that this coolant feed to the throttle bodies was to prevent throttle blade icing on really cold days.

As for the 4.6l DOHC, I don't see any references to coolant feed to our throttle bodies, in the "upper manifold removal" section. And I don't believe any coolant flows through the upper intake manifold, so.....

However, I do see something odd... reference to disconnecting PCV coolant hoses. WTF? Might actually result in the same effect: PCV gases on their way to the throttle body might get warmed up with coolant at this part, and then the warmed gasses blast the throttle body and keep it warm? I suppose this method would excuse us from having to warm up the ENTIRE throttle body for nothing... hey, could be, they did put a lot of thought into the Marauder intake system after all.

I'll have a closer look tomorrow when I pull the car out, but if this is the case, then the throttle body bypass mod is even easier than most other cars: just disconnect both coolant hoses, and insert a fitting between both, completely bypassing the PCV line (not the PCV valve, from what the diagram seems to indicate, but rather the intake side).

My honest opinion: probably not worth the hassle to do, power-wise.

[01 Interceptor]

Well I live in WA state, as you know we are famous for rain. I have had my TB bypass for over a year now and have had no problems during the winter months. We didn't get much snow last year, but the car ran flawlessly.

[TripleTransAm]

Originally posted by MitchB
What do you consider to be 'really cold'? Throttle body icing is most likely at high humidity at temperatures between 40 and 50 degrees.


Well, it's never happened to me on a fuel injected car, throttle body injected OR port injected (as the Marauder). But I did get the throttle blades on my carb'ed '84 Civic to ice up on a long highway drive up north for a Xmas beer bash at a coworker's log cabin up in the wilderness, almost a decade ago.

I don't recall the exact temperature but it must have been between -10 C and freezing. From memory, the roads were wet and slushy but the snow itself was not melting nor wet... this tells me that the road wetness was salt-related and that the temperature was not below -15 C. Up here, those temperatures and high humidity make for an icky day indeed.

I started to notice the icing at some point on the secondary highway, once the main highway ended. We're talking some 3 hours north of Montreal, so you start to notice the shorter trees and mostly coniferous evergreens. I was thankful for two things at that point: that I had a good clutch and good brakes, and that I only had to contend with a maximum of 76 hp. 4000 RPM idle speeds under no load can be eye-opening (3000 RPM in 5th at highway speeds).

You have to consider that the car itself was a hack job. Desperate for a winter car to allow the storage of my GTA and the Parisienne, I purchased 2 dead '84 Civics for the princely sum of $500 Canadian. The hatchback had a good 1.5l 3Valve 5-speed with a rusted out body, and the 4 door sedan had a blown 1.5l with semi-automatic. Out of this combination came one world-class beater that lasted 4 years without so much as an oil change, using the good engine and tranny in the good body car (and various other tidbits). In my neverending quest for fuel efficiency, I bypassed the hot air riser and other bits like the vacuum throttle blade damper, etc. I'm sure the hot air riser delete is what iced up my carb.

[RF Overlord]

Originally posted by TripleTransAm

You have to consider that the car itself was a hack job. In my neverending quest for fuel efficiency, I bypassed the hot air riser and other bits like the vacuum throttle blade damper, etc. I'm sure the hot air riser delete is what iced up my carb.

/Steve, you are truly a Master of Bush-League Engineering... :shake:

[cyclone03]

The only carb I ever iced was on My Ducati.
The temp was the high 30's to low 40's with about 98% hum.
The pilots I talked with later that day confirmed that temp/hum. is a deadly combo for carb icing.

[TripleTransAm]

Originally posted by RF Overlord
/Steve, you are truly a Master of Bush-Leauge Engineering... :shake:


That saying holds true... "necessity is the mother of invention".

Consider it... I'd sunk all my money into this sports car, thinking (unrealistically) that I'd be driving it year-round. I mean, my parents actually gave me a set of winter rubber mats to put in the car that first Xmas I had the car in 1993. I grew up in a household where cars were considered appliances, disposable and to be thrown out when completely worn through.

I'm not sure what triggered my desire to store it, but it may have been due to a lack of funds for proper winter tires (the car was still shod with its original dried up Gatorbacks... 18000 miles only, but man those tires were rock hard after 6 years). The starter froze up during the first really cold (-20C) evening of the year, so I knew I needed to give it a proper "tune up". So I think it was then that the decision was made to keep the car in the garage and go through it during the winter, and I'd need a cheapo beater soon.

I got a line on a couple of traded in rust-monsters at a local Honda dealer. $500 and they were mine. Working in a car port during that vicious winter was heck... that was the winter where nightime lows dipped to -40 C (-50 with windchill). Nonetheless, one week later (my Xmas vacation :( ) the hybrid was on the road. I gave myself three months to kill that car, but if it hadn't been for the rusted out suspension in 1997, the car might probably still be on the road!

As all my cash went to dealing with all the extended-storage maladies of the GTA (18000 miles in its first 6 years = no-no), I kept dipping into the parts stripped off the hatchback Civic to keep the 4 door on the road. That even included adapting the sideways-mounted muffler of the hatchback to the front-rear orientation of the 4 door!

Aren't you regretting you asked? ;)

[Warpath]

Originally posted by RF Overlord
...They even admit this product "is manufactured by the same company that manufactured the IATR chip", a 29-cent resistor, that they called a "chip" which was added in place of the intake air temperature sensor to supposedly fool the motor into thinking it was getting colder air, and thereby produce more power (!!!)...they sold it for various amounts up to $10...it did NOTHING...neither will this...interesting how they claim the same HP increase for this product as for their bogus "chip": 10-15 HP...also of interest is the fact that the EXACT SAME part fits every fuel injected engine ever made...

This type of mod has been proven to work on Mustangs. The resistor fools the computer into thinking that it is getting cooler air as you stated. Since air is cooler, the computer advances timing and you get more hp. Mustang guys will reset the computer and install a resistor before a drag strip run. It works for a short while though. Every so often, the computer compares the intake temperature to the coolant temperature (I think) to verify the intake temp sensor is working properly. If you leave the resistor in all the time, it will eventually trip the check engine light.