Turbo TB – Engineering Masterpiece or Time Bomb?
04-01-08, 06:09 PM
#1
91 TII
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Turbo TB – Engineering Masterpiece or Time Bomb?
A mechanic told me that the Mazda FC Throttle Body is fragile – the steel throttle rod wears the opening in the aluminum body. This allows the throttle to jam wide open. The TB can’t be rebuilt and is dangerous. I’ve had the throttle jam open twice on my 91 TII. The first time Mazda replaced it and the second time I managed to find a new one.
What I want to know from you guys is if you’ve ever heard of this or if you know any horror stories. I’ve searched the archives and come across several ways the TB can get stuck at WOT such as –
floor mat interference (not my problem)
stuck throttle cable (not my problem)
problem with cruise control or cc cable
bound MOT rod
bolt stuck in TB control
dirty TB
my personal favorites -
razor blade stuck in throttle butterfly
gremlins
No one ever blamed the TB design. If there isn’t a basic design flaw, maybe I can clean up the TB with 64K miles and use it. If old TB’s are dangerous, we should all practice reaching for the ignition switch so that we can save our *** and engine when our toy goes WOT.
What I want to know from you guys is if you’ve ever heard of this or if you know any horror stories. I’ve searched the archives and come across several ways the TB can get stuck at WOT such as –
floor mat interference (not my problem)
stuck throttle cable (not my problem)
problem with cruise control or cc cable
bound MOT rod
bolt stuck in TB control
dirty TB
my personal favorites -
razor blade stuck in throttle butterfly
gremlins
No one ever blamed the TB design. If there isn’t a basic design flaw, maybe I can clean up the TB with 64K miles and use it. If old TB’s are dangerous, we should all practice reaching for the ignition switch so that we can save our *** and engine when our toy goes WOT.
04-01-08, 06:56 PM
#6
91 TII
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Wasn't the linkage or pedal for me. I think the cruise control is a possibility. If no one has ever heard of the sloppy hole theory, I've got o beleive the mechanic was snowing me. A lot of people make up stuff when they don't know or don't want to do something.
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04-01-08, 08:15 PM
#8
my tb stuck open once after i let it sit for a while.
the solution u ask? WD40 on the arms that move the butterflies. It never happened again. and I have 110k on it.
All the stories I've heard of are from what you've already found, and i think your mechanic is just either messing with you or blowing smoke
the solution u ask? WD40 on the arms that move the butterflies. It never happened again. and I have 110k on it.
All the stories I've heard of are from what you've already found, and i think your mechanic is just either messing with you or blowing smoke
04-01-08, 08:21 PM
#10
A mechanic told me that the Mazda FC Throttle Body is fragile – the steel throttle rod wears the opening in the aluminum body. This allows the throttle to jam wide open. The TB can’t be rebuilt and is dangerous. I’ve had the throttle jam open twice on my 91 TII. The first time Mazda replaced it and the second time I managed to find a new one.
What I want to know from you guys is if you’ve ever heard of this or if you know any horror stories. I’ve searched the archives and come across several ways the TB can get stuck at WOT such as –
floor mat interference (not my problem)
stuck throttle cable (not my problem)
problem with cruise control or cc cable
bound MOT rod
bolt stuck in TB control
dirty TB
my personal favorites -
razor blade stuck in throttle butterfly
gremlins
No one ever blamed the TB design. If there isn’t a basic design flaw, maybe I can clean up the TB with 64K miles and use it. If old TB’s are dangerous, we should all practice reaching for the ignition switch so that we can save our *** and engine when our toy goes WOT.
What I want to know from you guys is if you’ve ever heard of this or if you know any horror stories. I’ve searched the archives and come across several ways the TB can get stuck at WOT such as –
floor mat interference (not my problem)
stuck throttle cable (not my problem)
problem with cruise control or cc cable
bound MOT rod
bolt stuck in TB control
dirty TB
my personal favorites -
razor blade stuck in throttle butterfly
gremlins
No one ever blamed the TB design. If there isn’t a basic design flaw, maybe I can clean up the TB with 64K miles and use it. If old TB’s are dangerous, we should all practice reaching for the ignition switch so that we can save our *** and engine when our toy goes WOT.
All I can say is this is the first time I have heard a "sloppy hole theory" referred to in the context of RX7's. I think you might want to find a different mechanic.
04-02-08, 09:18 AM
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Engine, Not Motor
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Never.
The throttle bodies can stick because of dirty external linkages. They can accumulate dirt and grunge, which gets stuck in the springs and actuators. Due to the double throttle design (and the vacuum operated tertiary throttles) the FC throttle body has more linkages then normal but they aren't really prone to jamming.
Also keep in mind that almost any car made in the last 30 years has an aluminum throttle body with a steel shaft. Sometimes bronze...
Most of the time the throttle body will stick if it's been cleaned or lubricated. They are designed to operate dry and if oiled, the oil will attract dirt. A simple spray down with brake cleaner generally frees it up. WD-40 is such a light oil that it evaporates quickly when the engine heats up so normally no harm is done.
The throttle bodies can stick because of dirty external linkages. They can accumulate dirt and grunge, which gets stuck in the springs and actuators. Due to the double throttle design (and the vacuum operated tertiary throttles) the FC throttle body has more linkages then normal but they aren't really prone to jamming.
Also keep in mind that almost any car made in the last 30 years has an aluminum throttle body with a steel shaft. Sometimes bronze...
Most of the time the throttle body will stick if it's been cleaned or lubricated. They are designed to operate dry and if oiled, the oil will attract dirt. A simple spray down with brake cleaner generally frees it up. WD-40 is such a light oil that it evaporates quickly when the engine heats up so normally no harm is done.
04-02-08, 06:47 PM
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Probably, but the guy who said it didn't make any $$. He rebuilt carbs for a living. At the time, Mazda didn't stock any new ~1K TB's. I found a new one on the net for about $340 and had another mechanic install it.
04-03-08, 04:40 PM
#19
I have never seen a throttle body wear out to the point it would stick wide open. Even when covered in grease , grime and oxydation... Sounds to me like it was the linkage or the throttle cable or the gas pedal. I would say take a look up under your dash and make sure there is nothing impeding the pedal/linkage movement, like ghetto alarm wiring
post detailed pictures of said TB
post detailed pictures of said TB
04-03-08, 05:47 PM
#20
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i have never heard of the "sloppy hole theory" although i have seen a few. lol. i would lean towards cruise control on that one.
04-03-08, 11:32 PM
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I have never seen a throttle body wear out to the point it would stick wide open. Even when covered in grease , grime and oxydation... Sounds to me like it was the linkage or the throttle cable or the gas pedal. I would say take a look up under your dash and make sure there is nothing impeding the pedal/linkage movement, like ghetto alarm wiring
post detailed pictures of said TB
post detailed pictures of said TB
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