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symptoms of a bad throttle body? (Read 7673 times)
Betty454ss
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symptoms of a bad throttle body?
09/07/11 at 22:19:17
 
what are the symptoms of a bad throttle body. also what is a new good one to put on? or should i just look for a remanufactured/rebuilt one?
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1ONR90SS
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Re: symptoms of a bad throttle body?
Reply #1 - 09/08/11 at 17:07:32
 
The TB per se doesn't really go bad. The throttle shaft bushings could wear and create a vacuum leak that could cause poor idle, but even then, the ECM should adjust the fuel delivery to compensate for that... Huh (It is fuel injection after all, we're not drawing the fuel in by vacuum like a carb...)
Normally it is the injectors, sensors or the IAC (Idle Air Control solenoid) that could fail, and they are all replaceable.
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Rock454
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Re: symptoms of a bad throttle body?
Reply #2 - 09/08/11 at 18:49:22
 
Also rebuildable.  GP Sorenson makes a rebuild kit that includes all gaskets, diaphram, and screens for the injectors.

A new one (rebuilt) will run at least $400.

What problems are you having.  May be able to help you find it.
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Re: symptoms of a bad throttle body?
Reply #3 - 09/08/11 at 19:22:43
 
Ditto....what the entire issue? You've had a few post with a few "symptoms" but take time now to describe the whole proble, what the engine does, any non stock mods etc.....if you put all the info here, these cats can fix it!....it's not world peace, although can be just as fustrating!
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Betty454ss
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Re: symptoms of a bad throttle body?
Reply #4 - 09/08/11 at 21:53:02
 
its a 1990. it hesitates every time i step on the gas. and it sometimes back fires and bogs down when i step on it. it has eddel brock intake with injectors, i have replaced idle air speed sensor, distributor, ignition coil, map sensor, throttle position sensor, fuel pump, pcv valve,o2 sensor, exhaust and cat, all filters. im checking the temperature sensor tomorrow. other than that im completely out of ideas with how to fix it. Undecided
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VA454SS
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Re: symptoms of a bad throttle body?
Reply #5 - 09/09/11 at 08:06:43
 
Sounds like a fuel delivery issue.  Have you checked the fuel pressure?  Do you get a check engine light?
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Re: symptoms of a bad throttle body?
Reply #6 - 09/09/11 at 09:09:41
 
If I remember an earlier post of yours, this is the Edelbrock MPI replacement kit, correct? Not just a 3764 manifold with the stock TBI intact?
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2001 Tahoe (Daughter's ride now)
2008 Tahoe LS (Mommy's NEW ride)
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Re: symptoms of a bad throttle body?
Reply #7 - 09/09/11 at 16:34:52
 
I once had the same type backfiring.  Turned out to be that the base gasket had deteriorated and was affecting the air/fuel ratio.  Worn throttle-plate bushings can also be a problem.
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clay
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Re: symptoms of a bad throttle body?
Reply #8 - 09/09/11 at 16:36:28
 
Oh yeah - be sure your timing is correct.  Retarded timing produces results like yours.
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Re: symptoms of a bad throttle body?
Reply #9 - 09/09/11 at 21:56:09
 
this sounded like what happened to mine in may. I had the distributer melt down where the coil connects to it. Had the distributer changed along with plugs, wires and the coil. It would still hesitate after that so I drove it for a few weeks because I was going to have it rebuilt and then one day it just died while driving down the highway.

Found out a month ago when my mechanic ripped in to it that the timing gear had sheared of half it's teeth and bent all the intake valves. luckily the block was okay!
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Betty454ss
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Re: symptoms of a bad throttle body?
Reply #10 - 09/10/11 at 00:31:35
 
no check engine light. fuel pressure is very strong. timing is on point. and yes its the whole eddle brock intake/injector kit.
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Betty454ss
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Re: symptoms of a bad throttle body?
Reply #11 - 09/10/11 at 00:34:24
 
clay wrote on 09/09/11 at 16:34:52:
I once had the same type backfiring.  Turned out to be that the base gasket had deteriorated and was affecting the air/fuel ratio.  Worn throttle-plate bushings can also be a problem.


man, yea this is kinda my last resort because as you read i replaced amost everything? and ive been told the same thing and wanted to see if anyone else had that problem. thanks for sharing. im gonna check for leaks and then maybe just rebuild it all together. save some $$$.
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Rock454
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Re: symptoms of a bad throttle body?
Reply #12 - 09/10/11 at 21:22:14
 
Check for leaking gaskets (can do with a spray while running).  Replacing parts may or may not find it.  Would not be the first time they given you the wrong one or a defective one.  Best to diagnose first.
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2004 Yukon - Magnaflow cat back
2001 Seville STS
1990 454SS Whipple charged 7 psi, Edelbrock Performer TBI intake, Edelbrock TES, Borla Cat back, heated O2, Eaton limited slip, 2/4 lowered, Gear Vendor Overdrive, Belltech Rear Sway Bar, 13.54 sec @ 100.02 1/4 mile
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Betty454ss
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Re: symptoms of a bad throttle body?
Reply #13 - 09/10/11 at 22:21:10
 
Rock454 wrote on 09/10/11 at 21:22:14:
Check for leaking gaskets (can do with a spray while running).  Replacing parts may or may not find it.  Would not be the first time they given you the wrong one or a defective one.  Best to diagnose first.


will do. thankyou. by the way im loving the 454 ss air dam
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Re: symptoms of a bad throttle body?
Reply #14 - 09/11/11 at 19:54:02
 
Thanks.  Made it years ago, has a back light as well.
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...
2004 Yukon - Magnaflow cat back
2001 Seville STS
1990 454SS Whipple charged 7 psi, Edelbrock Performer TBI intake, Edelbrock TES, Borla Cat back, heated O2, Eaton limited slip, 2/4 lowered, Gear Vendor Overdrive, Belltech Rear Sway Bar, 13.54 sec @ 100.02 1/4 mile
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