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Print in friendly format Send this term to a friend  4L60
The automatic from 1992-1993. The same as the 700R4, just has a different name.

Either way, they are junk. There are some minor differences on a ...
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matts85vet what causes intake backfire?
Toledo, Ohio
52 Posts
Member since:
2009/12/6 15:59

and how do i fix it?

im getting some off-idle backfiring through the intake and im trying to figure out what i can do to fix it.

thanks in advance
Posted on: 2010/11/11 16:02
85 coupe, TPIS Miniram, auto 700R4, 3.75 gears, afr 180 eliminator heads 58cc, 11:1 compression ratio, comp cams 268XFI hydraulic roller cam, 1.65 roller rockers, 52mm throttle body, c5 calipers, hedman elite longtube headers, pypes dual exhaust w/x-pipe
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383tpimachine Re: what causes intake backfire?
Master Guru
Corpus Christi
847 Posts
Member since:
2009/7/25 15:07

Posted on: 2010/11/11 16:11
1985 Atomic Orange 400YSIT56-Racecar build
1970 El Camino-Awaiting LSX
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CentralCoaster Re: what causes intake backfire?
Senior Guru
San Diego, CA
9160 Posts
Member since:
2007/10/27 20:00

valve timing or a bent valve?
Posted on: 2010/11/11 22:28
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rklessdriver Re: what causes intake backfire?
Senior Guru
Woodbridge, VA
1058 Posts
Member since:
2008/1/3 19:00

What causes backfiring thru the intake manifold is the spark plug firing the A/F mixture when the intake valve is still open....

That can be caused by extremely low base ignition timing or a bent intake valve or an improperly adjusted intake valve (lash too tight).
Posted on: 2010/11/12 9:20
1992 Corvette. 383 LTX with ZF 6spd.
Best pass - 11.17@127MPH 1.78 60ft. Stock IRS on MT 315/35R17 Radials.

1984 Corvette. 427 SBC with TH350 auto.
Best pass - 6.02@113mph 1.246 60ft. Stock IRS on MT 28X10.5's.
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joeld Re: what causes intake backfire?
Lawrenceville Ga
544 Posts
Member since:
2007/12/29 19:00

Check for any spark plug wires "jumping fire". Also check the distributor cap for small hair line crack inside, and for carbon tracking.

Posted on: 2010/11/12 10:39
1989 Coupe,L98 automatic
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tpi421vett Re: what causes intake backfire?
Registered Vendor
Salt Lake City Utah
125 Posts
Member since:
2008/11/17 14:59

A intake valve hanging open would be the most common cause as mentioned. On flat tappet engines, if it pops back thru the tb at full throttle, the cam is going flat. And if the engine is extemely cold and the A/F ratio is was lean, they can pop back thru the carb or tb when cold. And also ignition problems as mentioned
Posted on: 2010/11/13 2:04
AFR Dealer, can sell at prices too low to advertise. 801-953-6391
08 C6 LS3,3LT,Z51,A6,NPP
91 vette,450ci, AFR 220, miniram,FAST, Crane 252/260 solid roller, 200 shot nos, ZF6, 4 link, 9", DA corrected to 1300 ft 9.65@145.xx
450ci now with AFR 235...
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blr33439 Re: what causes intake backfire?
Guru Newb
9 Posts
Member since:
2010/10/1 20:23

How old is the distributer and cap. I had a similar problem on an 84 and it ended up being a bad distributer. Ran great after that.
Posted on: 2010/11/19 15:18
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Tech Re: what causes intake backfire?
Guru Newb
25 Posts
Member since:
2010/11/2 1:36

If it also has trouble at WOT it can be a week ignition/ low voltage. It takes more energy to fire at higher compression pressures.
If it does it at all rpms it can be the valve train. It is a fixed relationship. Has it been over reved?
A carbon tracked cap will usually have issues at all rpms.
Arcing plug wires sometimes show up in the dark.
If it sputters like you need a new accelerator pump when you give it a little gas but runs fine if you punch it, it can be a worn throttle position sensor with a flat spot in it.
Posted on: 2010/11/20 1:23
93 Corvette
The first Chevy that I have ever owned
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