LT1-LT4 Modifications 1993-97 Gen II Small Block V8

back fire through intake

Thread Tools
 
Search this Thread
 
Old May 14, 2009 | 07:35 PM
  #1  
ElkySS's Avatar
Thread Starter
11 Second Club
iTrader: (6)
 
Joined: Oct 2007
Posts: 2,149
Likes: 31
From: Houston Tx
Default back fire through intake

iv been trying to solve this problem for god knows how long. at first i thought it was just i miss, then i listened real close and found out its actually a backfire through the intake. only under load, at high rpm and its intermittent. it also changes. sometimes its not there, sometimes its barley noticeable, othertimes its so bad i think its gonna give me whiplash. anyone have any itdeas, nothing i do seems to change it at all.

new parts: opti, coil, plugs, icm, lifters, injectors, fuel pressure regulator, walbro 255 w/ hotwire kit.

it was dyno tuned with a bed opti on it and im thinking thats the cause but i dont wanna drop more money on a retune for them to tell me thats not it.
Reply
Old May 15, 2009 | 08:01 AM
  #2  
ElkySS's Avatar
Thread Starter
11 Second Club
iTrader: (6)
 
Joined: Oct 2007
Posts: 2,149
Likes: 31
From: Houston Tx
Default

bump..
Reply
Old May 15, 2009 | 09:43 AM
  #3  
96SCTA's Avatar
TECH Fanatic
 
Joined: Sep 2002
Posts: 1,112
Likes: 0
From: BLOOMFIELD, NY
Default

Was it doing this after you got it back from the dyno tune or did it start shortly after? You listed all the new parts are these all new after the problem started or are they recently installed then this problem occured. Johny five needs more input
Reply
Old May 15, 2009 | 06:48 PM
  #4  
ElkySS's Avatar
Thread Starter
11 Second Club
iTrader: (6)
 
Joined: Oct 2007
Posts: 2,149
Likes: 31
From: Houston Tx
Default

injectors, ls7 lifters, and acdelco fpr wer installed with the cam, everything else was after.
it was barely running before the dyno. i thought the cam was too big to run on the stock tune when we got it tuned but it turned out to be an opti
Reply
Old May 17, 2009 | 02:04 AM
  #5  
ElkySS's Avatar
Thread Starter
11 Second Club
iTrader: (6)
 
Joined: Oct 2007
Posts: 2,149
Likes: 31
From: Houston Tx
Default

bump..
Reply
Old May 17, 2009 | 02:18 AM
  #6  
hitmanws6's Avatar
TECH Veteran
iTrader: (20)
 
Joined: Dec 2008
Posts: 4,041
Likes: 5
From: Orange, CA
Default

longshot but the plugs could be fouled
Reply
Old May 17, 2009 | 06:57 AM
  #7  
Anthony0908's Avatar
On The Tree
iTrader: (1)
 
Joined: May 2009
Posts: 142
Likes: 0
From: CO
Default

make sure there are no vac leaks any were . Unmetered air in the engine will cause this. Do you have a SES?
Reply

Trending Topics

Old May 17, 2009 | 08:23 AM
  #8  
Blown427conv's Avatar
Registered User
iTrader: (1)
 
Joined: May 2009
Posts: 42
Likes: 0
Default

What about a weak or broken valve spring or sticking (slightly open) intake valve?
Reply
LS1 Tech Stories

The Best V8 Stories One Small Block at Time

story-0

6 Gifts Neither Your Dad Nor Grad Will Shove Into the 'Trinket Drawer'

 Brett Foote
story-1

Topdon ONE vs. Artidiag 800 BT2: Which is the Diagnostic Tablet For You?

 Pouria Savadkouei
story-2

Gas Monkey Built a 6-Wheel Ferrari Testarossa With a Corvette LT4 Engine

 Verdad Gallardo
story-3

7 Most Reliable High-Performance Engines GM Has Ever Built

 Verdad Gallardo
story-4

Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin

 Verdad Gallardo
story-5

6 Common C5 Corvette Failures and What's Involved In Repairing Them

 Pouria Savadkouei
story-6

Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph

 Verdad Gallardo
story-7

Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked

 Pouria Savadkouei
story-8

Top 10 Most Powerful Chevy Trucks Ever Made!

 
story-9

Hennessey's New Supercharged Silverado ZR2 Has 700 HP

 Verdad Gallardo
Old May 17, 2009 | 12:10 PM
  #9  
ElkySS's Avatar
Thread Starter
11 Second Club
iTrader: (6)
 
Joined: Oct 2007
Posts: 2,149
Likes: 31
From: Houston Tx
Default

i put in new springs, rockers, push rods when the cam went in and have been out since to fix a head gasket. and it was doing it before the head gasket. no ses. its kinda hard for obd1 to pop a code lol
Reply
Old May 17, 2009 | 12:12 PM
  #10  
ElkySS's Avatar
Thread Starter
11 Second Club
iTrader: (6)
 
Joined: Oct 2007
Posts: 2,149
Likes: 31
From: Houston Tx
Default

my maf is descreend. (i bought it like that) could this or a bad maf cause this?
Reply
Old May 17, 2009 | 12:21 PM
  #11  
Patriotpa's Avatar
Teching In
 
Joined: Sep 2008
Posts: 41
Likes: 0
Default

Yes. With the screen removed the MAF is getting turbulent air that will skew its readings. I'd swap out the MAF. OEM and Granatelli Performance are about the same price.
Reply
Old May 17, 2009 | 12:28 PM
  #12  
ElkySS's Avatar
Thread Starter
11 Second Club
iTrader: (6)
 
Joined: Oct 2007
Posts: 2,149
Likes: 31
From: Houston Tx
Default

ill borrow one from my buddy and see what happens
Reply
Old May 17, 2009 | 02:20 PM
  #13  
Blown427conv's Avatar
Registered User
iTrader: (1)
 
Joined: May 2009
Posts: 42
Likes: 0
Default

A dirty MAF will do that too. Cleaned a few (carefully) and fixed some stumbling and backfiring problems.
Reply
Old May 17, 2009 | 03:12 PM
  #14  
ElkySS's Avatar
Thread Starter
11 Second Club
iTrader: (6)
 
Joined: Oct 2007
Posts: 2,149
Likes: 31
From: Houston Tx
Default

unplugged the maf and went for a drive, no change (except the ses light)
Reply
Old May 17, 2009 | 03:15 PM
  #15  
ElkySS's Avatar
Thread Starter
11 Second Club
iTrader: (6)
 
Joined: Oct 2007
Posts: 2,149
Likes: 31
From: Houston Tx
Default

well the plate on top of the tb is leaking. im thinking that MIGHT have something to do with it if it pulls a vacuum there. how do you guys get that thing to seal? the rubber expands when it gets oil on it. do you just use rtv or regular gasket material or what?
Reply
Old May 17, 2009 | 03:16 PM
  #16  
Anthony0908's Avatar
On The Tree
iTrader: (1)
 
Joined: May 2009
Posts: 142
Likes: 0
From: CO
Default

Originally Posted by ElkySS
unplugged the maf and went for a drive, no change (except the ses light)
I dont think your car should run it it unplugged? lol?

Originally Posted by ElkySS
well the plate on top of the tb is leaking. im thinking that MIGHT have something to do with it if it pulls a vacuum there. how do you guys get that thing to seal? the rubber expands when it gets oil on it. do you just use rtv or regular gasket material or what?
If there is no gasket to it i dought it draws air in.
Reply
Old May 17, 2009 | 05:14 PM
  #17  
creepingdeath94's Avatar
TECH Regular
iTrader: (1)
 
Joined: Feb 2009
Posts: 399
Likes: 0
From: PSL, FL
Default

If you unplugged your MAF and there was no difference in driveability, I think something is wrong there. The MAF is important enough that it should run poorly without it hooked up and if it is the same, I think your problem lies there somewhere.
Reply
Old May 17, 2009 | 05:25 PM
  #18  
ElkySS's Avatar
Thread Starter
11 Second Club
iTrader: (6)
 
Joined: Oct 2007
Posts: 2,149
Likes: 31
From: Houston Tx
Default

well lt1s (maybe ls1 too) have a redundant system. when you unplug the maf it runs off of speed density
Reply
Old May 18, 2009 | 02:19 AM
  #19  
robsquikz28's Avatar
TECH Veteran
iTrader: (246)
 
Joined: Mar 2008
Posts: 4,984
Likes: 1
From: Chicago/Crown point
Default

dude it will run like **** if not even start
Reply
Old May 18, 2009 | 02:26 AM
  #20  
hitmanws6's Avatar
TECH Veteran
iTrader: (20)
 
Joined: Dec 2008
Posts: 4,041
Likes: 5
From: Orange, CA
Default

Originally Posted by ElkySS
well the plate on top of the tb is leaking. im thinking that MIGHT have something to do with it if it pulls a vacuum there. how do you guys get that thing to seal? the rubber expands when it gets oil on it. do you just use rtv or regular gasket material or what?
i forget the name but its a black liquid in a little tube. kragen sells it for a few bucks
Reply



All times are GMT -5. The time now is 01:28 PM.

story-0
6 Gifts Neither Your Dad Nor Grad Will Shove Into the 'Trinket Drawer'

Don't get dad new socks or a grill brush this year.

By Brett Foote | 2026-06-09 14:55:56


VIEW MORE
story-1
Topdon ONE vs. Artidiag 800 BT2: Which is the Diagnostic Tablet For You?

Slideshow: We take a close look at the ONE and Artidiag 800BT2 diagnostic tools from Topdon and the reasons to buy one over the other.

By Pouria Savadkouei | 2026-05-28 11:05:11


VIEW MORE
story-2
Gas Monkey Built a 6-Wheel Ferrari Testarossa With a Corvette LT4 Engine

Slideshow: The controversial Ferrari F6 swaps its original flat-12 for a Corvette Z06-derived LT4 V8 and sends power to four rear wheels through a custom-built drivetrain.

By Verdad Gallardo | 2026-05-26 18:23:54


VIEW MORE
story-3
7 Most Reliable High-Performance Engines GM Has Ever Built

Slideshow:These GM engines didn't just make huge power, they survived abuse, boost, track days, and six-digit mileage with a reputation for refusing to quit.

By Verdad Gallardo | 2026-05-21 16:45:27


VIEW MORE
story-4
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin

Slideshow: This heavily modified 1971 Camaro mixes classic muscle car styling with a fifth-generation Camaro interior and modern LS3 power.

By Verdad Gallardo | 2026-05-12 18:06:42


VIEW MORE
story-5
6 Common C5 Corvette Failures and What's Involved In Repairing Them

Slideshow: From wobbling harmonic balancers to failed EBCMs, these are the issues that define long-term C5 ownership and what repairs typically involve.

By Pouria Savadkouei | 2026-05-07 18:44:57


VIEW MORE
story-6
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph

Slideshow: A modern Camaro transformed into a retro icon, this limited-run "Bandit" build blends nostalgia with brute force in a way few revivals manage.

By Verdad Gallardo | 2026-04-21 13:57:02


VIEW MORE
story-7
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked

Slideshow: Cadillac didn't just crash the high-performance luxury vehicle party, it showed up loud, supercharged, and occasionally a little unhinged...

By Pouria Savadkouei | 2026-04-16 10:05:15


VIEW MORE
story-8
Top 10 Most Powerful Chevy Trucks Ever Made!

Slideshow: Top ten most powerful Chevy trucks ever made

By | 2026-03-25 09:22:26


VIEW MORE
story-9
Hennessey's New Supercharged Silverado ZR2 Has 700 HP

Slideshow: Hennessey has turned the Silverado ZR2 into a 700-hp off-road monster with supercharged V8 power and a limited production run.

By Verdad Gallardo | 2026-03-24 18:57:52


VIEW MORE