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Backfires "pops" through intake

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Old Mar 31, 2013 | 06:35 PM
  #1  
Livvie's Avatar
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From: Massachusetts
Car: 86 I-roc Z28
Engine: 355
Backfires "pops" through intake

Hello everyone I have an 86 Camaro, 5.0 TPI. The car runs great within the first 5 miles. After that, she wont take throttle. She will hesitate, stumble and backfire through the intake. I am contantly getting codes 33 and 36. Both related to MAF circuit. I have replaced the burn off as well as the power relay. I have cleaned the MAF several times and also checked all duct work for leaks. All wiring, plugs and fuses appear OK. Fuel pressure checks OK and TPS is within spec. Is there anything left to check before I spend the ca$h on a MAF?

Thanks!
Olivia
"Livvie"
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Old Mar 31, 2013 | 08:12 PM
  #2  
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From: Il
Car: 1989-92 FORMULA350 305 92 Hawkclone
Engine: 4++,350 & 305 CIs
Transmission: 700R4 4800 vig 18th700R4 t56 ZF6 T5
Axle/Gears: 3.70 9"ford alum chunk,dana44,9bolt
Re: Backfires "pops" through intake

Have you done any work to the car or has it just started dong this?
Sounds like more than 1 problem
My quick check 1st list.

Check the timing
Check the fuel PSI
ohm the injs if org
check plug wires for arcing or burn thru
Also work thru the codes in the factory service manual.

Last edited by TTOP350; Apr 1, 2013 at 07:56 AM.
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Old Mar 31, 2013 | 11:23 PM
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Chevy86 IROC-Z's Avatar
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From: Far West
Car: 1986 Camaro Z28 IROC-Z
Engine: 350 Tuned Port Injection, for now.
Transmission: 700R4
Axle/Gears: Posi - 3.23
Re: Backfires "pops" through intake

unplug the maf sensor and take it out for a spin. See if the backfiring will stop. Does your speedometer cable work?
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Old Apr 29, 2013 | 07:15 PM
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From: Union, KY
Car: 85 Firebird
Engine: 87' 350 TPI
Transmission: 700R4
Re: Backfires "pops" through intake

I am new here but looks like i found someone with the same problem.
Mine takes a little bit to get started you have to turn it over quickly a bunch of times then it starts. Idles great but if you try to rev. it up it will pop like you said or it will want to die. I tried to disconnect the maf but couldn't get it to start. I don't have a scanner either any recomendations to try would be appreciated.
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Old Apr 29, 2013 | 08:55 PM
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From: Far West
Car: 1986 Camaro Z28 IROC-Z
Engine: 350 Tuned Port Injection, for now.
Transmission: 700R4
Axle/Gears: Posi - 3.23
Re: Backfires "pops" through intake

Originally Posted by Cjohnson
I am new here but looks like i found someone with the same problem.
Mine takes a little bit to get started you have to turn it over quickly a bunch of times then it starts. Idles great but if you try to rev. it up it will pop like you said or it will want to die. I tried to disconnect the maf but couldn't get it to start. I don't have a scanner either any recomendations to try would be appreciated.
Now that I think about it, I had a very similar problem. I didn't have a distributor when I rebuilt my engine. So my uncle let me borrow a old electronic dizzy from a Caprice. It would turn on but once we gas it has, it would sputter like crazy and we couldn't get the Rpms over 2,000. So I decided to buy everything in the dizzy which included the in cap coil, carbon pin, pick-up coil, rotor, and cap. s I was disassembling the dizzy, the pick-up coils magnet came out in pieces. After putting everything back together, my Camaro fired up right away and I was able to put the pedal to the metal. Perhaps that is the issue. Also, you don't need a scanner to read codes. Just put a paper clip across the pins in the ALDL in A & B. then turn the key to "On" but don't crank. The Check Engine light will flash a 1,2 code three times. Then any other codes after will flash. When the codes are done, it will flash the 1,2 again. Hope this helps.
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Old Apr 29, 2013 | 08:57 PM
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Chevy86 IROC-Z's Avatar
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From: Far West
Car: 1986 Camaro Z28 IROC-Z
Engine: 350 Tuned Port Injection, for now.
Transmission: 700R4
Axle/Gears: Posi - 3.23
Re: Backfires "pops" through intake

Originally Posted by Cjohnson
I am new here but looks like i found someone with the same problem.
Mine takes a little bit to get started you have to turn it over quickly a bunch of times then it starts. Idles great but if you try to rev. it up it will pop like you said or it will want to die. I tried to disconnect the maf but couldn't get it to start. I don't have a scanner either any recomendations to try would be appreciated.
Here is a guide on how to use the trouble codes and the aldl. The troublecodes are very similar too.

http://www.gnttype.org/maint/malf.html
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Old May 6, 2013 | 06:27 PM
  #7  
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From: Union, KY
Car: 85 Firebird
Engine: 87' 350 TPI
Transmission: 700R4
Re: Backfires "pops" through intake

Originally Posted by Chevy86 IROC-Z
Here is a guide on how to use the trouble codes and the aldl. The troublecodes are very similar too.

http://www.gnttype.org/maint/malf.html
I actually figured that out over the weekend before i read this and it showed that i did not have any codes. After finding that out i thought about the fuel pump and little filter on the end of it. I pulled out the sending unit and looked down in the tank and the fuel was brown looking. I figured that i could be bad fuel. I poured new gas into a bucket and put the pump in there. Started right up. When i reved it up it sounded like a f***ing race car. Did that a few times and figured that was it. Sucked out the old gas and added new. Reassembled and went to take it on a drive seemed ok for the first hundred yards or so, so i floored it and it smoked the tires then dropped out like it lost fuel then back on again. Next i think i may check the length on the sending unit to make sure it is not mashed to the bottom of the tank?????????????????????????????????????????????????????
Thanks for the suuggestions.
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Old May 6, 2013 | 07:55 PM
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Chevy86 IROC-Z's Avatar
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From: Far West
Car: 1986 Camaro Z28 IROC-Z
Engine: 350 Tuned Port Injection, for now.
Transmission: 700R4
Axle/Gears: Posi - 3.23
Re: Backfires "pops" through intake

How much fuel did you add after removing the old fuel? Sometimes in my Camaro, when the fuel is low, it'll turn off or sputter when I take a turn. The fuel swishes accordingly in a turn, during braking, and during acceleration. If there is no fuel to be sucked up, the fuel lines will lose pressure and the injectors will not function correctly do to drop of pressure. This may of have been the issue for you. But I don't know.
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Old May 28, 2013 | 10:57 AM
  #9  
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From: Massachusetts
Car: 86 I-roc Z28
Engine: 355
Re: Backfires "pops" through intake

I have replace the cap and rotor. New wires, new coil & module. Timing is set. New mass air flow. Cleaned IAC. Also new fuel pressure regulator. The injectors ohm out OK. New fuel pump and fuel filter. Being told it may possibly be contaminated fuel causing bad fuel at injectors. I'm at my wits end!!

Last edited by Livvie; May 28, 2013 at 11:06 AM.
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Old May 28, 2013 | 11:18 AM
  #10  
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From: Massachusetts
Car: 86 I-roc Z28
Engine: 355
Re: Backfires "pops" through intake

And it runs better with the MAF unplugged. Still falls on its face when you lay into the throttle. Car wont go over 2000 rpm without dropping down to zero rpm and back up. Only getting 2 codes, 33 (MAF or circuit high) and 44 (Lean exhaust) prior to unplugging air flow sensor.
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Old May 28, 2013 | 11:19 AM
  #11  
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From: minnesota
Car: 89 Firebird
Engine: 5.7
Transmission: 700r4
Axle/Gears: unkown
Re: Backfires "pops" through intake

Originally Posted by Chevy86 IROC-Z
unplug the maf sensor and take it out for a spin. See if the backfiring will stop. Does your speedometer cable work?
did you try this?
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Old May 28, 2013 | 11:39 AM
  #12  
Livvie's Avatar
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From: Massachusetts
Car: 86 I-roc Z28
Engine: 355
Re: Backfires "pops" through intake

Originally Posted by NotsosleepyZ
did you try this?
Yes I did. Just got back from a ride and it still runs like garbage. And the speedometer does work

Last edited by Livvie; May 28, 2013 at 11:45 AM.
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Old May 30, 2013 | 11:59 PM
  #13  
Sojer's Avatar
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From: Detroit, MI
Car: 1987 IROC-Z red t-top
Engine: Nothing much
Transmission: I wish t56
Axle/Gears: 9bolt 3.27 4sale
Re: Backfires "pops" through intake

Having this problem 2 on modded motor swap
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Old Jun 2, 2013 | 08:15 AM
  #14  
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From: Rincon, Ga.
Car: 91 Camaro RS
Engine: 305 TPI conversion.
Transmission: T56
Axle/Gears: 3.73 posi 4th gen rear
Re: Backfires "pops" through intake

mine is doing the same and the only issue I see here is my speedo quit. its a 91 5 spd. what does the speed play into this?
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Old Jun 5, 2013 | 12:50 AM
  #15  
Sojer's Avatar
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From: Detroit, MI
Car: 1987 IROC-Z red t-top
Engine: Nothing much
Transmission: I wish t56
Axle/Gears: 9bolt 3.27 4sale
Re: Backfires "pops" through intake

Ok fixed mine I think. I tighten the rockers (just put on rollers) I was able to rev and some of the back firing stopped. Adjusted the timing and the back firing stopped. but when I tap the gas is stall out. So I unplug the maf it act better but won't idle cold. So new (used) maf I will pick up on the c list
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