popping through intake
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Teching In
Joined: Jul 2018
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From: corpus christi tx
popping through intake Hi everyone im new here! just want to start off like everyone else and say i love these forums ive been reading them for years lol
heres my issues .( sorry long read)
i have a 2002 lq4 w/4l80e that had 480k on it ive recently rebuild it heres the the list thats been done
hot dipped
3 angle valve job on heads
ls6 blue valve springs
tsp 216/220 .550/.550 low lift cam
1 7/8 long tubes
no other mods were made to heads or intake
all internals are new and assembled by a professional.
i recently got it tuned and it started hesitating/ popping through the intake on acceleration. while the a/c is on its even worse. i took it to another tuner he said that everything looked fine the only issue was the 02s were tuned off.
I UNPLUGGED the MAF and it ran BETTER no popping or hesitations. only lacked power. also my brake light and abs light on dash come on and off randomly. i also have a slight lifter tap i guess i cheaped out on them idk .before the tune and rebuild everything was fine had plenty of power didnt pop. ALSO i have power loss under load .like if im in sand or mud it just sits there even petal to the floor. please help im stumped
heres my issues .( sorry long read)
i have a 2002 lq4 w/4l80e that had 480k on it ive recently rebuild it heres the the list thats been done
hot dipped
3 angle valve job on heads
ls6 blue valve springs
tsp 216/220 .550/.550 low lift cam
1 7/8 long tubes
no other mods were made to heads or intake
all internals are new and assembled by a professional.
i recently got it tuned and it started hesitating/ popping through the intake on acceleration. while the a/c is on its even worse. i took it to another tuner he said that everything looked fine the only issue was the 02s were tuned off.
I UNPLUGGED the MAF and it ran BETTER no popping or hesitations. only lacked power. also my brake light and abs light on dash come on and off randomly. i also have a slight lifter tap i guess i cheaped out on them idk .before the tune and rebuild everything was fine had plenty of power didnt pop. ALSO i have power loss under load .like if im in sand or mud it just sits there even petal to the floor. please help im stumped
Hi everyone im new here! just want to start off like everyone else and say i love these forums ive been reading them for years lol
heres my issues .( sorry long read)
i have a 2002 lq4 w/4l80e that had 480k on it ive recently rebuild it heres the the list thats been done
hot dipped
3 angle valve job on heads
ls6 blue valve springs
tsp 216/220 .550/.550 low lift cam
1 7/8 long tubes
no other mods were made to heads or intake
all internals are new and assembled by a professional.
heres my issues .( sorry long read)
i have a 2002 lq4 w/4l80e that had 480k on it ive recently rebuild it heres the the list thats been done
hot dipped
3 angle valve job on heads
ls6 blue valve springs
tsp 216/220 .550/.550 low lift cam
1 7/8 long tubes
no other mods were made to heads or intake
all internals are new and assembled by a professional.
Thread Starter
Teching In
Joined: Jul 2018
Posts: 7
Likes: 0
From: corpus christi tx
in park it free revs fine no stumble or popping. its almost like when in D and about to take off my air/fuel ratio is screwed up or im running lean/rich then it stumbles and pops then it accelerates fine after it back fires through intake. i can't remember it doing it right after the build .i Remember taking it to the exhaust show the day after the build but idk if it did this then .
What do you have on there for exhaust? Do you think that you might be leaking little exhaust and be running a little rich? If so, that exhaust can pop when it hits the fresh air. (If this happens near the headers, it may sound like its coming from the intake.)
Backfiring through the intake usually means something destructive is going on through the valve train - and that doesn't seem to be happening here!
I wonder if something is twisting and causing a gap in your exhaust when you take off??? If this only happens when you are taking off from a stop - I'd think this points more at an exhaust leak.
Backfiring through the intake usually means something destructive is going on through the valve train - and that doesn't seem to be happening here!
Thread Starter
Teching In
Joined: Jul 2018
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From: corpus christi tx
as far as exhaust leaks i know for sure i have one at the collector on the driver side header but its a pin hole from a weld. i sont feel and leaks at the flange on the heads. i unplugged the mass air flow sensor and it didnt do it but it was for sure sluggish.
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Thread Starter
Teching In
Joined: Jul 2018
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From: corpus christi tx
sorry im not understanding how a pin hole would cause a hesitation/stumble and a pop feom the intake if the exhaust leak is down stream. its at the collector where the header ends and the exhaust piping begins. my question is whats causing the explosion??
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Verdad Gallardo What I'm saying is that I don't think this is coming from your intake. It's probably coming from the pin hole. (If you can't re-create this at idle, how would you know for sure where it's coming from?) BTW - I expect that repeated intake backfires would set your air filter on fire or shred it at some point.
You might try this:
- Open the hood at night and disconnect the MAF sensor. (This could cause you to run a little rich.) BTW - This may give you a MAF code in the PCM, which you'd need to clear.
- See if you can get the pop at idle and visualize the explosion in the dark.
Thread Starter
Teching In
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From: corpus christi tx
i tried tge at night in idle thing before. it revs fine no popping nothing. unplugged the MAF still revs fine throughs a code pluged it back in took it to get pulled and that was it came back MAF cleared it plugged MAF back in still popped .
No cats on truck .is also tuned they turned o2s off .
it could be lean while MAF is plugged in and run rich when i unplug it. but wouldnt it pop more? more fuel more explosions? no pops no stumble when MAF is unplugged.
no codes either that i can see .
first tuner i took it to turned the 02s off idk why
second tuner i took it to verified that there was a code for them and the previose tuner turned the code off and the o2s OFF also .i thought they TUNED from the o2 sensors, map and MAF?
thank ou for every bit of information youre giving me. i will get the pin hole welded and see what happens .
No cats on truck .is also tuned they turned o2s off .
it could be lean while MAF is plugged in and run rich when i unplug it. but wouldnt it pop more? more fuel more explosions? no pops no stumble when MAF is unplugged.
no codes either that i can see .
first tuner i took it to turned the 02s off idk why
second tuner i took it to verified that there was a code for them and the previose tuner turned the code off and the o2s OFF also .i thought they TUNED from the o2 sensors, map and MAF?
thank ou for every bit of information youre giving me. i will get the pin hole welded and see what happens .
Yes. If it's a true backfire type of situation, there needs to be excess unburned fuel in the exhaust stream.
It's the opposite of unplugging the MAF. It would force the engine to go back to the MAF sensor to figure out the air/fuel mix, but... depending on your specific tune some other things could be going on.
I think this is still a good first start since you need to do it, anyway. I suppose you could have a small leak in the valve train by where some exhaust gas is passing by a "closed" intake valve and you are getting a small, non-destructive backfire in the intake before a flame front reaches the air filter. I would think the only way to confirm this would be to take off the intake and look for charring in one of the ports?
It's the opposite of unplugging the MAF. It would force the engine to go back to the MAF sensor to figure out the air/fuel mix, but... depending on your specific tune some other things could be going on.
I think this is still a good first start since you need to do it, anyway. I suppose you could have a small leak in the valve train by where some exhaust gas is passing by a "closed" intake valve and you are getting a small, non-destructive backfire in the intake before a flame front reaches the air filter. I would think the only way to confirm this would be to take off the intake and look for charring in one of the ports?
Thread Starter
Teching In
Joined: Jul 2018
Posts: 7
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From: corpus christi tx
thats an idea! i havent got the pin hole fixed yet but i will .yesterday i couldnt for the life of me get it to pop and then this more it started doing it again .i will update when i remove intake and look for an issue
i might also take heads off and check .or atleast do a leak down test on them
thank you!
i might also take heads off and check .or atleast do a leak down test on them
thank you!