Occasional backfiring in between shifts

Backlash2032

Backlash2032

New Member
Sep 20, 2010
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So there's one fault with the GTE swap so far. It likes to backfire inbetween shifts. I thought it would be the TPS out of adjustment, so I pulled the codes, no 51. Ohmed out the TPS, with no shim there was resistance, same with a .5mm shim, and then infinite with the .9mm shim. I double and triple checked this.

Then I noticed that the dashpot diaphragm thing that screws to the throttle body was loose, so I tightened that up, and adjusted the dashpot. Having no tach (since its still an N/A tach), I just tried to mimic my old N/A throttle bodies dashpot movement. If that makes sense.

So I took it out for a drive, and everything seems normal. Then I hit boost a little (no where near WOT) and I go to shift and whaddya know.. It backfires. I have no idea what could be causing it to run rich inbetween shifts. Completely bone stock where it matters (stock AFM, stock turbo, stock bov whatever. The only aftermarket parts are the pistons (NPRs) and the headgasket (Titan MHG)). It never did this when I had my TPS disconnected due to it not working (before I replaced it).. Could it be another bad TPS?
 
te72

te72

Classifieds Moderator
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Mar 26, 2006
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Well, I've never known a stock electronic 7m to NOT backfire when you stick an exhaust on it, so I wouldn't worry about it much. Are you running a catalytic converter?

The turbo cars like to run rich, particularly when you run a BOV to atmosphere, but if you have the stock BOV...
 
emericaskater285

emericaskater285

Badass
Sep 19, 2011
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Mine runs real lean around 3500 right as I am going into boost, and I try to take it easy until I can get a proper tuning screw in (tomorrow when I get it back). I back fire quite often, and it is a lean back fire not rich, as I have a wideband and it is reading real lean.
 
Backlash2032

Backlash2032

New Member
Sep 20, 2010
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No I don't have a wideband.. But I mean I could understand a little gurgle or two.. But this is like I just shot a rifle. And for the record I'm running open DP WITH the factory cat in the DP.
 
jetjock

jetjock

creepy-ass cracka
Jul 11, 2005
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People are always so quick top blame the EFI system when it's usually not at fault. It's not your TPS. And are we talking real backfire here or after-fire?

Edit: Never mind. I see you have an open DP...
 
Last edited:
BrandonW

BrandonW

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Jun 25, 2007
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every now and then i get a nice "pop" from the exhaust but its because i run rich between shifts with the vented bov
 
Backlash2032

Backlash2032

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Sep 20, 2010
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I think I may have found the problem. The EGR pipe that goes to the plenum was not connected to the EGR. Granted, the EGR isn't hooked up either but that's just a giant un-metered air leak. I have yet to drive it after fixing this, but I have a feeling this was my problem.
 
91whitepack

91whitepack

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May 23, 2012
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slidell, louisiana
Mine has always done this. Even before I installed my atmospheric blow off valve. If I bring it right where it gets over zero and granny shift it will shoot a flame Everytime.
 
S

Skeezix

Supradope
Dec 30, 2009
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Regina, SK
My car after-fires quite often but not every time. Its just the combo I have, stock ECU, atmospheric BOV, BIC DDP. Timing is bang fuckin on too. If you put a muffler or some more exhaust on it might quite it down or not let it happen at all.
 
suprarx7nut

suprarx7nut

YotaMD.com author
Nov 10, 2006
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Mine does this as well. Stock JDM ECU, no EGR, 3" turbo back Raptor Racing exhaust, open element filter, Bosch BPV (recirculated), Stock timting, TPS is good, etc, etc...

My wideband shows I'm around 14.5 until I'm WOT or into boost. At that point it will slowly go richer until it hits about 11.5 or so. To me, that seems perfectly normal, so I'm not sure why it pops so much.
 
Backlash2032

Backlash2032

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Sep 20, 2010
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Anybody have any ideas to this? I find it hard to believe that Toyota's flagship gt car afterfires normally...

Sent from my ADR6425LVW using Tapatalk 2
 
S

Skeezix

Supradope
Dec 30, 2009
229
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Regina, SK
Backlash2032;1849763 said:
Anybody have any ideas to this? I find it hard to believe that Toyota's flagship gt car afterfires normally...

Sent from my ADR6425LVW using Tapatalk 2
Click to expand...

Why? It only makes sense being tuned pig rich from the factory, and then you opened the exhaust...
 
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