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Discussion Starter · #1 ·
Here's one for you guys. I replaced the engine out of my 82 Toy with a 85 4-Runner 22R in October. I recently developed a popping/back firing sound out of my exhaust when I down shift. This was just after my temperture gauge in my dash went f**cked. I figured my fuel mixture was high so I backed it off a bit, but that didn't help. So I figured that it might be in the carb so I rebuilt it last week. Still no better. I replaced my muffler yesterday hoping that maybe I wasn't getting enough back pressure, but still no improvement. The one thing I did figure out is that the old engine didn't have an EGR system where as the new one does. Any ideas on how to by pass the EGR? Is it really necessary? Please help!!!
 

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I had that same sound sorta of a poping sounds when down shifting going down hills right?. I never did figure out what the hell it was it sorta went away when the temperatuer warmed up I think. don't think the EGR would have anything to do with it now my engine was also a 22-re Have you checked your timing?. could be also a build of carbon in the cylinders. Just some Ideas for ya :)
 

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Discussion Starter · #3 · (Edited)
yah, my timing was the second thing I checked after the fuel mix. I also changed the plugs and the plug wires along with the distributor cap and rotor. I'm totally lost. Someone please help!!!:confused: :(
 

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Gullygossner said:
it sounds like you could have a leak somewhere at the exhaust manifold.
this is the problem gauranteed. when youre decelerating, there is high vacuum sucking fuel from the carb, but not enough oxygen to burn it completely due to the closed throttle. fresh air gets sucked in through a leak in the exhaust and the unburnt fuel ignites inside the exhaust system. the leak could be anywhere, manifold, pipe or even the egr system.

you can trash the entire egr system. just plug the vac lines at the carb and the holes in the manifold. some systems had an exhaust gas cooler bolted to the back of the head. either replace the cooler with the steel plate off of a non egr engine, or cut off the tubes and leave the cooler in.
 

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Discussion Starter · #6 ·
cool!! thanks guys. I'll check my exhaust right away. I think I remember hearing a leak actually between my header and exhaust pipe. Would that do it?
 

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Discussion Starter · #8 ·
well, I think I found the problem. There's a break in my exhaust pipe about an inch behind the flange that attachs to the header. If air is getting in anywhere it will probably be there. I'll just get it welded back together and that should hopefully do the trick. It's really been pissing me off cuz my truck runs great besides the popping when gearing down. Thanks everybody!!:)
 
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