YotaRunner1980

So I'm stumped on the issue at hand and thought id throw it out here. A little background; Had the truck for 12+yrs and its been in the shop once in this time. I have done all the upgrades and maintence myself. I swapped a motor into it about 2.5yrs out of a 88 that had fresh rebuild. My Runner is an 89. It has headers and exhaust as well cold air intake.

The issue started about two months back and started overnight. As it ran fine one day and went to start it the next day and started backfiring and poping when id try and excelerate. Took it to a shop to run diagnostics and came back clean. Found the TPS was sticking 1/2 open at times so that was replaced. Was still backfiring and lacking power when i left the shop. Seemed to clear out and run better after a couple days??

Now it has gotten worse as when I first start it backfires until its warmed up alittle. Than seems to idle fine and you can rev the motor in neutral and sounds great. But when you get out of 1st gear it falls on its face and backfires. I have found its real bad when at freeway speeds and trying to excelerate in a tall gear.

I have recently cleaned throttle body, Adjusted TPS, Replaced temp sensor, Adjusted timing, Ect.

Any suggestions on direction to go? I am thinking distributor or ignition issue?

TNRabbit

Have you pulled codes yourself?

Backfiring is generally a timing issue. Could be distributor, but that's a big expense to guess at.....

YotaRunner1980

I have pulled codes with self diagnostic and only code that has come up is open circuit on TPS (Code 41). If the ECU was bad i would think it would have popped up at the shop when they ran there diagnostic? Another stumper is it had no codes when it first started acting up but now almost two months later i pulled a code 41?? Trying not to throw parts at it as I know most are by no means cost effective!!

91_TOYOTA_4x4

Hey man. I just read this on pirate 4x4.-
41- loss of TPS VTA signal or IDL is on and VTA output exceeds 1.45v for 1/2 second or longer

Dont know if thats right but thats what i found in a 30 sexond search. If you are back firing its because of un burnt fuel and it can only happen form a few things from what im aware of. Being timing way off, stuck open injector or injectors, and im not sure on this one but when a set of heads i tried that hadent ever had the valves shimmed it ran like crap because it left a couple intake and exhaust valves open. Im not a pro but start with code 41 then maybe take your timing cover off because the timing belt could have slipped.

Sturmcrow

It's almost too much of a coincidence to be correct, but another fellow just posted in this forum that his eight-month, very expensive battle to figure out why his 22RE was backfiring through the intake was due to a flattened cam. His problem also happened pretty much overnight too. His ended up being so expensive because he put in new part after new part with no improvement.

If your engine is fairly newly rebuilt, they might have put in an aftermarket cam that couldn't take it.

rworegon

Vacuum hoses all in good condition and in their proper place?

YotaRunner1980

It backfires out of exhaust not intake. all vacuum lines have been checked and are in order. shop ran tests for fuel pressure. Vacuum leaks. was put on scope. ect.. its weird because it clears out and runs fine as soon as it reaches normal idol?? It does seem to run rich? Gonna pull plugs and check them again. I did pull some wires from cap when running and it didn't seem to effect the idle to much?? Least not as much as I've seen in the past with other engines??

hiGis

Mine does this (93' 4x4 V6) it starts fine, runs fine for about 5-10 minutes then starts backfiring trought the intake (it sounds like it) no power and if I let go the gas it stalls.
it does this only when cold (first morning start)

turn it off and back on again and it will be all ok for te rest of the day! haha that's why I havent really done anything to fix it.

don't want to trheadjack but seems like a really similar problem. any thoughts would be aweosome

YotaRunner1980

I would say it sounds like maybe a sticking egr valve or cold start injector?? Pulling any codes?

YotaRunner1980

When I had my exhaust done the shop did sawzall the exhaust at cat which knocked the guts loose. as a result it seem to get plugged. I ran some sea foam thru it and about half way thru tank it almost died on take off and backfired. blew a big cloud of smoke and ran like a champ until this issue??