Ok i'm new here and just for the record I have searched quite a bit and found plenty of useful information. I just bought a 1990 5 spd pickup with the 3vze and it had a misfire from hell and it wouldn't idle unless I feathered the gas.

Now I got it home and started tearing into it and found the mass air flow had been tampered with. Wires inside were all screwed up. So I made an adventure out to the local junkyard and found me a maf sensor for 30 bucks and it ran 10000x's better. But it still had a miss and it backfired everynow and then.

I moved onto doing a tune up. Dizzy cap, button, NGK plugs (gapped to spec) and wires. It ran even better but still had a little miss. I pulled each wire one at a time off the distributer and found that all but #1 and #3 made it get durastically worse. At this point I was concerned it had a blown head gasket, worn piston rings or valves. I checked the coolant for oil and visa versa and it was fine. I ran a compression test and it was 150 psi across the board.

When I was pulling the plugs for the compression test I found that #1 plug hadn't even been firing. It still looked brand new after 2 days of being in. The rest of the plugs looked normal. Even #3 looked normal. But it still had that damn miss.

Now this is where i'm stumped. I'm looking for advice on what to look into next. Could it possibly be a bad plug right out of the box? I've heard of it before but very very rarely. I'm leaning more towards a problem in the injectors. I have a good feeling that would cause my problems but like I said i'm not 100% sure. Any advice on this would be fantastic. I apologize for the long post but I wanted to make sure I gave as much information as I could. Thanks in advance.

 

Check the intake boot. The one taht attaches to the throttle body/intake. Often that boot will split, and allow unmetered air into the engine. It will cause the backfires and misfires you are describing.

If that is ok, check out the injectors, make sure they are all actually firing. Also, what brand of plug/wire did you use? Often times aftermarket wires will cause big problems with the 3VZ

 

If i were you i'd just pull out the injectors and take them to some place and have them completely cleaned and new rubbers and cap. i just did mine in my 22re was like $25 an injector. And now it doesn't even turn over once before it fires. I was told by the guy at the shop that Toyotas are notorious for dirty injectors.

 

I bought NGK plugs and just a regular set of wires from advance auto.

 

my cousins montey carlo had a simalar problem all but one cylinder was fireing ended up blowing a head gasket, took it to the shop an they just said it was wires but when i pulled the engine it ended up the valves were completly shot the intake an exhust valve werent opening right so air couldnt go in to ignite the spark

 

That would show up on a compression test though right? Also I do have a decent rip in the intake piping after the mass air flow. I'll have to see if the junk yard has that piece soon.

 

Search 'ISR mod'. Its a better/cheaper option then putting the stock intake back on. Frees up a good amount of engine bay room.

 

That ISR mod looks fairly simple. I'm gonna have to give that a shot. Beats the hell outta driving out to the junkyard and searching for the stock piping with little chance's of success for finding it haha.

 

i just had a similar problem. clean you maf, all plumbing and throttle body. are you sure that you have your firing order right from the cap to each plug? that will cause weird backfires and lack of power.

 

The maf is clean, i'm doing the "ISR mod" and the throttle body is clean. All the plugs are good, attached, and in the correct order. I'm in no way new to cars and/or working on them so I know that's right. I'm still lookin to figure out why cylinder one isn't firing at all. I'm pulling the injectors next and having them cleaned and all that. Hopefully it'll take care of what's left of the miss.

 

whoa dude, that wasnt a shot at you mechanical capability/manhood.
i just had a similar problem and it turned out to be my maf and throttle body were dirty. i had also mistakenly arranged my plug wires amongst all the fiddling i was doing trying to trouble shoot why my truck was misfiring and backfiring.
its an easy mistake to make.
happens man, sometimes you overlook the obvious.

you said cyl 1 and 3 were the problems? did you try switching the wires? they are on the opposite side of the engine from the distributor. there's a lot of wire between them, it'd be easy to mix em up. i had 2 and 4 crossed. switched em up. no more problem.

 

I apologize, I wasn't trying to sound like an ass at all. I was just saying. I'll have to take a look in the morning just to be positive.

 

Ok so im new to forums but cant figure out my issue ive reading codes of throttle body temp sensor ,ingnition signal,and throttle body position sensor could it be those and how do i solve ignition