Backfire/Studder under acceleration

[theizzardking]

I ruled it out because I tested it with a multimeter which showed it was working fine and I ran the truck with it plugged in and without it just to be sure and it ran way better with it plugged in. But as a friend of mine has informed me those aren't for sure ways to test a MAF. Apparently you have to hook it up to some machine and blow air through it while monitoring the read outs blah blah lol. So I bought a cheap MAF to be for absolute sure. If it turns out has been the cause the whole time I might just go bang my head on a rock cause it is one of the first thing that I looked at lol

oh ok, that's nuts!!! he's right on the read out, but USUALLY just checking it with a multimeter would tell you, that's a very funky case you got going on there buddy, i feel for you!!! can't believe it's so close to being in spec that it passed all of the normal testing....it happens though, really sucks for you though man, good luck and hope this stops you from pulling your hair out! lol

 

[T4RFool]

Update:

I got the new ebay MAF today and happily took it out to the truck in great anticipation of moving past this problem. I reset the ECU while I was put everything in and back together. I got it all put back together and started it up. My excitement was soon replace by :ybrick:. its still there. nothing has changed and back to square one. Its not the fuel pump, fuel filter, spark plugs, plug wires, igniter, injectors, or MAF :ybrick:

 

[Drcoffee]

I got the new ebay MAF today and happily took it out to the truck in great anticipation of moving past this problem. I reset the ECU while I was put everything in and back together. I got it all put back together and started it up. My excitement was soon replace by :ybrick:. its still there. nothing has changed and back to square one. Its not the fuel pump, fuel filter, spark plugs, plug wires, igniter, injectors, or MAF :ybrick:

Just catching up with a quick read but when did you rule out the injectors and how?

When my #4 injector crapped out, it multimetered just fine cold but not hot. The trick is how do you test #4 while its still hot? If you only resistance checked them it could still be an injector fault. Jsut saying.

 

[PitbullRescuer]

A multimeter won't rule out a clogged injector. With all the money you've already thrown at it, send your injectors to WitchHunter. It's not going to hurt anything to have them rebuilt and cleaned anyway.

 

[T4RFool]

Just catching up with a quick read but when did you rule out the injectors and how?

When my #4 injector crapped out, it multimetered just fine cold but not hot. The trick is how do you test #4 while its still hot? If you only resistance checked them it could still be an injector fault. Jsut saying.

I gave this method a shot as suggested by spectre6000:

Alright, i spent an hour outside under the hood and managed to not shock myself which in its self is good news. Unfortunately that is the only good news. I removed spark from each plug and ran the engine for each plug and that yielded no significant result other than the hesitation/stutter/stupidengine problem is still there. I removed spark from each plug and started it up each time and there was no change, I also tested the spark of all the plugs since I was there (as suggested by Spectre6000) just to eliminate them, they all had good strong spark. So with that all in mind I'm inclined to think that this is not injector related unless all the injectors are clogged :shrug:

A multimeter won't rule out a clogged injector. With all the money you've already thrown at it, send your injectors to WitchHunter. It's not going to hurt anything to have them rebuilt and cleaned anyway.

When I tested the injectors initially with a multimeter and they all tested positive all within spec at 15ohm, I was a bit frustrated. So I tested them by removing spark from each individual cyclinder and started it up to test each cylinder for changes/improvements. Each time i started it up it behaved the same with each cylinder which gave me the indication that it wasn't an injector problem unless every injector was clogged. I'm not saying its not possible, i'm saying that it seems unlikely.

 

[Drcoffee]

When I tested the injectors initially with a multimeter and they all tested positive all within spec at 15ohm, I was a bit frustrated. So I tested them by removing spark from each individual cyclinder and started it up to test each cylinder for changes/improvements. Each time i started it up it behaved the same with each cylinder which gave me the indication that it wasn't an injector problem unless every injector was clogged. I'm not saying its not possible, i'm saying that it seems unlikely.

Yea, thats not conclusive. Do yourself a favor and call witchhunter and talk with them. They helped me understand how these injectors work and I'm sure they will help point you in the right direction.

WitchHunter Performance - Injector Cleaning & Flow Testing Services

 

[T4RFool]

Yea, thats not conclusive. Do yourself a favor and call witchhunter and talk with them. They helped me understand how these injectors work and I'm sure they will help point you in the right direction.

I am Seriously considering this method. The only question about all of it is about the seals for the injectors. I looked all over the site and could seem to find whether or not they replace the seals or if they just clean. I know that after you remove the injectors the seals are required to be replaced.

 

[PitbullRescuer]

Mine came back ready to drop right in. They even returned the old seals with them in a separate bag.

 

[Drcoffee]

I am Seriously considering this method. The only question about all of it is about the seals for the injectors. I looked all over the site and could seem to find whether or not they replace the seals or if they just clean. I know that after you remove the injectors the seals are required to be replaced.

They come ready to install with new seals. I dab a little Vaseline on the O rings before installing. Their website says motor oil.

 

[T4RFool]

Out of curiosity, wouldnt this service do pretty much the same thing to take it to the shop and have them hook it up to a machine that they use to clean injectors?

 

[PitbullRescuer]

I'd rather someone that only works on injectors handle mine.

 

[Whackmaster]

My brothers Tacoma had the same problems you have.We banged our heads for a week trying to figure out the problem. When I was under the hood checking stuff out I saw some pinkish/white flaky stuff down by the harmonic balancer. His water pump had been leaking a little and the calcium had accumulated (over time) on the bottom timing belt gear causing the belt to jump a couple of teeth. We replaced the water pump and timing belt and it hasn't had any problems in over a year..

 

[T4RFool]

My brothers Tacoma had the same problems you have.We banged our heads for a week trying to figure out the problem. When I was under the hood checking stuff out I saw some pinkish/white flaky stuff down by the harmonic balancer. His water pump had been leaking a little and the calcium had accumulated (over time) on the bottom timing belt gear causing the belt to jump a couple of teeth. We replaced the water pump and timing belt and it hasn't had any problems in over a year..

I had the Timing belt and Water pump, along with thermostat and tensioner pulleys done back in december of last year.

 

[T4RFool]

I decided to setup an appointment at the shop where I had my timing belt done to have the timing double checked. Figured I could have that eliminated as a possibility before taking off for my trip next week. If it turns out not to be timing, it cost me nothing. If it is the timing than I will have it fixed before leaving, giving me one less thing to worry about while I'm gone.

 

[T4RFool]

Alright, I dropped it off at the shop. The trip there was somewhat nerve racking. It sputtered off and died less than a mile from my house which wasn't a good sign considering the shop is 10 miles away. I had to jump out and reset the ECU to get it going again. I crawled it down the road until I eventually made it. I had a short conversation with the guy at the shop, told him the symptoms and told him all the things I have already replaced and checked, I also mentioned the code that was thrown. He seemed to think that it wasn't the timing but we'll see later today.

 

[T4RFool]

A shop update

I took it into the shop yesterday early afternoon and it has been in there a full day. They've had it hooked up to diagnostic machine and haven't been able to figure anything out yet. it's been a full day and he said he hasn't been able to figure anything out! He told me it might have to go to a dealership to have it figured out, which I really don't wanna do!

 

[nevada]

beg, borrow, or steal another ecu to try.

 

[spectre6000]

They've had it hooked up to diagnostic machine... a full day

There's your problem; they don't know what they're doing. It's a plug and play shop. If they can plug it into a computer, and plug in a new part, they can play; otherwise they just spend all day futzing around not doing anything productive. A dealership might not be that much better.

Find yourself an OLD dude who's been doing it for a long time, I'll bet you he figures it out in under an hour. I only know the old stuff, but someone who's been doing it long enough to have been doing it the old fashioned way AND have extensive experience with newer cars will have you up and going fast.

 

[T4RFool]

The shop that I took it to are not your usual young guys working in the shop. There are 3 shops in my town and I don't trust anyone of them. I took it to a shop off the interstate. The guys that work there are definitely not tied to the computer diagnostics. He's was telling me that his shop does not do a whole lot of computer diagnostics. That's kind of what I was looking, that and not getting ripped off by the interstate shops.

 

[T4RFool]

A shop update

They didn't find anything. The guy at the shop said he couldn't figure out anything which is terrible news. The only upside is that nothing is owed since nothing was figured out. A day and a half in the shop and no cost, I'll take that as being not a total loss. I'm still left with a useless vehicle. It's gotta be the ECU, that is the only thing I have left that it could be. I'll pick it up later today and get to working on it again and see if I can figure anything out. I would take it to a dealership but there is no way to get it there without a tow.The closest one is over an hour away through a city, it wouldn't make it on its own.
:ybrick: