i'm at a loss...misfire continues

[bama16]

my misfire continues. I have replaced:

plugs
plug wires
fuel filter
fuel pump
fuel injectors

tested the coil packs and they are within spec, but i do have 3 new ones ready to go in.they are the most expensive of the attempts at fixing and i don't believe they are the issue.

The issue seemed to initially clear up with plug wires, but then returned shortly after. Then after replacing the injectors i thought it was fixed, it runs a lot better but the misfire came back.

it only happens now from a standstill, engine warm, and heavy gas pedal. if the engine is cold it does fine. If i ease onto the throttle i can avoid the misfire, and any downshifts while cruising are smooth.

I'm still throwing money at it since the CEL isn't coming on. what would cause the stumble, only when warm, when mashing the gas pedal? at this point i'm down to TPS, MAF, and crank position sensor.

i'm pullin my hair out and i'm ready to have this thing driving normal again!

 

[Doc2012]

So there's no CEL, but you think you're getting a misfire? You've changed all that stuff, and haven't given any thought to the transmission or anything like that?

Maybe it's time you started looking into the transmission being the problem and not a misfire.

I'm going to edit this, and throw something else in.

You've changed plugs, wires, injectors, fuel filter, fuel pump, ect ect.

TPS could cause it.

If you change the TPS and it's not better, start looking into the transmission slipping.

 

[LittleCaesar]

Done a compression check?

Cleaned the MAF?

 

[KidVermicious]

How's your coolant level? What's your oil look like?

 

[bama16]

So there's no CEL, but you think you're getting a misfire? You've changed all that stuff, and haven't given any thought to the transmission or anything like that?

Maybe it's time you started looking into the transmission being the problem and not a misfire.

I'm going to edit this, and throw something else in.

You've changed plugs, wires, injectors, fuel filter, fuel pump, ect ect.

TPS could cause it.

If you change the TPS and it's not better, start looking into the transmission slipping.

this stumble happens even in neutral, but is more prevalent under load. If i hold the brake and hit the gas it'll misfire, unless the engine is colder.

Done a compression check?



Cleaned the MAF?

this is on my list, i'm just hoping that there's no internal issues. i'm just about to hit 160k. MAF was cleaned during the parts replacement.

How's your coolant level? What's your oil look like?

oil looks fine. I'm not burning anything appreciable, and no water in the oil.

 

[BrianSD_42]

Is it a continuous misfire? (flashing cel)

or does it throw a code every so often?

When you clear the code how long until it comes back?

What are the code or codes?

... I see you mentioned the codes haven't returned yet you believe it is misfiring.

 

[bama16]

Is it a continuous misfire? (flashing cel)

or does it throw a code every so often?

When you clear the code how long until it comes back?

What are the code or codes?

... I see you mentioned the codes haven't returned yet you believe it is misfiring.

I haven't had a single CEL this whole time. It has never lit up at any time. I have a video i'm loading now. The TPS is unplugged so i'm getting the CEL light in this video, but that's the only time it's shown up. results are the same whether it's plugged in or unplugged.

 

[LittleCaesar]

I forgot to ask earlier when is the last time the timing belt has been changed?

Don't have a live data reader by chance?

California emissions?

 

[bama16]

I forgot to ask earlier when is the last time the timing belt has been changed?

Don't have a live data reader by chance?

California emissions?

It was replaced about 40k miles ago. no data reader and no cali emissions.

car sputters upon initial throttle when in neutral. The misfire was inconsistent when in drive and holding the brake.

http://vid33.photobucket.com/albums/d74/bama16/4runner/VIDEO0005_zpsbb7npbrr.mp4

http://vid33.photobucket.com/albums/d74/bama16/4runner/VIDEO0004_zpspkxvfhus.mp4


CEL is from the TPS unplugged...car responds the same whether it's plugged in or unplugged.

 

[angus]

Well I guess you need to find out if it is spark or fuel related.

I wonder if it is a bad ECU?

 

[absalom]

Do you have FSM? The troubleshooting flow chart is very easy to follow for misfires.

 

[uihsongshi]

I'm going to edit this, and throw something else in.

 

[Kenworth]

Had similar problem on a celica finally replaced maf with new one problem
Cured

 

[bama16]

Do you have FSM? The troubleshooting flow chart is very easy to follow for misfires.

I don't. All of the links i found through a search were no longer any good. Either to the source of the link, or at the source.

 

[jgue467]

FSM is 3rd link down: http://www.toyota-4runner.org/3rd-gen-t4rs/69744-3rd-gen-faq-tutorials-documentation-reference.html

That's a lot of parts replaced and no solution - try the fsm's method and it will lead to success. Luck!

 

[Andy in Pa]

Have you tested the TPS? I once had a stumble just off idle in a Jeep, and it because the TPS had a dead spot. It was not getting a smooth reading from the potentiometer in the TPS. The ohm value should change slowly/smoothly with no major jumps as the pedal is depressed slowly.

I am not familiar with the TPS on 3rd gen T4R's yet, but most are easy to test with an ohm meter.

 

[LittleCaesar]

When is the last time you have cleaned the throttle body and IAC? It looks as if the tach is reading a little high, though they aren't always as accurate as what the ECU is reading. Thus the need for a live data reader.

 

[absalom]

The Toyota FSM is better than any other OEM's or Bentley FSM I've ever used. I am still very impressed by it.

 

[bama16]

Have you tested the TPS? I once had a stumble just off idle in a Jeep, and it because the TPS had a dead spot. It was not getting a smooth reading from the potentiometer in the TPS. The ohm value should change slowly/smoothly with no major jumps as the pedal is depressed slowly.

I am not familiar with the TPS on 3rd gen T4R's yet, but most are easy to test with an ohm meter.

it works when cold, and has issues with warm. Do you think this would eliminate the TPS?

When is the last time you have cleaned the throttle body and IAC? It looks as if the tach is reading a little high, though they aren't always as accurate as what the ECU is reading. Thus the need for a live data reader.

I cleaned the TB when i removed everything to replace the injectors. I havne't cleaned the IAC, but i think the high idle is due to the TPS being unplugged.

I was giving it gas merging on the highway this morning, and was hearing a couple pops out of the intake. Which is usully either a misfire or lean condition. would the crank position or cam position affect this?

thanks all for the help!

 

[Andy in Pa]

it works when cold, and has issues with warm. Do you think this would eliminate the TPS?

Not necessarily. Figure out how to test the TPS with an ohm meter (I am sure its on this site somewhere), let it get good and warm, and then test it. You should see a smooth change in ohm value as you open/close the throttle plate on the TB. If it jumps around or drops to zero, it could be a bad TPS causing your issues.