1999 3.4L random miss fire-turns to nothing but miss fire

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colorado4runnin

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Alright, I know a few people have had almost the same problem but I want start fresh with this and see if any one has some new ideas or tips and tricks.
1999 4runner, 3.4L limited 204K
so recently I've had erratic start ups, it seems to take a few seconds to crank over, then when it does it feels like it starts harder then normal. No problem I thought maybe it was time for a starter. Well a week ago it would crank and crank then start up and stay around 200-300 rpm and sounds/feels like there's a miss fire. It would come back to normal rpm when I gave it some gas. So today I go to start it this morning here on beautiful cold Colorado morning and it cranks and cranks then starts with a miss fire. And will not come out of it even by feeding it gas, it was pretty close to stalling out from the sounds of it.
(Side info) I have a valve tick on my driver side) I will try and get a link to a video I shot tonight. So any ideas or help would be great. Fyi I have check all my electric concnetions and ever thing is intact and apparently operational.
Thanks-Jake
 
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Not to sound like a smart@ss but 1 of 3 things lacking: air, fuel or spark. Have you checked the fuel pressure from the pump? Dirty fuel filter? If you can get to them, unplug one injector at a time and see which one doesn't affect the idle.
Pull your spark plugs and look at them for anything out of the ordinary. Try the simple things first.
No code does not mean that there isn't a misfire. Every manufacturer has certain conditions that have to be met in order to set a DTC.
Good luck!
 
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On waste spark ignition, partner cylinders can both be affected if only one of the 2 have an issue. If you have a DVOM, check the resistance of the plug wires. Should be < 10k ohms
per foot.
 
chimpy said:
Not to sound like a smart@ss but 1 of 3 things lacking: air, fuel or spark. Have you checked the fuel pressure from the pump? Dirty fuel filter? If you can get to them, unplug one injector at a time and see which one doesn't affect the idle.
Pull your spark plugs and look at them for anything out of the ordinary. Try the simple things first.
No code does not mean that there isn't a misfire. Every manufacturer has certain conditions that have to be met in order to set a DTC.
Good luck!
Click to expand...

So I have eliminated spark, changed ICM because originaly that's what the signs pointed towards. Tonight I did plugs and wires. Still no changes. I have not tested fuel pressure yet, I'm going to test the fuel injectors along with fuel pressure tomorrow. The fuel filter is close to brand new. I run injector cleaner through it about once every two months. And had changed the orings on my injectors about 3 months ago. They looked good but looks can be deceiving... Does any one have a link to or know what the iinjectors should test to on resistance ?
And what pressure am I looking for at the fuel rail?
Thanks
-Jake
 
A weak fuel pump could be the culprit.A quick way to check for a weak but functioning fuel pump would be to find the pump relay (on my 2001 it was under the driver side dash , close to the steering column)and remove it. Use a fused jumper wire with terminals that are properly sized for the relay socket and connect terminals 30 and 87. Set the DVOM to DC amperes. Clamp a current clamp around the fused jumper wire and read the display. Most port fuel injection pumps(35-45 PSI) = 4-8 amps.
I performed this test on mine and got a reading of approximately 4.5 amps. A little on the low side but my 01' has 186,000 miles on it. This test can be used as an indicator of pump motor condition in regards to commutator/brush wear.
I am not certain of the ohms spec for the injectors but I would expect to believe that if an injector has completely failed, there would be a DTC present.(P03??)
Does the hard start issue occur on cold start only or any time that you try to start the 4runner?
Wish I could help you more.Keep us posted.
 
chimpy said:
A weak fuel pump could be the culprit.A quick way to check for a weak but functioning fuel pump would be to find the pump relay (on my 2001 it was under the driver side dash , close to the steering column)and remove it. Use a fused jumper wire with terminals that are properly sized for the relay socket and connect terminals 30 and 87. Set the DVOM to DC amperes. Clamp a current clamp around the fused jumper wire and read the display. Most port fuel injection pumps(35-45 PSI) = 4-8 amps.
I performed this test on mine and got a reading of approximately 4.5 amps. A little on the low side but my 01' has 186,000 miles on it. This test can be used as an indicator of pump motor condition in regards to commutator/brush wear.
I am not certain of the ohms spec for the injectors but I would expect to believe that if an injector has completely failed, there would be a DTC present.(P03??)
Does the hard start issue occur on cold start only or any time that you try to start the 4runner?
Wish I could help you more.Keep us posted.
Click to expand...

You may have just saved me a trip to the stealership. I'll attempt this tonight and see what I can find. The hard start hahappene cold warm hot. It didn't matter no it sounds like it wants to start great but goes to the rough idle /miss fire/timing retarded way no matter what and it won't pull out of it. I've had my battery unplugged for over 24 hours now. I'm going to see if that changes anything at all. High hopes I guess...
 
chimpy said:
A weak fuel pump could be the culprit.A quick way to check for a weak but functioning fuel pump would be to find the pump relay (on my 2001 it was under the driver side dash , close to the steering column)and remove it. Use a fused jumper wire with terminals that are properly sized for the relay socket and connect terminals 30 and 87. Set the DVOM to DC amperes. Clamp a current clamp around the fused jumper wire and read the display. Most port fuel injection pumps(35-45 PSI) = 4-8 amps.
I performed this test on mine and got a reading of approximately 4.5 amps. A little on the low side but my 01' has 186,000 miles on it. This test can be used as an indicator of pump motor condition in regards to commutator/brush wear.
I am not certain of the ohms spec for the injectors but I would expect to believe that if an injector has completely failed, there would be a DTC present.(P03??)
Does the hard start issue occur on cold start only or any time that you try to start the 4runner?
Wish I could help you more.Keep us posted.
Click to expand...

This is awesome! thanks. Hopefully we'll get this thing figured out soon!
 
I started having intermittent stumbles on the highway one day that quickly turned into a lost cylinder entirely. In my case it was a dead fuel injector (corroded solenoid no longer fired). You can test the resistance across each injector to see if one is an obvious anomaly.

I'd first trace it to a particular cylinder either by reading the CEL code P0300... whatever is the specific one for that particular cylinder. Check by pulling the plug boots one at a time with the engine running. The one cylinder that doesn't change the idle by taking out a 2nd cylinder out of action is the cylinder of interest. You could swap coils to eliminate that as a variable as well.
 
I thought I had read that there were no DTCs yet. Hard to say to what degree of intermittent spark due to a faulty coil would throw a p3?? code. Being a waste spark system, wouldn't both partner cylinders be affected by their parent coil? Something to consider if a p3?? code rears its ugly head.
 
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Update...

Alright thought I'd update what I've done tonight along with everything else.
So Monday morning I start my Runner, idleing really rough and wants to stall out. Before that happened Monday sometimes when I'd first start it it would take a few extra cranks and start rough. I could hit the gas a few times and it would pull out of the rough idle and go back to normal.
Now back to what is going on.

Rough idle, feels like the timing has been retarded.
almost like a miss fire but more towards the timing being really slow. It will idle around 300-800 RPM but jumps around. Now when I start it it wants to fire right up, sounds really healthy/strong start but right away it goes back to the rough idle.

Details-
1999 Toyota 4runner.
204K 3.4L
slight valve tick that's been there since 199K

What I've done already-
New plugs, wires, New fuel filter, New fuel pump, Newer injectors,
I borrowed one of my buddy's coils packs off his 4runner and swapped it through all my coils (prerks of having other 3rd gen buddy's.) Still no changes after doing all of that. Also borrowed his MAF sensor. No change.

NO CHECK ENGINE LIGHT OR CODES.

So now that I've done all this, where do I go from here? It's perked up a lot since I've done all of this but still no over all changes.

And when it was running I had to move it, and my brakes are hard I get one pump of the breaks and then they tighten up or get hard if you will. I don't know if that's related or not but that's all the info I have

Thanks everyone for the help
I really don't want to take it to a shop. Lol
 
If you had a misfire the PCM would code for it to protect the CAT from overheating and melting down.

Have you tried running injector cleaner through it? I'd go to Walmart or wherever and buy two bottles of chevron Techtron injector cleaner for 20 gallon tank and fill up with high test and those two bottles and run the tank to the low fuel light before topping off.
 
Bad News Today

Did a compression test today, found #6 is dead. Thinking I have a burnt valve considering I have that valve tick on that side. Going to pull the head tomorrow and confirm this. May be looking for a new head....
 
Better than having to look for a new engine. Glad you have apparently solved this mystery. Good luck with the repair. We are all here if you need advice/help.
 
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