Cannot find what's causing misfire!!
Mar 20, 2017 | 08:16 PM
#21
Wow that filter has some nasty stuff in it. I suspect it came from the fuel tank, did you replace the tank (or at least inspect the inside)? If not, the fuel pump has a screen in the tank, it could be plugged too, and the rust came from somewhere, so there's probably more in the tank. I wouldn't think low fuel pressure would cause a misfire like this, but I guess anything could be possible.
The spark plug appears to be firing (light brown buildup) so it's kind of strange it's the cyl that's missing. Maybe it's missing sometimes and other times it's not missing. Could be possible two wires were swapped which could give a similar situation, you 100% sure the wires from the distributor are going to the correct cylinders?
An old school tactic to keep the fuel tank from rusting on the inside is to fill the tank(s) before it sits. The logic is gas is basically a very thin oil, so it prevents rust and it displaces the air which most tanks are vented in some fashion and can get moisture inside the tank. Gas and oil float on water, so if there was water in the tank, it would rust on the bottom, and moisture in the air would rust the top section, stopping at the gas level. I'm not sure if this is advisable anymore with the crappy gas we have to deal with today (it's ~10% ethanol, aka E10, similar to E85 being 85% ethanol). Very few places offer ethanol free fuel.
For the valve adjustment, I'm not sure how often it calls for on the 3vz, but I don't really see why the motor home would require it to be adjusted more often than a pickup. Yea it has a bit more load, but there isn't a difference between 2wd, 4x4, or 1 ton pickups (i think). Valve adjustment *should* be done every so often, but most people never touch their engines until something breaks, or there's a noise. If the valves were out of adjustment to cause the cylinder to not fire, I'd think that would have showed up in the compression test.
The spark plug appears to be firing (light brown buildup) so it's kind of strange it's the cyl that's missing. Maybe it's missing sometimes and other times it's not missing. Could be possible two wires were swapped which could give a similar situation, you 100% sure the wires from the distributor are going to the correct cylinders?
An old school tactic to keep the fuel tank from rusting on the inside is to fill the tank(s) before it sits. The logic is gas is basically a very thin oil, so it prevents rust and it displaces the air which most tanks are vented in some fashion and can get moisture inside the tank. Gas and oil float on water, so if there was water in the tank, it would rust on the bottom, and moisture in the air would rust the top section, stopping at the gas level. I'm not sure if this is advisable anymore with the crappy gas we have to deal with today (it's ~10% ethanol, aka E10, similar to E85 being 85% ethanol). Very few places offer ethanol free fuel.
For the valve adjustment, I'm not sure how often it calls for on the 3vz, but I don't really see why the motor home would require it to be adjusted more often than a pickup. Yea it has a bit more load, but there isn't a difference between 2wd, 4x4, or 1 ton pickups (i think). Valve adjustment *should* be done every so often, but most people never touch their engines until something breaks, or there's a noise. If the valves were out of adjustment to cause the cylinder to not fire, I'd think that would have showed up in the compression test.
Mar 20, 2017 | 08:55 PM
#22
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Wow that filter has some nasty stuff in it. I suspect it came from the fuel tank, did you replace the tank (or at least inspect the inside)? If not, the fuel pump has a screen in the tank, it could be plugged too, and the rust came from somewhere, so there's probably more in the tank. I wouldn't think low fuel pressure would cause a misfire like this, but I guess anything could be possible.
The spark plug appears to be firing (light brown buildup) so it's kind of strange it's the cyl that's missing. Maybe it's missing sometimes and other times it's not missing. Could be possible two wires were swapped which could give a similar situation, you 100% sure the wires from the distributor are going to the correct cylinders?
An old school tactic to keep the fuel tank from rusting on the inside is to fill the tank(s) before it sits. The logic is gas is basically a very thin oil, so it prevents rust and it displaces the air which most tanks are vented in some fashion and can get moisture inside the tank. Gas and oil float on water, so if there was water in the tank, it would rust on the bottom, and moisture in the air would rust the top section, stopping at the gas level. I'm not sure if this is advisable anymore with the crappy gas we have to deal with today (it's ~10% ethanol, aka E10, similar to E85 being 85% ethanol). Very few places offer ethanol free fuel.
For the valve adjustment, I'm not sure how often it calls for on the 3vz, but I don't really see why the motor home would require it to be adjusted more often than a pickup. Yea it has a bit more load, but there isn't a difference between 2wd, 4x4, or 1 ton pickups (i think). Valve adjustment *should* be done every so often, but most people never touch their engines until something breaks, or there's a noise. If the valves were out of adjustment to cause the cylinder to not fire, I'd think that would have showed up in the compression test.
The spark plug appears to be firing (light brown buildup) so it's kind of strange it's the cyl that's missing. Maybe it's missing sometimes and other times it's not missing. Could be possible two wires were swapped which could give a similar situation, you 100% sure the wires from the distributor are going to the correct cylinders?
An old school tactic to keep the fuel tank from rusting on the inside is to fill the tank(s) before it sits. The logic is gas is basically a very thin oil, so it prevents rust and it displaces the air which most tanks are vented in some fashion and can get moisture inside the tank. Gas and oil float on water, so if there was water in the tank, it would rust on the bottom, and moisture in the air would rust the top section, stopping at the gas level. I'm not sure if this is advisable anymore with the crappy gas we have to deal with today (it's ~10% ethanol, aka E10, similar to E85 being 85% ethanol). Very few places offer ethanol free fuel.
For the valve adjustment, I'm not sure how often it calls for on the 3vz, but I don't really see why the motor home would require it to be adjusted more often than a pickup. Yea it has a bit more load, but there isn't a difference between 2wd, 4x4, or 1 ton pickups (i think). Valve adjustment *should* be done every so often, but most people never touch their engines until something breaks, or there's a noise. If the valves were out of adjustment to cause the cylinder to not fire, I'd think that would have showed up in the compression test.
I am on a Toyota motorhome forum also,and they cannot stress enough how important it is for these to be adjusted every 60000 miles,and thats what it calls for in the manuals that comes with these motorhomes.On almost every occasion the valves are checked,well heres a quote:" My 91 Warrior has about 72,000 miles on it and I'm finding that all of the 6 intake clearances are good (borderline, but good), and all of the 6 exhaust clearances are way tight. Pretty much the norm, from what others have said." unquote
This is another post from last week:
"Got my motorhome back this afternoon "valve adjustment."All of the intakes were .009 - .010 so they were not touched.The exhaust were another thing. #1 - #6 were all .005. Too tight. They are now .012 for 5 of them and .013 for the 6th one.Valve specs are: Intake: .007 - .011 Exhaust: .009 - .013The engine does idle smother now, it was a very slight random miss at idle. I had noticed a rougher idle the past year. Don't anticipate any great improved performance.We bought this motorhome 5-13-2013 at 36,805 miles, it now has 73,744 miles." unquote
So like I said,these motorhomes need the valves adjusted a lot more often than a pickup or 4 runner,but whether that has anything to do with my misfire I dont know,but I doubt it.
The distributor caps on this vehicle has all the plug wires numbered,2 wire is going to drivers side front,4 is going to middle,and 6 to rear,is that correct?
Mar 20, 2017 | 09:52 PM
#23
Found this reference, could have just ran outside and looked at a 3.0L, but meh google was faster and gave a pretty photo 
. Based on that, passenger front is #1. Firing order is 123456.
. Based on that, passenger front is #1. Firing order is 123456.
Mar 21, 2017 | 03:22 AM
#24
Mar 21, 2017 | 04:47 AM
#25
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So should I try pulling plug again when I get home from work tonight? When I get home I will start it and let it run 1 minute then turn it off and check plug to see if its wet.
Any other ideas?
Thanks
Mar 21, 2017 | 05:57 AM
#26
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From: San Francisco East Bay
Mar 21, 2017 | 06:08 AM
#28
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From: San Francisco East Bay
....So I bought the flamethrower injs off ebay....8
You don't want to disassemble the fuel system if you can avoid it. You COULD remove the plenum, pressurize the rail with the FP pin, slide a strip of paper down the lower intake to under the injector, then pulse each injector (or the suspect one) manually.
Mar 21, 2017 | 09:09 AM
#29
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If you had that much matter run out of the filter when you removed it, I suspect that the rest of the fuel system had even more. Meaning; your new injectors probably got a pretty good snort of crud. I don't know about "Flamethrowers," but the injectors for this truck have a tiny screen on the input side. Since you've confirmed the injector pulse, it is possible that no fuel is getting through (listening for the injector click won't help; if the screen is clogged the injector will still click). It could even explain the problem "moving" from one cylinder to another; the crud in the filter of each injector moves around. Which means your problem could "go away," only to return again later.
You don't want to disassemble the fuel system if you can avoid it. You COULD remove the plenum, pressurize the rail with the FP pin, slide a strip of paper down the lower intake to under the injector, then pulse each injector (or the suspect one) manually.
You don't want to disassemble the fuel system if you can avoid it. You COULD remove the plenum, pressurize the rail with the FP pin, slide a strip of paper down the lower intake to under the injector, then pulse each injector (or the suspect one) manually.
Also when old injs were in there I ran 3 bottles of seafoam thru it{not at the same time}when that didnt work I used the Berryman 3 step fuel inj cleaning process as shown in this video,it might have cleaned up the fuel rail some.So none of that worked so thats when I put in new injs but still have misfire on 4.
Mar 21, 2017 | 09:34 AM
#30
I like the idea of the manual injector test stated above.
Fuel injector cleaner isn't going to remove rust, it might dissolve some tarnish or carbon buildup, but I don't think it's a strong enough acid to remove rust, if it did, it probably would eat steel too. No source, just my thinking on the matter. Besides, if the stuff did eat rust, the fuel filter would have been "cleaner" and more would have gone though the engine in a dissolved form.
Fuel injector cleaner isn't going to remove rust, it might dissolve some tarnish or carbon buildup, but I don't think it's a strong enough acid to remove rust, if it did, it probably would eat steel too. No source, just my thinking on the matter. Besides, if the stuff did eat rust, the fuel filter would have been "cleaner" and more would have gone though the engine in a dissolved form.
Mar 21, 2017 | 10:02 AM
#31
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I like the idea of the manual injector test stated above.
Fuel injector cleaner isn't going to remove rust, it might dissolve some tarnish or carbon buildup, but I don't think it's a strong enough acid to remove rust, if it did, it probably would eat steel too. No source, just my thinking on the matter. Besides, if the stuff did eat rust, the fuel filter would have been "cleaner" and more would have gone though the engine in a dissolved form.
Fuel injector cleaner isn't going to remove rust, it might dissolve some tarnish or carbon buildup, but I don't think it's a strong enough acid to remove rust, if it did, it probably would eat steel too. No source, just my thinking on the matter. Besides, if the stuff did eat rust, the fuel filter would have been "cleaner" and more would have gone though the engine in a dissolved form.
Mar 21, 2017 | 11:58 AM
#32
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If you had that much matter run out of the filter when you removed it, I suspect that the rest of the fuel system had even more. Meaning; your new injectors probably got a pretty good snort of crud. I don't know about "Flamethrowers," but the injectors for this truck have a tiny screen on the input side. Since you've confirmed the injector pulse, it is possible that no fuel is getting through (listening for the injector click won't help; if the screen is clogged the injector will still click). It could even explain the problem "moving" from one cylinder to another; the crud in the filter of each injector moves around. Which means your problem could "go away," only to return again later.
You don't want to disassemble the fuel system if you can avoid it. You COULD remove the plenum, pressurize the rail with the FP pin, slide a strip of paper down the lower intake to under the injector, then pulse each injector (or the suspect one) manually.
You don't want to disassemble the fuel system if you can avoid it. You COULD remove the plenum, pressurize the rail with the FP pin, slide a strip of paper down the lower intake to under the injector, then pulse each injector (or the suspect one) manually.
http://www.ebay.com/itm/261228448791...%3AMEBIDX%3AIT
I dont know what the FP pin is and how do I pulse each injector?
Thanks
Mar 21, 2017 | 01:22 PM
#33
The Fp pin is in the diag port in the engine bay (passenger side fender I think). You jump it from B+ to Fp which provides power directly to the fuel pump whenever the key is on.
I'm not sure what the best way to fire the injector. The Black with red stripe wire is the positive, and the white and white with red striped wires are the ground. They have power with the key on for the black/red wire, and the computer normally switches the ground side to make contact. Manually wiring power to it, or trying to back probe the connector while it's plugged in, you'd want to be careful to now give power to it for long, just a quick tap is enough. Same story for testing old school coils, or atv coils without a multi meter. I'm not sure how many taps would be needed for the paper towel to be wet as I've never done it before.
One thing to point out, you mentioned you have to take a fuel line apart to get to the injectors. I suspect it's the cold start injector you're talking about. Could remove the cold start injector from the intake, and hook the fuel line back up to it just to block off the line. Any other fuel lines will need to be connected to something too so it can pressure up.
I'm not sure what the best way to fire the injector. The Black with red stripe wire is the positive, and the white and white with red striped wires are the ground. They have power with the key on for the black/red wire, and the computer normally switches the ground side to make contact. Manually wiring power to it, or trying to back probe the connector while it's plugged in, you'd want to be careful to now give power to it for long, just a quick tap is enough. Same story for testing old school coils, or atv coils without a multi meter. I'm not sure how many taps would be needed for the paper towel to be wet as I've never done it before.
One thing to point out, you mentioned you have to take a fuel line apart to get to the injectors. I suspect it's the cold start injector you're talking about. Could remove the cold start injector from the intake, and hook the fuel line back up to it just to block off the line. Any other fuel lines will need to be connected to something too so it can pressure up.
Mar 23, 2017 | 04:43 AM
#34
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The Fp pin is in the diag port in the engine bay (passenger side fender I think). You jump it from B+ to Fp which provides power directly to the fuel pump whenever the key is on.
I'm not sure what the best way to fire the injector. The Black with red stripe wire is the positive, and the white and white with red striped wires are the ground. They have power with the key on for the black/red wire, and the computer normally switches the ground side to make contact. Manually wiring power to it, or trying to back probe the connector while it's plugged in, you'd want to be careful to now give power to it for long, just a quick tap is enough. Same story for testing old school coils, or atv coils without a multi meter. I'm not sure how many taps would be needed for the paper towel to be wet as I've never done it before.
One thing to point out, you mentioned you have to take a fuel line apart to get to the injectors. I suspect it's the cold start injector you're talking about. Could remove the cold start injector from the intake, and hook the fuel line back up to it just to block off the line. Any other fuel lines will need to be connected to something too so it can pressure up.
I'm not sure what the best way to fire the injector. The Black with red stripe wire is the positive, and the white and white with red striped wires are the ground. They have power with the key on for the black/red wire, and the computer normally switches the ground side to make contact. Manually wiring power to it, or trying to back probe the connector while it's plugged in, you'd want to be careful to now give power to it for long, just a quick tap is enough. Same story for testing old school coils, or atv coils without a multi meter. I'm not sure how many taps would be needed for the paper towel to be wet as I've never done it before.
One thing to point out, you mentioned you have to take a fuel line apart to get to the injectors. I suspect it's the cold start injector you're talking about. Could remove the cold start injector from the intake, and hook the fuel line back up to it just to block off the line. Any other fuel lines will need to be connected to something too so it can pressure up.
I had been having a hard time finding a shop to adjust valves on this engine if and when I ever got misfire figured out.Finally found one,talked to the owner and he told me to try hooking up the vacuum pump again but this time not to the vacuum line from brake booster,because it had a check valve in it and that would give me a false reading.So I rented vacuum gauge again and hooked it up to 3 different vacuum lines and it passed the test,no erratic readings,so thats good.
Was watching a show I recorded called Tech Garage this morning.The host was going over the old style distributor engines and how to read plugs etc.He said you can also use this handy tool,hook it up to your spark plug and it will tell you whats going on.It was an oscilloscope made by UEI.Too bad AutoZone doesnt have this in their rent a tool program
1750 bucks.http://www.autozone.com/test-scan-an...ader/94926_0_0
Last edited by redskinman; Mar 23, 2017 at 04:45 AM.
Mar 23, 2017 | 10:22 AM
#35
I've never used an oscilloscope to diag cars/trucks, but I've watched a video of a guy diaging a 3.4L with a miss that would come and go. Pretty neat that he could hook it to battery ground and one of the injector signal wires, and he could read all the injectors and it overlayed them so you could see injector pulse, coil spark etc. In his case it was a bad injector.
Mar 25, 2017 | 01:50 PM
#36
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So took fuel injs,fuel rails etc back off today,thought I'd give it one last try before I give up.Re-Cleaned everything,took each inj,hooked a clear tube up to eac one{one at a time}filled the tube with some Inj cleaner,blew on tube while hitting contacts with battery to blow those out.Re-assembled everything.Started it up.........drumroll.........it's fixed!!!!!
Thanks for the help
Thanks for the help
Mar 25, 2017 | 03:56 PM
#37
Nice, thanks for reporting back on the mystery. Plugged injectors and junk in the fuel rail makes pretty good sense . That filter pic kind of helped us focus on the right area lol. Hopefully there isn't anything in the fuel lines, but worst case, you know how to clean it again if it came down to it.
. That filter pic kind of helped us focus on the right area lol. Hopefully there isn't anything in the fuel lines, but worst case, you know how to clean it again if it came down to it.
