3vze misfire, stumbling, rough idle: need help diagnosing
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3vze misfire, stumbling, rough idle: need help diagnosing
symptoms:
-i can hear and feel an intermittent miss at idle and throughout the rev range
-at 25% or more throttle the pinging begins
-no smoke from tailpipe
-no oil in coolant or vice versa
for years now, my 146k mile 3vze seems to ping under medium to heavy load, so i've been giving it 89 octane since that helps it out. i say it pings, but it sounds like ball bearings being shaken in a metal can, so that may or may not be the proper diagnosis. FWIW, it sailed through emissions just two months ago
well a month ago i was running low on fuel, so i stopped by a local Sunoco and filled up with 89. after pulling onto the freeway a few minutes later, the engine pinged like never before and was way down on power. i chalked it up to a bad tank of gas, and limped home, but after many more tanks of 89 and 93 octane the engine is acting the same and is misfiring.
what i've replaced:
-spark plugs (NGK u-grooves)
-plug wires (NGK blues...i broke the OE #3 removing it)
-battery (not related but added it here anyways)
-catalytic convertor because someone cut mine off
the problem got even worse after changing plugs and wires over the weekend, and i am sure the wires are not swapped. i disconnected the EGR vacuum line and plugged it, with no change. i've also cleaned the intake with throttle body cleaner and a 1/2 bottle of seafoam, with no improvement.
over the next few days i plan on testing the ECT, EGR (if i can get a vacuum pump and gauge), VAFM. i don't have a throttle body gasket or i'd pull it and test the TPS. i'm quite frustrated right now and hope i'm going down the right path. i really hate going under the hood on this truck as everything is so crammed and tight.
-i can hear and feel an intermittent miss at idle and throughout the rev range
-at 25% or more throttle the pinging begins
-no smoke from tailpipe
-no oil in coolant or vice versa
for years now, my 146k mile 3vze seems to ping under medium to heavy load, so i've been giving it 89 octane since that helps it out. i say it pings, but it sounds like ball bearings being shaken in a metal can, so that may or may not be the proper diagnosis. FWIW, it sailed through emissions just two months ago
well a month ago i was running low on fuel, so i stopped by a local Sunoco and filled up with 89. after pulling onto the freeway a few minutes later, the engine pinged like never before and was way down on power. i chalked it up to a bad tank of gas, and limped home, but after many more tanks of 89 and 93 octane the engine is acting the same and is misfiring.
what i've replaced:
-spark plugs (NGK u-grooves)
-plug wires (NGK blues...i broke the OE #3 removing it)
-battery (not related but added it here anyways)
-catalytic convertor because someone cut mine off
the problem got even worse after changing plugs and wires over the weekend, and i am sure the wires are not swapped. i disconnected the EGR vacuum line and plugged it, with no change. i've also cleaned the intake with throttle body cleaner and a 1/2 bottle of seafoam, with no improvement.
over the next few days i plan on testing the ECT, EGR (if i can get a vacuum pump and gauge), VAFM. i don't have a throttle body gasket or i'd pull it and test the TPS. i'm quite frustrated right now and hope i'm going down the right path. i really hate going under the hood on this truck as everything is so crammed and tight.
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today i tested my EGR. at idle i applied vacuum to the valve itself and my engine sputtered even worse. not so much that it died, and i cranked in 20in of vacuum, but it makes me believe my valve is OK. i don't have a vacuum gauge, so i was unable to run through the other EGR related tests. is it possible my EGR is leaking just a little bit? i'm not convinced but just bringing it up
another possibility i didn't think of is my fuel filter could be clogged. it is the original filter so it needs changing anyways. the pressure gauge i have doesn't have a banjo fitting, so i can't test the pressure. i did unplug and block off the pressure regulator, which audibly raised the idle, but didn't cure the misfire or whatever it is.
another possibility i didn't think of is my fuel filter could be clogged. it is the original filter so it needs changing anyways. the pressure gauge i have doesn't have a banjo fitting, so i can't test the pressure. i did unplug and block off the pressure regulator, which audibly raised the idle, but didn't cure the misfire or whatever it is.
#3
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if it started after you were low on fuel, its possible your fuel filter is clogged with some junk that was on the bottom of your tank..
Pinging is likely to be a timing or fuel problem, so you're at least looking in the right direction.
you don't need an intake gasket to test the TPS.. Don't have to take it off, just measuring the resistance across the pin connectors.. recent thread on here, TPS Adjustmen and Idle adjustment, good link in there.. you can test the tps in about 2 mins with a multimeter..
Pinging is likely to be a timing or fuel problem, so you're at least looking in the right direction.
you don't need an intake gasket to test the TPS.. Don't have to take it off, just measuring the resistance across the pin connectors.. recent thread on here, TPS Adjustmen and Idle adjustment, good link in there.. you can test the tps in about 2 mins with a multimeter..
#4
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Can you scan for codes? Look for lean code? 25? Check the distributor for wear/slop between shaft[rotor] and gear. Spark timing could be changing due to play. Ignitors go wacky. Code 14? EGR problems most of the time are vacuum control solenoid/modulator. Need vacuum gauge teed-in to vacuum hose of EGR and drive, only needs 5-10 inches to open.
#5
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You mentioned plugs & wires, did you also replace cap & rotor? My cap gets pitted even before my plugs are done.
Have you run a compression test? It's a good idea with a missing veezy.
Have you run a compression test? It's a good idea with a missing veezy.
#6
Save yourself all the work of checking this, measuring the tps resistance, testing vacuum, etc. Spend 5 minutes and do a quick compression test. I'd almost bet money you've got valve issues... especially if you've never adjusted valve lash is how many hundred thousand miles... The owners manual even recommends resetting valve lash every 60 or 75k miles IIRC...
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thanks for the tips
no codes in the ECU, so nothing to check there
i don't have a compression tester but it's on my list of things to test when i can borrow a friend's. i know the valve's need attention i just haven't had the time to pull the top covers and order shims since this is my only vehicle right now. i'm still putting my other car together after getting it painted
the last time i tried to check the TPS, i couldn't get a reliable reading with my test leads. i'll give it another go
also on my list is a look at the cap and rotor but i'm not expecting to find anything major there
no codes in the ECU, so nothing to check there
i don't have a compression tester but it's on my list of things to test when i can borrow a friend's. i know the valve's need attention i just haven't had the time to pull the top covers and order shims since this is my only vehicle right now. i'm still putting my other car together after getting it painted
the last time i tried to check the TPS, i couldn't get a reliable reading with my test leads. i'll give it another go
also on my list is a look at the cap and rotor but i'm not expecting to find anything major there
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#8
If you got a ball bearings in metal can kind of noise, then you've probably got bigger problems than an out of adjustment TPS or dirty cap/rotor. Start with a compression test and see where you're missing out. I'll be willing bet you dropped one or more cyl's.
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regardless, a compression check is long overdue
EDIT: oh yea, the engine only sounds rattles like that when under load. it is rattle free while revving it in neutral
Last edited by jht3; 11-26-2009 at 06:35 PM.
#10
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check your ignition timing.. it's possible that your distributor rotated..
the increased octane in 93 grade gas, increases its resistance to detonation. You've got a terrible detonation problem by the sound of it..
the increased octane in 93 grade gas, increases its resistance to detonation. You've got a terrible detonation problem by the sound of it..
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my fuel filter fittings are corroded fairly badly, so i hit them with PB blaster and was able to crack the input fitting loose, as well as the mounting bolts. i ran out of time and didn't get to free the output fitting.
checked my timing and discovered it set at ~50 BTDC. last time the timing was set was maybe 5 years ago by my local dealer, so i'm wondering what sort of damage that may have done, if any
my distributor cap and rotor have seen better days, so those are on the list for replacement
set my timing back to spec and adjusted the idle. i had to rotate the distributor CCW nearly to its max to set it. the timing mark jumps around a few degrees...that is normal right? the misfire feeling has nearly gone away, but i'm not convinced it is completely gone. regardless the pinging is GONE and it pulls to redline better than i can remember. a little less power off the red lights until the rpm's climb but i can deal with that
checked my timing and discovered it set at ~50 BTDC. last time the timing was set was maybe 5 years ago by my local dealer, so i'm wondering what sort of damage that may have done, if any
my distributor cap and rotor have seen better days, so those are on the list for replacement
set my timing back to spec and adjusted the idle. i had to rotate the distributor CCW nearly to its max to set it. the timing mark jumps around a few degrees...that is normal right? the misfire feeling has nearly gone away, but i'm not convinced it is completely gone. regardless the pinging is GONE and it pulls to redline better than i can remember. a little less power off the red lights until the rpm's climb but i can deal with that
Last edited by jht3; 11-27-2009 at 12:25 PM.
#12
If you have to set your distributor at its max setting to get the timing set right, then chances are you're overdue to have your timing belt replaced. I'd be willing to bet it's stretched pretty badly...
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it is still missing slightly. i know it because i'm looking for it, but it is barely noticable
new parts:
plugs
wires
cap
rotor
checked:
timing
engine coolant temp sensor (ECT)
EGR valve
todo:
replace fuel filter
test TPS on-car
check compression
new parts:
plugs
wires
cap
rotor
checked:
timing
engine coolant temp sensor (ECT)
EGR valve
todo:
replace fuel filter
test TPS on-car
check compression
#15
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Its not normal to have to rotate the distrib full CCW to set it - should be near the middle. Did you set the jumper in the check connector before checking timing?
If you did set the jumper, timing belt could be a tooth off, so could the distributor gear.
If its still missing, you need to check that compression. Also, what was the appearance of the plugs? All the same? Flat black with carbon? White deposits & worn, rounded electrodes? Or the normal tan/light gray deposits on all plugs? You could have a clogged injector or two.
If you did set the jumper, timing belt could be a tooth off, so could the distributor gear.
If its still missing, you need to check that compression. Also, what was the appearance of the plugs? All the same? Flat black with carbon? White deposits & worn, rounded electrodes? Or the normal tan/light gray deposits on all plugs? You could have a clogged injector or two.
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yes, i jumpered the connector. and it advances as it should when un-jumpered. i'm thinking something is definitely wrong but not sure what yet. this was all put together last by the dealer when my headgasket went in '03. i find it hard to believe the belt stretched this much and with such a dramatic effect on retarding the timing
i don't have a compression gauge yet, but i'll get one soon
when i pulled my plugs, all were the same except #5 was visibly a little leaner. i would say all looked a bit rich and the electrodes were rounded off. they have been in there for ~50k miles so i was expecting them to look worse. if i can remember, i'll take a photo of them
i don't have a compression gauge yet, but i'll get one soon
when i pulled my plugs, all were the same except #5 was visibly a little leaner. i would say all looked a bit rich and the electrodes were rounded off. they have been in there for ~50k miles so i was expecting them to look worse. if i can remember, i'll take a photo of them
#17
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yes, i jumpered the connector. and it advances as it should when un-jumpered. i'm thinking something is definitely wrong but not sure what yet. this was all put together last by the dealer when my headgasket went in '03. i find it hard to believe the belt stretched this much and with such a dramatic effect on retarding the timing
i don't have a compression gauge yet, but i'll get one soon
when i pulled my plugs, all were the same except #5 was visibly a little leaner. i would say all looked a bit rich and the electrodes were rounded off. they have been in there for ~50k miles so i was expecting them to look worse. if i can remember, i'll take a photo of them
Good luck.
#18
The best injector cleaner is the EFI cleaner that comes in the pressurized can... that plugs directly into your fuel rail (make sure you get it before the rail so it gets the cold start injector also). that stuff works wonders... I've seen it make cars that could barely hold an idle purr like a kitten after you run a can or two of that stuff through.
#20
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The concentrated, in-the-fuel-rail type injector cleaner does work better than the in-the-tank stuff. Sending the injectors to witchhunter is best of all.
It's the miles that get the timing belts, not the months so much. Toyota recommends replacement every 60k miles; but many of us replace them at 70k with no problems. Most of the ones you hear of breaking do so over 90k miles.
It's the miles that get the timing belts, not the months so much. Toyota recommends replacement every 60k miles; but many of us replace them at 70k with no problems. Most of the ones you hear of breaking do so over 90k miles.