Ecu misfire? (4 Viewers)
- Thread starter TTO5
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After the plug swap I'd look a the electrical side of the coils. There is a sub harness from the main engine bay harness on each bank that is for the coils that is cheap enough to just swap at ~$20 per side to rule out that leg of the wiring before you parts cannon the engine bay with new hardware unless you want to spent the time with a fluke ringing out and hand over hand checking the harness. I'd ring it out first but it is cheap enough to do the coil side and the main harness is like $900. I'd suspect the shop pinched a wire installing the engine or the harness was damaged shipping or you have a vacuum leak from a crap hose or a bulk leak from an open nipple.
(I think it the coil subharness is 8212634021 and 8212734050?)
(I think it the coil subharness is 8212634021 and 8212734050?)
- Thread starter
- #123
Wow thanks so much for that info. I'm a parts counterman at my toyota dealer so I'll look into this tomorrow. Also I'm going to check the toothed sprocket that the crank sensor reads to make sure a tooth wasn't bent or something when they transferred the toothed sprocket from my old engine to the replacement engine. I'll remove the crank sensor and use my new boroscope in the hole. Anyone know how hard it is to rotate the engine slowly via a front crankshaft bolt?
If you feel it stumble I'd start at ignition and plugs first before thinking the reluctor wheel is bad/bent (not sure why you'd ever change one unless the sensor ground into it). I doubt they pulled it unless they were going into a RMS replacement prior to dropping the block in. I think it is just forward of the flex plate on a 5.7? If the stumble is felt only at idle and intermittent I doubt the wheel is bad. If you had a missfire code and no stumble I'd start poking sensors earlier in the process but not as my first stop on this train.
Start at new plugs in the problem jugs then go from there. Try throwing a timing light on the problem jug when the problem is occurring to confirm dropped spark then work back from there to see where the trigger signal is intermittent.
If your at the parts counter- go by the grey beards lunch and a beer and talk shop- then bum the tech stream system and start diagnosing after the bays are shut down for the night. A blind parts cannon approach might fix this but will be $$$.
Start at new plugs in the problem jugs then go from there. Try throwing a timing light on the problem jug when the problem is occurring to confirm dropped spark then work back from there to see where the trigger signal is intermittent.
If your at the parts counter- go by the grey beards lunch and a beer and talk shop- then bum the tech stream system and start diagnosing after the bays are shut down for the night. A blind parts cannon approach might fix this but will be $$$.
- Thread starter
- #125
Lol. Well put. Just to clarify I never feel a misfire. Butter smooth until the computer goes into misfire protection mode. Only then is it rough as it shuts down the 2 cylinders . Spark plugs brand new. I did shotgun a crank sensor but it didn't help. The used engine arrived with no flex plate and no toothed sprocket so they had to swap that from my original engine. Again, never feel any roughness or stumble. Pictured is my replacement engine as it arrived
Thought I read that you mentioned a physical stumble- That changes things but maybe not for the better/easier - stick your finger in the crank sensor hole and see if the reluctor can move or sensor is loose/installed backwards when at TDC? (not sure it can go on backwards) Can you get to the TC from the lower access plate to see if it is loose? P30x Misfire DTC is a reading of crank and cam position sensors looking at variations in RPM/frequency/phase. Make sure the two sensors don't have bent pins and are seated in their connectors tightly then start working your way to the engine harness but youre goign to need to run it on techstream.
I think you need to get to know the FSM and techstream in the biblical fashion to find your problem if the reluctor and sensor are physically good. It starts with the old testimate of checking PCV, new plugs and meggering them, etc. then goes to the new testimate good stuff like using techstream in check mode and run the misfire load and missfire RPM test with freeze frame enabled and run the missfire count/margins with the cat overtemp alarms disabled.
I think you need to get to know the FSM and techstream in the biblical fashion to find your problem if the reluctor and sensor are physically good. It starts with the old testimate of checking PCV, new plugs and meggering them, etc. then goes to the new testimate good stuff like using techstream in check mode and run the misfire load and missfire RPM test with freeze frame enabled and run the missfire count/margins with the cat overtemp alarms disabled.
- Thread starter
- #127
You
You are the exact person I need looking at this. It's a shame that I work at a toyota dealer and can't find a technician that would do what you are suggesting. Let me try with a different technician maybe. Totally frustrating. You near new jersey?
Nowhere near NJ and I'd rather sell bibles door to door in eastern afghanistan than step foot on the east coast.
The loss of good mechanics that can operate at the enginerd level without the computer telling them what to do has killed the dealership service bays over the last 20 years for anything beyond basic fluid and brake jobs. Find the guy who gets all the problem child rigs, knows electrical diagnostics, and openly loathes book time as the failing of western civility. He probably cleans his dentures in carb cleaner while daydreaming dreaming about the glory of condensers and dwell.
Kidding aside - The service manual has a good fault tree that is pretty straight forward to run thru and doesn't require mastery of engine tuning or design- give it a shot with techstream or bootleg a copy and do it at home.
I like the idea of checking the crankshaft position sensor. Two different pistons on two different banks, only associated by firing order on each bank suggests it could be related by the crankshaft. Which spins twice for the full firing cycle of the engine.
As the engine is butter smooth, until the moment the ECU thinks there's a problem, it also lends to the idea that it's a false sensor/signal issue that only arises intermittently when the engine is hot.
With the sensor being at the bottom of the engine, albeit behind a small shield, I can see shipping and handling of the motor potentially compromising the sensor?
This needs to go all the way thru the diagnostic procedure and the results of each step listed - There are a bunch or ways to piss off a factory ECU and it is worse after major changes like an engine swap. I can see a couple ways this could be happening but the margin test will show if it is systemic and these two jugs are just the two that are barely over the x of 1000 revolutions (45'ish/1000 as I recall?) of misfiring and the remainder are just under or if these two are the only whacky jugs and they are way dead when they die or intermittently go in and out. Also would want to see if cat temp goes up before the MIL fires the DTC or if this is logged only off the RPM data. Could be crank reluctor isn't indexed correctly and idle timing rolls in and you end up thumping all the cylinders but these two trip it over the edge into OL fuel map before the others error out (I don't know the mechanical indexing of the crank flange aft). Closed loop max lean idle settings dial in and these two injectors are slightly plugged causing lean pings (IR gun the primary pipes or swap injectors around on the rails?). Or it is something in the coil trigger lines, grounds, bad plugs, oiled plug ceramic/boot/pack, bad MAP/MAS, Vac leak, or anthying in the harness that got pinched dropping in the engine and is now intermittent short/open. I lean towards install/shipping damage on the wiring or a vac leak but the freeze frame data grabs should point to the problem.
If it is wiring damage on the coil side - My money is on IGF1 having an intermittent/thermal open or short to power but that doesn't explain why 4 and 7 are the only ones popping when 1, 6, 4 and 7 are all hanging on IGF1. It would explain why 4 and 7 both have the same misfire count index in your one picture (need to see the count on 1 and 6 with the cat thermal alarm bypassed). You'd need to hang scope leads on the coils and watch the traces to dig this deep.
If anyone wants to geekout on toyota ignition failure modes:
automotivetechinfo.com
If anyone wants to geekout on toyota ignition failure modes:
How to Find Toyota Ignition System Faults Fast! Dotting the IGFs and Crossing the IGTs
Toyota’s Direct Ignition System (DIS) (also known as Coil On Plug (COP)) operation, best testing methods and typical failures.
automotivetechinfo.com
Certainly possible- I think the ecu checks correlation between crank and cam pulses (DTC P0019 looks to see if the cam and VVTI are wonky to crank position). Looks like it is a stamped part with angled out teeth so you can pull the sensor and see it and see where the gap starts relative to TDC. Wonder if you could install it flipped with the teeth against the flex plate? Doesn't explain the intermittent issue and only 2 jugs. but this is all internet pin the tail work until you dig into the testing. The reluctor has an index hole and the crank has a pin/button inside the flex plate bolt pattern. You should be able to set the engine at TDC and see if the tone ring gap is installed correctly
Heres a thought- if the scrap yard pulled the reluctor and flex plate - was the index pin in the crank still in the flange when you received it? Got a picture of the new engine's crank flange without the strap covering it? The crank fische doesn't show the pin as a repalceable part so I assume it is pressed in and losing the index pin would only walk you out a degree or two untill the mounting cap screws restrained the plate (unless it is off a full bolt index or more.) But on the other hand a full bolt index is 18 degrees and you can be 18 degrees off on ignition and still run (not great but....). cam timing would still be synced to the crank if this happened but things would be... honky and maybe knocking like a jahovah witness. I still lean towards the IGF feedback line being crap.
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- Thread starter
- #137
I suppose but have to be at a different time.
Holy crap. Is that the smoking gun? How does the reluctor even get damaged like that?
- Thread starter
- #139
Exactly. I will be reaching out to the install shop tomorrow and asking the same question. You can see the big gap on the scope represents the intentional area without 2 teeth for TDC location. Then it comes to the 1/2 tooth. This makes that dead zone wider than 2 teeth worth which the ecu interprets as the engine speed slowing down which it isnt really slowing down based on other sensors. The only conclusion the ecu makes is that it's a misfire. That broken tooth correlates with cylinder 4 which is shared with cylinder 7. When those two cylinders are at TDC (which happens at the same time, that broken tooth is lined up with the crank position sensor tip. Crazy s*** I tell ya
bloc
SILVER Star
Well done.
