99 Taco misfiring - TTORA Forum
 
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post #1 of 10 (permalink) Old 09-23-2018, 06:39 PM Thread Starter
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99 Taco misfiring

Hey gang,


My 99 Taco w/275k miles is giving me some trouble. While driving, it will feel normal, then suddenly enters into a mode where you can feel it shimming side-to-side a bit more than expected, kinda hear the exhaust "putt-putt-putt" instead of normal purr, and when I give it some gas, the engine stutters and the power just isn't there, and check engine light flashes and then goes away. Kinda reminds me of how it behaves with a bad plug. Sometimes when I start it, it's in this mode, and sometimes it only falls into it after twenty or thirty minutes of normal driving; once entered, it seems to stay in this mode across multiple off/on.


The first time this happened, it was throwing a P0306 Cylinder 6 misfire detected, another code to do with the Idle Air Temperature Control, and several times flashed a code about air fuel mixture too lean (my code reader seems to have deleted the actual codes). So we discovered the air filter box had a crack in it past the filter, which we repaired, and hit the MAF sensor with MAF cleaner, because it was fairly dirty.. Still behaved the same, and threw the same codes. Plug 6 looked fine, so we replaced the coil pack for 3&6. Still behaved the same, and threw the same codes. So I took it to a shop, they saw 0306, claim it had compression within spec, and replaced plug 6. It's still behaving the same, and I no longer have access to a code reader but I did see Check Engine flash a few times the other day.


Here's one stupid thing I did leading up to this: I ended up in a bit of a bind, and ended up having to tow a boat that was around 6800 pounds for about 50 miles, which is way over the 5000 pound safe tow limit. I'm hoping I didn't do anything more insidious like broken piston rod or blown head gasket... I do not see any vapor or colorful smoke coming out of the exhaust. I'm hopeful it's just a bad fuel injector or something.



Any ideas appreciated. This is above my pay grade, so I'm taking it back to the same shop that replaced the plug, telling them "it aint fixed", and hoping they come up with a better diagnostic based on recent check engine light flashing. It would be nice to get some insight from you guys in the interim. Thank you!!

  • 1999 Tacoma Limited Xtracab 4WD
  • OME 881 + NitroCharger Sport in front
  • OME Dakar + NitroCharger Sport in rear
  • BFG AT 33x10.5 15's on stock wheels
  • PPI 4100 driving 12" Kicker solobaric and MB Quart 216 separates
  • Just enough rust to seize up every last damned bolt on the undercarriage, but not quite enough to qualify for the rust recall
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post #2 of 10 (permalink) Old 09-24-2018, 09:03 AM
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The flashing light is a misfire situation. I'd suspect a fuel or injector issue at this point.
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post #3 of 10 (permalink) Old 09-24-2018, 09:44 AM Thread Starter
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Ok I'm totally on board with the injector issue, and nothing more serious! Thanks for your time. I'll follow up with results once I hear back from the shop.
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post #4 of 10 (permalink) Old 09-28-2018, 08:19 PM Thread Starter
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Well, the shop had to keep it for a few days until they were finally able to get the truck to run in the state where the engine was misfiring (since the problem is intermittent) and they diagnosed bad spark plug cables (sigh) and replaced them and said it didn't exhibit the problem anymore and wasn't throwing codes and to pick it up.



When I picked it up after hours and started it up, sure enough, putt-putt-putt, the engine was shimmying noticably side to side, and the acceleration was very poor. Misfire state again.


I had to do a road trip today, and it was driving hard in the misfire state for about 150 miles, flashing check-engine when I would accelerate, then the CEL would stay on, then it would clear out. Then suddenly out of nowhere it was driving great, no more putt-putt, no shimmying, I had normal acceleration, no CEL. Once I got where I was going, I hooked it up to the code reader:



P0300 Random / Multiple Cylinder Misfire
P0171 System too lean
P0505 Idle Control System


The P0300 was unexpected -- previously the misfire codes had all been cylinder 6 (P0306), both before and after replacing that spark plug. The only other change has been new spark plug cables, and now it's P0300.



I'm not really sure what to make of this or what diagnostics to do at this point. It's a bit frustrating. The shop doesn't seem to be helpful, and so I'm left to replace random spark plugs and fuel injectors I guess, and hope for the best. Any suggestions would be great.

  • 1999 Tacoma Limited Xtracab 4WD
  • OME 881 + NitroCharger Sport in front
  • OME Dakar + NitroCharger Sport in rear
  • BFG AT 33x10.5 15's on stock wheels
  • PPI 4100 driving 12" Kicker solobaric and MB Quart 216 separates
  • Just enough rust to seize up every last damned bolt on the undercarriage, but not quite enough to qualify for the rust recall
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post #5 of 10 (permalink) Old 10-01-2018, 12:28 AM
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Assuming you had compounded problems originally, the spark plug wire might have been the fix for part of the issue. The misfire, lean and IAC codes all point to an air mix problem. You might want to check the IAC and clean it along with the whole intake. I know you said you had a leak in the air box originally. You should also check everything upstream of the MAF to the throttle body and make sure the air box doesn't still have a leak.
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post #6 of 10 (permalink) Old 10-04-2018, 05:22 PM Thread Starter
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Got a new airbox and MAF installed, deleted all the codes, will report back if it fixes the issue! If not, next step is clean the IAC, and then if that doesn't work, replace it. Didn't see any cracks in the semiflexible rubber pipe that runs from the MAF sensor mount to the engine.


Interestingly, just before putting the new parts on, it started throwing a new code, P0301 misfire cyl 1. I think I was barking up the wrong tree chasing the spark issue, and hopefully it's an intake / air / MAF issue that fixes it.

  • 1999 Tacoma Limited Xtracab 4WD
  • OME 881 + NitroCharger Sport in front
  • OME Dakar + NitroCharger Sport in rear
  • BFG AT 33x10.5 15's on stock wheels
  • PPI 4100 driving 12" Kicker solobaric and MB Quart 216 separates
  • Just enough rust to seize up every last damned bolt on the undercarriage, but not quite enough to qualify for the rust recall
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post #7 of 10 (permalink) Old 10-07-2018, 10:39 AM
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Check Compression

Hmm... sounds like the same road we're on at 215,000 with our 2000 4Runner.

Sounds like you caught it early since you don't have the P0420 bad Catalytic Converter code yet.

For us, after cleaning then replacing MAF, new plugs, wires and coils... took it to a shop who found low compression attributed to a leaky exhaust valve in cylinder #1.

You can search on this forum for "burnt valve" to learn more.

Basically, as the engine ages, the exhaust valves loosen up or warp and the affected cylinder misfires - instead of generating compression to drive the piston, the combustion blows into your exhaust system. Your engine thinks its running lean, so it sends more fuel. With the accumulation of unburned gas in your catalytic converter, it eventually burns up.

If you don't resolve it on the air side, I'd check the compression.
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post #8 of 10 (permalink) Old 01-09-2019, 11:17 AM Thread Starter
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Fixed it!

Just wanted to follow up...


I replaced the airbox, got a new mass airflow sensor, cleaned out the throttle body. This is because, as I originally wrote, the airbox had a huge crack such that the air intake hose was pulling unfiltered air for god knows how long, after much dusty Sierra late summer off-roading. So first task was to make sure the intake was clean.



Problem still persisted, it continued to throw the same: P0306 Cylinder 6 misfire, sometimes a P0300 Random Cylinder Misfire, sometimes P0301 Cylinder 1 misfire, sometimes P0171 system too lean, sometimes P0505 Idle Control System.



The fix was to replace the #6 fuel injector, which solved the problem completely. It runs great now.



Note that, before I noticed the huge crack in the airbox, I had also replaced all the spark plugs twice, and the spark plug wires, to try to fix this problem to no avail. So if nothing else, my ignition system is in pretty good shape!

  • 1999 Tacoma Limited Xtracab 4WD
  • OME 881 + NitroCharger Sport in front
  • OME Dakar + NitroCharger Sport in rear
  • BFG AT 33x10.5 15's on stock wheels
  • PPI 4100 driving 12" Kicker solobaric and MB Quart 216 separates
  • Just enough rust to seize up every last damned bolt on the undercarriage, but not quite enough to qualify for the rust recall
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post #9 of 10 (permalink) Old 01-17-2019, 04:31 PM
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Thanks for posting the update and solution to your issue! Curious, did you test the injector or just decide to replace it?

02 Tacoma TRD 4x4, Ome 882's, Dakars, Bils, 4crawler 1" bl, CBI sliders...
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post #10 of 10 (permalink) Old 03-24-2019, 08:17 AM Thread Starter
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Quote:
Originally Posted by lunarmist02 View Post
Thanks for posting the update and solution to your issue! Curious, did you test the injector or just decide to replace it?

Sorry man, I just now saw your post, it looks like my email notifications are broken. In the spirit of better late than never ... I did NOT test the injector. I just replaced it. After the amount of diagnosis I'd done (replace wires, plugs, clean out throttle body, basically replace most of the intake and sensors, etc), to me it was pretty obviously the culprit.

  • 1999 Tacoma Limited Xtracab 4WD
  • OME 881 + NitroCharger Sport in front
  • OME Dakar + NitroCharger Sport in rear
  • BFG AT 33x10.5 15's on stock wheels
  • PPI 4100 driving 12" Kicker solobaric and MB Quart 216 separates
  • Just enough rust to seize up every last damned bolt on the undercarriage, but not quite enough to qualify for the rust recall
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