kihonhappo

Hello yota techs,

I'm looking for help with this extremely frustrating situation. My buddy is a longtime member and suggest I ask. A couple months ago my 95 tacoma suddenly started misfiring. Below is my story.
My symptoms –
95 tacoma 2.4L 2wd
- chokes between 1500 – 3500rpm when cold but does not stall.
(by choke I mean: engine stutters violently, looses any excelleration, but doesn't die.)
- Vehicle stabilizes more when warm, but… Engine experiences a noticeable skip/misfire between the above range.
Engine idles fine all the time.
Misfire isn’t noticeable when over 3500.

I’ve done the following:
- cleaned the MAF with MAF cleaner.
- Unplugged MAF to see if it would malfunction. It did.
- Cleaned the air intake, throttle body and all parts up to the intake manifold.
- Cleaned and checked egr. Scraped out the carbon buildup.
- Tested the egr by sucking on the vacuum hose. Engine died when vacuum applied at idle.
- Unscrewed and cleaned egr sensor.
- Replaced coil (only 1 located under the distributor cap.)
- Replaced the distributor cap, wires, and plugs.
- Replaced the TPS
- have all P300 - 04,

Dirt Driver

I didn't see a code check listed in the things you did...

Lummpus

x2 on checking the codes. they can give us a better idea of what going on also have you looked through the FSM it can tell you alot.

BTW Welcom to Yotatech.

abecedarian

Actually, the OP did post the codes- P0300-P0304. P0300 is Random / Multiple Misfire Detected, and the 0001-0004 denotes which cylinder(s)... so....

IF I had to guess, I'd start looking for loose wiring and connectors around the engine... not necessarily 'unplugged' ones, but ones that may make intermittent contact as the engine shifts during acceleration. Also, vacuum leaks and / or loose intake duct may be culprit however I think you'd likely have an O2 related code.

Do you experience the misfiring if you ease the engine up in rpm's or does it happen with the pedal floored, or both?

kihonhappo

Hello,

Thanks for the replies. Abecedarian, saw the odb codes. I could have made them a little more obvious. Like he said P0300 - p0304. random cylinder misfires, and that's exactly what it feels like.
-Early in the morning when the engine is cold it's a nightmare if I don't warm for 5-10 minutes.
- The idle is fine but if i step on the gas enough for it to peak over the 1500rpm mark it starts doing crazy things.
- It feels like i just pinched off the gas. When i release the peddle it goes back to normal idle.
- If that give you a good idea of what it's like.
- Usually when i do let it warm up for a few minutes i still get to experience some of that stuff until i get a few blocks out of the neighborhoood.
ONCE It's warm:
-If i excelarate hard, i don't feel anything.
- When i'm just coasting along on a side street below 1,750rpm, no problem.
- When i get on the normal street and cruise in the range i described in the post (over 1500 - 3000rpm), there's a mild to medium skip/miss in the engines rhythm.
- It doesn't stall or cause any danger on the road but it's obvious there's a problem.

On an up note i went and passed my NC State auto inspection yesterday. I cleared the engine light and waited about 80miles and took it in. I had been avoiding the inspection for 3 months.
Just for the guy to laugh at me an tell me they don't hook up to the engine on anything older than 96.

scuba

I think this thread is in the wrong section..

abecedarian

Scuba, I agree, it is in the wrong section considering it's a Tacoma with OBDII. But the Tacoma did come out in 95 (late 94 IIRC) so technically it's in the proper section.
Maybe the yotatech forums should be amended to reflect OBDII vehicles instead of hard year cut-offs. Not my call though.

abecedarian

Sounds like it's an intermittent issue since you passed emissions. And LOL at the test station. Anyhow, you passed.
As for the engine operation issues, it seems to be an intermittent issue, not a constant based on anything particular, else you wouldn't have passed the emissions, no?
Random misfires can be attributed to poor engine grounds and improper spark plug gaps... and a whole lot more from fuel pressure to the knock sensor.
Since you got your emissions test done, I'd say pull the battery ground for an hour or so. Then reconnect and drive. Worse thing that can happen is the issue returns. Best thing is that there isn't a problem. Either way, we won't know if you don't try.

kihonhappo

It's very constant. The light just came back on 109miles.
I had anticipated it would return sooner.
I looked at my wording on my last post and i left out a word or

I meant to say they don't plug into the odb or check emissions with the stick in the tailpipe which i didn't know. On models older than 96 they just check safety stuff like leaking oil or dead light bulbs.

****************************************
I've checked for loose vacuum hoses and connections.
***************************************
I was looking up the path of whatever sends the sparks to my engine isn't doing it properly. Which would be pretty expensive to repair and is why i'm here checking for advice of the experts.

kihonhappo

Scuba,

I pondered that thought for some time. 80-95 or 95 -2004?

should i switch to the other since i'm odb II if that's the criteria?

abecedarian

A few things (sensors) are used to determine (even with OBDII) when to fire the coil- throttle position, air flow, engine rpm, crankshaft (or camshaft) position and knock sensor. Given the problem is intermittent makes singling out any one sensor as a probable cause all that more difficult, exacerbated by the fact you're not getting trouble codes relating to any other sensors.
Hate to say it but I think the truck needs put on a dyno and scope to try to isolate the condition(s) that cause the misfire to occur.

abecedarian

it's often frowned on, cross-posting to multiple forums, but sometimes you may get answers from people more familiar with your system.

scuba

I think regardless of obd whatever, if you have a 95.5 tacoma it should be in that section.
Not trying to be a forum nazi just sayin

abecedarian

uh... Tacoma's came out mid/late 94, as a 95 model (depending on the source of the 411), so a 95 Tacoma would fit in the 86-95 forum, no?
Stop being so stubborn.

mattaway

my 92 22re does almost the samething. the only differences are mine runs perfect before it warms up and mine has stalled in 5 o'clock traffic a couple of times.

i'd really like to know what the problem is, it's almost to the point where i want to either get another chevy and say F---orget the 'yota, or find a doner and make my 'yota a chevy.