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Old 09-04-2012, 09:50 AM
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Default Odd "stumble" in the Taco

I didn't come up with anything in the search, so I'll throw this out to the experience of the group.

On the way out to Ouray, the truck started showing a slight "hiccup" at about 2000RPM (+/- 200 or so). I wouldn't call it a stutter, per se. There is no noticeable RPM drop (at least on the tach), but you can feel yourself lean forward as is the brakes were momentarily engaged. The whole thing is about a second long.

On the trail, I didn't seem to have any trouble, mostly the issue seems isolated to steady throttle position on flat roads.

Nothing about the "stumble" is violent, but it is certainly noticeable, and it happened too many times to count on the way home from Ouray.

I initially thought I had some bad gas on the way to Tincup, but the fact that I went through a couple of tanks during the trip seems to rule that out. May run a little Seafoam through it just for grins.

The truck has almost 93K on it. It is a 2004 Tacoma DC, 3.4, Auto. Always Toyota parts and service intervals. Plugs are in good shape, MAF is clean. Maybe a plug wire or a coil? RPM-specific symptom makes me think it isn't fuel related, but that could be wrong.

Any ideas?


Thanks,

BJG
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Old 09-04-2012, 11:49 AM
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I'd sure check for pending OBD codes, if there is no MIL showing. I agree that it sounds more like a coil than a fuel issue. Changing the fuel filter might be good insurance, at the age/mileage you have, too.
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Old 09-04-2012, 01:53 PM
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Thanks Steve. My code reader doesn't read the pending stuff, but I've got an appointment to stop by a buddy's shop and have a look.

Another thought is the TPS. Not sure how often those go out, but it does seem to happen only with light pedal pressure and around the same amount of travel. Agreed on the FF. Will probably pick one up and change it just for good measure.
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Old 09-04-2012, 03:05 PM
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No help on a Tacoma but on an 80 that symptom has been linked to a cracked air intake hose or chaffed wiring (in a big loom) causing intermittent shorts (usually when power is applied that "torques" the engine and moves stuff around).

Knowing nothing about Tacomas I don't know if you might have any similar items as above
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Old 09-06-2012, 08:57 AM
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Quote:
Originally Posted by bgoodheart View Post
Thanks Steve. My code reader doesn't read the pending stuff, but I've got an appointment to stop by a buddy's shop and have a look.

Another thought is the TPS. Not sure how often those go out, but it does seem to happen only with light pedal pressure and around the same amount of travel. Agreed on the FF. Will probably pick one up and change it just for good measure.
Had this same issue on my Tacoma. It turned out to be too much oil on the K&N filter that saturated the TPS. At least that's what the mechanic said.
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Old 09-06-2012, 03:42 PM
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Thanks Trav, no K&N here, and I haven't ever had one. You're right though, it is a lot like what another buddy's Taco did with oil on the MAF and a gummed up throttle body from his K&N. I clean both (MAF and TB) every 15K or so, but I'm definitely going to pull them apart and check. I found the resistance specs on the TPS, so I'm going to pull that off and throw the meter on it too.
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Old 09-06-2012, 05:01 PM
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Motor magazine had a story where cheap Chinese air filters give off fuzz that contaminates the MAF, just as excess K+N oil would, so sometimes these problem are not only K+N related.
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Old 09-06-2012, 06:11 PM
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Huh, thanks Steve. I used Toyota filters until I put in an AFE Pro Dry last year. Have to do a "fuzz" check.
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Old 09-06-2012, 10:12 PM
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have the codes pulled to see if there are any "easy outs". if your on the south side swing by my shop and ill read the computer for you.

well your approaching the magic 100k mark. and at 100 the timing belt and plugs are due.
if they haven't already been replaced id highly suggest doing it now (denso ). your issue has many different areas of possible failures, expectually with 100k. approaching. but before worrying about anything. id do all maintenance first. then see if the issue is still there.. if so then you have a issue that requires diag.
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Old 09-07-2012, 11:00 AM
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Thanks Tim, I did all the maintenance already. All Toyota parts. Did it a little early because I was in town and it was convenient, so everything has had a few thousand miles to settle in. Had the codes checked on Tuesday. Not a thing there, and nothing pending. I'm going check the relevant sensors this weekend and see what I come up with. I'll put an update in this thread if I find anything good.
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