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Ted Ritter
Ted Ritter, Toyota Master Tech
Category: Toyota
Satisfied Customers: 4400
Experience:  Toyota Master Tech, ASE Certified
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It hesitates upon acceleration from start and poor power,

Customer Question

it hesitates upon acceleration from start and poor power
JA: How old is the transmission? Have you checked the fuel filters?
Customer: it's a 99 Tacoma 4 cyl 2.4L
JA: Are you hoping to fix this yourself? What have you tried so far?
Customer: yes I"m a do it yourselfer. I pulled the fuel filter a while ago, it seemed fine. I could blow through it and there was no crap in it at all. it looks like someone might have changed it before I bought it.
JA: OK. Got it. I'm sending you to a secure page on JustAnswer so you can place the $5 fully-refundable deposit now. While you're filling out that form, I'll tell the Toyota Mechanic about your situation and then connect you two.
Submitted: 1 year ago.
Category: Toyota
Expert:  Ted Ritter replied 1 year ago.

Thanks for posting

Other than the fuel filter has anything else been replaced yet, spark plugs?

Does the check engine light stay on when driving?

How is the idle? smooth or rough like a misfire?

Customer: replied 1 year ago.
I've done a lot to it, I'm fairly handy, just don't have tools.
I checked compression, around 165 on all 4 cylinders (this is a 1999 Tacoma with over 200K miles), so that kind of compression looks excellent to me.
I checked spark plugs, they look ok, I haven't replaced them yet.
I checked the fuel filter, seemed ok.
I just pulled all 4 injectors and cleaned them just now, so I don't know if this will take care of it, but they all seemed to work (resistance about 14.7ohms, all clicking when power applied, was able to spray carb cleaner through them.
Customer: replied 1 year ago.
idles nicely, pretty smooth. it doesn't seem like it missfires, but
when I take off from a stop, it acts like it chokes or something.
slow accelleration. once it gets going, it's ok.
Customer: replied 1 year ago.
I put a little seafoam through it a few weeks ago, it didn't seem to solve things.
at one point it had a code 0304 (missfire on cyl 4, and the cyl 4 sparkplug looked a little fouled, but not too bad. I reset that, and it hasn't come back recently. also several months ago it had I think it was p0172 (but not sure), I think it was about the O2 sensor. that code hasn't come back.
Customer: replied 1 year ago.
also just yesterday I did a smoke test on the vacuum lines, and it doesn't really look like I have any major vacuum leaks. there is a tiny whisp of smoke that comes from under the EGR filter cap thing, but very little.
I have an OBD scanner plugged into it, so I have screenshots from my phone taken while I was driving if you're interested in seeing different parameters.
It seems to me like the timing is a bit too advanced, but I can't adjust that.
Oh and I checked the MAF sensor, and sprayed it with cleaner. it looked new.
Customer: replied 1 year ago.
I haven't replaced wires I guess. that could be a possibility. but would prefer to diagnose as much as possible, before I start replacing expensive stuff.
Expert:  Ted Ritter replied 1 year ago.

I can help you with that, I need to know if the check engine light stays on while the engine is running.

Also it's very important for me to know how it idles, does it have a misfire at idle?

Customer: replied 1 year ago.
no, there is no engine light on it at this point
it doesn't sound to me like it has a missfire at idle (I'm deaf, but I use cochlear implants - which is part of the reason why I prefer chat)... but engine seems to idle fine to me
Expert:  Ted Ritter replied 1 year ago.

No check engine light pretty much leaves out a misfire but you mention a loss of power and acceleration, did this happen gradually or just all of a sudden?

Expert:  Ted Ritter replied 1 year ago.

Can you get fuel trim information both long and short if possible?

Customer: replied 1 year ago.
I would say gradually got worse. it is driveable now. I drive it to work. it just sorta hesitates when taking off but once it gets past 20-30mph it seems better. Sure, I will send you some screenshots from my phone, I just took it for a spin (I had just put the injectors back in this morning and now I reinstalled the air duct thing. It starts and idles very nicely, at first in P it idles a little high (around 1178 rpm) but once I drive it a little, the idle and I stop (but still in gear), it idles around 750rpm.
Expert:  Ted Ritter replied 1 year ago.

Sounds pretty good, let's see what the fuel trim looks like and go from there.

Customer: replied 1 year ago.
is there an email or something where I can send screenshots from my phone?
I'm having trouble logging into this from my phone
Expert:  Ted Ritter replied 1 year ago.

You can jst tell me what the readings are, is that ok?

Customer: replied 1 year ago.
Expert:  Ted Ritter replied 1 year ago.

The only problem I see is the fuel trim, pretty far off on both screens, normal is around .02 or so the close to zero the better, I would try a new mass airflow sensor. I would also check to see what the actual intake vacuum is, could also be a partially clogged converter or exhaust.

Customer: replied 1 year ago.
i noticed that the vacuum value on the scan tool, pretty much stays at -14.7 all the time. that seems odd to me. I would think there would be some variation while driving however minor, but it never changes at all.
anyway, I will check out those items ... the MAF sensor looked brand new to me, but I will see if I can swap it and see if it makes a difference.
Yeah I did think of the clogged exhaust/cat converter. I will look into figuring out how to diagnose that.
I will get back to you with my findings.
Expert:  Ted Ritter replied 1 year ago.

All right. The 14.7 hg vacuum is too low, if it's actual intake manifold vacuum, should be at least 18 to 19. A clogged cat can cause this.