2003 Toyota Tacoma V6 hesitation

BTW I only had starting problems after I replaced the MAS. It would need 3 starts to stay running everytime, weather made no difference with starting.
BUT after I changed the MAS again and put in an OEM one, the starting problem went totally away.
I really wanted to keep this truck till' 300,000 miles since it has NEVER needed anything except brakes, tires ect and I've been hauling a boat trailer, car trailer, horse trailer and plowed with it and still never a brake down!
And of coarse what kind of resale would I get for a 10 year old 200,000 mile truck anyway.

 

Do any of you have a "check engine" light on while experiencing this problem? I have never had one pop up. The folks I talked to said the o2 sensors, coils, or injectors would all throw codes. I am also having the problem of fixing something, having the problem go away, only to come back. I thought the vacuum plug was it but the issues came back the other day. It is a real PITA to drive this truck when it is running like this!

 

I get a check engine light and the codes are for an O2 sensor code as well as several others but they have gone away (for a while anyway) when I put on a new MAS.

I'll put on a new O2 sensor and see what happens. Is that a quick install ? What did the part cost ? Did you buy it from the dealer or aftermarket?

 

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can it be a tranny problem? what about catalytic converter> dont know just trying to figure out this problem, really getting annoying now.

 

they have this part on ebay for 70 bucks..

 

I have not had a check engine light regarding this issue. The only light I did have was an oxygen sensor which I replaced and the code was reset. Then the nuts ended up rusting off of the studs and it started rattling and threw a code again. I got a new gasket and new nuts, tightened that back on and the code reset itself again. I had hopes that this was related to the hesitation, but it wasn't. The hesitation is still there.

I thought it might be the catalytic converter, but I can't imagine that wouldn't throw a code.

 

I thought about the cat too. Went and got a back flow test but it turned out fine. Another

 

....bit of money wasted trying to hunt this problem down.

 

Are there 2 oxygen sensors for the Taco? Cause' I searched the web for prices and was asked if I needed the "before" cat 02 sensor or "after" cat 02 sensor?

In reading on the web it seems that 02 sensors are really only expected to last about 50,000 miles or 2000 starts. Also since they are critical for feedback for fuel mixture info that they certainly could be the problem. But if 2 are needed then changing only 1 may not do it.

If there are 2 I'll buy both then change 1 then go for a test drive. If fixed save the other until it happens again.

 

Well, this is crazy. Been having this "hesitation" problem myself for a couple of weeks now. We are currently having bands of hurricane Isaac coming through South Florida and while I was out running errands, it hesitated so bad that I thought it was going to stall or just leave me in a very bad spot trying to merge into traffic

So it appears it may be related to heat and/or rain/water. I have driven through some wicked puddles with this storm, so it makes me wonder if I got water up there somewhere that it shouldn't be. It's pouring right now, so I won't be able to check for a while...but what would the recommendations be for me to check that are easy and fairly accessible? I'm thinking air intake or electrical, so I will check whatever I can on those items.

Also, I used to run Lucas gas treatment in my Mazda 3 because it REALLY didn't like the ethanol in the gas. Ran like a top using that stuff. So, when I traded the 3 in on this truck, thought I would do the same with this. Since I've been using it and don't know if treatments were used before, is it possible for it to have dislodged something from the fuel system and clogged up the fuel filter?

Hoping we can all find a resolution to this! Any input appreciated

 

I feel your pain! Finally got a check engine light yesterday and was hoping it would lead to something. Codes were po441,442, and 446. Those all seem to do with the EVAP system and I believe they might be popping up because I messed with the tank to install the fuel pump recently. Gonna recheck all of that tomorrow but what I can find online those codes would not really make a noticeable power loss.

The past 2 days mine has been horrible also. It is freaking supercharged and I am having to floor it and have full boost to climb the smallest hill! Sounds like crap. Denotes like hell at full throttle under a load.

I have noticed that it runs worse in the afternoons than in the early morning when I go to work. It does seem heat related. We haven't had a whole bunch of rain so I don't think that it is but who knows?

Fuel injectors are going off to be cleaned as soon as I can get a ride or enough time off work to send them out and get them re-installed.

Good luck with yours!

 

And just for reference, the things I have tried to remedy this problem (in order)

1. Changed plugs-initially this seems to be around the time my problem started. End of March on a long trip.
2. Changed plugs to one heat range colder. Ran ok for a couple of days then came back.
3. Changed plugs back, cleaned MAF, throttle body, air filter. Same, went away and came back.
4. Sea foam thru tank and vacuum line. No improvement.
5. Replaced plug wires, ran a little better but came back.
6. Cleaned MAF even better and changed stupid $17x3 plug boots under coil.
7. Replaced MAF, ran better for short time and then came back.
8. Replaced fuel filter. Ran good but in a different way. Like the filter was bad but not what was causing the loss of power.
9. Replaced fuel pump to waldoro 190 lph. No change! Arrrrghhhh!
10. Found a vacuum port of on the back of s/c, plugged it, reset ECM. Ran great for several days. Back again!

Getting a tad bit frustrated!

 

FramerKat, your problem seems to be my problem exactly. I know that water has to be collecting somewhere, but where? Toyota didn't have a clue and neither have the other three mechanics I've had look at it. I've been waiting for a check engine light or for the truck to leave me stranded, but that just won't happen because no matter what, this truck will get me where I need to go(although sometimes very friggin' slowly at intersections when I feel like I might get hit by another car if I try to turn in front of it).
Well maybe some good will come out of hurricane Isaac for us and you can solve our problem...keep me posted.

Crunchy taco, since your truck is supercharged and from your description, I'm not 100% sure we have the same exact issue. I would still appreciate you keeping me posted on any fixes though. It still is possible we all have the same stubborn issue.

If I have any updates, I will certainly post them. This has been such a thorn in my side for the last 4-5 years and I'm pretty close to selling this truck if I can't fix it. I'd love to fix it and drive this thing for another couple hundred thousand miles...

 

ToyotaDually, please let me know if the O2 sensors change anything.

 

Well, since the rain has finally subsided here, thought I'd take a look under the hood. I checked all of the spark plug connections and one actually felt a tad loose (the front right one when facing the engine). It popped back into place with a bit of pressure. I'm wondering if it was enough to cause it to miss intermittently on that cylinder. Hoping it didn't allow water to get in also from driving through one of the (deep) puddles around here that past few days.

Will drive to work today (20 miles each way) and see how it does. Wish me luck ;-)

 

Eriksen,

Our symptoms are different but I figured they may be form the same problem. I started a thread on here a while back without any help so I thought some might come thru this thread.

BTW, have you looked into the Tacoma APPS problems? You can google it. Apparently out trucks (03-04's) have a fly by wire throttle body. There is only one cable and it operates a "limp home" feature. The throttle has a TPS and an APPS (accelerator pedal position sensor). Lots of folks have some symptoms sorta like yours. The TPS is replaceable, the apps is not. If it goes bad then you gotta pony up $1300 for a new throttle body. Worth taking a look at.

 

My code reader only showed a PO442 and PO456 both are EGR codes. :< No 02 sensor codes.
I guess I'll take it to the dealer. I'm getting a new and constant rear diff whine with occasional crunchy sounds from the rear too....be spending some money soon. Least I'll be spending it at 210,000 instead of 50,000 like I did with my GMC 3500 then my Ford F550.

 

Well, I have an update after this morning. I started to go on my way this am and had a slight hesitation as I pulled away from my parking spot, nothing at all on my 20 minute (mostly highway) commute, then another hesitation as I neared my destination.

Then, on my way home, everything ran fine until the engine was fully warmed up and I was either pulling away from a stop or going under 40mph. I think it must have happened about a half a dozen times, but still not nearly as bad as it was in the rain yesterday.

I'm still wondering if water managed to get down that spark plug boot and possibly fouled the plug.

 

Yet another update...I've now narrowed it down to happening when the rpms are between 1250 & 1750...above or below, it doesn't happen. Don't know if that would point to anything in particular though.

Since I'm over 100k, I think the first thing I'm going to do is spark plugs and wires. I found that Advance Auto has the recommended plugs for a reasonable price, so probably going to pick them up there. Thinking I'll get them and take them to my mechanic...it's been too long since I did plugs...and don't want this to get worse from me doing something wrong.