Sluggish acceleration - cold start in damp/cool weather?

[dbsoundman]

We've been having quite a lot of rain and cool/damp weather here in Colorado this year, and I've started to notice that my '00 acts a little strange when I first start it up on mornings where it's pretty wet outside. It starts fine and idles normally, but if I start driving off soon after starting it up, I notice that it almost feels like the accelerator is being throttled back intermittently. It's a subtle feeling, but it's definitely noticeable. It just feels like I intermittently lose a little power. Within about 60 seconds of running, that issue goes away, and it runs normally.

Talking to my boss, he suggested it could be O2 sensors or maybe a clogged cat, do you guys have any other ideas? I do get a periodic "Bank 1 too lean" check valve light, but that's been going on for over a year, and usually it only trips when I'm accelerating onto the highway. I've never noticed a drop in performance because of it so I haven't worried about it. The MAF and throttle body were cleaned last December, so I should be good there.

Thanks for your ideas!

 

[dbsoundman]

OK, so no one has any ideas. I've got a few of my own:

1) Replace MAF. I've already cleaned it and the throttle body once, but I still get a P0171 every once in a while, so I'm thinking it needs replacement.
2) Replace spark plugs. Not sure when this was done last anyway (I've never done it in the ~2 years I've owned this 4runner)
3) Replace PCV
4) Maybe try some fuel injector cleaner in the gas tank?

Beyond that, I don't have any ideas. I've noticed that his happens basically every time I start now when it's cold, for about a minute. Idle is slightly (and I mean VERY slightly) rougher during this time as well. Around the time the fan gets down to normal speed, it runs and drives fine.

 

[Jaketino]

Just needs to warm up more. Mine does similar things if I just start it up and begin to drive. Give it a few moments to warm and your engine will thank you.

 

[Ladywithafan_321]

OK, so no one has any ideas. I've got a few of my own:

1) Replace MAF. I've already cleaned it and the throttle body once, but I still get a P0171 every once in a while, so I'm thinking it needs replacement.
2) Replace spark plugs. Not sure when this was done last anyway (I've never done it in the ~2 years I've owned this 4runner)
3) Replace PCV
4) Maybe try some fuel injector cleaner in the gas tank?

Beyond that, I don't have any ideas. I've noticed that his happens basically every time I start now when it's cold, for about a minute. Idle is slightly (and I mean VERY slightly) rougher during this time as well. Around the time the fan gets down to normal speed, it runs and drives fine.

I had a run in with the O2 sensors ages ago on my 2000; got the same code, replaced & that cleared that up ~ however, when it's colder/damp outside I have the same issue which is from what I understand, just the way it is for the 2000's ~ they eat O2 sensors.

 

[dbsoundman]

I had a run in with the O2 sensors ages ago on my 2000; got the same code, replaced & that cleared that up ~ however, when it's colder/damp outside I have the same issue which is from what I understand, just the way it is for the 2000's ~ they eat O2 sensors.

Interesting...so a non-O2 sensor related code is triggering because of the O2 sensor. Let me guess...it's the forward one that's the problem, right? @%#$ expensive thing!

 

[gs300tt]

I would replace the 3 plug wires and the 3 boots on the coil packs. It sounds like moisture effecting the ignition system and then drying out. These are good things to replace even if it does not solve the problem.

 

[dbsoundman]

I would replace the 3 plug wires and the 3 boots on the coil packs. It sounds like moisture effecting the ignition system and then drying out. These are good things to replace even if it does not solve the problem.

Good call, I was thinking about that. Found the NGK wire set on Amazon. I'll check prices at my local dealership too.

 

[JRZEE2000TR4LTD]

We've been having quite a lot of rain and cool/damp weather here in Colorado this year, and I've started to notice that my '00 acts a little strange when I first start it up on mornings where it's pretty wet outside. It starts fine and idles normally, but if I start driving off soon after starting it up, I notice that it almost feels like the accelerator is being throttled back intermittently. It's a subtle feeling, but it's definitely noticeable. It just feels like I intermittently lose a little power. Within about 60 seconds of running, that issue goes away, and it runs normally.

Talking to my boss, he suggested it could be O2 sensors or maybe a clogged cat, do you guys have any other ideas? I do get a periodic "Bank 1 too lean" check valve light, but that's been going on for over a year, and usually it only trips when I'm accelerating onto the highway. I've never noticed a drop in performance because of it so I haven't worried about it. The MAF and throttle body were cleaned last December, so I should be good there.

Thanks for your ideas!

Do you have one cat or two? How many miles on your truck? With that CEL and if you have 2 cats, it may be the front A/F sensor. Which looks just like an o2 sensor but is more expensive. May also have a failing or clogged cat.

 

[dbsoundman]

Do you have one cat or two? How many miles on your truck? With that CEL and if you have 2 cats, it may be the front A/F sensor. Which looks just like an o2 sensor but is more expensive. May also have a failing or clogged cat.

I have about 175k miles. Stock non-California setup, so I think that's 1 cat.