Acceleration issue...

[Skrillah]

Hey guys,

In the mornings when the engine is cold, upon getting it up to 30-40 mph, I'll notice the engine will sort of surge. By that I mean, the RPMs fluxuate ever so slightly. Its very suttle, and almost feels like you are being pushed by a strong wind.

I've checked vacuum lines, checked the TPS, put new air filter in, and checked just about everything I can think of. The plugs are new and I don't notice any arching from the plug wires, nor do the wire boots look bad. I haven't run sea-foam or anything like that through it, because well I think of that more as a safe guard type of thing, more like standard maintenance. With something like this, I feel there is more of a chance something is physically wrong with a component rather than just a gummed up intake or something...but that might be a stupid view-point... :screwy:

So before I just start throwing parts at it, do you guys have any other suggestions? Like I said it only does it when its cold, once it warms up its fine. I'm thinking I might have a problem with one of the injectors but again it doesn't do it when its warm. Only other thing I can think of is O2 sensor as I know I haven't replaced them and I doubt the previous owner did, but I don't know if that would cause the symptoms I'm having?

Help me out here...my signature below has my truck specs. Thanks!!

[Lee]

i dont remember if my old 3rd gen did this, but it had a v6. my 00 camry with a 4cyl does this in order to warm the engine up... not sure if its a general 4cyl trait or not. sorry i cant be of more specific help.

[Nuthuts96]

Do you let the engine idle (well, 1200-1500rpm) right when you start up for a little bit? When it was cold here in WA a month ago, I found myself going out to the truck and starting it 10mins before I left to warm up the interior, but also to give the engine a chance to warm up before I put any load on it.

I know the manual says something about letting it warm up (but I think it's only for a few seconds).

When it was cold and the engine was REALLY cold, I noticed by warming it up like this, nothing out of the ordinary was occurring. Like Lee said, it's probably just the ECU putting alternating load on the engine until it warms up enough..

[Lee]

i usually try to sit for about 3 minutes after turning it on, but i admit when i am late, i turn it on, wait about 30 seconds and go, shifting into N at the red lights i hit.

usually by the 3rd red light the engine is fully up to temperature, i dont ever push the engine in any way until it is.

i love this camry :)

[Skrillah]

Hmmm...well alright interesting idea. Last winter I lived in a location that didn't require me to get it up to speed quite as quick so I may not have noticed it like I do where I'm at now...

[Skrillah]

Any other suggestions...its still there and almost seems worse....

[4runnerchevy]

Is there a fifth injector on the 2.7, I am reffering to the cold start injector ? Also maybe a faulty time switch. Of course I am also grabbing at straws. Is there any smoke at cold temps ?

[Skrillah]

Is there a fifth injector on the 2.7, I am reffering to the cold start injector ? Also maybe a faulty time switch. Of course I am also grabbing at straws. Is there any smoke at cold temps ?


Good question, I don't believe I have a cold start...but could be the fuel regulator which is inline with the injectors...hmmmm.

Not sure about the switch...and no smoke. It doesn't leak or drink a drop of anything either.

[Skrillah]

Could fuel injectors or o2 sensor do this? On start up, sometimes, it kind of stumbles for a quick second before it hits a high enough RPM and smooths itself out and is fine the rest of the way...

[MTL_4runner]

Could fuel injectors or o2 sensor do this? On start up, sometimes, it kind of stumbles for a quick second before it hits a high enough RPM and smooths itself out and is fine the rest of the way...


That sounds a bit suspicious, worth checking out anyway.

My suggestion would be to take the vehicle for a ride with an OBD scanner setup so you can view all the sensors and engine inputs/outputs, etc and it could point to your issue for acceleration. It will often let you save the data and then you can post it here so we can all have a look to see if we spot something out of the ordinary. It won't pick up mechanical issues so you might have a leakdown and compression test done as well as checking fuel pressure at the rail on top of that just in case.

[corax]

O2 sensors don't even start reporting data until the engine is half way warm, they have to get to ~600*F to work. Maybe what you're feeling is the fuel trim being adjusted when the O2 sensors come on line? Probably not very likely though.

[MNyota]

Sorry to dig up an old thread, but I thought it would be better than starting a new one.

Did anyone find a fix for this surging issue? I'm having the same problem with my 3rd Gen. 2000 4-Runner. It's not a big deal, just an annoyance.

[MNyota]

I've heard that this is a common issue with 3rd Gen Toyotas. Doesn't anyone have any ideas?

[mastacox]

If I were trying to fix this issue, I would:


New Throttle Position Sensor
New plugs and possibly wires
Seafoam
Reset ECU
Clean MAF
Change Air Filter
Possibly change fuel filter

[TheDurk]

I like the suggestion of the OBD scan run. Specifically, you need to know if this is occurring during open-loop (start-up mode) operation where exhaust sensors are basically ignored, or right after the switch over to closed loop, when the exhaust sensor is used to adjust timing and trim. A look at your short-term and long-term trim numbers might also tell you something about what is going on as you see things settle down.

EDIT: Hey, I didn't realize I never posted here before. I've been lurking for a while. I guess I'll do a sig.