No power when accelerating and tries to shut off after slowing down - Toyota 4Runner Forum

Sir_LR · 01-08-2025, 09:26 AM

My 4Runner has been acting weird lately it’s running ok then I take it out and it has like no power whatsoever when I’m trying to get up to speed it does slowly accelerate but not as much as before and after that stutter in acceleration if I try to slow down to stop the engine rpm drops to below 500 and stalls the engine occasionally. If I restart the engine it drives fine for a while and then does it again. I just got another engine put in it so I’m going to be doing maintenance like plugs what else should I look for. The fuel filter is 2 years old. Could a timing belt on its way out cause this? Any help appreciated

Sir_LR · 01-08-2025, 11:58 AM

I will upload a video later

Twisted Sid · 01-08-2025, 02:06 PM

No codes?
I'd start with vacuum leak testing

spartacus · 01-08-2025, 07:57 PM

Quote:

Originally Posted by Sir_LR

My 4Runner has been acting weird lately it’s running ok then I take it out and it has like no power whatsoever when I’m trying to get up to speed it does slowly accelerate but not as much as before and after that stutter in acceleration if I try to slow down to stop the engine rpm drops to below 500 and stalls the engine occasionally. If I restart the engine it drives fine for a while and then does it again. I just got another engine put in it so I’m going to be doing maintenance like plugs what else should I look for. The fuel filter is 2 years old. Could a timing belt on its way out cause this? Any help appreciated

What year. How many miles on the motor? Any codes? Plugs wires. Clean maf, clean throttle body and timing belt might help.
Edit: A new Pcv valve and tps sensor could help.

Sir_LR · 01-08-2025, 08:56 PM

It’s a 2000 and I cleaned the maf replaced pcv the engine has 220k km on it and currently have timing belt on order and plugs and wires.

Sir_LR · 01-08-2025, 09:02 PM

https://drive.google.com/file/d/19KV...w?usp=drivesdk

Hungryhawk · 01-09-2025, 01:24 AM

An idea to see what result reveals.
I assume you are in drive"D". Does it act same in S4?
Have you turned off VSC and see if any difference?
My 2cents

Ibrad · 01-09-2025, 10:48 AM

A stretched timing belt would not be resolved by restarting. Did this start occurring right after the motor swap? If so it may be a sensor related issue caused by the computer receiving the wrong signsl after calling for sensor input. When input is received it goes wonky then on restart it happens all over again. If it's this scenario codes should be present. More information is needed.

Sir_LR · 01-09-2025, 12:02 PM

Quote:

Originally Posted by Hungryhawk

An idea to see what result reveals.
I assume you are in drive"D". Does it act same in S4?
Have you turned off VSC and see if any difference?
My 2cents

My truck does not have s4 or vsc

Sir_LR · 01-09-2025, 12:04 PM

Quote:

Originally Posted by Ibrad

A stretched timing belt would not be resolved by restarting. Did this start occurring right after the motor swap? If so it may be a sensor related issue caused by the computer receiving the wrong signsl after calling for sensor input. When input is received it goes wonky then on restart it happens all over again. If it's this scenario codes should be present. More information is needed.

It’s been over a year since installing the engine I just don’t know what maintenance history it has. I’m hoping to do some simple maintenance and fix it like plugs wires timing belt and clean the iac. Could this be caused by a fuel pump not sending enough fuel occasionally or is that not possible. Thanks for all the input

Sir_LR · 01-09-2025, 12:05 PM

Quote:

Originally Posted by Sir_LR

It’s been over a year since installing the engine I just don’t know what maintenance history it has. I’m hoping to do some simple maintenance and fix it like plugs wires timing belt and clean the iac. Could this be caused by a fuel pump not sending enough fuel occasionally or is that not possible. Thanks for all the input

There’s no codes showing at all

Ibrad · 01-10-2025, 10:33 AM

A faulty fuel pump could be possible. Could hook a fuel pressure gauge to it and see what it shows. How long after shutting off and starting again do the symptoms come back?

Sir_LR · 01-10-2025, 10:44 AM

Quote:

Originally Posted by Ibrad

A faulty fuel pump could be possible. Could hook a fuel pressure gauge to it and see what it shows. How long after shutting off and starting again do the symptoms come back?

After shutting it off and starting sometimes it wouldn't even come back like it did yesterday but occasionally it does. I got the IAC gasket on order and I'm going to clean that out first and go from there with plugs and timing belt. Ill test fuel pump pressure while I'm at it, will report back with any findings

TheDurk · 01-13-2025, 12:17 PM

The runs fine and then goes wimp is characteristic of a defect that is linked to the switch over from open loop to closed loop operation. In my case, a TB body clean was what it took, but it could br AF, MAF, or anything in that loop. Definitely not fuel pump, timing belt or anything else not in that loop.

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