Lack of power on acceleration

Tiny
ZIPS
  • MEMBER
  • 2006 TOYOTA SIENNA
  • 3.3L
  • V6
  • 2WD
  • AUTOMATIC
  • 205,000 MILES
Every now and then the vehicle will lack power on acceleration. It seems that when the outside temperature is between sixty five and seventy five degrees Fahrenheit the car runs well (or I should say I have noticed it does not seem to occur ), anything above seventy five and less than sixty five degrees outside it seems more noticeable. I am wondering if I have an issue with my MAF sensor. I have tried the propane gas around all of my vacuum hoses and the intake manifold, and the throttle body, no vacuum leaks detected. The car idles fine, and other than this issue runs with out problems.
Saturday, January 6th, 2018 AT 1:06 AM

7 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,796 POSTS
Good morning.

If you had an issue with the MAF sensor, it would code for irregular readings.

I would check fuel pressure to start to be sure the pump is supplying proper pressure.
I would also look at the timing system. A loose or worn timing belt could also cause this issue.

Roy
Was this
answer
helpful?
Yes
No
+1
Saturday, January 6th, 2018 AT 4:05 AM
Tiny
ZIPS
  • MEMBER
  • 4 POSTS
I had thought about the fuel pump, and also the fuel pressure regulator, the problem for me is the apparent difference in performance based on the ambient temperature and the fact that it is intermittent. Sometimes fine and other times noticeable. I will follow your advice and check the pressures on this vehicle. I need to install a fuel access point to check fuel pressures.

I should add this, it happens when I really want to scoot so if I step on the pedal expecting to just go anywhere between 1800 rpm's and 3500 rpm's this happens. I do not notice it if I just press the accelerator and want to go faster, only during a load situation, uphill or get out in traffic and go.
Was this
answer
helpful?
Yes
No
+1
Saturday, January 6th, 2018 AT 10:28 AM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,796 POSTS
You may have to T into the fuel filter to check the pressure.

Roy
Was this
answer
helpful?
Yes
No
-1
Saturday, January 6th, 2018 AT 10:30 AM
Tiny
ZIPS
  • MEMBER
  • 4 POSTS
I edited my previous post. As this does occur under load conditions, hard acceleration and uphill acceleration. 1800 and 3500 rpm's. Is the normal range where it lacks the oomph?
Was this
answer
helpful?
Yes
No
Saturday, January 6th, 2018 AT 12:08 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,796 POSTS
It sounds like you may have a clogged catalytic converter. You need to have the back pressure tested to verify. You can also drop the head pipe from the exhaust manifold and drive it to see if it is any better.

Roy
Was this
answer
helpful?
Yes
No
+1
Saturday, January 6th, 2018 AT 12:17 PM
Tiny
ZIPS
  • MEMBER
  • 4 POSTS
1: If the catalytic converter is clogged would I not notice the lack of acceleration at all times and not intermittently?
2: Is there a tool to check for exhaust back pressure?
3: I am thinking if I disconnect the exhaust at manifold - the A/F sensors might behave differently for example make the mixture more rich seeing too much O2 and I really would not know for sure?
Was this
answer
helpful?
Yes
No
Sunday, January 7th, 2018 AT 1:29 AM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,796 POSTS
Yes, there is a tool. It is a back pressure tester. You remove the O2 sensor and insert it and run the engine and it measures the back pressure. You would do it on both sides.

If you do not have the tool, dropping the head pipe will let the engine breathe and you can see if the issue stops. Yes, it will set codes for the O2 sensors but you just need to clear them when you have it back together.

Roy
Was this
answer
helpful?
Yes
No
+1
Sunday, January 7th, 2018 AT 2:47 AM

Please login or register to post a reply.

Related Engine Low Power Content

Fix an Engine with Low Power!
VIDEO
Fix an Engine with Low Power!
Instructional repair video
Symptoms of Low Engine Power
GUIDE
Symptoms of Low Engine Power
The power your car's engine is producing is important. When you step on the gas you need your car to accelerate, mainly to keep you out of trouble when getting onto the...
VIEW MORE