Toyota 3.4 loss of power after timing belt


Registered User
I changed a timing belt on a friends 2002 Tacoma 3.4 with 230,000 miles. Round 1: the truck had a real hard time starting and when it did start it ran poorly.
Round 2: I tore Iit back down thinking I must have installed the belt a tooth off. Miraculously the marks on the belt lined up again and all looked good. I pulled the belt and made sure it was the same as the old one. All was good. My best guess was the cam sensor may be going bad so I replaced it. Now it starts right up but still very sluggish.
Round 3: Replaced the spark plugs and no change.
Any suggestions as where to go next? I saw a video suggesting the crank cog could be worn and miss aligned. Any suggestions will be welcomed. BYW no check engine light.



Davis County
Did you remove the cam or crank gears to replace the seals?

Long shot but the crank reluctor ring could have chipped a tooth or maybe the woodruff key got mashed allowing the crank to be just slightly out of time.

How long have you run it? Long enough to post a code if it was going to?


Registered User
I didn’t remove the crank or cam cogs. I marked the old belt before I remembered it and have the same number of teeth between the marks. A new crank cog may not be to expensive of a try. Just the fun of tearing it down again.


Premium Member
Supporting Member
I just finished the timing set and fired up a '99 3.0 Camry, I was paranoid about it after reading this!

Think I'm good though.

Wish I had any ideas for you but if all the marks are lined up, I dunno...



Registered User
So my neighbor has been driving it for a few days. Still no codes. We are going to replace the spark plug wires and the crank position sensor. I hate the shotgun approach. We did find a crack in the air intake hose that runs from the mass airflow sensor to the throttle body. He ordered one of those. We taped it up for the time being. Didn’t make any difference. I sprayed starting fluid around it and it doesn’t seem to be leaking.