How is the timing and engine air flow adjusted?

25

Asked by Aug 31, 2007 at 07:44 PM about the 1999 Toyota 4Runner

Question type: Maintenance & Repair

The performance of my Toyota changed after the 90,000 mile service. I noticed initially that the engine had to turn over more to start and that the rpms were reduced.  On the highway and in town, my milage was also reduced.  The vehicle did not seem to have the zip anymore either.
I questioned the dealership repeated when coming back for oil changes but they always claimed only to have replaced the spark plugs. I had the vehicle checked out at another dealership and everything was in specifications.
Last October I drove to western Colorado and could not drive more than 50 mph in the mountains.  I had purchased the vehicle in Idaho and never had any power problems driving at high elevations before.  Upon returning to the midwest, I had the dealership check the vehicle again with the same results.  
I want to know what could have been done to change the timing (rpms) or the airflow to decrease the performance and still have the vehicle appear to be in specs.  
No one has been able to correct the problem and the dealerships have not asked Toyota customer support for assistance in fixing it.  What`s to be done?

1 Answer

42,115

Sounds like a possible malfunctioning sensor in the engine or transmission. The timing and air flow are controlled by the PCM on this vehicle, there is no external adjustment for timing. If a sensor is giving faulty readings to the PCM, driveability would be affected.

Your Answer

Add photo

Related Questions

Search Toyota 4Runner Questions

Toyota 4Runner Experts

#1 Kurt Burton
Kurt Burton
Reputation 1,150
#2 azurro
azurro
Reputation 650
#3 kbro
kbro
Reputation 610
View All

Related Models For Sale

Used Toyota Tacoma
525 Great Deals out of 37,789 listings starting at $2,900
Used Jeep Grand Cherokee
800 Great Deals out of 70,054 listings starting at $995
Used Toyota Tundra
506 Great Deals out of 32,271 listings starting at $2,995
Used Chevrolet Tahoe
616 Great Deals out of 27,687 listings starting at $600
Used Toyota RAV4
572 Great Deals out of 66,107 listings starting at $999
Used Toyota Land Cruiser
19 Great Deals out of 1,169 listings starting at $3,995
Used Ford Explorer
725 Great Deals out of 74,779 listings starting at $750
Used Nissan Pathfinder
312 Great Deals out of 23,005 listings starting at $2,250
Used Ford F-150
2,439 Great Deals out of 210,728 listings starting at $895
Used Jeep Wrangler
282 Great Deals out of 19,084 listings starting at $3,295
Used Toyota Camry
846 Great Deals out of 91,596 listings starting at $1,300

Used Cars For Sale

2017 Toyota 4Runner For Sale
6,943 listings starting at $32,927
2016 Toyota 4Runner For Sale
47 Great Deals out of 5,261 listings starting at $27,567
2015 Toyota 4Runner For Sale
39 Great Deals out of 1,426 listings starting at $22,995
2014 Toyota 4Runner For Sale
35 Great Deals out of 1,057 listings starting at $19,300
2013 Toyota 4Runner For Sale
31 Great Deals out of 802 listings starting at $18,995