fourharts56
New member
This post is to help those that maybe suffering the same symptoms that I have been over the last couple of years and provide an alternative to replacing many components to fix multiple problems.
Over the last year I have noticed that my 2000 4Runner Sport 5spd manual has been declining in performance, such as lower MPG, valve tapping, long hot starts and less power. Over the years I have installed the TRD Headers, TRD Exhaust and an Injen CAI. I assumed this was due to years of use and 175,000 miles. I had no codes other than the occasional P0420 from the changes with Ethanol gas and having to weld on the CAT for the header installation and CAT CLEAN once a year seems to keep it at bay.
Several week ago I started to smell burning oil and discovered upon investigation that my valve cover gaskets had started to leak and drip occasionally on my headers so I prepared for a complete software change out of the valve covers to include the valve cover gaskets, spark plug gaskets, throttle body gaskets, intake gaskets, various vacuum lines, camshaft plugs and half moon inserts. I also cleaned and re-oiled my CAI filter (done this many times over the years).
After putting the truck back together, I started throwing P0171 codes. They would not come in until the second time I drove it for the day, usually on the commute home (25 miles one way). After reviewing several forum suggestions I re-cleaned the MAF sensor but still got P0171 codes. I then assumed that I had messed up a vacuum line as most troubleshooting leads you too. I went over everything, checked all hoses and put zip ties on hoses that don't usually have them just to make sure system was tight. No change.
Before I tore everything apart again, I remembered I had a spare MAF sensor so I cleaned it and replaced the original one that had been in the car since I bought it in 1999 and swapped them.
Bottom line is now a week later there has been no codes, the valve tap is completely gone, starts easier both hot and cold starts, gas mileage is back to where it was when I bought it and it seems to have the power it was borne with. So my life lesson was throw away the CAI, go back to factory intake and replace your MAF when performance degrades and valves start tapping, don't wait until the MAF code comes in to replace. After thinking about this, I assume I was damaging my MAF over the years with the oiled air filter and it makes sense about the fuel economy and tapping since the MAF has a large input into the EFI to control fuel air mixture.
Hope this helps someone!
Over the last year I have noticed that my 2000 4Runner Sport 5spd manual has been declining in performance, such as lower MPG, valve tapping, long hot starts and less power. Over the years I have installed the TRD Headers, TRD Exhaust and an Injen CAI. I assumed this was due to years of use and 175,000 miles. I had no codes other than the occasional P0420 from the changes with Ethanol gas and having to weld on the CAT for the header installation and CAT CLEAN once a year seems to keep it at bay.
Several week ago I started to smell burning oil and discovered upon investigation that my valve cover gaskets had started to leak and drip occasionally on my headers so I prepared for a complete software change out of the valve covers to include the valve cover gaskets, spark plug gaskets, throttle body gaskets, intake gaskets, various vacuum lines, camshaft plugs and half moon inserts. I also cleaned and re-oiled my CAI filter (done this many times over the years).
After putting the truck back together, I started throwing P0171 codes. They would not come in until the second time I drove it for the day, usually on the commute home (25 miles one way). After reviewing several forum suggestions I re-cleaned the MAF sensor but still got P0171 codes. I then assumed that I had messed up a vacuum line as most troubleshooting leads you too. I went over everything, checked all hoses and put zip ties on hoses that don't usually have them just to make sure system was tight. No change.
Before I tore everything apart again, I remembered I had a spare MAF sensor so I cleaned it and replaced the original one that had been in the car since I bought it in 1999 and swapped them.
Bottom line is now a week later there has been no codes, the valve tap is completely gone, starts easier both hot and cold starts, gas mileage is back to where it was when I bought it and it seems to have the power it was borne with. So my life lesson was throw away the CAI, go back to factory intake and replace your MAF when performance degrades and valves start tapping, don't wait until the MAF code comes in to replace. After thinking about this, I assume I was damaging my MAF over the years with the oiled air filter and it makes sense about the fuel economy and tapping since the MAF has a large input into the EFI to control fuel air mixture.
Hope this helps someone!
