RJoyce99
New Member
- Joined
- July 17, 2003
- Messages
- 5
- Reaction score
- 0
- City, State
- Harrisburg, PA
- Year, Model & Trim Level
- 99 XLT
Since this is an ongoing problem with the explorers, I am going to add my long search and eventual fix for this problem. My explorer is a 99 SOHC with 111,000 miles. I bought it three years ago with 77,000 miles on it and within 3 monthes had to get the intake manifold gaskets/ chain tensioner fix which Ford did for free. I still had the engine knock on acceleration so I tightened the upper intake manifold, used Seafoam, premium gas, & cleaned the MAF. Over the past three years I have used those fixes to try and keep the engine knock somewhat under control. About a month ago it started to get so bad that it was tripping the CEL for codes P0171 and P0174, running lean on banks 1 & 2. So it had to be a vacuum leak or not enough gas (or so I thought). I had my mechanic replace the fuel filter and check the fuel pressure which was 20 lb Hg before the fuel filter was replaced and 25 lb Hg after, which still too low so I had him replace the fuel pump and screen. It was still tripping the CEL so I decided it was time to buy a scanner so that I could determine what was going on before it got really expensive. I bought the Actron Super Autoscanner CP9145 from Pep Boys ($180 after rebate). It pulls and clears codes and shows about 16 live data feeds. The ones that interested me were the Long Term Fuel Trims on both banks which were going to the maximum of 25% within a minute after the cpu was cleared, also the MAF was showing 0.44 lbM/min, which is low at idle (warm). Note that I had cleaned the MAF about 5 times over the last 3 years. I pulled the plug off of the MAF and then watched the live LT Fuel Trim levels which went back down to 0%. I ordered a rebuilt MAF, put it in and now the LT fuel trims are 0% and no more engine knock (the MAF now reads 0.68 lbM/min at idle - warm). Sometimes you need the right equipment to figure out certain engine problems. I hope that this helps someone on the board since this board has been a great help to me (I also have a 96 X w/120,000 miles).
