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driveabilITY and PDWERTRAIN - RELATED ISSUES
| 题名： | driveabilITY and PDWERTRAIN - RELATED ISSUES |
| 正文语种： | eng |
| 作者： | 'G' TRUGLIA |
| 摘要： | Below are four case studies that were a challenge to us...but challenges help us grow stronger and become more knowledgeable. We had the right tools, supportive information, and technical support on hand. But it was the great attitudes of the technicians that made it all work out in the end.Our first vehicle had 90,960 on the odometer. It came in with an illuminated MIL and two DTCs: 1. P0171 (System Too Lean, Bank 1)2.P0174 (System Too Lean, Bank 2)We interviewed the vehicle owner to make sure we knew what his concern was and followed that with a good visual inspection. The inspection uncovered an aftermarket intake air tube and air filter. These both can be suspect when dealing with a lean mixture.After reviewing scan data PIDs on the ATS eScanELITE, we reviewed the freeze frame data. It showed:1. Bank 1LTFT17 percent 2. Bank 216 percent (recorded at idle)3. MAF=5.5 gps (grams per second)The MAF value seemed to be in the correct range for this 4.6L engine. However, knowing it's a Ford, I thought that we had better check the MAF sensor by obtaining volumetric efficiency readings (Figure 1). That was a good call, as you can see by the test data.Moving on, we ran the STFT and LTFT test that confirmed that the MAF numbers were a low of+22 percent and a high of+54 percent on the fuel trim chart (Figure 2). That test confirmed we had a problem with the MAF system. You may be wondering how this test can be performed if the shop you're working in does not own an EScan. Not a problem; you must work a bit harder and use any scan tool (in generic scan mode) that will allow the user to confirm this issue. Start by checking DTCs followed by looking at freeze frame PIDs. Most of the time, viewing the high fuel trim reading on a generic scan tool (other than eScan) will not provide you with a defined failure of the MAF. |
| 出版年： | 2022 |
| 期刊名称： | Motor age |
| 卷： | 141 |
| 期： | 9 |
| 页码： | 52-54,56,58 |
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