Originally Posted by IntlHarvistar
Hi. I have a 96 t444e. It is the 4th 7.3L engine I have owned and am familiar. I am leaking oil slowly at front of valley. I recently lost power, got worse then died once oil / engine is warm. Re started limped home. I have had warn engine light on since I bought it. MAP sensor out of range. I replaced map and cleaned tube, still have same Warn Engine code after clearing it.
1. any ideas on map?
2. do you think i should replace hpop first? 271k miles on her.
FIRST RULE OF TROUBLESHOOTING:
DO NOT throw parts at problems.
If the MAP sensor is out of range the fuel mixture cannot be properly maintained. This alone can cause all manner of running issues including loss of power, engine stoppage, failure to start, and more.
Determine the cause of the MAP code (test and inspect the sensor and the wiring to it) and correct THAT problem first.
As for the HPOP,..... AFTER you resolve the MAP code, if yo still have issues, TEST the HPOP and inspect it. If it fails, THEN you would replace it.
Parts failures have two main times that they fail.... when they are very old (as in beyond design lifespan) and when brand new. Throwing new parts at a problem without having diagnosed that part as having failed introduces additional potential points of failure into the equation. Just troubleshooting, by disconnecting and connecting plugs and other connections introduces potential failure points. In the end, you may well find that the initial problem was solved by one of the parts thrown at an issue but that you had introduced some other failure point before throwing that part at it.... such as a bad out of the box component that you threw first.
If you're troubleshooting a failure and, after throwing the latest part at the problem and the failure mode remains but symptoms have changed..... there's a good chance that one of the earlier parts introduced a failure mechanism (the part, it's wiring, or something displaced or damaged while replacing that part).
ALL THAT SAID..... there are failures and symptoms that an experienced mechanic will throw a part at because over the years it's the most common cause. For instance, a code indicating "gross evap system leak" will have the experienced mechanic IMMEDIATELY go to the fuel cap and check that it's on and also that it operates properly (the venting system). I don't know how many gross evap leaks I've repaired by putting the gas cap on or by replacing a bad one but it's A LOT.