Can the MAF-with-built-in-IAT issue on 2000 5.0L MM be clarified please?

[rigbyrigz]

have them also run the codes they have better scan tools and it is free

thanks for reading and advising. my local smalltown Advance (and others)still refusing to give free tests "due to covid" sigh. so im on my own sort of (plus you guys thanks)

 

[CDW6212R]

The Fords all have a schrader valve, it's on the fuel rail, fairly easy to get at. The cost to rent one of those fuel testing kits is likely about the same $30-$40, but you get it back when you return it.

 

[rigbyrigz]

by way of UPDATE -- the enhanced OBD2 scanner & fuel pressure tester not yet engaged, but a newly purchased (Genuine OEM) xf2f-12b579-AA MAF arrived that had the IAT built-in, and seems sturdier material than the earlier one...

...after battery disconnect 30-minute strategies and stuff to fully clear ECU of historical trim data and maybe more, the install was followed by a followed hodgepodge of relearning guidelines involving 10 minute idling, RPM revving intervals, etc. Thereafter seemed to idle smoothly and then took the 2000 Mercury Mountaineer V8 for a test drive:

most of the driving seemed good - normal or better - but of 3 forays into 65-70 mph acceleration pushes, 1 made the check engine light flash... I think 3 times, but didn't stay flashing or lit. Many sources suggest a cylinder misfire is what 3 quick flashes that go away means, and may be related to a half dozen different causes including MAF issues. There's a chance it's just an isolated event that won't repeat and possibly not bear drastic attention.

Of course, need another driving cycle or 2 and perhaps 50 miles distance to see what codes do pop up, although there is some evidence 2-3 driving cycles as ECU / MAF is RE-Learning might make those codes go away if they appear... so I don't think I will do an immediate erase/reset if they appear. Eventually, some OBD2 data or fuel pressure checks may reveal more; will post.

Thanks all.

 

[rigbyrigz]

well someone asked for a ride said ok... shuddering and rough idle, ok lets disconnect the MAF, no change. Can see Sparks. Learned someone (nephew mechanic in jail) that was supposed to change spark plus on this V8 last year only changed 4 (or none... and it's been a long while), and the wires seem suspect. Wire harness looks ok. Also saw 2 hoses, one we think is (pricey) vapor canister purge hose looks sucked-in flat, might have had dry rot? Another hose same, seems similar in appearance but goes to lower intake assembly not the vapor cannister...

and getting cylinder8 check engine code P0308 solid lit up

...not sure if earlier AGGRESSIVE testing blew these apart or what. Plan now is to buy 2 hoses and 8 spark plus and wires (kit?) and replace all that with a willing assistant. and fingers crossed. Guidance welcome. Sigh. Darn these skeeters are hungry. Thanks.

 

[rigbyrigz]

Interesting that the hose that now looks sucked-in / flat in places (only dry rot was noted before) is known for perhaps causing fuel trim issues that show up as P0171 and P0174. Perhaps I have had a leak there all along.

Seems this is one of several unknown or undocumented hoses in the vehicle series. Folks seem hard-pressed to replace it, (as it is important,) with an actual part name or number (several try to ghetto up an ordinary vacuum hose.)

It appears to run from intake manifold to emissions purge valve under the battery. Perhaps this diagram captures it:

Or maybe the hose is long and runs up higher than what I circled (in red.)

Anyone per chance have a (hose) part name (or number) or other helpful tale or hint? Thanks.

 

[C420sailor]

Post some pics of the hoses. That diagram isn’t for an Explorer.

 

[donalds]

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[CDW6212R]

Check out those hoses carefully, they all have vacuum and could be part of the lean codes, a vacuum leak not yet found.