Code reader in the mail.

Problem was so random and seldom occurring that at first I suspected something in the fuel. I changed the fuel filter, no change in problem.

Engine runs and idles smoothly, then randomly (originally) every few days, changing to (now) randomly at stops when idling, or even very low coasting speed in drive, fuel seems to be cut.

Whatever the over-rides for warming the engine, they keep rpm's around 1000. Now and then I hear a relay click and rpm's rise a little. That's probably normal. This other thing happens, and rpm's drop to nil, but with no associated relay click or hiss or clunk or whatever.

Once the engine is warm, idle is normally smooth at 650, but when the phantom strikes, 800 is not even safe, I have to press the gas pedal to get past the dead zone.

Actually now the problem does have a second mode. First mode, rpm's drop to none, mode two, rpm's start rising and falling but as long as the bottom is 600 rpm that can continue for 30 seconds before the die.

Any checks come to mind, while code reader is on the way? I know I could borrow a code reader at an autoparts store, but that would spoil "Christmas".

 

Are you getting any warnings, OBD II codes?

 

Yes, the check light is on. I won't have a code reader until the week of April 8-12 sometime.

i have seen warnings for Both Tail Lights Out, one light out, which go away if I turn on/off lights. Odd false warnings can signal moisture in connectors and throttle body connectors and throttle position sensor connectors, some favs I have been reading about here. The solution is to clear moisture by spraying WD40 on connections. I should try that on some of the typical areas tomorrow.

 

Chances are it's a (vacuum) hose leak. Commonly the elbow under the manifold. Lots of threads. If a perished hose only sometimes opens then you get a sudden leak and engine cuts out. Such sudden smallish leaks only matter at low engine load like idle as otherwise the extra air just disturbs the AFR (not good) without being so overwhelming that engine dies.

When OBD tool arrives, look at LTFTs (see below) at idle and again at 2500rpm. If there's a leak quite often you'll see lean trim especially lean at idle. If it all happens suddenly then it helps if you can record data and when it has cut out replay it and look at what the readings show. But... may hardly show if it's sudden. Any codes are likely to be related to lean or misfires.

 

+2, plus: did you happen to screw around the area where the electrical plugs attach to the injectors? A member (4.2 L) recently realized an electrical plug wasn't properly attached to the injector, cutting off the engine.

 

If the car is drivable take it to your local auto parts place (Autozone, Advance Auto) and get them to read the codes and then post the codes.

 

+3 on vacuum leak, +1 on possible loose injector connector - or 1 or more intermitient failing coils (at idle) - these are the most propable causes - once you can get us some codes - we can steer you in the right direction...

 

All good.

No obvious vac hiss or visual vac problems. I couldn't figure where to put the paper towel for o-ring test, and the other vac hoses are under the manifold cover. If I take that off, I should have gaskets for that and all the parts including hoses and o-rings. First, codes.

I wiggled electrical connectors. Will do full wd40 or noalox de-moisturize later.

Air intake cover was unsnapped. Jiffy Lube had changed the air filter, oil filter, oil, extra detergent oil change atf, power steering fluid, cleaned injectors. They didn't snap the air intake box.

Idle kicks up a little on some signal, from 650 to 800, probably on miss. Run at 2500 for 30 seconds, then idle smooth at 750-800 for a while, sudden die(can't tell if miss there). The only way to defend against the sudden die on the highway in stop-and-go rush hour gridlock is oscillate the gas pedal, going deeper for a major fuel hit to pick up rpm on sudden die.

Codes. I couldn't afford the Ford Rotunda JLR v133, so I settled for OdbPro and TOAD(odb2 elm327). I will be reporting in one of the code scanner threads on how they work. They are supposed to have CAN and P codes.

I'll work a little more on damp elec connectors now. Sunny day above 60F.

My mother is dead, but I do want to preserve my odb2 virginity until the mail comes for another reason. I can tell the TOAD guys that the odbpros have their software working in linux, so fix the TOAD software for linux before the mail comes. That's my pre-nuptial agreement. (...odbpros software also works on TOAD's elm327, for extra embarrassment factor!)

 

Sorry- don't follow what you're trying to tell us.

 

Normally no hiss.

Seem to be overthinking and very much overhyping/overeacting.

 

You have an extremely common set of problems which are very well documented in the FAQ.

The V-6 has a list of issues but they are all minor and can be fixed DIY. Read the the FAQ's, do the work and then report back what your car is doing. Don't skimp do it all at the same time.

All V-6's at some point will need that maintenance done.
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When I wiggled vacuum hoses, I found a hissing one at red arrow below--

...JagV8 and abonano said vac leak most likely.

Temporarily I ziptied the hose to apply pressure to close the pucker of the hole. I couldn't see the hole with engine warm but I'll drive to dealer parking lot, make sure I can get the part, then when I have replacement in hand, do something that might ruin the existing hose. It may break off if I pull on it. Call it done. Thanks so much.

 

Those exact two rubber pieces just failed on my S-type. In the process of trying to find part numbers now. Sorry to necro-bump this thread but any chance you still know the part numbers?