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1997 Mercury Grand Marquis 4.6L 123k miles


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lkmaryfla
Novice

Jul 19, 2019, 9:02 PM

Post #1 of 13 (232 views)
1997 Mercury Grand Marquis 4.6L 123k miles Sign In

A couple of weeks ago a check engine light came on and when i checked it was P0430 Catalyst low efficiency. I took it to my brother that works as a service advisor for ford lincoln mercury. They said it needed a catalytic converter and O2 sensors, so they did the job and all was good for about a week and now the code is back. I cant tell anything is wrong if it wasnt for the check engine light. Any ideas what it could be? Thanks


Tom Greenleaf
Ultimate Carjunky / Moderator
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Jul 19, 2019, 10:21 PM

Post #2 of 13 (224 views)
Re: 1997 Mercury Grand Marquis 4.6L 123k miles Sign In

Hmmm? Code came right back with that - not surprised just a miss on diagnosis.
Runs fine and just this light back on? Try this outside the box for this car:
Feel exhaust for a putt at idle just a random skip and maybe some odor?
Now open hood and carefully listen for a tick at those long spark plug extended hard plastic boots down to the plugs. It's been a while those dang things would short out to inside unseen.
Try to locate which one it will be just one usually.
Let it cool down and pull the likely one out you may see a tiny spot where there's carbon tracing. Check another that there's not for comparison.
Careful handling those they bust just handling them. If you cancel the bad one bet engine doesn't run all that poorly - don't ask me why it doesn't run like total crap.
If so may not show on equipment well. Look for just one good wire hopefully just lay over new one coil to that one and secure out of the way. Go for a good ride the light will go out and it will run fine decide on new wire set or just the one can be had at the right outlets.


That was so freaking common once (to me - customers) I carried the longest one with me in another type of car early on whole wire sets were costly compared to others save a good wire thing.
Don't ask - these seemed to suffer low use, low mile, short trip complex for lack of anything more technical????
Do see if any are oil wet means do the valve cover gaskets (no fun) and do it up they were pretty good all around for a basic now huge car that wasn't a pig and had enough power with this engine.


Good luck - that fooled a lot of high end techno checking was a dumb plug wire the root cause,


Tom



Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jul 20, 2019, 3:59 AM

Post #3 of 13 (217 views)
Re: 1997 Mercury Grand Marquis 4.6L 123k miles Sign In

What you are going to find is a small exhaust leak somewhere forward of the Converter. That is about the only thing that can fool the computer into setting that code falsely.

Also make sure they changed the correct converter. That code would be for bank 2 which is the driver's side on a Ford.

The only way that code sets is the rear 0/2 has to mirror the front 0/2 in readings. This can happen if air is being introduced in front of the sensor, basically fooling them.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Tom Greenleaf
Ultimate Carjunky / Moderator
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Jul 20, 2019, 6:30 AM

Post #4 of 13 (210 views)
Re: 1997 Mercury Grand Marquis 4.6L 123k miles Sign In

OK from me: Said up top the suggested work was done? If not all bets off or if a problem with hacking in a converter or IDK what they did, T


lkmaryfla
Novice

Jul 20, 2019, 6:14 PM

Post #5 of 13 (191 views)
Re: 1997 Mercury Grand Marquis 4.6L 123k miles Sign In

The wire and plugs have are about 2 months old and are factory motor-craft. Done at a Lincoln/Mercury dealer that my brother works at. So was the Cat and it is a factory Cat. Ive looked as at the exhaust and cant visually see a leak. How could I check? I really do appreciate yalls knowledge and willingness to help. Thank you


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jul 20, 2019, 6:25 PM

Post #6 of 13 (187 views)
Re: 1997 Mercury Grand Marquis 4.6L 123k miles Sign In

Those leaks can be tricky to find. The best wast is using a smoke machine. I've seen it happen with just a fine crack in the pipe.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Tom Greenleaf
Ultimate Carjunky / Moderator
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Jul 21, 2019, 2:32 AM

Post #7 of 13 (168 views)
Re: 1997 Mercury Grand Marquis 4.6L 123k miles Sign In

? What prompted you do replace wires, plugs or anything that 2 months ago? Seems there's the clue it didn't go so well or parts not so great. Don't be fooled by the box or markings either anymore. If "Motorcraft" the wires have a date marked on them what is it? If not they're probably clones.
Just back to these plugs and wires alone. Plugs are deep down with a long hard plastic boot end that also must seal. Dropped plugs, crossed threads and that hard plastic is so easy to break before you install it even.
Was the code there first or this work? It couldn't be wildly bad or would come right back had CEL stay off was just reset took some time. I don't trust that reading as far as I can throw it - yet. A clue of something unseen as of yet.
It's not in front of me/us I think if a quiet spot you'd hear the flaw and or look at what was touched to do the work/things mentioned - what wires got pulled or disconnected to do that by now they'd bust be sending all wrong signals they really want to be in place right where they were as does most anything.
A brother in the mix - still absent of mal-intent it's just fussy now dealing with an older car near always sold new to the die-hard standard layout car that wasn't a municipal car as many Crown Vics were,


T



lkmaryfla
Novice

Jul 26, 2019, 6:29 PM

Post #8 of 13 (153 views)
Re: 1997 Mercury Grand Marquis 4.6L 123k miles Sign In

The wires and plugs were replaced because they were at 41k without being changed and i was going on a 1600 miles trip and wanted to before the trip. I also changed the belt, tensioner, coolant, and front brake pads just to feel safe. Everything was done at a lincoln/mercury dealer. My brother is a service advisor there so i watched the tech do everything. They were factory motorcraft wires, he used dielectric grease, and checked gaps on plugs. I can only take in and get free labor 3 times a year. Ive used 2 so far so i dont want to waste a time. Whats odd is it runs amazing, its peppy, it doesnt hesitate like it was. I have noticed a gas smell pretty strong recently and have looked around and noticed the second injector on the drivers side was wet around the base and all other werent. When I take it in they dont really do much diagnosing, and seem kinda rushed so maybe theyre overseeing something. Could a leaky or faulty injector cause it? Thanks for your time and knowledge


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Jul 27, 2019, 1:38 AM

Post #9 of 13 (136 views)
Re: 1997 Mercury Grand Marquis 4.6L 123k miles Sign In

(Hope you can read - I just wrote a lot, sorry for typos - not all my fault this site changes some words??)
OK? I think? Free isn't a bargain many times you seem focused on that and is interesting.
Quote ">When I take it in they dont really do much diagnosing, and seem kinda rushed so maybe theyre overseeing something.<"
So is that to say just do anything you say and don't diagnose anything? It's seeming like that. Wires at just 41k doesn't mean they are bad tossing stuff like mentioned is opening the book to tossing good for lousy new stuff go easy on what boxes are marked with "Motorcraft" the parts should be also bet they are NOT! Wires from "Motorcraft" should be dated and marked - these cross over the top thru plastic help combs that bust easily ages ago for these go read one without touching a thing. Not real Ford parts are they? It's too old*
Now you say you smell odor of fuel and an "injector" is wet or a plug was wet? Why was anyone looking at an injector a plug would be wet or oil down there means the plug isn't going to fire properly for long and guess it didn't.
Said these engines have an uncanny way of covering up a total misfire assorted causes and still haver power? That I can't answer as to why.
* Side note on that: I drive these and have two right now about 10 years older than this! Not this engine the one before and have since about 1991. ||Those would be 3 year old cars|| Worked for Ford and later associated with Lincoln-Mercury dealers had first crack at routine trade in cars could find some super cream puff trades or get executive test models of assorted Fords not sold at first to the public still end up at dealers. Sub notes: They don't always want these they aren't listed well for info you actually have to work hard to diagnose when things go wrong if anything kinda spend all your time diagnosing and you have NONE!


On that you smell odor and that's left unchecked. That's the problem and a free tech isn't interested in that. THAT'S NOW THE PROBLEM. There's your code and leaking exhaust a reason you can smell it - so much for FREE work.


Case closed. Now maybe pay someone who can find this and fix it IMO it's not a great idea to quick go put 800 miles{is that each way or 1,600?} on this if failing in this way you wreck that new converter that also high bet is not a Ford product a lot of that isn't when they are new either - other companies contracted to make things the manufacturer doesn't make the wild majority of the parts even then and it's lots worse NOW,


Tom
(trying to edit out typos??)



(This post was edited by Tom Greenleaf on Jul 27, 2019, 1:43 AM)


lkmaryfla
Novice

Jul 28, 2019, 2:46 PM

Post #10 of 13 (113 views)
Re: 1997 Mercury Grand Marquis 4.6L 123k miles Sign In

Ive always changed plugs and wires every 50k on everycar. I had these changed 9k early because of the trip i went on. The cat is an aftermarket closest to factory. The wires and plugs are both geniune mastercraft. I found the leaky injector by looking closely to my motor. Could a leaky/faulty injector ruin a cat? Could it set off a cel p0430? Im kinda tight on money right now so i camt off. To mechanic. Could I buy a single injector and change out the one or do they all need changed at the same time. When i take it to dealer they do scan it with a computer but they dont look closely at the motor. Pretty much they see an error on the computer and fix. As soon as i can afford im gonna take it to a mechanic and have them diagnose everything. Thanks


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jul 28, 2019, 4:29 PM

Post #11 of 13 (107 views)
Re: 1997 Mercury Grand Marquis 4.6L 123k miles Sign In

No, the computer does not do the diagnostic work. It merely recognizes something that is not electrically where it should be. The technician then has to determine the cause.

You are changing ignition parts way too soon also. Times have changed, systems have changed. Ignition voltages are higher so there is far more reserve voltage to make up for a little resistance in the wires. Computer controlled fuel injection causes plugs to burn far cleaner now too.

Those wires should last far in excess of 100K if they are not saturated with oil.

If the injector is leaking fuel into the cylinder, then yes it can ruin the cat. If it is only leaking externally, then it is just a fire hazard.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Jul 29, 2019, 2:39 AM

Post #12 of 13 (92 views)
Re: 1997 Mercury Grand Marquis 4.6L 123k miles Sign In

 
HEY - FYI, POWER WENT OUT FOR OVER 5 HOURS WHERE I AM THIS MAY BE ALL OUT OF ORDER NOW JUST TRYING TO CATCH UP||
Yes, an injector could ruin the cat. Aftermarket or not should want it to work as long as possible could be a long time? Check a leaking injector if it can be cleaned or what? I'm not certain and blame lousy fuel sold in I'm told over 200 different mixes of junk that isn't pure "gasoline" is hell on some things - tanks, lines, filters right on till out the tail-pipe.
Ugg on plugs? When to do them? Many it's important to not allow them to get seized up in heads more of a problem than the plug itself? That's a snag and was for ages how things are handled along the way. I would always look for packing if damaged a plug really shouldn't be dropped if by mistake just looking at one mark that one suspect it first later if trouble.
Diagnostics: That should be the game and do know codes are just clues to lead you to the circuit it notices not what to replace or do about it.
Parts etc.: Hose, wire and more is or was marked for type, date made, ratings. Check for that as some proof? IDK anymore ended up with lots of junk in good name packaging! Uggh!


Good luck with it,


Tom

(This post was edited by Tom Greenleaf on Jul 29, 2019, 3:03 AM)


lkmaryfla
Novice

Aug 8, 2019, 10:40 PM

Post #13 of 13 (38 views)
Re: 1997 Mercury Grand Marquis 4.6L 123k miles Sign In

Ended up taking it to another shop and it ended up being an intake gasket. Car runs great and no cel.






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