Bad idling after spark plugs change ?

[sebvegas]

Hi everyone,
so here is my problem : last week I went to the garage to change the spark plugs and since then, the idling is not correct and goes up and down. When I drive the car, it runs good and when I stop to a light or a stop, it goes all the way down and time to time stalls.
I went back to the garage and they told me I need a new custom tune.
I have a SCT tuner with custom tunes from Doug (CL performance).

What do you guys think about that ?

thanks to help me out.

 

[stkjock]

Sounds like the ahop is FOS

Did u go over all the electrical connections? Clean the MAF recently?

Miles in car?

 

[Chilliwack 42]

You shouldn't need a tune for spark plugs. What we're they gapped to? Did the garage disconnect the battery when they did it? The computer might be re-learning the idle.

 

[kylecm85]

You need a new shop. Changing plugs would not be recourse for a new tune. What plugs did you go with?

 

[itsslow]

Load the tune again? Did you try putting your old spark plugs back in to see if it still did it? Why did you need a shop to put in your spark plugs? Just curious.

 

[skwerl]

I'd check gap, also double check all the coils are fully seated and the power leads are fully connected. Also look around for any disconnected vacuum lines.

As far as the idle relearn, that takes about 3-4 minutes.

 

[fdjizm]

New custom tune for plugs? don't go to that shop again.

 

[itsslow]

New custom tune for plugs? don't go to that shop again.

Maybe they were a step colder or something like that? Wouldn't they need a tune?

 

[stkjock]

Maybe they were a step colder or something like that? Wouldn't they need a tune?

 

[retfr8flyr]

It sounds like a vacuum leak to me but I would also check all the plug connectors. You really need to find a new shop if they are telling you that you need a new tune with a spark plug change.


Earl

 

[Chilliwack 42]

If the shop is claiming you need a new tune I'm willing to bet they didn't even check the gap. I also wouldn't be shocked if the coil on plug connectors aren't seated. Check the vacuum lines like the others suggested.

 

[kojack]

Our cars like to have the spark plugs torqued check box for proper tq, and use the proper spark plug socket(deep).Cracked two with wrong socket first time I did it.Ford has a TSB on this procedure, check this site for it. Good Luck

 

[sebvegas]

Thanks a lot guys for your answers.
Yeah actually, I thought about not going over this garage anymore but they seemed mustang specialists, that's why I went over there ...
I didn't changed the plugs myself because first I am not a mechanic and second of all, I live in an apartment and the car sits outside, no garage, and the residence I live forbids any mechanic maintenance of this kind where the car is parked.
Anyway, tomorrow I will check all the connections and the vacuum hoses. Do you guys have a photo of the parts I should look up for ?
thanks again for the advices

 

[AbdullaGT500]

Maybe they were a step colder or something like that? Wouldn't they need a tune?

Some people should stay out of the Tech section...

Put your stock plugs back in, if you still have them, and see if that fixes your problem. It is definitely possible that you received a bad plug, though I would think you would have a misfire under load. What plugs did you put in it?

 

[sebvegas]

I don't have the stock ones because the garage threw them away.
They installed double platinum plugs I believe. I can give you the ref of the new spark plugs if needed.

 

[Fastbreak]

Maybe they were a step colder or something like that? Wouldn't they need a tune?

 

[sebvegas]

OK so I checked everything, one hose was kind of loose, I fixed it. Installed back the 91 octane custom tune, runs way better but still the idling goes all the way down to 500 rpms after a stop and then go back to around 800. And I still get this noise, a ppff ppff just like something is not firing up properly the engine.
I took off the air filter to clean it and I will re install it tomorrow morning, meanwhile, if you have any idea ?
By the way, where is the MAF sensor and how to clean it ?
thanks a lot guys

 

[sebvegas]

OK so the problem seems to come from the spark plugs themselves and not a vacuum leak. On the invoice, the ref of those plugs is PZH 1F at $19.16 each.
Do you guys have any idea if those are the right spark plugs for my cars ?
As well, my gas mileage went from almost 19 mpg all the way down to 13 ...

 

[Greg Hazlett]

What year is your car?

 

[stkjock]

That plug seems to be for the 5.4 3v motor. IDK if they are equivalent.