spark plug changing

i just had a tune up done on my 99 windstar which ran pretty good before the tune up no knocking or anything. the wierd thing is that when the spark plugs were changed i was told that the gap was suppose to be .54 by autozone and pepboys. when the old plugs were taken out they were really worn out and the gap was .74 my friend said that he did not remember seeing anything like that before i bought bosch platinum plugs i wanted double but they did not have them. my friend put them in and at the end thoght about if they were pregaped. i called autozone and was told they were not and that the double platinum was. since it was dark by now he left it til the next day. for the whole day the car would start to cut off when i was sitting at a light for longer than 30 seconds and when the rpm was just under the 1. he changed the plugs to the right gap and it still did the same thing then i told him to gap it at what the old ones was .74 and it still did the same thing after checking he realized that when he was changing the plugs in the back he knocked 2 air hoses out and thats what was causing the problem. MY QUESTION IS WHAT EFFECT DOES HAVING THE .74 GAP IN THE PLUGS HAVE ON MY VEHICLE SEEING AS THOUGH IT WAS LIKE THAT BEFORE I BOUGHT IT AND IT RAN PERFECT AND THE NEW PLUGS ARE STILL AT .74 MY FRIEND TOLD ME THAT HE WAS TOLD BY A MECHANIC FRIEND THAT HE SEEN IT DONE BY SOMEONE TO SAVE ON GAS AND THAT THE PREVIOUS OWNER OF MY WINDSTAR PROBABLY HAD THE SAME IDEA.

My Van Had The Same Gap. When I Changed The Plugs I Gaped Them To Specs In Manual. Fuel Got Worse, But It Did Improve The Problems I Had With Highway Driving Shutter. Also Bucking When Driving Up Steep Hills.

The large gap was no doubt due to years of wear. Changed mine out at 150,000 Kms and the gap was huge. Replaced them with double platinums (factory specs.) and no issues. I would double check for factory gap and also check out your wires. Perhaps in changing the plugs a wire was damaged.

IIRC the Bosch line of plugs are not suitable for our engines, that could be the cause of your troubles...! Best match for Windstar engines are original Motocraft Double Platinum or Autolite Double Platinum plugs. Check the forum for more info on this issue, hope it helps.

My '96 3.8L was running just fine with that large gap.......I found that the rear was slightly greater gap than the front.
I would change those bosch out for some Motorcraft or Autolite double plat's.......an they do carry them at Autozone and Advance Auto Parts.
They must have been sold out of your plug.
Not to say that the Bosch is a bad product.....but from what I have seen......not applicable to the Windstar application.

changed my plugs last week at 105,000 miles. Original plugs gaps were larger than spec. I bought the Autolite double platinum as suggested here and gapped them to the spec out of my owners manual.

Your problem is puzzling. The rear plugs are very hard to get to but I don't remember any danger of knocking a vac hose off, or anything like that, but that is where I would start looking. The front three are no brainers, so do a detailed visual inspection first. Did he do anything but a plug change....also check the spark plug wires....obvisously.

I've posted this before but getting the rear plugs out is easy if you raise the front end and get the plugs from underneath.

A wider gap tends to create a hotter spark and delays engine timing slightly. The wider gap requires more coil voltage, causing them to run slightly hotter.

One reason platinium is used is to reduce errosion of the plug electrodes. I've read DIS equipped vehicles see more wear on the center electrode of one plug and more wear on the ground electrode of the other plug of two connected to the same coil. This is a result of firing polarity. Therefore using a double platinum plug for where the ground electrode sees more wear is recommended.

http://www.mightyautoparts.com/pdf/articles/tt105.pdf

Also, using a larger gap increases the amount of wear, since the higher spark voltages accelerate the process. The wider gap will also cause an increase in the amout of cylinder misfires. Reducing misfiresis one of the primary reasons OEM use platinum plugs, in order to meet Federal Emissions Guidelines.

I've posted this before but getting the rear plugs out is easy if you raise the front end and get the plugs from underneath.

That is how I do it, jack it up and change them from the bottom. I wouldn't say its easy but its doable.

It's much easier than removing the cowling (which is easy anyways). Even with the cowling off I still didn't have enough room to get the plugs from the top. Having a heavy duty truck jack at work is a plus!

I've posted this before but getting the rear plugs out is easy if you raise the front end and get the plugs from underneath.
I raised up my 2001 Windstar and I can barely see the plugs from underneath. I don't see a hole to get my hand up there to change them. Am I missing something, if it is easier from underneath?

I raised up my 2001 Windstar and I can barely see the plugs from underneath. I don't see a hole to get my hand up there to change them. Am I missing something, if it is easier from underneath?


When jacked up look right above where the intermediate shaft connects to the rack and you will see the coil.

Found it, thanks. Had to use one spot right behind the transmission pan and another one a little further back depending on which plug I was after. It sure would have been easier if my arms were a little skinner. I could just barely get to the plugs. It's all good now though.

Bigger gap changes your Plug Firing timing by a hair or two.

Retarding it. It may have lower performance by a hp or two. If you have Any Carbon sitting in the Cly or Valves with a Large GAP on the plugs, You may hear more Pinging. Red HOT carbon firing the Fuel mix, before the Plug even Jumps the gap causing PING.

You should REset your PCM after your New Plugs To relearn you PCM. Pull Battery cable for a few mins, Reconnect, and start engine until hot in park at idle. Then Cycle thru every gear then back to park. Then Go Drive.
It takes 100 miles to relearn including Trans shifting.
Since your plugs were in there a long time, The PCM is use to them and how they fire. Changing them changes your Fuel burn "Better burn" and the pcm is like WTF. I had this burn thing perfect and now Its searching for that perfect mix again. It will figure it out on its own but 100miles worth of maybe a searching PCM.