car running like crap after tune up...WTF?

Kilgore Trout · Apr 11, 2005

You made one of the worst possible plug choices... Please kick the Autozone employee in the nuts for Mustang owners everywhere

Also, if you cleaned your K&N I really suspect that you contaminated the downstream sensors (MAF and IAT). I know you said you cleaned the MAF but could have have failed to seat the plug in it properly upon re-install?

Also, it probably would not hurt to reset your PCM by disconnecting the battery for about 5-10 minutes.

You can also try cleaning the IAC, replacing the PCV, and cleaning out the PCV pipe...

All this stuff is cheap so why not try it?

bigDogs02GT · Apr 11, 2005

Just picked up some 764's and will install them in the morning before leaving for work since the motor will be cold. Already replaced the IAC, MAF is seated good, and dont believe the sensors are contaminated. Is it possible that I have air in the fuel system? When I changed the fuel filter, I disconnected the switch and ran it out of gas to relieve the pressure in the lines. Any ideas?

stangman · Apr 11, 2005

bigDogs02GT said:
Just picked up some 764's and will install them in the morning before leaving for work since the motor will be cold. Already replaced the IAC, MAF is seated good, and dont believe the sensors are contaminated. Is it possible that I have air in the fuel system? When I changed the fuel filter, I disconnected the switch and ran it out of gas to relieve the pressure in the lines. Any ideas?

did you happen to unplug the maf?

Mike97gt · Apr 11, 2005

bigDogs02GT said:
Changed the plugs (Bosch Platinum 4+), fuel filter and cleaned the K/N filter, now the damn thing surges and bucks. It does it mostly if I'm going like 25-30mph and lightly on the gas (have to go that slow on post) and when on the highway and let up it surges and jumps too. Almost like it's starving itself of fuel. What's going on? Anyone got a clue............

it's the plugs... use the stock plugs.. we have a ton of misfire problems due too non stock plugs...

joshheat25 · Apr 11, 2005

Someone made a quote about Autolite plugs saying that the 764 was for performance and the PP764 was if you didn't want to change them for 100,000 miles I bought the PP764's and plan on installing them will this make a big difference?? and also Is there any precautions when taking off everything above the spark Plugs??

green_fow_six · Apr 11, 2005

The Bosch aren't the best choice but they shouldn't be causing your problems, I know a few fellow 4.6 ers that have had the quad plugs in for over 3 years without a problem. How about the plug wires? what shape are they in? That could also cause some problems. I would definitely look more into your airfilter/maf. If you have a drop in filter, try putting a cheapo paper one in to see if it fixes it. I had a similar problem a few years ago when I didn't re-oil the K&N properly. good luck.

Kilgore Trout · Apr 11, 2005

The site www.bullittarchive.com has how to articles on plugs and many other maint items.

You have coil on plug right? If so:

Do not remove fuel rails, gas is smelly and messy
Remove coil
Blow out plug well to completely remove all dirt before removing plug
Remove plug and "read" plug to determine cylinder "health"
Use silicone spray to clean coil on plug rubber boot
Use silicone dielectric compound on all electrical mating surfaces
Use very light coat of anti sieze on plug threads, do not get on plug shoulder
Install new plug and torque plug to spec to avoid REALLY BAD things like plug blowout
Lather, rinse, repeat...

I like to do it one plug at a time, some people like to do it assembly line style... One at a time is probably a little slower...

stangman · Apr 11, 2005

green_fow_six said:
The Bosch aren't the best choice but they shouldn't be causing your problems, I know a few fellow 4.6 ers that have had the quad plugs in for over 3 years without a problem. How about the plug wires? what shape are they in? That could also cause some problems. I would definitely look more into your airfilter/maf. If you have a drop in filter, try putting a cheapo paper one in to see if it fixes it. I had a similar problem a few years ago when I didn't re-oil the K&N properly. good luck.

02gt doesn't have plug wires

Mike97gt · Apr 11, 2005

green_fow_six said:
The Bosch aren't the best choice but they shouldn't be causing your problems, I know a few fellow 4.6 ers that have had the quad plugs in for over 3 years without a problem. How about the plug wires? what shape are they in? That could also cause some problems. I would definitely look more into your airfilter/maf. If you have a drop in filter, try putting a cheapo paper one in to see if it fixes it. I had a similar problem a few years ago when I didn't re-oil the K&N properly. good luck.

i know it dont make much sense but over the years i have had several cars come in with similar problems and just had bosch plugs put in.. i never really looked into it too find out why but a set of motorcrafts solved the problem..

the next time i see somthing like this i will look more into it and see why the plugs cause the problem..

another thing that can cause problems like this also related too the plugs is..

hairline cracks in the plug from overtighting them.. i have seen this a few times and this can cause problems like that..

the other things that was listed by others can cause this too.. a bad maf fuel filter installed backwards..

if you have a friend with a mustang try his maf.. try a set of motorcrafts if that dont work.. and then if thats not it chack the fuel filter... arrow needs too point too the line that goes too the engine.. not from the tank..

green_fow_six · Apr 11, 2005

c2see21 said:
02gt doesn't have plug wires

heh, forgot that his was a 99 up.

bdcardinal · Apr 11, 2005

theres nothing wrong with the double platnium plugs, however you generally see better performance with copper plugs, as compared to the platniums. plus on a car as easy to do plugs on as a 4.6 changing them out once a year is easy.

i know someone will say that its hard, but i dare you to do plugs on a 3.8 taurus or a v6 camry, then we can chat.

UhadMEatGT · Apr 12, 2005

I have always had good luck, smoother with better throttle response, and better in the higher RPM band with +4's. Most people will tell you not to spend money on good plugs, etc.....then waste money on neon lights, or spray painting their interior, etc. Though I must say I have never used them in my Mustang, but have in my past three cars with very good results. I was told that Ford recommends a double platinum plug for the 97 4.6L sohc, and thats what I bought (motorcraft)

Mike97gt · Apr 12, 2005

bdcardinal said:
theres nothing wrong with the double platnium plugs, however you generally see better performance with copper plugs, as compared to the platniums. plus on a car as easy to do plugs on as a 4.6 changing them out once a year is easy.

i know someone will say that its hard, but i dare you to do plugs on a 3.8 taurus or a v6 camry, then we can chat.

worst car ever too do a tune up on was the 93-97 LT-1 F-bodys...

GM enginers---> <---- me

joshheat25 · Apr 12, 2005

So there is no big difference between the regular platnum and double platnum then?

kev1919 · Apr 13, 2005

If your K&N was real dirty you may have to relearn your computer the computer may be used to the dirty filter

car running like crap after tune up...WTF?

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