Need Help

[SonicBlue02-3.8]

Ok, I just changed my spark plugs w/motorcraft stock plugs, I have 34,000 on the engine and this was the first change. After I changed them I get a weird almost knocking shound coming from maybe the passenger side of the engine, that I hear inside the car when I'm stopped at say a light, but if I let off the brake it goes away????? It comes and goes, but does not do it under acceleration, only when stopped. Also, when I pulled the plugs I noticed some white fouling or "ash" on the #4 cylinder (front of engine driver side) plug electrode, what does this indicate? Some had a little bit and other plugs had none. I need new batteries for my camera, but once I get them I'll take a picture to show you. The only thing i have done is MAC CAI, which was done 32,000 miles ago. Also, if this might help, when I put the new plugs in, I did not check the gap b/c i lost my spark plug gapper and I didnt' feel like running back out. The guy from ford said that they are already pre-gapped so I didn't think that it would matter. Thanks.

 

[ChingonStang]

34k and you had to have it tuned up? Was it running bad before? Like bad gas milage, idling hard or running rough?

I was always told, if it aint broke, don't fix it.

Just curious about why you had to change plugs out soo soon?

 

[FunkMasterFlex]

I was always told, if it aint broke, don't fix it.

well with us car guys its more like

if it ain broke then fix it until it is

 

[SonicBlue02-3.8]

Nothing was really wrong with the car, I just wanted to give her a little tuneup while I was home. The apartment complex I live in now doesn't let you work on your car, so I was at my parents home and decided to tune her up as preventative not to fix something.

 

[Lsredy2kstang]

White plugs usually mean a lean condition if I am not mistaken?

How were the plugs when you took them out?

And I have changed my plugs twice as a PM thing with only 70k miles on it.

I will be changing them again when I do a compression check for the nitrous.

 

[SonicBlue02-3.8]

the #4 cylinder plug had white ash on it, which signifies lean condition or excessive idling, but that was really the only bad one, another 1 or 2 were close, but not as bad, I have to take pictures and then I'll post them. Any ideas on what the damn rattling or knocking is at idle??? It only happens every once in a while and if i give it just a little bit of gas it goes away or if I let off the brake it usually goes away. This is weird...maybe bad gas??

All six plugs from left to right is Cylinder #1 - #6. The most fouled one with light brown ash is #4 cylinder (Front Driver Side Cylinder) and the next most fouled one was the #1 cylinder (Front Passenger Cylinder).

Another shot

And another Shot

Cylinder #1

Cylinder #4

 

[Lsredy2kstang]

Yes, sound like some pinging. You may want to try some mid grade gas to see if it still happens. Do you have a chip in the car?

 

[SonicBlue02-3.8]

no chip...why would i get pinging all of a sudden??? If i didn't get pinging with those 2 fouled plugs how could i all of a sudden get it with new plugs??? Let me know if the pictures worked above, they work for me, but i dont know if everyone can see it.

 

[ChingonStang]

well with us car guys its more like

if it ain broke then fix it until it is

exactly....forgot about that.


No...can't see the pictures.

 

[SonicBlue02-3.8]

why can i see them and you can't?

 

[SonicBlue02-3.8]

Also, doesn't pinging occur at higher rpms and not at idle? Correct me if I'm wrong but that is what i understood. Also, do you think its my MAC CAI hitting against the engine bay? I did have to remove it and put it back in to get to the spark plugs? If the engine dipped to a certain rpm range and caused the engine to vibrate just a little more it would cause the sound that I am hearing?? Just a thought. Anyone with any ideas?? Also, and idea why I would have light brown ash on two of the plugs both front of engine? Do fuel injector cleaners do that?

 

[MustangLX-5.0]

It's possible that something on the intake could be vibrating against the side of the chassis.Different engine speeds create different vibration patterns,and this also depends on the condition of the engine (Gaskets,Seals,PCM sensors,Motor/Tranny mounts,Clutch/Throwout bearing in Manual trans,Mechanical and also vacuum hoses).Now,when my car idles (96-V6),there's not too much vibration going on throughout the entire RPM range.And this is only after it's been running for a few minutes and coolant temp is low.Now,if it's been running for awhile,say 25 minutes and the temp was up a quarter to allmost half way,it had a slightly bit more vibrating to it at idle speed (730 RPM) but it still seemed smooth..At this time,if I throttle the engine up just a notch to about 940 RPM,it shakes quite a bit like it has some sort of running issues.And what is really weird is it only does this at PRECISELY 940 - 950 RPM.The RPM Range after this to Rev limiter is quite smooth.

Don't know if that's typical with 3.8's.What I would try,and this works very well.Wedge a long pole,such as a broom or mop handle between the brake pedel and the drivers seatback or wedged underneath on the back of the seat frame.A short length of 2 X 4 works best.Now you can go under the hood and check out that noise you are hearing.

If you still can't figure it out,maybe record a short clip of it in MP3 and post it here.

As for Cyl. 1 & 4,I would most likely guess that the fuel injectors for these 2 Cyl's are partially clogged with some deposits thus becoming a lean mix.The only other thing I can think of is sticking valves but that would be highly unlikely with the very low mileage you have.Then again,if you never had the injectors cleaned or shot any carb cleaner (Intake spray) through your throttle body,it's possible there may be build-up deposits...then again,this goes right back to the partially clogged (Or sticking) injectors.

Has the motor ever been serviced for any general maintanance or repairs?

 

[SonicBlue02-3.8]

I have had the car in for regular service, just had the coolant system flushed and trans fluid changed, only at 34k. I have used fuel injector cleaners in the past like Lucas or something along those lines liek Chevron. As to the noise, it does not happen all the time, usually I think I'm in drive and stopped at a light. I can't get the noise to replicate if I try. That is why its so hard to pinpoint. Thanks.

 

[n0v8or]

At idle, in drive, with the hand brake applied, try turning on the AC to load the engine a little more and see if you can reproduce the noise that way.

 

[SonicBlue02-3.8]

I fixed it, it was the intake hitting the shock tower. Also, anyone know why my injectors would have that light brown deposits on them? Its says lean condition or additive deposits? I have used fuel inject cleaner in the past so i think that could be the reason. Why would there be a lean condition, its all computer controlled?