I have a nasty vibration that started two weeks ago. I originally assumed the cause was a cylinder miss since an OBD2 test indicated cylinders 1 & 8 were missing. I fixed cylinder 1 by simply replacing the plug. Cylinder 8 was not so easy, and I ended up pulling the injector and had it cleaned and tested before the computer would clear the code.

Since eliminating the misses on the cylinders I have driven the truck about 250 miles. The vibration is still present, but the computer shows no new or pending trouble codes.

The vibration is begins as soon as the truck is started and gets worse when put in gear. While in drive the vibration seems to increase from 1500-2000 rpm, and decrease from 2500-3000 rpm.

Because the vibration is present when idling, I've eliminated all drivetrain components except the engine and transmission. Since the computer is not showing any trouble codes, I am wondering if it is possible for the vibration to be coming from the transmission. I just had the transmission replaced in February, and there is less than 1,500 miles on it.

Any help that can be given is most appreciated.

 

I doubt this is the problem, but I will throw it out anyways. Is it the belt or pulleys?

 

I don't believe that's the problem, but I'll check it tomorrow anyway.

I wan't to exhaust all the simple solutions before I give up and take it to a professional. I've already spent $2,500 this year replacing the transmission, and once this problem is solved my wife wants to sell the thing before it creates an even bigger hole in our bank account.

 

What a coincidence my truck just started a similar problem yesterday! It has been raining heavily here for the last week and I think there may be moisture in the gas lines (I had not used the truck in a week, it has been sitting static) I an going to try a fuel additive to see if this will help. It is cheap way to find out if there is moisture in the fuel lines. You might want to give it a go. Rick

 

problem is still likely a misfire just not bad enough to set a misfire code. one of the plug coils likely bad. I would buy one new coil and try on the cylinders you origianlly had the misfire codes on. when you changed the one plug you may have disturbed the coil enough so not as bad ??

 

moisture in fuel is very uncommon these day but very likely bad coil boots will fail in high moisture, I have realy not had too many, but a few, bad coils. Usually the boots form to the original plugs and don't seal good to the repacemant plugs or new plugs were not installed ontil over 100K miles and the large plug gap caused it to arc through boot instead. once that happens there is a pin hole and it will always be easier to arc through boot, many times hard to see. I change out all the coil boots every time I change plugs. About $20 for 8 boots. The vibration is a misfire. Ford goes through great attempts to not turn on a check engine light in a misfire ontil it is definite. In a yearly refresher class they are telling us in the newer tarus and 500's the computer will turn off the injector in the case of a mifire to clean up the tailpipe emisions so they don't have to turn the check engine light on and will briefly turn the injector back onat each keycycle and each time it reruns the misfire monitor but will log a code. The instuctor would not tell us why they are doing it but I suspect money is involved.

 

Here's an update: I changed the remaining 6 sparkplugs. I replaced the plugwires a few months ago (one got too close to the fan and got a knick in the insulation, they have a lifetime warrenty from Schuck's so I got a new set for free). I read on the Forum that some members had success eliminating intermitent misses by using silicone dilectric grease on the inside of the sparkplug boots. I will give that a shot tomorrow.

Today I cleaned the mass air sensor with electrical parts cleaner, but there was no improvement. I also checked all the lug nuts and the driveshaft universal joints (since the vibration gets worse while driving I just wanted to make sure), as I suspected there was no problem with those parts either.

I have also checked the seal where the air duct connects to the throttle body. That was loose last year and I spent $50 for an engine diagnostic test to find the problem. Thankfully, the mechanic didn't charge me any extra to tighten the screw on the hoseclamp.

It's irritating the computer won't tell me what cylinder is missing. If I can find it I can fix it. I'll try running another can of fuel injector cleaner through the engine. If that doesn't help I may have to spend $50 for another engine diognostic test.

By the way, I saw that several Forum members recommend a product called Seafoam. I had never heard of it before, so I looked for it today at Schuck's (part of the Checker/Kragen chain of parts stores) but didn't see it. I'm in Washington State, does anyone know a place that carries it here?

Thanks for the help.

 

Had a few misfires on my 97 F150 4.6L, the first one right after changing plugs. Just played with the plug wire & injector plug, went away on its own. Last time (same cylinder), 2 days after washing engine compartment. Lots of water droplets on spark plug boots, LOTS I mean. Let air dry after a drive, all good.

Wanna find your misfire ? Try this :
Start engine, put in gear, park brake on & wheels blocked (misfires come out more obvious when loaded); pull plug wires off one at a time, listening to engine sound. When you unplug a good one, the engine misses more, a Lot more. When you unplug the defective one, the engine sound won't change, or very slightly. That's how I found mine last time !!!

 

Thanks for the tip on loading the engine to find the miss. I'll give it a try in the next day or two.

Since my last post I added dielectric silicone grease to the inside of the plug boots. There was no improvement, but I did get to spend about an hour and a half trying to figure out how to remove a pebble from plug hole. The pebble fell in when I pulled the plug boot off. I didn't have compressed air available to blow it out, so I had to use a pick tool with a 90-degree bend at the end to get under the pebble and carefully lift it out. It wasn't easy, especially when you can barely see down the hole to watch what you are doing.

I also put a can of Sea Foam in the gas tank yesterday. I've put a little over 100-miles on the truck so far, and while it seems to be idling a little better, the miss is still quite apparent.

In the next couple days I will be home (I'm currently on a Navy base waiting for my retirement paperwork to be finished) and have access to all my tools. Hopefully, I can finally resolve this issue, if not I'll have to admit defeat and take it to a shop (god I hate doing that).

 

even though you don't have an active code, connect the scanner and see if you have any stored codes. you know most auto parts stores read them for free.

 

If you're curious about how the computer detects a misfire, do a search for it and look for my post. I go into great detail in a few of them...
For your problem now, try to find someone who has a diagnostic tool, and not just a scanner. A diagnostic tool will enable you to see the engine information real-time and pinpoint any failures, including misfires...I have Autotap, which is an excellent program...

BTW, I'm an ET2 in Kings Bay...

 

put a new (or new)
cap
rotor
wires
plugs(.035 gap)
points (28-32 degree dwell)
condenser
oil
oil filter
fuel filter
air filter
turn the key
and call it a day


...zap!

 

Zap, you're showing your age... All of these things are outdated...

 

i know that

just for laffs

...zap!

 

Well I still haven't been able to solve this problem. I pulled the plug on cylinder 8 the other day and it had oil on it. I've noticed smoke coming from the tail pipe on occasion. The smoke is not constant, usually if I'm idling for a long time, but can be heavy.

The #8 plug is the only one with oil on it, and changing it did not have any effect on the vibration (which is more of a shake). The engine has become harder to start than normal. It used to fire right up, but now it takes a couple seconds of cranking.

The shake is most noticable when the truck is idling, and when it shifts into overdrive on the highway at 60 mph. Also on the highway, if I let my rpms drop a little while going down a small grade, then apply the throttle lightly the truck bucks (like the engine is lugging) until the RPMs come back up to 2000 or the transmission downshifts.

While I know the oil in cylinder 8 is a problem, I don't believe it is the cause of the shake since there was difference when the plug was changed. I've now driven more than 600 miles since I cleared the last code (a miss on cylinder 8) from the computer and nothing else has come up. Is there any chance at all the shake could be related to the automatic transmission or torque converter?

If I had the money, I'd take the thing to the shop today.