Strong vibration when accelarating

[20Bonneville00]

I took my car to the shop today under suspicion of bad spark plugs. it had been sputtering at starts sometimes and would die occasionally. The mechanic said that the old plugs were okay still but since I had new ones there, we decided to just replace them all. He also replaced the fuel line. After the job was done i drove home (just through town) and didn't notice anything out of the ordinary but later i took the car on the highway and experienced some major missing by some of the cylinders and also some strong vibrations when going about 50mph and raising the rpms to about 3000. I just took the car out again to show a friend what the problem is to see if he knew anything. while driving it, the check engine light started blinking and then stayed on. I would assume that the missing is due to a bad install by the mechanic but I have no idea what would cause it to vibrate. What makes this all worse is that i am supposed to drive it 4.5 hours back to college tomorrow. hopefully someone knows what's going on. maybe the mechanic bumped/broke a sensor or wire or something? I have no idea.....

[crash93ssei]

Usually a blinking CEL and vibration is a code P0300 which is random multiple cylinder misfire. Many parts stores will now scan for codes for free so if you can, swing by one and scan to confirm. Were the wires changed as well or plugs only? If the wires have not been changed and the code is P0300, I would start there and see if that makes any difference.

[20Bonneville00]

Only the plugs were changed. During the job he did pull two of the boots off of the wires and then had to re-crimp two new ends onto those two wires. I'd assume that would be the problem. Is it alright to drive with it like this or am i dead in the water?

[crash93ssei]

If it only misfires under heavier throttle it should be fine to drive to get new wires or up to the parts store for a scan to confirm the code, just drive easy.

[MrJiggy716]

You should always replace the wires with plugs just good measure to avoid situations like these, the old wires become brittle and are more prone to break crack or strip during install/re install . You can pick up a decent set at advance for under 25 bucks...

[20Bonneville00]

I scanned it at O'reillys. The code is P0303 so a misfire in cylinder 3. I still don't understand what was causing the vibrations? and why it only vibrates while driving and doesn't vibrate while in park?

[crash93ssei]

Often a bad plug, wire, or coil will only show under load, not always at idle. I would replace the wires and see if that changes anything. If it still misfires, change #3 plug again, even though it is new.

[imidazol97]

I scanned it at O'reillys. The code is P0303 so a misfire in cylinder 3. I still don't understand what was causing the vibrations? and why it only vibrates while driving and doesn't vibrate while in park?

Does it miss so you can feel it if you hold the brakes and accelerate the engine against that resistance?

No one has mentioned injectors as a source of a miss.

I had an occasional miss at light throttle or when starting the engine. Finally set engine light and I switched coils, checked spark plug, switched compete spark control unit with my 98 engine to troubleshoot. Injector had lots of gunk in intake.

I put in Techron Injector Cleaner and that seemed to help clear up the problem after switching injector from #6 to #4.

[redzmonte]

probably a bad plug or wire.. try replacing plug 3 and if it still continues i would get a set of wires (beldin from Napa are a local favorite). Cyl 3 is the front middle cyl. so it will take literally 5 min to remove, gap plug and replace plug and wire.

[20Bonneville00]

I got a set of wires from O'reillys and I only had time to change number 3. All I did was switch the wire out. It didn't help at all. Next move should be pulling that plug and checking the gap? Then if the gap is correct, where does that leave me?

[crash93ssei]

If the wire didn't change anything, I would just get a new plug. I have seen them many times bad right out of the box.

[20Bonneville00]

So here is a curve-ball for everyone. I went ahead and replaced the rest of the wires and took it for a drive. Oddly enough, it ran beautifully. Now here's the weird part. When I put the scan tool on it, it showed that the code was a misfire on cylinder 3 (p0303). When I replaced the wire for that cylinder (the middle one in the front), I had no improvement. During in initial install of the new plugs, the mechanic accidentally separated two of the wires from their boots/metal connector pieces. The two wires that he broke were going to cylinder 2 and 5. When I saw that the code said cylinder 3 was misfiring, I assumed that the problem wire would be one of the ones that we had to re-splice. But if that is true, then the code I got on the scanner doesn't match the cylinder numbers if you go by firing order, but it does match if you just count from left to right 123 on the front. Can anyone confirm this or am I just super confused through all of this?

[DaMaroon]

It's by firing order only. It's a convention just like the left and right side of the car is determined by sitting in the drivers seat. Otherwise it gets confusing.