Have an odd RPM related vibration happening, need opinions! - 99 Ram 5.2
Hey folks, prepare for a long winded and pretty detailed explanation of what's happening to my truck here. Trying to figure this out and need a couple more experienced opinions.
So I have a very awkward vibration happening with my 99 Ram. Has a 5.2 Magnum motor with close to 169k miles on it. Feels like it has a ghost misfire.
First start on a cold morning, whistles through the intake and the truck has a shake to it. You open the hood and you can see the motor shaking like it has a misfire, but there are no misfire CEL's occuring. Now I've attributed the whistle to the Idle Air Control as the truck makes the same noise when I pour some Seafoam down the throttle body as well as the noise dissipating completely when the truck has warmed up and idle settles down.
Now to the shake. It's felt through the entire truck and it's more prevalent when the truck is cold. As the truck warms up, you feel the vibration less and less. When the truck gets fully heated, you can't feel the vibration at idle, but you can see the RPMs on the tach jumping about 200 - 300 rpm and you can feel a bit like it misfires. When I accelerate you can feel the vibration shake the truck and it goes away a bit when it hits about 1500rpm. It really depends on how I accelerate. If I would accelerate quickly, the vibration isn't felt and the truck pulls very hard.
Regardless of whether or not the truck is in park/neutral, drive, reverse, or in 4x4, the vibration is still there. When I rev the truck in park/neutral, the you can feel the vibration. Same goes for in drive. Again, it feels like its a misfire, but there are no codes.
What has been done
- Rebuilt trans 3k miles ago - The PO did this to the truck, I have receipts and all. I got the truck in trade and aside from driving around perfectly, this vibration is all that has been bothering me.
- New Cap, rotor, spark plugs, plug wires
- 2x seafoam treatments - truck burns off a lot of white smoke mixed with blue (oil) smoke after a couple minutes of running with the seafoam. My guess is the oil being burned is residue after years of driving? My Datsun did the same thing and stopped after I Seafoamed the hell out of it.
- Cat converter has been hollowed out - I did this as more of a preventative measure. I heard of these trucks clogging their cats and since I have no emissions, I only did what was natural and gutted the cat. I DO have a CEL for my after cat O2 sensor though. This can be remedied by a defouler to move the sensor further away from the exhaust.
As for some random things that occur, if I drive through a puddle on my passenger side (or get anything considerably wet for that matter, only on that side) my truck will try to bog down and will backfire like it lost spark. The only way to get the truck from bogging out is to go full throttle. Then it picks itself up and goes. At that point, I still have no other CEL's other than my after cat O2 sensor, and that only came up after I gutted the cat.
So, any ideas gents? I do all of my own work, so no need to bring it to a shop, just lay it on me.
Since you mentioned the trans was recently out and the problem intensifies when the left side gets wet, the first thing you should do is verify that the CKP sensor wiring isn't/wasn't pinched between the block and bell housing. Also check inside the connector fo signs of moisure intrusion. If all that checks out, you need a scan tool that can read OBDII monitors so you can see which cylinder is causing the problem. I would then scope the CKP pattern and see what it looks like. If the pattern is normal, move onto a leakdown test to check for any compression loss due to worn or damaged components.
Crawled around the truck today and cleaned off every connector I could find. Crank sensor wiring is untouched and 100$ perfect. Connector and all.
I have no access to a scope.
I'll be conducting a compression and leakdown test when I get a chance next.
Thank you thus far!
Also, not sure if its related:
The truck is always somewhat slow to crank. Cranks over a couple times then fires right up. Battery is great as once it cranks for a considerable amount of time (say with the ignition coil unplugged) it cranks quickly. There are occasions when I will get a click of the starter and I'd have to put the truck in neutral (truck may move a tad) and then the truck will be able to crank.
Again, not sure if this is related at all or a problem in itself.
Compression numbers on every cylinder are 155 +/- 5 or so. Which to me, at 169k miles seems like pretty damn healthy motor! Leakdown is OK. I've ruled out a valve or poor compression as being an issue.
Brought the truck to a mechanic friend of mine to put the truck on a scope and his expensive scanners and with the limited amount of time we spent on the truck we found that cylinder #6 wasn't firing correctly. Used a couple other tools and it seemed like the #6 injector wasn't firing properly or was clogged.
So I got a new injector, put it in - STILL has the same issue! Nothing has improved, nor has it worsened.
Ideas? I'm absolutely stumped by this thing, it's ridiculous.
What was the leak down percentage on #6? Have you swapped the plug an wire from #6 to see if the misfire follows either component?
I have not switched any plugs. I'll be going at it with the truck in the next 30 mins. Will be going over my firing order again, cleaning spark plugs of any deposits, and starting with the basics. I'm also going to check my fuel pressures in the next few days, see how everything is on that front.
Truck is driven everyday as it's currently my only vehicle - other than this shudder/vibration it runs fine! At idle you can feel what seems to be a small miss and that's it. Its really pestering me.
Well after today:
Plugs have been regapped
Put new plug wires and routed them per bulletins I saw posted around the net.
Fuel pressure is just under 50psi
Cap and rotor were pulled off and checked for signs of arcing. Everything is clean.
Crank sensor is good as is wiring.
Throttle body has been removed, cleaned and new gasket installed.
While I removed the throttle body, I checked the plenum - no pooled oil or anything of the sort. It's fairly clean, I have no reason to believe I have a blown plenum.
Now what I HAVE noticed:
Directly behind the alternator, there seems to be a small two prong sensor that is has the plastic pieces on it broken off. This sensor is more to the passenger side of the motor.
Now, just the the right, I have a sensor that also is a two prong sensor. When I unplugged this particular sensor, my coolant temp on the cluster wasn't reading.
What is that sensor that is broken off and has no connector to be found ? It's right behind the alternator and is very small.
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