About two weeks ago i noticed on my truck (98' 4.6L 4x4) that whenever i get up to above 80Km (on the speedo, its about 10km or so faster, my speedo is out quite abit ) that my truck really starts to shake, and when i give it more gas i can't reach speeds anywhere faster above 90km, it feels like my truck is dragging and has nothing , and thats with my foot all the way to the floor!! also the whole truck will be shaking really bad the whole time, Its actually quite scarey. Once you let off the gas it shakes even more, until it drops below 75-80km. That all started two weeks ago or so, and it slowly been getting worse. This weekend me and my dad took the whole rear axle apart, and checked the carrier and pinon, and also a couple of the bearings (we never checked the inner bearings) and everything seemed fine and didn't seem like it could be causing any problems, the spiders were worn a little bit but nothing horrible. We changed a couple of the bearings and replaced the U-joint on the rear end of the driveshaft (the front seemed in perfect shape, but we're gonna change it tomorrow just for the hell of it). We put it all back together and crossed our fingers that maybe we solved the problem...Not even close going to school this morning i couldn't even reach speeds above 60km without it starting and its shaking worse now too. At lunch i decided to take a rip around and just check some things out. I noticed that: in first if i reach 40km (redlined it) it seems fine other then the fact its redlined, if i put it in 2nd and get up to 60km it doesn't shake at all and seems fine. Its when im cruising around like normal and have it in 3rd or 4th even 5th is when it starts shaking. Also an observation i had when it first started is that if i have it in 4th it started shaking at about 70kmish and then if i put it in 5th it stopped until i got up to 80kmish. Im 90% sure it has to be seeming the the rear end because when it shakes real bad and you still give it gas you hear some strange noises from back there and you get some pretty bad klunking sometimes. We're completely lost on ideas, anyone know what to do??? Oh and about a month ago we had pulled my tranny and put a new clutch in, could we have messed something up there thats causing this now??

Thanks for all the help!!

 

Is there an rpm range that it seems to be shaking the worst in? I am thinking you may be misfiring. Crank the engine and see if the engine shakes even a tiny bit. Also give it some gas and check. If it shakes then you have a misfire. My truck was acting a lot like that and come to find out it was missing on 3 cylinders. You may also have burnt a valve. While the engine is running take a dollar out of your wallet and put the tip over the exhaust. If the corner goes away from the pipe then no problem. If the corner gets sucked in then burnt valve.

 

I don't think it has a rpm range seems i can go from idle to redline in first without any shake and also get up to 60km in secound without it shaking either. Ill definitly try that valve test tomorrow, thanks. I do have a couple Dtc codes up right now but they have been on way before this started and i believe there only because of a o2 sensor, but ill right um down tomorrow and put um up here, and hopefully you guys will see something i don't! Thanks for the help. Keep it coming guys!

 

If you are running with o2 sensor problems then you may have a vacuum leak or fuel problems. With the clunking sounds and such that may not be your problem. Not to up on tranny problems. To test for a vacuum leak start the engine and before it gets warm (as not to ignite the spray) spray carb cleaner around and behind the throttle body. Also follow the vacuum lines. If the engine idles higher while spraying over a certain spot then there is your leak. Quick question: when you pulled the ds for the u joints, could you possibly have not but it back exactly lined up as it was when you pulled it off?

 

Well it was my dad who had swapped the U's and he's done quite a few in his life time so i'd suspect he did them right, but ill ask him. Ill go grad the dtc's right now!

 

here:
PO443 - Evaporative emissions vapour management fault
PO161 - Heater circuit malfunction
PO171 - Bank 1 Lean
PO174 - Bank 2 Lean
PO1000- OBD Readiness test not complete
P1500- Unknown

I also tried that coin test and after starting the truck it was just on the ground so i don't think its a blown valve then. Its been getting alot worse, it starts at 40km now and i can't even drive it to school anymore...

 

I would clean the MAF, EGR, and **** even seafoam the ****er out to get rid of carbon buildup. If the ****er can't breath you are gonna experience some strange ****. Heater circuit malfunction I'm guessing has something to do with the heater core electricals? Also when was the last time you got new tires? If those ****ers are unbalanced or worn unevenly you are gonna get some strange feelings at higher speeds. Just a thought, and **** off to anyone who thinks any of this **** sounds stupid. Check the ****ing basics before you start moving onto the expensive ****.

 

Wow somebody had their coffee today ^. Don't worry about the P1000 code it's just a drive cycle. As for the others, start with cleaning the throttle body, EGR ports, and MAF. The lean codes and P1500 are concerning. It could be due to a wire grounding out on the harness or a bad ECU but most likely it's a vacuum leak. Check all the vacuum hoses (visual and ether test). After everything is clean and checks out, clear the codes and see what comes up. Hate to see people throw money at things that aren't the problem. Cleaning and inspecting are cheap and easy starts to finding the causes.

 

Eh having a bad day and need to do a little venting. Also I'm tired of stupid bitches who say "throw parts at it man and something will get fixed." They make leak down, compression, power balance, coolant tests, etc. for a reason. Quick note on vacuum leaks you can use a propane torch or CC to find them. You'll notice that the idle and engine changes dramatically because you're choking the intake.

 

Ye id really prefer not to through money into something unnessisary too, rather save it for a 4bta , but im really sure it's something the the rear guys. Im not to concerned about those dtc's atm because they've been there for a long time and the truck drove fine with them there. If i solve this problem and there still there ill defaintly starting checking other things to remove them for sure. Because i think your right i might have a vaccum leak, and i do gotta clean my MAF i actually had picked up the contact cleaner the other day for it! I say i think its in the rear because tonight me and my dad took it out driving and we noticed when rolling at real slow speeds that you can hear a real good, clu-cluck and its steady and goes faster the faster you role...my dads looking into a new carrier but i really don't know The vibrating is insane now when you get to + 70Km. And im really starting to worry all this vibrations gonna start causing other problems.