Need help diagnosing. 2000 V10 X vibrates from 40-55MPH when OD is on. When OD is off, significantly less vibration - very minor between 40-50MPH. Bad OSS?

I had codes for misfires on #4 and #8. I replace the spark plugs and coil packs on all 10 cylinders and codes changed to P0354/P0358 - primary/secondary circuit. Wondering if that is contributing to it.

I did the full reset process on the PCM. Codes cleared throughout the entire process. But once I stopped and restarted truck, codes came back.

My thinking is to get a replacement PCM first. I haven't done a lot looking over the wires to #4,8 coil packs. cursory look they seem to be fine.

 

Maybe switch the coils around moving #4 and 8 to different cylinders and see if the codes follow. The likelihood of getting 2 bad coils and then installing them on the same cylinders as what you problems with is pretty low but still it doesn't cost to switch them and rule them out fully.

Also does the vibration go away if you shift to neutral? That may give you an idea if you are dealing with a misfire or rotational vibration.

 

Vwags,
I actually replaced both coil packs with an extra new pair I had. Codes remained. Did the reset 3-4 times, too. What I've read on it is that if it's not the plug or coil, then it's the harness or the PCM. Highly unlikely but I could be so unlucky that I get two bad coil packs back to back. Just can't see it being plugs. They are Motorcraft. The coils were Ebay sourced. 8 of 10 seem to be working fine (so far) so I'm hesitant to conclude it's a bad coil pack. Given I've gone through 2 new ones. Engine does not sound like it's misfiring at all. Haven't tried actually swapping with a good cylinder but I suppose I can try that and see what happens. I might get lucky. WRT vibration, what happens is that (with OD on) I hit about 40-45 and it seems like the transmission is shifting isn't downshifting for acceleration. Vibration will go away if I take my foot off the accelerator. I made another loop and turned off OD, no vibration at all. Tranny seemed to shift much better and all the way through the gears. Got up to 60MPH with no vibration. Only time I had a slight vibration was when I was steady at 40-45MPH. Then the same thing with vibrations when tapping the accelerator. For some background, I bought this truck a few weeks back for less than $2k and it needs some work to pass emissions (I've gotten it to pass inspection). Also - I found out that the front shaft axles were pulled (my fault for not checking) so I need to either get a new full axle or replace the shafts (assuming there's nothing else wrong). Never had a truck before so perhaps this maybe just my ignorance on when to use O/D. I did replace the OD assembly switch on the end (ordered a cap and it came with it) Maybe I should put the old one back one. I have driven other trucks with OD and I never noticed this kind of difference. Just seems bizarre that it's rattling and vibrating that much. It shakes the dash and all the seats. Felt like the thing was going to fall apart under me a few times. Early this week, I did get codes alluding to the OSS (something like P0720 or P0700). After I did the reset this morning and went through the whole idle and drive sequence, the only codes that come back are P0354 and P0358. There were actually 6 codes early this week. So I guess it's getting better. Hence my decision to just get a new PCM and have it reprogrammed. I'm also going to go ahead and replace the OSS and rear axle ABS switch. I read a post of someone doing that when they were having vibration problems. Not sure how it's related but given how old the truck is and that it wasn't well-taken care of, I'm going to start with some easy stuff first. BTW - on the OD - is the default on or off? This morning, it defaulted on.

 

The OD light was also flashing early this week when I got all the extra codes... Could it be that the OD gear is worn out?

 

Truck has 177K miles.

 

OD light flashing means it is setting a transmission code, many code readers can not access these codes, may need to be read at a dealer or shop to see those trans codes.
Yes OD "ON" is the default setting, the 4R100 trans is designed to use OD nearly all the time including while towing, it only needs to be set to OD "OFF" if it starts hunting frequently between OD and 3rd gear as that will build up the heat in the trans too much. Typically this would only happen if towing in a hilly area.
Any idea why the front axle shafts were removed? Are both sides missing and is it the whole shafts or just the outer stub shafts that are gone?
Does the vibration also happen in second gear or third gear at the same RPM as it happens in OD? Try testing and looking for that vibration based on RPMs vs speed.

 

Both inner and outer shafts are gone. One end was sealed with a foam sealant. Other end was open with traces of fluid leak. No idea why they removed it. Previous owner did a lot of really tacky repairs to it - for instance, the lens for the interior door lights were broken (my guess) so they took Expedition lens covers and screwed them into the door rather than get replacement Excursion lens covers. They also put that crappy purple tint on the rear windows which I was able to remove but I need to get the adhesive reside off the original (nice shape) tint - also because VA only allows 35% on the rear windows. My guess is that they needed to replace the u-joints or seals and were too cheap to do it so they just took them out. At least that's what I hope.


The Computer did throw out the P0720 code. I haven't had a chance but I will do a complete Transmission fluid change on it. Perhaps that will help alleviate the problems I'm having. P0720 code disappeared after I did another PCM reset today. Now just the P0354 and P0358. Read on other posts that some people had similar problems with vibrations and these codes. I ordered 2 more spark plugs and will replace both plugs in these cylinders and swap coil packs to see what happens.


Vibration only happens in OD (4th gear). I can get through 1st, 2nd, 3rd with no issue... Once it shifts to 4th/OD, I start to get the vibration, RPMs drop very low, though. To about 1700 RPMs... The vibration disappears when I take my foot off the gas. As soon as I touch the gas, vibrations kick in and RPMs are loathe to climb at all... Reminds me of driving a stick shift and trying to accelerate and missing a gear - say from 2nd and accidentally hitting 5th instead of 3rd and the car bogging down. Didn't have vibrations then... just the car being sluggish.

 

Last time I had a vibration in OD at lower speeds (as in just engaged), it turned out the intermediate shaft Torrington bearing had worn out and the shaft was bottoming out.

Not to scare the crap out of you, just my experience with your symptoms.

 

Appreciate the heads up... as a newbie - can you give me more details? Where do I find it? I want to inspect and repair in case that's what's the problem is.

 

You'll find it inside the transmission after you remove the entire thing and disassemble it about 52%. Not a newbie endeavor my friend. You could start by draining the transmission fluid, and while doing so let it run through a strainer to immediately see any metallic debris. Then drop the pan and inspect it, the magnet, etc.

Another member here posted up a pic of some metal shards he found in his trans pan - after checking through my rebuild supplies, it turned out one of his torrington bearings had blown apart. It's not common, but not unfeasible either. The broken parts might not even dislodge based on their location - the intermediate bearing is surrounded and sandwiched pretty well.

 

If that happens to be the case, I'll just get a replacement tranny. Going to change the OSS and do a trans fluid flush and see how it behaves. Assuming not metal shards, then it's possible the shaking could just be a problem with the 4 and 8 cylinders misfiring. Swapping both CP and sparkplugs today to see if the codes remain. Perhaps it's the engine sputtering when in OD that's the cause of all the shaking.

 

PO 720 is almost always a bad ground. Check the battery to chassis connection for corrosion at either end and acid wicking sown the cable from the battery end. I replaced the frame to chassis ground on mine, but it didn't affect the PO720. I had a corroded battery cable connection that I didn't notice. A bad ground from the battery cable will cause the coils to short to the spark plug wells; it's an easier ground. Once it starts, you may have to replace the coil. Do a mode $10 on a scantool to find the missing cylinder.

 

Thanks for the tip. I will check that. I've been meaning to replace the batter connections - they look pretty crappy. The two cylinders are 4 and 8. I ordered a few replacement Coil connector ends yesterday. Will swap out those out also just to eliminate that as the culprit.

 

Would you happen to know the location of all the grounds? Know of a couple but I'm reading there could be as many as 4 that I should check.

 

The battery connection is the most likely culprit. Don't use the painted steel connectors. The battery to chassis is right beside the battery. There is a braided frame to chassis on the passenger side towards the rear. Mine was green. There is a block to chassis that I couldn't find. If the battery connections hadn't solved my problem, I would have simply made one with sheet metal screw in the firewall and a connection to a bolt on the block.