Engine Studder, No Codes

[xJohnnyOx]

Hey all,

The old 2000 Expedition (5.4l, AWD, EB Package) has been doing well, till now. I have over 250K miles, am enjoying it and want to keep it going, but I have a problem that has been going on for about 2 months now and it has me stumped.

A little history, I have had COP #4 (back side passenger side) go bad two times over the last 10 years. It has always thrown a code, and I economize by picking up used ones at the local salvage yard. I do know that that failure feels like and am prepared with more COPs to change them out if needed.

The new problem is similar, but with two twists:

1. From a cold start, the engine runs like brand new, for about 7 minutes.
2. After 7 minutes, when accelerating from a stop light, or just trying to keep up from 35-45 mph in overdrive, the engine has a significant studder. It seems to still be making power, and if I turn off overdrive, the problem diminishes, but does not go away.
3. I have been trying to keep it in the studder zone to set a code (or even show up in the pending codes list). Try as I might, it will not set a code.

Does anyone have any ideas. Right now, I will probably try the following:

1. Verify all vacuum hoses are intact and not leaking.
2. Change TPS (saw a similar thread in the F150 Forum and a fellow there was adamant that had a high potential of being the problem)
3. Maybe install a full new set of COPs (can't be cheap forever I guess)

Does anyone else have any ideas on this? Like I said, the two twists in this are: 1. problem only starts after the engine is warmed up, and 2. no code is being set.

Thank you for any help you can give on this!!!

Johnny O

 

[S20Workstation4]

Sounds like the torque converter is slipping when it locks. On a cold start, the TC won't lock until a certain Trans temp has been reached, so that explains why it runs OK on a cold start. A TC that is bad will slip the most when it is locked in the overdrive gear, and at lower RPMs (35-45MPH). A bad TC also won't set any code.

When the truck starts to shudder next time, look to see if the RPM's start fluctuating. The RPM's fluctuating indicates that the TC is slipping and is switching between lock/unlock.

Any grinding noises when it starts to shudder?
If the ATF hasn't been changed in a while, I would start with just a pan drop and new fluid/filter.

Hope this helps

 

[jr1under]

This may not be relevant to your 7-minute problem but...

I had a P0304 in 2018, fixed it with a new, aftermarket COP. But soon after another coil on the same bank failed and eventually all 4 on bank 1 went bad and were replaced. Then the fails started repeating on the new COPs. Cutting to the chase, the lasting solution was replacing the entire bank with new matching Motorcraft coils. They may not have to be new but I think they should be the same part #.

Edit: Forgot to mention that not all of those fails immediately produced a DTC.

 

[whtbronco]

Sounds like the torque converter is slipping when it locks. On a cold start, the TC won't lock until a certain Trans temp has been reached, so that explains why it runs OK on a cold start. A TC that is bad will slip the most when it is locked in the overdrive gear, and at lower RPMs (35-45MPH). A bad TC also won't set any code.

When the truck starts to shudder next time, look to see if the RPM's start fluctuating. The RPM's fluctuating indicates that the TC is slipping and is switching between lock/unlock.

Any grinding noises when it starts to shudder?
If the ATF hasn't been changed in a while, I would start with just a pan drop and new fluid/filter.

Hope this helps

What he said.

LubeGard Shudder Fix seems to have a pretty good reputation and might be a good option to help isolate the issue. I don't think it's a long term fix, but for troubleshooting

Instant Shudder Fixx - Lubegard

www.lubegard.com

 

[xJohnnyOx]

Thank you all for the replies!!!!

whtbronco, regarding the LubeGard, that was the first thing I tried, with no change in the symptoms.

S20Workstation4, regarding the suggestion about the ATF and filter, yes I had previously changed those earlier, as the second thing I did, but I soon figured out that it was coming from the motor itself. You were right that it does feel like a Tranny issue, but when I took it out of gear, I could fee the engine was still doing some stuttering. I was also watching the RPMs closely during the stuttering event and they were not fluctuating. Not sad about doing that fluid change though. The old ATF was a deep brown burgundy color and was due for a change. Inspection of the sludge at the magnet showed no significant metal chips (just the fine stuff). I changed both the fluid I could get from the pan area along with the Fluid from the Torque Convertor Drain. Now its a nice bright red. I will also make a project schedule to get to the transfer case, rear diff and front diff. The truck has been good to me, so after 250K miles, I will show it some TLC.

OK, now for the update, the issue is gone and the Expedition is running like a champ again. I have taken it on some longer freeway trips and local trips around town, with no issues at all. Whew, glad its not going to be an expensive day with getting the tranny replaced (I found a used one from a friend who was going to give me a good deal on an exact match).

jr1under, you will like this. I resolved it by doing all of the above items I mentioned earlier (replaced TPS, replaced vacuum hose that comes off the back of the butterfly assembly to the green do-hicky on the drivers side of the firewall, and a new full set of NAPA COP's. I would bet that the fix was the COPs. My MPG has immediately shot up by 1 MPG, and may go a little higher.

Again,

Thank you all!!!