Lincoln Continential 4.6 Miss?? Shudder?? Jerk?

[skidoo700]

Have a 1998 lincoln continental 4.6 170,000 miles jerks? misses? under load at low rpms. Checked out and found #2 coil bad, valve covers leaking full of oil in the plug hole. Replaced #2 coil,and both valve cover gaskets and all spark plugs. Still had same issue occurs around 1600-2200 under light to med accel. Stress tested all coils found 2 others bad replaced them no change. Found egr sensor reading high at idle 2.01 volts replaced no change. Injector flow test passes. Also tried different maf sensor no change. Mode 6 data shows all cylinders 0 missfire WTH?? I need Help with this one. No codes

[mchan68]

Broken valve spring(s)?

[skidoo700]

A good way to verify?? It won't miss a beat at idle or a wot run. Only miss durong light to med accel..

[Bruce Amacker]

Mode 6 won't show anything until it meets the preconditions and runs the monitor, so if anyone cleared codes or unhooked the battery M6 will be empty for a while. If it won't complete the misfire monitor make sure CKP profile is learned. (I think it has to run CKP correction, 3 decels 60-40, to enable misfire monitor. It reads in datalogger whether it's met the crank learn or not under PID MP_LRN) If the gas gauge is broken it won't run MM, either. If it won't complete the misfire monitor I'd unplug stuff and verify the PCM will set codes.

 

Can you get it to miss by power braking it in the shop? If so, have your assistant PB it and feed it some propane or ether to fatten it up and see if it's a lean misfire. This is quite common due to clogged injectors or funky MAF (I know, I know, but stranger things have happened.)

 

What are STFT and LTFT for each bank? There may be some clues there.

 

A running compression test may show broken valve spring(s). Scoping the O2s would show which side(s) the miss is on, if you're set up for scoping.

 

Disable the EGR and RT it to make sure one cylinder isn't getting too much EGR. (Which I'm not sure can happen on this engine. I remember the ports clogging in the intake horn, though).

 

My guess would be ignition or lean miss. A long shot is a partially clogged cat. (BTDTGTTS)

 

Good Luck!

 

[mchan68]

To add to Bruce's post, how are the IMRCs working? I believe that engine is equipped with them too.

[Brad Clayton]

Power balance should pick that up since its under 2000 rpm. Take if for a rip up a nice hill and have someone ride with ya to watch the power balance screen, or just look at the memory traces.

[Brad Clayton]

Also, check the history on the vehicle. Someone could have had the motor apart at one point or another and miss timed it. These things will still run 1 tooth off and not to bad at that.

[Bruce Amacker]

Does it have Power Balance? I thought that was just CAN vehicles and this should be SCP, right? This is crazy- asking a bunch of diesel guys for help on a gasser! Spark plug? What's that?

 

 

[Brad Clayton]

Power balance goes waaaayyy back. All the way to '95s and some '94s.

[BrunoWilimek]

Have a 1998 lincoln continental 4.6 170,000 miles jerks? misses? under load at low rpms. Checked out and found #2 coil bad, valve covers leaking full of oil in the plug hole. Replaced #2 coil,and both valve cover gaskets and all spark plugs. Still had same issue occurs around 1600-2200 under light to med accel. Stress tested all coils found 2 others bad replaced them no change. Found egr sensor reading high at idle 2.01 volts replaced no change. Injector flow test passes. Also tried different maf sensor no change. Mode 6 data shows all cylinders 0 missfire WTH?? I need Help with this one. No codes

This was on a 2000 Lincoln LS, but could be same issue. It had an intermittent miss as well, worse when hot and I started out replacing 2 COP's and all the plugs. When miss was still there, I found more coils bad. I eventually had to replace all of them to get rid of the miss. I suspect they all hit critical mass at the same time. I have also seen something similar on a 4.6 F150 of around 2002 vintage, which kept getting one coil replaced at a time(extended warranty). Customer was pissed as it cost him the $100 deductible every time, but we could only replace the ones we found bad.

[Jim Warman]

The car should have the PID MP_LRN (misfire profile learn) and this should be toggled <YES>. As Bruce indicated, a series of close throttle coast downs should toggle the indication... do NOT apply the brake...

 

Think about this.... "crowding" the throttle will keep the PCM in close loop (going WOT will send the PCM into <open loop - drive>)... this will affect fuel delivery (hence the need to watch fuel trims). Additionally, crowding the throttle can deliver torque convertor chuggle.... this may not work on your app.... but try lightly applying the brake (just enough to turn on the brake lights) while trying to recreate the concern.... Applying the brake "should" unlock the TCC completely.

 

You can also monitor one of the TCC PIDs - and I can't, for the life of me remember which one at the moment - looking for a sawtooth pattern... seems to me it was some kind of a TCC slip PID (been a long, lllooonnnggg time).