Tremor while in gear & need help - 97 Thunderbird LX Sport 4.6L

[theterminator93]

I don't have any good pics of it. But it's where I have the arrow pointing. It's what the throttle blade actuator arm rests against when the springs have it fully closed.

 

[NEURO]

I don't have any good pics of it. But it's where I have the arrow pointing. It's what the throttle blade actuator arm rests against when the springs have it fully closed.

View attachment 6428

Thanks, Terminator.
I'll give that a try today...or tonight when it's not a thousand degrees in my garage.
Vegas summers

 

[supergordo]

This thread has become just as much about will Gordo show as it is about fixing this tremor. LOL

Well...

 

[NEURO]

This thread has become just as much about will Gordo show as it is about fixing this tremor. LOL

I'm holding hostage a socket Gordon left behind when he tried to fix my soft brakes.

Our live studio audience waits with bated breath to find out the fate of the socket.
Will our hero save the socket...or leave its fate in the hands of an evil & perverted tool deviant and his Car?

Proof of life photo attached.

 

[theterminator93]

THE car?

 

[NEURO]

The CAR

 

[1997ThunderbirdLXV6]

So I haven't followed every detail of this thread...but after @Rodeo Joe 's recent experience, have you considered trying another PCM?

My apologies if that has already been discussed.

 

[NEURO]

So I haven't followed every detail of this thread...but after @Rodeo Joe 's recent experience, have you considered trying another PCM?

My apologies if that has already been discussed.

No, that hasn't been tried because I don't have a spare PCM. And it seems a bit extreme at the moment.
The car drives & performs beautifully and is silky smooth...except for that idle tremor in gear.

No codes...and the plugs, wires, ignition coils have all been replaced with new Autolite/Motorcraft parts.
The tremor started 2-3 weeks after these parts were replaced.

Since then, the IAC & MAF have been properly cleaned. EGR was cleaned & tested good. Throttle body also cleaned.
All vacuum/emissions lines have been replaced...even the ones behind the passenger-side bumper/fender.
Other parts have been tested good.

Gordon says he's going to pop over to my place with a spare IAC & MAF to try out.

But so far, the tremor has been a stumper that's gone on months.

 

[supergordo]

I'm holding hostage a socket Gordon left behind when he tried to fix my soft brakes.

Our live studio audience waits with bated breath to find out the fate of the socket.
Will our hero save the socket...or leave its fate in the hands of an evil & perverted tool deviant and his Car?

Proof of life photo attached.

Tune in next week! Same Bat time same Bat channel!

 

[Sniper83rdID]

No, that hasn't been tried because I don't have a spare PCM. And it seems a bit extreme at the moment.
The car drives & performs beautifully and is silky smooth...except for that idle tremor in gear.

No codes...and the plugs, wires, ignition coils have all been replaced with new Autolite/Motorcraft parts.
The tremor started 2-3 weeks after these parts were replaced.

Since then, the IAC & MAF have been properly cleaned. EGR was cleaned & tested good. Throttle body also cleaned.
All vacuum/emissions lines have been replaced...even the ones behind the passenger-side bumper/fender.
Other parts have been tested good.

Gordon says he's going to pop over to my place with a spare IAC & MAF to try out.

But so far, the tremor has been a stumper that's gone on months.

Is it idling any lower than normal when you drop it in gear? If so, have someone get in the car, drop it in gear while you adjust the throttle plate a smidge to bump up the RPM back to normal and see if that helps... if not, adjust it back and check it off the list.

 

[Grog6]

...

No codes...and the plugs, wires, ignition coils have all been replaced with new Autolite/Motorcraft parts.
The tremor started 2-3 weeks after these parts were replaced.

Do you still have the old parts? I'd swap them back, and see what happens. There's little qc these days, so a bad new one isn't unheard of. A leaky coil usually leaks more the hotter it is.

 

[NEURO]

Do you still have the old parts? I'd swap them back, and see what happens. There's little qc these days, so a bad new one isn't unheard of. A leaky coil usually leaks more the hotter it is.

Posted about that already...I put the old ignition coils back in a week or so ago. No change.
I'm leaving them in for now and will swap the new ones back in when this issue is resolved.

 

[theterminator93]

Is it idling any lower than normal when you drop it in gear? If so, have someone get in the car, drop it in gear while you adjust the throttle plate a smidge to bump up the RPM back to normal and see if that helps... if not, adjust it back and check it off the list.

The PCM will target 560 RPM idle in gear. If the throttle blade is open so much as to keep the car idling at 800 RPM all the time, it would likely have other repercussions that affect driving characteristics (e.g. accelerating with your foot off the gas and brake when normally you'd coast).

 

[NEURO]

Is it idling any lower than normal when you drop it in gear? If so, have someone get in the car, drop it in gear while you adjust the throttle plate a smidge to bump up the RPM back to normal and see if that helps... if not, adjust it back and check it off the list.

Terminator suggested that earlier in the day and I've been trying to find the set screw to do that.
He provided a photo of the location, but all I can find is a 'screw' that's threaded on both ends.
Thunderbird service manual doesn't have any info about it, either, except to say don't adjust the idle, while referencing a different service manual for more info.

The PCM will target 560 RPM idle in gear. If the throttle blade is open so much as to keep the car idling at 800 RPM all the time, it would likely have other repercussions that affect driving characteristics (e.g. accelerating with your foot off the gas and brake when normally you'd coast).

@theterminator93 ...doesn't this conflict with what you advised on Thursday?
"Maybe even 1/4-1/2 turn or so either way on the TB set screw (mark it first so you can put it back if it doesn't help or causes other ill effects)."

Attached:
Photos what I think is the set screw we're discussing, but it's threaded on both ends. Even if I wanted to try adjusting, no way to...unless using pliers or Vise-Grip that would destroy the threads.

 

[theterminator93]

Yes, that's it. It's not milled for a tool to turn. This is a temporary "what happens" kind of thing - just to determine if the reason the idle is wonky is related to too much air entering. Just grab it with pliers on one side and close it slightly (I would lightly score it with a screwdriver or something so you can put it back to normal later), or open it slightly and observe any changes.

The PCM is programmed with the mass of air that gets into the engine with the TB and IAC closed. If reality doesn't match this data somehow, it will cause problems. So we're just adjusting the air through the throttle blade as an intermediate troubleshooting step to determine if it's possible that the amount of metered air entering at idle is off spec.

 

[NEURO]

Yes, that's it. It's not milled for a tool to turn. This is a temporary "what happens" kind of thing - just to determine if the reason the idle is wonky is related to too much air entering. Just grab it with pliers on one side and close it slightly (I would lightly score it with a screwdriver or something so you can put it back to normal later), or open it slightly and observe any changes.

The PCM is programmed with the mass of air that gets into the engine with the TB and IAC closed. If reality doesn't match this data somehow, it will cause problems. So we're just adjusting the air through the throttle blade as an intermediate troubleshooting step to determine if it's possible that the amount of metered air entering at idle is off spec.

Ah...gotcha.
Will-do and let you know what happens.
Thanx

 

[Grog6]

Before You mess with the Idle, Clean the Throttle Blade first; There gets to be a crust at the edges that can cause issues. To adjust it correctly, disconnect the iac electrical connector, while keeping it running with our thumb on the blade. Then adjust the screw to BARELY keep it running. Reconnecting the iac should still run normal. Reset the computer after Reconnecting the iac , it should still run normal.

 

[KevinVarnes]

Did you try swapping the old wires back on yet? I really want Gordo to get his socket back!

 

[NEURO]

Before You mess with the Idle, Clean the Throttle Blade first; There gets to be a crust at the edges that can cause issues. To adjust it correctly, disconnect the iac electrical connector, while keeping it running with our thumb on the blade. Then adjust the screw to BARELY keep it running. Reconnecting the iac should still run normal. Reset the computer after Reconnecting the iac , it should still run normal.

Not sure I'll be able to adjust the screw...damn thing is frozen.
I've hit it with PB Blaster overnight and small-medium Vise-Grips and the thing won't budge.

 

[NEURO]

Did you try swapping the old wires back on yet? I really want Gordo to get his socket back!

No...it took me hours to install that octopus of new wires and I'm not keen on undoing all that and redoing it with the old wires.

What I might do is simply unplug each new wire from the coil & spark plug, then jump in the appropriate old wire to see if the tremor vanishes.
Rinse & repeat with all eight of them, one at a time, and see if a culprit shows up or not.

I'll report back the results when I get that done.

 

[NEURO]

Update on tremor troubleshooting:

To check the new Motorcraft spark plug wires for a defect, took the longest old wire and substituted it for each new wire, one by one.
For example, disconnected new wire for a given cylinder from the coil and spark plug...then jumped in the old wire.
Did this for each cylinder.

No change...tremor was present on each wire change-out.

Note: Old wires were original, but still good when I replaced them with the new Motorcraft wires in March '24.
I only replaced them because of age and the growing scarcity of Motorcraft parts.

Next idea, fellows?

 

[NEURO]

Update a month later:
Went to the grocery store yesterday afternoon...and the tremor has gotten a little worse.
Sitting at red lights, the tremor felt like she wanted to stall or go full-blown rough idle.

But again, it's not a typical rough idle, but more like the tremor the Car would experience if she were an alcoholic who tried to stop drinking...and it comes through the steering wheel and driver's seat when in any gear, but not in Park.

Otherwise, there's no performance issues and she's smooth & powerful when in motion.

I've done everything I can think of, as well as most of the suggestions posted by others here...and the issue remains.

I have no idea where to go from here.
Any ideas?

 

[Vicinity]

I had a few tremors the other day. You could see the voltmeter dipping when it had happened. I know that my Battery is passed its date, and that my positive post is imperfectly secured. I'm not necessarily saying that's the reason however

 

[Rodeo Joe]

Thinking out loud here, but figured I'd ask. Where are you buying your gas?

Seems like you've checked everything there is to check, with all new parts and everything.

Joe

 

[NEURO]

I had a few tremors the other day. You could see the voltmeter dipping when it had happened. I know that my Battery is passed its date, and that my positive post is imperfectly secured. I'm not necessarily saying that's the reason however

Battery has no problems that I know of and always starts the car without issue.

It's a Duralast Gold Battery Group 65 that was bought in July 2020. Through the years, no matter which top-end battery I bought, I'd get 3 years out of them at most, because the Vegas summer heat just chew them up...and they always died in summer, so every 3 years, I could count on buying another $200+/- battery for her. I even have an Outlook Reminder for when the 3 year date is coming up on a new battery...LOL, just so I'm aware that it'll die anytime after that point.

But in the past year, I bought a battery charger/maintainer that has desulphate capability. Once a month, I hook up the charger and let it do its thing for the next 10-12 hours till she hits peak charge and shuts off. As of this month, I'm now on year four with this battery since doing that, not the typical 3 year lifespan I'd get. I also measure the battery's charge with a multimeter that has specific a battery-testing good/no-good setting and it always checks out good with voltage usually clocking 12.4-12.8 volts, depending on time of month.

Also, I keep the battery posts properly maintained & cleaned of any corrosion that occurs.
I don't like my women being corroded.

 

[NEURO]

Thinking out loud here, but figured I'd ask. Where are you buying your gas?

Seems like you've checked everything there is to check, with all new parts and everything.

Joe

Depends...sometimes 7/11, Maverik, Chevron, 76, Arco AM/PM (if I'm in the mood for those delicious shitty foil-wrapped burgers in the glass warmer).

Occasionally, I'll buy a bottle or two of injector cleaner to pour into the tank.
Also recently replaced the fuel filter with another Motorcraft one.

 

[Sniper83rdID]

Depends...sometimes 7/11, Maverik, Chevron, 76, Arco AM/PM (if I'm in the mood for those delicious shitty foil-wrapped burgers in the glass warmer).

Occasionally, I'll buy a bottle or two of injector cleaner to pour into the tank.
Also recently replaced the fuel filter with another Motorcraft one.

Hmmm.... just a random thought but maybe try a can or two of Liquid Moly Valve Clean... They're small cans but pack a hell of a punch in cleaning injectors, valves, rings everything. Just add a can when you fill it up, run out the tank and add another can next full up. Stuff worked AMAZING in my '77 Maverick.... Hopefully it would work the same for you.

 

[Rodeo Joe]

It was just a thought, I was thinking maybe you were getting bad gas somewhere.

Joe

 

[NEURO]

It was just a thought, I was thinking maybe you were getting bad gas somewhere.

Joe

No problem...it was a valid thought.
I considered that too when the tremors started.
But considering the variety of stations I've used, plus changing the fuel filter, bad gas would be unlikely now.

 

[NEURO]

With 69K miles on the clock, do you guys think it's worth removing the throttle body assembly & throttle body adaptor from the intake manifold to clean them out, as another possibility to resolve the tremor issue?

If so, besides needing the throttle body to adaptor gasket and the throttle body mounting gasket, is there any other part or tool I need...or something I need to know or watch out for, so I don't bork something or brick The Car because I'm missing something?

Thanx