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

[Grog6]

Moddern spark plug wires won't check with a meter. They don't contain a wire.

 

[NEURO]

Moddern spark plug wires won't check with a meter. They don't contain a wire.

Our wires can be measured for resistance (Ohms), since their values can affect spark.

I measured & compared the resistances of my original Motorcraft wires in December 2023, on Gordon's recommendation, when troubleshooting a code for a Cyl #1 misfire:
----------------------
Cyl 1=14K Ohms
Cyl 8=16K Ohms
Cyl 3=13K Ohms

Wires were fine. The issue turned out to be the #1 plug gap had grown to 0.060", so re-gapped and all was fine.

 

[Kidd-7]

So the gap has been causing your tremor?

 

[NEURO]

So the gap has been causing your tremor?

No...this was back in December 2023, months before the tremor started.
Car's CEL lit up for the first time in her 27 years and threw code P0301 - Cylinder #1 misfire.

I installed the plugs back in 2007 with the proper gap (she only sees about 1K miles/year).
Pulled the #1 plug and the gap had grown to 0.060". Pulled the other plugs, but they were fine.
So re-gapped & reinstalled it...no more CEL.

After this, I decided age issues might start cropping up with all her original parts...that's when I replaced all the plugs, wires, coils, vac/emissions lines, brakes, fuel filter, etc, etc. She was smooth before, but was eerily smoother afterwards.

Weeks after that, the tremor started.

 

[Kidd-7]

As I stated in my other thread #5 wire was loose, it popped off the plug a couple times. I doubt that of your issue.

 

[NEURO]

As I dated in my other thread #5 work was loose, it popped off the plug a couple times. I doubt that of your issue.

I've checked them...but I'll check them again.

Whatever the cause is, I have a feeling it's so simple that it's embarrassing.

 

[NEURO]

Update on in-gear tremor:
Tested EGR valve, pulled it & cleaned it, then re-tested it with engine off & on.

1. On-car, engine off - Tested EGR valve several times with new MityVac vacuum pump at 10-15in Hg and it held vacuum.
2. Next, removed EGR valve and cleaned innards & the throttle body adapter port on the manifold with a brass wire tube brush and throttle body spray cleaner.
   1. There was no gunk or obstructions in either, just normal black soot lining the metal.
   2. EGR tube in same condition with no visible obstructions with the limited view I could get of the innards.
3. Off-car, after cleaning EGR valve - Tested vacuum again with MityVac with 15 in Hg and it held.
4. Reinstalled EGR valve with new gasket.
   1. NOTE: Fel-Pro gasket boltholes are too small and require a bit of reaming to enlarge.
5. On-car, engine off - Retested EGR vacuum with MityVac to 15in Hg and it held
6. Reset PCM by pulling fuse 15 & cranking, although there were no codes.
7. On-car, engine on & cold idling - Pulled vac line from EGR, connected MityVac, and tested at 15 in Hg several times:
   1. Engine would stumble for a moment, then recover, but never shut down.
   2. Released vacuum, engine would resume normal idling
   3. Did this several times with same results.
8. Reconnected vac line to EGR...tremor still exists when in D, R, 1, or 2, whether engine cold or fully warmed-up.
9. Went to Harbor Freight to buy more tools with their 30% sale to console myself...tremor still exists in gear during drive & frustrating me.

Additional info:
Tremor is most felt in the steering wheel & driver's seat, when idling in gear, such as at a stop light.
Performance is still great & smooth under any driving conditions with no noticeable issues, except for the tremor.

Photos are of EGR valve before & after cleaning.

 

[theterminator93]

Does it still run rough if you leave the EGR valve vacuum line disconnected? You can safely plug it (the line to the EVR near the coil) to prevent a vacuum leak while driving. If it fixes the issue the EVR is leaky.

Ruling things out, once item at a time...

 

[Generalee0527]

how much dielectric grease are you putting on/in tip of plug boot? I had a case of poor idle when I was too liberal with it and had to clean up the plug tips and it fixed that.

 

[NEURO]

Does it still run rough if you leave the EGR valve vacuum line disconnected? You can safely plug it (the line to the EVR near the coil) to prevent a vacuum leak while driving. If it fixes the issue the EVR is leaky.

Ruling things out, once item at a time...

"Does it still run rough if you leave the EGR valve vacuum line disconnected?"
> No. Disconnecting the vac line from the EGR while idling has no effect on idle quality, at least while idling in the garage. The only time she stumbles for a moment is when I apply a vacuum to the EGR valve with the MityVac...then she recovers and seems to idle normally.

"You can safely plug it (the line to the EVR near the coil) to prevent a vacuum leak while driving. If it fixes the issue the EVR is leaky."
> EVR? What is that?

 

[NEURO]

how much dielectric grease are you putting on/in tip of plug boot? I had a case of poor idle when I was too liberal with it and had to clean up the plug tips and it fixed that.

I applied dielectric grease to the inside of the plug boots with Q-Tips.
It's possible that I used too much and having the same issue you had.
I'll have to pull the boots and see if I can swipe any out with a Q-Tip, as well as inspect the plug tips for too much grease being left on them from the boots.

Hadn't thought of that, so thanks.
I know I wondered if I was using too much or too little grease when I was installing the new plugs & wires.

 

[theterminator93]

The EVR (EGR vacuum solenoid) regulates manifold vacuum to the EGR valve. It's attached to the front of the engine on the passenger side by the coil pack; red and green vacuum lines run to it.

 

[NEURO]

The EVR (EGR vacuum solenoid) regulates manifold vacuum to the EGR valve. It's attached to the front of the engine on the passenger side by the coil pack; red and green vacuum lines run to it.

Gotcha...I'll try what you suggest and let you know.
To get your answer, does it have to be done while driving and the engine is fully warm...or cold while idling in garage?

 

[Grog6]

Something else you didnt hit, that I Personally had issues with, is the egr tube itself. There's an orifice of a certain size, and it's the difference in pressure on both sides, that feeds to the sensor. Mine clogged. I cleaned it with brake parts cleaner and a long brush.

 

[theterminator93]

Nah, what I'm trying to help figure out in this round is if the EVR isn't sealing completely when closed. If it isn't, then it's possible a small amount of vacuum is reaching the EGR valve, opening it slightly. You could test from idle by just disconnecting the vacuum line from the EGR valve. If the idle smooths out and/or if you notice any vacuum on the disconnected hose, it might be the problem.

 

[NEURO]

Nah, what I'm trying to help figure out in this round is if the EVR isn't sealing completely when closed. If it isn't, then it's possible a small amount of vacuum is reaching the EGR valve, opening it slightly. You could test from idle by just disconnecting the vacuum line from the EGR valve. If the idle smooths out and/or if you notice any vacuum on the disconnected hose, it might be the problem.

Got it...on my to-do list today.
Thanks

 

[NEURO]

Nah, what I'm trying to help figure out in this round is if the EVR isn't sealing completely when closed. If it isn't, then it's possible a small amount of vacuum is reaching the EGR valve, opening it slightly. You could test from idle by just disconnecting the vacuum line from the EGR valve. If the idle smooths out and/or if you notice any vacuum on the disconnected hose, it might be the problem.

Results of what you recommended with the EGR/EVR:

1. Disconnected vac hose from EGR, under following conditions:
   1. After starting cold engine and while cold idling = No change in idle, no vacuum detected at hose end.
   2. After idling for 10 mins to warm up = No change in idle, no vacuum detected at hose end.
   3. Went to grocery store & returned to garage.
   4. After returning from grocery store, engine idling very warm with outside temp 108 degrees (Yeah, Vegas summers) = No change in idle, no vacuum detected at hose end.

In all cases above, tremor still existed when car put in gear.

 

[Grog6]

egr only gets commanded when you're in 4th, at over 45 mph, iirc. The flow sensor reads the diaphragm in the egr tube, but the solenoid is eec commanded, a handheld vacuum gage will let you see if it's leaking. I stuff mine so that I can see it in the hood gap.

 

[theterminator93]

OK, so EGR is working properly and there are no signs it's contributing to the issue. At least we can rule all that out.

Weird suggestion, but if you throw it in D or R and ever so slightly open the throttle to add 30 or 40 RPM, does the stability of the low idle change at all?

 

[NEURO]

OK, so EGR is working properly and there are no signs it's contributing to the issue. At least we can rule all that out.

Weird suggestion, but if you throw it in D or R and ever so slightly open the throttle to add 30 or 40 RPM, does the stability of the low idle change at all?

Just tried that now, while making dinner.
It's hard to add just 40ish RPM, but I went as light & slow as I could with the throttle (while left foot was holding the brake pedal).
There was no change in the tremor until I got into the 750's-900 RPM range, where she becomes smooth as glass, almost like she's in Park.

 

[Grog6]

That sounds like plugs and wires, to me. That ould be a vacuum leak; at that throttle setting,the airflow could be overwhelming the leak, or bad iac. But I think it's unlikely to be trans related.

 

[Grog6]

Our spark is really high voltage, it soaks longer at low rpms, so it can be more likely to leak. It can also keep it from accelerating, just to be thorough.

 

[NEURO]

That sounds like plugs and wires, to me. That ould be a vacuum leak; at that throttle setting,the airflow could be overwhelming the leak, or bad iac. But I think it's unlikely to be trans related.

Plugs, ignition coils, and wires were replaced in March 2024 with Autolite Double Platinum & Motorcraft.
Everything was fine before & after the replacements. I replaced the wires & coils only because of their age and being original parts.
The tremor started a 2-3 weeks later.

 

[NEURO]

Our spark is really high voltage, it soaks longer at low rpms, so it can be more likely to leak. It can also keep it from accelerating, just to be thorough.

Yeah, I read in another posting that our coils put out something like 160kV each.
But no issues with acceleration or performance, before or after replacing the plugs, coils, and wires in March 2024.

 

[NEURO]

how much dielectric grease are you putting on/in tip of plug boot? I had a case of poor idle when I was too liberal with it and had to clean up the plug tips and it fixed that.

Update on tremor:
I pulled all the new plugs to check gap & condition...all were fine, still gapped at 0.052", and look like the attached photo.
Also, as per @Generalee0527 suggestion, wiped all the dielectric grease off the plug tips, inside the plug wire boots, and inside the ignition coil boots/ports/whatever they're called with Q-Tips & rags.

Also cleaned out the throttle body & plate again with a blue shop towel sprayed with throttle body cleaner.
Deep inside at the back, I can see some soot build-up when I shine a flashlight down the barrel. I can't reach back there with anything to clean it, which might mean pulling the throttle body & adapter off and cleaning them, if that's a possible cause of the tremor.

Pulled fuse 15 to reset PCM, etc.

Went driving today to grab smokes, pizza, and other treats for my July 4th dinner.

Tremor remains in any drive gear. No change.
Performance remains great and she's silky smooth while driving.

But this tremor is driving me batshit.
I don't know what else to check.

What suggestions are next?

 

[theterminator93]

If I was working on this, I'd try to get my hands on known good parts to swap in to see if anything changes. I know I've said I don't think they're the source of the issue but we're running out of things to try...

If Gordo has a good MAF and IAC to test with those are easy enough to swap out to test. O2s might also not be a bad idea to check. 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).

 

[supergordo]

I do have a MAF and IAC. Just need to get my lazy ass over to see the car!!

 

[NEURO]

If I was working on this, I'd try to get my hands on known good parts to swap in to see if anything changes. I know I've said I don't think they're the source of the issue but we're running out of things to try...

If Gordo has a good MAF and IAC to test with those are easy enough to swap out to test. O2s might also not be a bad idea to check. 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).

Yeah, I know...it's bizarre.
I've thought about the MAF or IAC being fluky, since they've been the source of issues for many others...but don't have spares and don't want to throw a couple Benjamins at those on hope.

And yeah...that Gordo guy needs to make an appearance.

I didn't know there was a set-screw on these TB's (still learning). Would you have a photo of it, so I know what to aim for?

 

[NEURO]

I do have a MAF and IAC. Just need to get my lazy ass over to see the car!!

Yeah, you do.
Text or call me and we'll set it up.

 

[Kidd-7]

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