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

Grog6 said:
And load, and rpm. If it stumbles, you should see rpm changes.
Click to expand...
Got it...thanx.
There's no stumble...just a tremor at idle. I don't even think it qualifies as a rough idle.
 
@Grog6, @theterminator93, @supergordo

I've attached a Zip file of the FORScan data, because the forum doesn't allow .CSV or Excel file uploads, except as zips. Because I'm not sure what will work for you to look at the data, I've saved the data in various formats, including: .CSV, .XLSX, .PDF, and two screenshots of the Dashboard view and Oscilloscope view.

If there's any questions or more data that I can provide, let me know and I'll work on it.

I'm still learning my way around FORScan, so any details for providing what you need will be helpful.
I simply don't have the experience & knowledge you guys do to interpret this data and know what it means, so I do appreciate your help telling me what's going on with her and what's right or wrong and/or what needs to be fixed/replaced.

After midnight tonight, The Car & I will be taking a run around Vegas on some errands and can collect live data again, if that's needed.

Vehicle: '97 Thunderbird LX Sport, 4.6L, 69K miles
Issue: Tremor in Drive while idling that seems masked in Park because of higher idle...but performance while driving is great.
Everything done to The Car and all the parts replaced before the tremor issue arose are posted at the beginning of this thread.

Thanx
 

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Another FORScan live data run from 4-6AM this morning, same file formats as yesterday's zip file upload: .CSV, .XLSX, .PDF, and screenshots of the Dashboard view and Oscilloscope view.

Each file name is suffixed with the date and either a -1 or -2.

-1 suffix = Live data from home to destination
-2 suffix = Live data from destination to home

The Car ran beautifully, like usual...except for the tremor at idle in Drive.
 

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  • FORScan Data 05192024.zip
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Been super busy the last two weeks. Give me a bit and I'll come by and experience the issue first hand.
 
I understand. Thank you for your time, Terminator.
 
supergordo said:
Been super busy the last two weeks. Give me a bit and I'll come by and experience the issue first hand.
Click to expand...
Thanks Gordon. I'd also like to revisit & resolve that soft brakes issue.
Just let me know when's good for you and we'll pencil it in.
 
Update forgot to mention:
Had to run out to Green Valley's Harbor Freight yesterday.
Like usual, The Car ran like a bat out of hell...performance is great, even with the A/C on.
But that damn tremor is perplexing.
I have also had absolutely schiffy gas mileage for years...maybe related or another issue, I don't know. If I'm lucky, I'll get 200 miles on a tank.
 
Bump...I haven't heard back from anyone after I posted the FORScan data, regarding the tremor.
Anyone have any ideas?
 
tremor could be anything. Trans, engine, plugs, tc, dirty EGR, bad coil pack... You'll just have to evaluate.
 
Sorry, I got busy and forgot!!

I spent some time and filtered out the CSV and re-headered it to make it more readable, then eliminated some of the unhelpful columns and finally reordered everything to make it easier for me to identify correlations between data fields. That file is attached.

Next I filtered the data to show me only samples when the car wasn't moving with your foot on the brake and the throttle closed.

Observations:

The way the CSV was created seems to be one column per sample, and it took over 4 seconds to start recording all PIDs. It's hard to know if it's reading all PIDs for each time sample, or only a subset. If the latter, the entire dataset might be skewed in terms of data sync. I hope not! :)

RPM seems to fluctuate between 590-600 RPM.

IAC duty cycle remains at 0 during idle. I don't see an ISC integrator PID, so I don't know if PCM thinks too much air is getting in to idle properly, keeping the IAC closed. This is doubtful, but worth mentioning.

STFT switching looks normal. (An STFT in the negative means a lambda of less than 1.00, or rich.)
LTFT at idle pretty consistently shows about -8% on the driver's side and -4% on the passenger side. IIRC, numbers less than 0 indicate rich and pulling fuel. Assuming I've got it right, this could be natural variance/aging in injectors, O2 variance/aging, MAF variance/aging, fuel pressure regulator variance/aging...

Overall, I couldn't find any trends to link RPM surging to any particular operating variable - fuel or spark.

Desired idle is 560. It seems your idle is hovering between 590 (when lean on the O2s) and 600 (when rich).



Thoughts:

It's really hard to draw conclusions. I have a couple hunches, but I'm speculating.

The O2s, if original, might be skewed ever so slightly.

The IAC, if original, might be slightly crudded up, preventing accurate fine adjustment at idle. I would have expected to see minor adjustments in IAC duty cycle at idle, not just 0% across the board. BUT - without the ISC integrator PID, I can't be sure, because the PCM might be using a different PID to measure ISC duty cycle at idle. If you remove the IAC and can easily blow through it, it might need replacement.

If the EGR valve is leaking when closed (due to carbon buildup) it would cause weird idle rumblings. If you were to remove the valve, you shoudn't be able to blow through it.

If most of the other emissions components (e.g. O2s) are original, they're almost 28 years old now and, regardless of mileage, probably need to be replaced as part of a larger tune-up.
 

Attachments

  • datascan.zip
    1.2 MB · Views: 1
Grog6 said:
tremor could be anything. Trans, engine, plugs, tc, dirty EGR, bad coil pack... You'll just have to evaluate.
Click to expand...
Read my first posting, where I describe everything done to her.
Others have requested the OBD data to analyze what's going on.
 
theterminator93 said:
Sorry, I got busy and forgot!!

I spent some time and filtered out the CSV and re-headered it to make it more readable, then eliminated some of the unhelpful columns and finally reordered everything to make it easier for me to identify correlations between data fields. That file is attached.

Next I filtered the data to show me only samples when the car wasn't moving with your foot on the brake and the throttle closed.

Observations:

The way the CSV was created seems to be one column per sample, and it took over 4 seconds to start recording all PIDs. It's hard to know if it's reading all PIDs for each time sample, or only a subset. If the latter, the entire dataset might be skewed in terms of data sync. I hope not! :)

RPM seems to fluctuate between 590-600 RPM.

IAC duty cycle remains at 0 during idle. I don't see an ISC integrator PID, so I don't know if PCM thinks too much air is getting in to idle properly, keeping the IAC closed. This is doubtful, but worth mentioning.

STFT switching looks normal. (An STFT in the negative means a lambda of less than 1.00, or rich.)
LTFT at idle pretty consistently shows about -8% on the driver's side and -4% on the passenger side. IIRC, numbers less than 0 indicate rich and pulling fuel. Assuming I've got it right, this could be natural variance/aging in injectors, O2 variance/aging, MAF variance/aging, fuel pressure regulator variance/aging...

Overall, I couldn't find any trends to link RPM surging to any particular operating variable - fuel or spark.

Desired idle is 560. It seems your idle is hovering between 590 (when lean on the O2s) and 600 (when rich).



Thoughts:

It's really hard to draw conclusions. I have a couple hunches, but I'm speculating.

The O2s, if original, might be skewed ever so slightly.

The IAC, if original, might be slightly crudded up, preventing accurate fine adjustment at idle. I would have expected to see minor adjustments in IAC duty cycle at idle, not just 0% across the board. BUT - without the ISC integrator PID, I can't be sure, because the PCM might be using a different PID to measure ISC duty cycle at idle.

If the EGR valve is leaking when closed (due to carbon buildup) it would cause weird idle rumblings. If you were to remove the valve, you shoudn't be able to blow through it.

If most of the other emissions components (e.g. O2s) are original, they're almost 28 years old now and, regardless of mileage, probably need to be replaced as part of a larger tune-up.
Click to expand...
Thanks for the analysis, Terminator.

Just to recap, before I posted about this tremor issue on May 1st:
Plugs, wires, and coil packs were recently replaced with new Motorcraft/Autolite parts. Except the plugs, the other parts were original.
Before replacing these, there was no tremor. A couple weeks after is when the in-gear tremor started.

Last month, pulled the MAF (first time ever) and it was spotless, but I sprayed it down with MAF cleaner anyway, never touching the wire.
Tremor still occurs.

A couple weeks ago, pulled off the original IAC...no gunk, just some carbon soot that I cleaned out and reinstalled with a new gasket.
Tremor still occurs.

After cleaning the MAF, I pulled the fuse and cleared the computer...and the slow/low rhythmic oscillations in her RPM at idle vanished.

In summary, she idles smooth in Park, but has the low tremor in any other gear.
Performance-wise, she runs fantastic, smooth, and strong...but I'm lucky to clock more than 200+ miles of city driving on a full tank. Not sure if that points to something being amiss...or my 'spirited driving' being the cause.

I thought about going after the EGR, O2's, and other items you mentioned, but was waiting to see the feedback from you & others, before blindly throwing a ton of money & parts at her. I've already spent over a grand since February on rebuilding/replacing/servicing most of the brake system and replacing other parts due to age. If I knew what was wrong, no problem...just don't want to blindly replace parts & waste money.

I've considered pulling the new plugs to check them and putting the old coil packs back on, to see if the new coil(s) are the issue...I'll try that this weekend.

Attached photo is IAC before cleaning.

Just for shits & giggles a couple weeks ago, I balanced a nickel on the intake while she idled in Park.
Video on Google Photos: https://photos.app.goo.gl/wLgoK3FeEnxvMkJd6

Thanks again. If you think of anything else, please let me know.
 

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Hey James, I need to come visit. Just been busy. Terminator made good points. The EGR can be inspected without buying one. I do want to come over and see the tremor.
You are definitely in the category of age over mileage. Interesting that it didn't happen before the plugs, wires and coil packs... Have you tried swapping the old coil packs back in one at a time to see if it is the same?
 
I'm assuning you'e checked the vacuum lines. Does it do it in reverse? and 1st?
 
If it's doing it in reverse, and first, it could be the TC. Otherwise It could be the forward clutch There's seriously a million things it ould be. Pay Gordo to figure it out. He's good.
 
NEURO said:
but I'm lucky to clock more than 200+ miles of city driving on a full tank. Not sure if that points to something being amiss...or my 'spirited driving' being the cause.
Click to expand...

If you're actually talking "city", as in constant stop & go plus repeated short trips, then I don't find that number all that shocking.

I owned Ford V8s while living in NYC, and 12-14 mpg average was the norm.

Has the exact same driving pattern previously produced better gas mileage?
 
supergordo said:
Hey James, I need to come visit. Just been busy. Terminator made good points. The EGR can be inspected without buying one. I do want to come over and see the tremor.
You are definitely in the category of age over mileage. Interesting that it didn't happen before the plugs, wires and coil packs... Have you tried swapping the old coil packs back in one at a time to see if it is the same?
Click to expand...
Hey Gordon...sorry for the delay responding. I haven't been on the PC since Friday or Saturday, because my lower back was in agony again. I'm back to normal now...in other words, normal back agony...and will be doing the following today/tomorrow/this weekend:

  1. Pull & check the EGR - I read that pulling the EGR on pre-97's is a PITA, but that '97's are much easier, since it's just sitting there on the back of the throttle body. I'll grab a gasket from the parts store first...anything else or tips I need to know before pulling it?
  2. Replace the new coil packs with the old ones (one at a time) and see if there's any change.

  3. If I can, I'll pull the new plugs to inspect & re-gap, just to ensure one of them isn't the issue.

I have a feeling it's something simple that's causing the tremor, like the EGR, IAC, or something else...or else all that data would show something significant and/or the car would be having other issues. But she doesn't...she runs fantastic when moving.

We also need to figure out why the new brakes are still spongy-ish and not firm at all.

As usual, you're welcome by anytime. Just give me a heads-up.

Thanx
 
Grog6 said:
I'm assuning you'e checked the vacuum lines. Does it do it in reverse? and 1st?
Click to expand...
All vac & fuel/evap hoses were replaced in April '24. That was one of my first troubleshooting/maintenance items to tackle when the tremor started, but the tremor remained.

The tremor occurs in all gears, except Park.
 
1997ThunderbirdLXV6 said:
If you're actually talking "city", as in constant stop & go plus repeated short trips, then I don't find that number all that shocking.

I owned Ford V8s while living in NYC, and 12-14 mpg average was the norm.

Has the exact same driving pattern previously produced better gas mileage?
Click to expand...
95% of my driving are short trips to the store, docs, Harbor Freight LOL...stuff like that. Very little freeway driving, because most of where I go is within a few miles of home.
I work out of my home, so it's infrequent & small trips like that...so The Car sees daylight maybe once/twice a week and only clocks about 1,000-1,200 miles/year.

But I'm sure if I hit the highway from Vegas to SoCal, I'd probably clock 400+ miles on the tank, instead of the pissant mileage I'm getting in the city.

Sounds like your experience with mileage indicates that mine is 'normal'...which sucks LOL.
 
Grog6 said:
Does it occur in reverse?
Click to expand...
I believe so...but I need to double-check to be certain about Reverse.
I'll be hitting the auto parts store today or tomorrow for the EGR gasket, so I'll determine for sure and let you know.

For certain, the tremor exists in all forward gears, but not Park.
The tremor occurred a couple weeks after I replaced the plugs with Autolite Double-Plats gapped at 0.052" and replaced the wires & coil packs with new Motorcrafts. She was very silky smooth afterwards...then the tremor occurred a couple weeks later.

As an aside about the tranny...I drained & replaced the tranny fluid and filter, including draining the converter, with Motorcraft Mercon V back in 2014 with 58K on the clock. She now has 69K miles...only 11K miles since the tranny fluid was replaced. But maybe the fluid is bad from age, not miles, and causing the tremor in gear, although the level is fine and still red?
 
Update on tremor:
Just went to the parts store for the EGR gasket and this is what I observed in the garage when I returned home:

  1. In Reverse, Drive, and 1st & 2nd = Tremor exists
  2. In Park and Neutral = No tremor
  3. BUT...if I go from Park or Neutral directly to 1st = RPM's suddenly drop to 500 (dash tach), car shudders heavily for a moment like she's going to stall, then RPM's come back up to in-gear normal RPM's and the normal tremor resumes. The 500 RPM & heavy shudder lasts only a couple of seconds before resuming normal in-gear RPM's and normal tremor. Going from any other gear to 1st doesn't cause this...only from Park or Neutral directly to 1st.
 
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NEURO said:
Update on tremor:
Just went to the parts store for the EGR gasket and this is what I observed in the garage when I returned home:

  1. In Reverse, Drive, and 1st & 2nd = Tremor exists
  2. In Park and Neutral = No tremor
  3. BUT...if I go from Park or Neutral directly to 1st = RPM's suddenly drop to 500 (dash tach), car trembles heavily for a moment like she's going to stall, then RPM's come back up to in-gear normal RPM's and the normal tremor resumes. The 500 & heavy tremble lasts only a couple of seconds before resuming normal in-gear RPM's and normal tremor. Going from any other gear to 1st doesn't cause this...only from Park or Neutral directly to 1st.
Click to expand...
Sounds like we have a vacuum leak somewhere..
 
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