Grandpa's old M100 (White)

[TRAK]

Recently I inherited my Grandfather's two beautiful Fed Spec Elans. He drove both of the cars daily for over 10 years, was constantly ordering parts for them, although only let his trusted mechanic do any serious work on them while utilizing my youth to teach me the less-than-serious jobs. This thread will only focus on the White as the Red M100 is its own can of worms.

Projects Completed:

-Oil Change
-Coolant Flush
-Thermostat Replacement
-Fuel Injector Cleaning
-Spark Plug Replacement
-Fuel pipe (From pump to fuel filter) Replacement
-Fuel Filter Replacement
-Potentiometer Replacement
-VSS Replacement
-Instrument Cluster Bulb Inspection/Replacement
-Battery Replacement
-Fuse Inspection/Replacement

Problems:
-ElanScan
I've scoured through the forums and have downloaded every patched version I could find to get the program to work on Win11 to no avail. Working on acquiring a Win10 laptop to hopefully get some scans!
-Tacho capping at 3k RPM.
This seems like a mechanical issue as there is a small silver piece showing where the needle stops rising. The engine continues to rev and it doesn't disturb the drive at all.
-Fuel Gauge reading 3/4 after a full tank
Read some helpful articles that suggest the bobber in the tank might have fuel inside. Not a real priority at the moment
-Dash not Illuminating* FIXED
When driving the highway at night, after cruising at 75mph I accelerate to ~85mph in 5th gear, and suddenly the lights on the instrument cluster and throughout the dashboard go dark. The Battery Voltage, Boost, and Oil Pressure gauges included. All of the other lights still work around the car (head/taillights) and even the headlamp pods are fully functional. This is an issue that has happened twice now, at the same place, around the same time, and on different days. I cannot diagnose a cause. After the first time this happened, I replaced the Potentiometer, and switched the Rheostat Control Modules between the Red and White cars and still no success. Switched back to the original Rheostat Control Module and then hand checked every wiring connection I could find underneath the dash. Checked the fuses throughout the car, all were healthy and in the right place. Feeling defeated because I never felt or heard any defining movement or click, I decided to test the illumination and THERE WAS LIGHT! I drove the Lotus multiple nights over the next week with the gauges glowing the classic burnt orange, and definitely over 85 mph. It wasn't until I was driving home from work (at night) at seemingly the same spot of highway at the same speed that the lights go out again! Very perplexing issue, how do I find a cause?

[chrism]

TRAK, dapinky has made the EScan files that you need (ElanScan_beta_USB + New ElanScan.ini) - that specifically relate to win 11 users - as a 'sticky' at the top of the 'Elanscan' LEC section.

The old EScan and .ini files were supported up to early versions of win 10 and win 11 'left them behind' - so LEC 'boffs' updated the old to produce these versions which, I'm grateful to say, work fine with (certainly my) win 11.

(Within this category you can follow the recent history and development of the posts and threads which led to the new beta version and new .ini files that you need.)

[dapinky]

Hi TRAK,

My bad, I authorised your first post and didn't write anything to you.....

....obviously, welcome to LEC, and I hope we can help you along with your project(s).

Now that you have a post approved, and are a full "member", you will see a tab on the banner at the top labelled "Manuals" - whilst it does go to my website with all the Workshop Manuals listed, it also has a lot of other (useful?) links.... one of which is to Elanscan - but as Chris says, they are a bit outdated (preceded W11), so going to the sticky thread on Elanscan will get you the latest versions..... but the info on the Manuals website may still be useful to you.

[chrism]

TRAK, attached below is the 'sticky' zipped file of the win11 ElanScan upgrade.

Erm...the 'New ElanScan.ini' file I mentioned is actually the 'new M100ALDL protocol.zip' file and the zip instructions refer to replacing an the superceded EScan.ini file in the %Appdata% Roaming folder.

You're starting from scratch, so after unzipping and installing new 'ElanScan_beta_USB' just copy or drag-and-drop this 'new M100....zip' file into the Roaming folder. (EDIT: ...or if there's the old one there just replace it...)

Hope this helps

[TRAK]

Thank you all for the tips! I will take another crack at getting my first scan and report back.

[chrism]

Yep, zip file your EScan data on here. I'm not sure it'll relate to the problems you've outlined, but I'm sure LEC-ers will offer any advice they can...

[TRAK]

Update:
Dashboard Illumination issue is fixed. Found the RH Sidelamp wiring was loose and would pop the fuse. Consequently, turning off the dashboard illumination.

Attached is my first scan. Cold start and mainly highway driving. Let me know what you think!

It might be worth mentioning, as far as the drive is concerned I don't notice any issues and the car feels excellent after the spark plug replacement (correctly gapped now) and fuel injector cleaning. I went for a SMOG test (a western US auto-emissions test for registration) and the car failed due to high levels of unburnt fuel at high speeds. Thankfully, Nevada has a loophole for classic cars and passing SMOG is not necessary in my case. Actually looking to remove the CAT down the road

[chrism]

TRAK, some really odd EScan results. I've found it helps to compare data so I've overwritten some of your blue data with mine in black:-







Top two are spark advance (should vary around 16*?) and coolant temp (your temp control looks decidedly 'dodgy')

Middle two are O2 sensor (yours works but is a little slow and erratic) and a:f ratio (yours shows irregular dips)

Bottom is knock counter (mine is str line along the x = 0 axis) I reckon knocks are complaints made by the car

I'm not an expert - and these are only my opinions - but I reckon you ought to at least think about replacing that temp sensor and/or thermostat, and replace any stale fuel in the tank then check the timing. Perhaps either or both will get rid of engine 'knocks'.

Sounds to me like Grandpa might have left it standing around unused for a while...?

Any other comments would be really interesting...

[chrism]

ps My ES data was just a stationary warm-up scan in the garage and I realise your data is from a run... - but not everone can repeat your particular driving circumstances.

Yet I suppose we can all do a 15 or 20 min stationary warm-up scan and know that fair comparisons (and consequent superimpositions) can be made under these similar sets of conditions in the first instance.

[TRAK]

Thank you for the help chrism! Granddad drove them both as his daily drivers for over 10 years (his way around the 5,000mi/yr classic vehicle cap) and since his passing 2 years ago they have never gone more than 6 months without being driven ~50-100mi. Which is why I'm also surprised Red is being so stubborn.. (different topic to come)

I agree with some of the dodgy readings. Theorizing that possibly the O2 sensor is faulty and consequently putting the IAC out of wack? I've read on the forums that IAC valves are seldomly replaced, although Granddad left 4 brand new Lotus IAC Valves in his parts box. Very interesting being there are only 2 cars..

I noticed that the MAP sensor is reading on the low side as well. The closed-loop service notes and that indicates the car running on the lean side. This combined with the higher than ideal Target Idle (Lowest was 1037.5rpm) makes me wonder if there may be a vacuum leak somewhere as well.

On a short drive home not long after the scan I noticed the temp gauge read at 1/2 for the first time since its been in my care. It looks like I have a coolant leak close to the thermometer, yet the actual thermometer housing was dry. Back in the garage, I cant see any obvious holes in any of the coolant lines. The coolant temp sensor is dirty and has been...cleverly engineered. One silver lining is that I know the temp gauge works on the dash! lol

P.S. I did find a post talking about the dangers of the yellow coolant cap. The one thing I did change because I found 2 new ones in the parts box. Don't know if there is a direct correlation because there were no signs of leakage from the coolant cap or anywhere near the coolant tank, just a strange coincidence...

Tuesday I plan on checking timing, vacuum leaks, coolant leaks, doing a thorough coolant system flush(s), and if all goes well I will have a 15-20min stationary warm up scan for you when I return

[chrism]

Hmmm...I've never seen my temp gauge go up to the 1/2 mark while it's been running and air's flowing through the rad. I suspect it got very hot?

I suppose these old hoses get brittle over time and the clips squash them into submission giving us air and water leaks

There's nothing wrong with yellow caps, in fact I have one . Some of them don't have a long enough thread to hold the cap on securely - ask RonR about his experiences.

Yep let's have a look at your EScan. Perhaps run it up enough to get the fans whirring? This'll be ~107degC (I think) so you'll be able to see if the 'stat cuts in ~82degC (or whatever that is in degF...)

[andrewp]

From years ago, I discovered if the speedometer cable is not connected to the speedometer drive unit (at the top of the transmission) then when the engine revs beyond 3000 RPM a check engine light activates. More importantly, the engine will not be allowed to rev past 3000 RPM from this point on. To correct this, unplug the vehicle battery and it resets.

This may explain your lack of revs past 3000 RPM.

[Tuga2112]

From years ago, I discovered if the speedometer cable is not connected to the speedometer drive unit (at the top of the transmission) then when the engine revs beyond 3000 RPM a check engine light activates. More importantly, the engine will not be allowed to rev past 3000 RPM from this point on. To correct this, unplug the vehicle battery and it resets.

This may explain your lack of revs past 3000 RPM.

I Think Trevor had that issue. took a long time to figure it out with Ron's help. i think it turned out to be damage in the back of the instrument cluster electrical traces ? there is definitely a thread within the past 2 years about it...

[Tuga2112]

I noticed that the MAP sensor is reading on the low side as well. The closed-loop service notes and that indicates the car running on the lean side. This combined with the higher than ideal Target Idle (Lowest was 1037.5rpm) makes me wonder if there may be a vacuum leak somewhere as well.

vacum leaks are an annoying one to trace there is a particular hose that goes to the back middle-bottom of the engine for the secondary throtle actuator. that is not only the hardest to see and reach in my experience. but also due to its location. the one most affected by heat.

im not suggesting its the most likely to be an issue. just pointing out the existence of it. and brace yourself for the access dificulty

[TRAK]

Coolant: I found the leak and yes, it was due to an old brittle hose. Once I saw the temp gauge get that high, I immediately pulled over and called for a tow. There was only white steam coming from the culprit. Was an easy fix and now no liquid leaks!
Maybe I will give the yellow cap another shot. I'm using the luxury of having a daily driver to give these cars a face lift through the process. Very excited to share the before and after with the forum down the road.

Vacuum: I didn't want to try the water trick on the air lines because the idle is already dodgy without external manipulation. The o-ring type seal around the Air Filter outlet adapter just after the Air Filter Housing was disintegrating so I put a replacement seal on for the scan. I would like to find a better one for the long-term.
Furthermore, I have seen my daily driver read 120F (48.89C) on the highway out here in the middle of summer so I will put the pesky hose on my check list. Hopefully cross it off before the floor becomes lava!

Tacho: The check engine light has never come on when its not supposed to, and I checked the bulbs lol. In my scans I get readings of over 3,000rpm and by the sound of the engine when I'm driving, it doesn't seem to cap out. I've never hit the limiter, although I have driven the engine over 3,000 rpm so I believe it might be a mechanical issue with the needle itself. There is a little metal piece and the physical needle seems to get caught on it. (Any tips on uploading .jpg to these posts?)
Tuga, your videos have helped me tremendously on many projects and when I first took out the dash to check the continuity of the circuits everything seemed to check out. That was a couple months ago and I want to do another check with the information I have now. The main thing stopping me from opening up the cluster is how brittle it is. While I was working with it, it was easy for the tabs to disintegrate and the clear plastic front is crudely glued to the back housing. I'm not keen on the local laws when working that close to the odometer, especially when my registration depends on it, so I want to make sure I know what I'm doing.

Attached is a 20min warm up scan, thank you all for your input!

[chrism]

TRAK, some correlations; again O2 sensor and coolant sensor/thermostat type stuff

Thermostat opens really early then after 600s everything seems to 'crash' rather like a loose connection/earth. I'd be inclined to run it again to see if that 600s crash is random. I'd have thought the O2 sensor would be hot enough to keep going, hence the random loose connector/earth/alternator-ish thought.

I've overlaid my spark advance in black cos I reckon yours varies a bit too much again - and goes a bit wild later. Could it be CAS wear/play I wonder?

I'd be really interested in other comments tho'. I reckon there could be a couple of issues complicating each other here...

(Dunno what O2 sensor integrator tells us but it's connected to the sensor voltage and goes flat after 600s like the voltage.)

[TRAK]

Hmm.. The CTS does look like it needs replacing. It looks like the original although it is not the OEM harness. The closed-loop manual is saying the MAT and Coolant Temp should be similar, this doesn't seem to be the case. The MAT is spec and brand new. https://postimg.cc/KKtSQwPx

It might be interesting to note the coolant crash on my first scan happened when my rpms dropped as I was getting off the freeway, although that was with 0% throttle as I coasted to a stop from 70mph (112kph) in high 60F (~20C) weather. https://postimg.cc/kB3DfP3h
Very curious to why the thermostat opens so early since I replaced that in January.. Wrong model? Admittedly, it was in the parts box and I blindly trusted Granddad. I have since learned through other projects that not everything in the parts box fits the M100.

The idle is rough and on a short run around the block pre-scan, you can feel the rough idle when cruising. I mainly noticed it when I was in 4th gear going about 45mph at ~3200rpm(bad tacho).

Are we leaning more toward the O2 sensor going out or the IAC being wacky? Feels like a chicken and the egg situation. Right now I have a fuel additive in the tank which might explain the spark advance? (Absolutely guessing here) The first scan did not have fuel additive. Lucas Oil Deep Clean Fuel System Cleaner is what I put in the engine and only run 91 Premium.

[chrism]

Oh, so this wasn't a stationary warm up from cold then? Perhaps you can post one of these and keep it as simple as poss for the moment - then my comparison data would be more relevant. eg spark advance and a/f ratio might change with engine load?

As you've seen, when driving all sorts of things change according to airflow, load, revs etc.

Yep CTS anomalies and O2 sensor seem as suspicious as your last moving scan.

[Tuga2112]

to confirm your rpm needle is fine. you can just start the car in neutral. and rev it. a stuck needle will be stuck. but you will clearly hear the engine getting louder after the needle stops moving.

if the needle continues moving past the 3k then you know its ok.

another alternative is to get up to 3k revs in 5th or 4th gear and quickly downshift. the same speed on a lower gear will always bring your rmp above rthe 3k... but its not a very safe means to test

[simonbuk]

Are you any further with finding a solution to your problem ?