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Discussion Starter · #1 ·
I recently purchased my first Lotus, but have an issue that I would like your opinions on. I have searched, but can't find the answer I am looking for. After the car is properly warmed up and I get on the throttle the tach is very laggy and seems to just stop at around 5k RPM's. I can hear the second cam kick in and then what sounds about 2k RPM later the shift light comes on and I hit the limiter as I think it should, but I would like to get the tach to respond how it should. I have tried the reset procedure with the rest button on the column, but the problem remains. Any ideas would be greatly appreciated. I am in Utah, so there isn't a dealer anywhere close to me.
 

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Wow Such Admin
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Have you tried a cluster reset?

1) open door 2) hold reset button in 3) insert key into ignition, turning to II position quickly
 

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Have you tried a cluster reset?

1) open door 2) hold reset button in 3) insert key into ignition, turning to II position quickly

Wow, didn't know that!
I was about to mention a wiped lobe on intake cam.

I'll have to remember that one?


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Dumb question. Did the previous owner have the cluster out and the needles off and just not seat the tach needle fully?

I have seen this on other vehicles. There is enough friction on the needle to move it somewhat but not full travel.

And with the in depth threads about back lighting and gauge face changes, this jumped right out at me.

Just a thought.
 

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Discussion Starter · #6 ·
I guess that is possible. The gauge faces look stock to me, are there any other signs to look for that the cluster has been apart?
 

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Pull your plug coils check for moisture or brown marks from arcing. Coat the shafts liberally with dielectric grease and reinstall. The check fuses in in engine bay. Start up and then try


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Pull your plug coils check for moisture or brown marks from arcing. Coat the shafts liberally with dielectric grease and reinstall. The check fuses in in engine bay. Start up and then try
While that really can't hurt, I would be very surprised if the Tach signal was derived from spark. The ECU has a crank sensor and drives the tach directly. It isn't like an old inductive tach.
 

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Where in Utah are you? Steve Harris Imports still does Lotus work, though they aren't a dealer anymore. They'll charge you an arm and a leg, and talk down to you cause you don't have a Ferrari though.

Turbo Lab in Orem has done tons of Lotus work, including turbo charging four or five Elise's. I've done part time work there, and they know their stuff.

I do all my own work now days, and if you ever feel like driving way out to Heber City, I'd be happy to help troubleshoot. I've had my cluster apart...the check engine light was annoying me so I took it out. :) But then I've got a stand alone engine management system and so it wasn't providing any real feedback.

Anyway, feel free to PM me. If you are interested we've also got a utah lotus owners group. It's not very active, but you can find links to our facebook and google+ pages at uloco.org.
 

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While that really can't hurt, I would be very surprised if the Tach signal was derived from spark. The ECU has a crank sensor and drives the tach directly. It isn't like an old inductive tach.
Tach signal is sent to the cluster via canbus from the ECU. It's picked up off a hall effect sensor on the crankshaft pulley, and sent to the ECU (There's also a 1/2 RPM signal coming off the cam position sensor used to determine cylinder, and the VVT angle ).

If that sensor was broken the car would be throwing error codes all over the place, and probably not run. The issue is most likely in the motor for the tach, an issue in the canbus, or some of the circuitry is fried. It also can happen if the needle was pulled and then put on too tight. It seems to swing in such a way that the tip of it hits the display and it stops moving if you've got the needle on too far.

And yeah I know that cause I made that mistake. :)
 

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Discussion Starter · #13 ·
Thanks a lot Deja Vu. I'll definitely be sending you a PM soon. I am located in the Tooele area about 30 mins west of slc. Heber is not very far at all.

Thanks for the replies guys, sounds like I better hope someone put the needle in wrong for the easiest fix. I have already checked all the fuses, and they all checked out fine.
 

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Wow Such Admin
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If that sensor was broken the car would be throwing error codes all over the place, and probably not run. The issue is most likely in the motor for the tach, an issue in the canbus, or some of the circuitry is fried.
This. With my money being on the malfunction being in the cluster itself.

He said he heard/felt the cam switch over so the engine seems like it is operating normal, just that the tach can't keep up with the actual rpm. So it is very unlikely that it would be a coil or something similar on the mechanical side of things. Like I said, my bet is on the cluster.
 

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It might be worth it to buy a cheap OBDII scanner / torque app and see what your actual RPMs are
 

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Discussion Starter · #16 ·
Just a quick update to this thread... Went on a 200 mile mountain drive over memorial day and about 60 miles in a tach started working perfectly and has been great ever since. Not sure what caused it, but glad everything is working. Loving the car.
 
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