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Lotus Elise SC Throttle Problem

446 Views 11 Replies 3 Participants Last post by  Catsailr27
Hi guys,

I've got a throttle problem with my Lotus SC. Whenever I stab/blip the throttle quickly (Rev matching/shifting quickly) the engine would cut off like it's running out of fuel. After releasing the throttle, it would return to normal.
Redlining, idle, part throttle are all perfect.

I've replaced/checked most of the obvious such as new spark plug, reset ecu, vacuum routing, ecu wires intact, etc

Finally when I was taking off the TB to check and clean, I realized that it's making buzzing and crackling noise.
TB Crackling Noise

Also scanned the OBD and getting these codes:

Is it time for a new throttle body?

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1 - 5 of 12 Posts
Maybe just a Pedal Position Sensor (PPS) which will be far less expensive than a TB! And easy to swap yourself.
If that doesn't fix it, check the contacts on the PPS (senses your pedal position). I'm presuming this is a 2006+ model year. The codes you reported mention both TPS and PPS so if one doesn't fix it, the other should be checked too.

Odd that they don't have unique codes for PPS and TPS. They are entirely separate and the ECU can easily differentiate.
Need a scope on the signals to know for sure which sensor is causing that. The PPS reports what your want to the ECU, and the TPS reports what the valve is really doing. The ECU basically tries to "match" the second to the first, with some algorithms in between based on engine conditions.

If I had to guess, I'd fault the TPS. An easy scenario would be that when you punch the pedal the ECU tries to get the valve to react faster too, but if the TPS reports invalid data the ECU may cycle the valve as an attempt at recovery. It's harder to explain this behavior based on PPS failure, because if the PPS fails the ECU shouldn't command the TB to do anything... after all, what would be the "correct" throttle setting when the PPS data is corrupt?
The PPS is part of item 15 in that image. I'm not near an Elige right now but expect #15 to be under the dash. If you want to replace it, I'd seek to replace just the dual pot and not the whole assembly. Very likely it is an off the shelf part.

I still think the TPS is more likely, though. No reason to suspect the TB (yet), the actuator appears to be working just fine.

You've only messed with the connectors. The elements and wipers are much more likely to be the culprit. But the sensors are not serviceable, so you would need to replace each sensor as a unit. Not necessarily the whole pedal assembly nor whole TB, just the sensor(s).
That may be how Lotus sells them, but the sensors themselves are standalone parts they bought from someone. There may be a part number or other ID on the sensors. Worth quite a bit of money to check!
1 - 5 of 12 Posts