Car shows "limp mode" or "reduced acceleration" warnings (possible ECU issue)

[kitkat]

If driving your car fast after break in nulls your warranty, get a good lawyer. In fact, just get a bad lawyer, because you might as well save a few bucks on this very easy case to win.

Someone let Toyota know

 

[Sandalwood]

Someone let Toyota know

I think they walked back that whole GR debacle, didn't they?

 

[crestima]

It's not a minivan, and even if it were, I've never seen a warranty with limitations on driving speed.
180mph huh? Nice!
The only nulling you need to be concerned about is your driver's license, if the cops catchya.

 

[Jjrho]

Hi , my car went into the limp mode again today....all 3 similar situation ...
Ambient temp >100F, water temp 200 instead of usual 190.... going up hill hitting redline.... and around 3500 to 4000 ft elevation, the car goes into limp.mode n fuel cuts out at 4k rpm.... my car has 1500 miles n it supposedly has the latest ecu update.... it's there a solution yet ?

Oh n btw, as other 2 times, after I came to the car hour later, it was fine n it didn't happen again as I was driving back DOWN the mountain not hitting nearly close to redline....

'24 h yellow
3rd cat deleted
Miktek valve controller

James R
So.Calif

 

[Rupes]

Might be coincidental, but I seem to see a correlation between limp mode and those with the Miltek valve controller and/or 3rd cat delete.

 

[seriously]

Might be coincidental, but I seem to see a correlation between limp mode and those with the Miltek valve controller and/or 3rd cat delete.

I was going to say the same about the valve controller and limp mode. Based on the other post about how you need to install correctly to avoid recalibrating.

 

[Speedy Emira]

Might be coincidental, but I seem to see a correlation between limp mode and those with the Miltek valve controller and/or 3rd cat delete.

I have both of those fitted and had limp mode both before and after fitting them. Turned out to be a faulty lambda sensor and since being replaced I haven’t had a single issue.

Does anyone know if the lambda sensors are standard or wide band?

 

[skydude]

I have the valve controller and I get limp mode after washing my Emira. Wonder if the connectors aren't properly sealed. Once the car is dry after driving a bit it goes away again.

 

[Kimmax]

I have the valve controller and I get limp mode after washing my Emira. Wonder if the connectors aren't properly sealed. Once the car is dry after driving a bit it goes away again.

It's your ECU being drowned.

 

[Jjrho]

i don't think it's directly related to the 3rd cat delete nor valve controller, as i've heard of people having limp mode on their way home from the dealer after picking it up for the first time....

there really is no way to incorrectly install them either....

as to washing your car and it goes to limp w/r/t valve controller...i don't know...i did apply silicon glue all over mine in the wiring loom area/connector cause i was worried about it AND i also did not place the unit in the back by the grill...i pulled it forward and installed mine on the rear subframe where I hope there wouldn't be deluge of water when driving in the rain... (...' seems it never rains in southern california.'.... lol )

could be lamba sensor and fuel trim parameters that are too 'tight' per lotus.... they need to look into this and fax it; as it's affecting many Emiras ....

the fact that it's inconsistently consistent is BAD...

james R
'24 Hethel yellow
3rd cat delete/MIltek controller

 

[Kimmax]

could be lamba sensor and fuel trim parameters that are too 'tight' per lotus

They are not too tight. The ECU gets drowned in water when washing. This shorts out "the connector" / pins whatever of the lambda sensor. Lambda sensor will be damaged by this.

The broken lambda sensor will either:

• read a stuck value
• never come alive
• jump around in the whole range multiple times in a second
• work just fine

Depending on what broken state the sensor is in the car will either run very rough, seemingly normal, smelly or into limp mode. This is due to the ECU trying to compensate the erroneous lambda values using fuel trims. If you drive the car for a bit the ECU might detect "something wrong" after a while and ignore the sensor and instead use a fallback value - car runs seemingly "normal" after that happens. There is no indication for when that happens. The car might also throw some codes or non at all.

I know this because I had this problem (probably the first reported) and it took six(!) sensors until we figured out what was going on and what was frying sensor after sensor. My mechanic macgyver'd the ECU waterproof after we came up with our theory and installed yet another new sensor.

Never had the problem again.

All of the above is a result of me dealing with this problem. I'm not a mechanic, but some info of that in the hands of your trusted Lotus dealer should at least get you going into the right direction.

This is not the "ESC Service required" / "Parking brake" / "ABS" + limp mode error.

 

[Blackthought_]

I can’t fathom how it could be the ECU getting drenched and throwing the car into limp mode. I have over 6500 miles and have wash the car 20+ times and have driven in rain and no issues. The water diverter plastic was installed by my dealer about 1k miles ago.

 

[crestima]

They are not too tight. The ECU gets drowned in water when washing. This shorts out "the connector" / pins whatever of the lambda sensor. Lambda sensor will be damaged by this.

The broken lambda sensor will either:

• read a stuck value
• never come alive
• jump around in the whole range multiple times in a second
• work just fine

Depending on what broken state the sensor is in the car will either run very rough, seemingly normal, smelly or into limp mode. This is due to the ECU trying to compensate the erroneous lambda values using fuel trims. If you drive the car for a bit the ECU might detect "something wrong" after a while and ignore the sensor and instead use a fallback value - car runs seemingly "normal" after that happens. There is no indication for when that happens. The car might also throw some codes or non at all.

I know this because I had this problem (probably the first reported) and it took six(!) sensors until we figured out what was going on and what was frying sensor after sensor. My mechanic macgyver'd the ECU waterproof after we came up with our theory and installed yet another new sensor.

Never had the problem again.

All of the above is a result of me dealing with this problem. I'm not a mechanic, but some info of that in the hands of your trusted Lotus dealer should at least get you going into the right direction.

This is not the "ESC Service required" / "Parking brake" / "ABS" + limp mode error.

where exactly is the ECU located in the Emira?

 

[Kimmax]

where exactly is the ECU located in the Emira?

As per Porter: "The Engine Control Module sits in the left side of the engine bay tucked forward of and above the airbox inlet."

The positioning is strategic and it shouldn't be exposed to high amounts of water there, but still happened on mine. I drove in pouring rain and washed it using a pressure washer. I obviously did not aim it deliberately into the engine bay, air intakes, etc., but I wasn't overly cautious too. After all it's a car that should be able to handle a normal wash. It might look and feel special, but it's still a fairly well-known car format that shouldn't have any of the comical high number of water issues.

I didn't hold back and living the luxury of having a dedicated Lotus dealer nearby we fixed issue for issue and now I have a car which can handle rain downpours and being washed just fine without frying whatever sensors or breaking the AC - I'd recommend everyone else do the same. First one and a half years of driving were always with the possibility of not making it home, none of that now.

It's a blast.

 

[Kimmax]

I have over 6500 miles and have wash the car 20+ times and have driven in rain and no issues.

Love to hear that! Maybe they did actually fix most of the issues on the US cars by now. The water diverter is for the AC, so good thing you have that fitted since it's water ingress problem #1.

I can’t fathom how it could be the ECU getting drenched and throwing the car into limp mode.

I don’t have specific answers for why the ECM seemed to work "just fine" even with water ingress, except for consistently frying the same lambda sensor over and over again. It was always the same bank and position, by the way. The reason this can lead to limp mode is straightforward:

Cars continuously adjust the fuel/air mixture to achieve the best possible combustion in terms of being "clean" and efficient . They do this using sensors in the exhaust stream that measure O2 levels. This data is fed back to the ECM, which, along with additional information, calculates the correct amount of fuel to mix with air. This process is known as a closed feedback loop.

If the ECM receives data from the lambda sensor that "doesn’t make sense", it might switch to an open feedback loop. In this mode, the ECM ignores real-time measurements and instead relies on predefined maps. While these maps aren’t perfect in all situations - since factors like environmental conditions, engine wear, and fuel quality affect combustion - they’re more reliable than calculations based on faulty data. Open loops are also used when sensor readings aren't available yet, for example starting the car or when reaction time is key, like wide open throttle scenarios.

Any combination of this can trigger a lot of different codes. If a sensor is only slightly off or stuck, it might, for example, trigger a "fuel too rich" code, even though the underlying cause of the rich mixture is actually the incorrect sensor reading itself.

Sometimes, no error code was triggered at all in my case(s). The car just ran rough - sometimes it was barely noticeable or only happened at idle, and other times it was almost undrivable. Occasionally, I could get it running better by stepping on the throttle when it was acting up, likely forcing it into open-loop mode. I'm not sure why this didn’t result in a long-term error code.

Don't kill me for half-knowledge - I learned that from dealing with my car and reading on the topics.
Car electronics are mysterious man.

 

[skydude]

One would think a car designed and built in the country of perpetual rain would be able to handle some water :/

 

[Beachbum]

One would think a car designed and built in the country of perpetual rain would be able to handle some water :/

Ireland ?

 

[JClem]

One would think a car designed and built in the country of perpetual rain would be able to handle some water :/

Not to be pedantic but average rainfall at Hethel is less than the French Riviera or the Amalfi coast!!

Still no excuse.

 

[crestima]

Not to be pedantic but average rainfall at Hethel is less than the French Riviera or the Amalfi coast!!

Still no excuse.

Absolutely, no excuse, no matter where one lives. Btw, it may rain a lot more frequently in Ireland, England and all UK Commonwealth nations, and I personally can attest that it does, but I live in Miami which is in the, so called, Sunshine State. When it rains here, it F@*&%#*^ing pours buckets and our streets quickly resemble urban rivers.

 

[Sandalwood]

Absolutely, no excuse, no matter where one lives. Btw, it may rain a lot more frequently in Ireland, England and all UK Commonwealth nations, and I personally can attest that it does, but I live in Miami which is in the, so called, Sunshine State. When it rains here, it F@*&%#*^ing pours buckets and our streets quickly resemble urban rivers.

Yeah, I picture the UK as mild drizzle most of the time, but then a lot of the American South is "mostly sunny, with a chance of life-altering floods".