Miltek Exhaust = limp mode? Possible?

[EmirOfDenmark]

This morning I had the Miltek exhaust installed.

Straight from the installation, 5 minutes in, it reported “Reduced engine acceleration” and limited revs.

Switched it off, it reset to normal. Drove on highway, no issues.

Then this evening I took it out again, as soon as I pushed it a bit it reported same error, limited revs. Switched off again, reset.

Continued driving, happened again. Switched off, this time revs back to normal but engine light on. Drove back with engine light on, but no issues, no rev limit.

Parked it, had dinner, came back, switched on, everything back to normal. No engine light. (Haven’t tried driving it since).

Any ideas? Can an OEM exhaust cause this to happen? Had no such issues before the Miltek exhaust install today.

Thanks!

 

[Nova]

The only thing I can think of is the exhaust valve flap - either it's not communicating, or it's not communicating the correct thing. Does Miltek replace the exhaust valve flap sensor or adapt the OEM one to fit?

 

[EmirOfDenmark]

The only thing I can think of is the exhaust valve flap - either it's not communicating, or it's not communicating the correct thing. Does Miltek replace the exhaust valve flap sensor or adapt the OEM one to fit?

No, the stock valve motor and electronics are remounted on the Miltek manifold. It works when I cycle the modes.

 

[KAR120C]

Was your error occurring with the flap open or closed, or both?

 

[EmirOfDenmark]

Was your error occurring with the flap open or closed, or both?

Open, thus far

 

[Nova]

No, the stock valve motor and electronics are remounted on the Miltek manifold. It works when I cycle the modes.

If it is intermittent, or catches occasionally, it will throw codes. In my experience with electronic flap valves on the exhaust, it can absolutely cause limp modes.

 

[Kimmax]

Already had flap control issues on my stock exhaust. Dealer recalibrated it and it never complained again. Probably yours was right on the edge of needing calibration and remounting it was the last nail in the coffin.
Sadly you can’t recalibrate yourself, nor your ordinary backyard mechanic. Official Lotus Insight tool is needed. You can confirm my suspicions using a regular OBD II reader, the code thrown will be exhaust related.
I recommend anyone with an Emira to get a reader anyway 😂

 

[EmirOfDenmark]

Already had flap control issues on my stock exhaust. Dealer recalibrated it and it never complained again. Probably yours was right on the edge of needing calibration and remounting it was the last nail in the coffin.
Sadly you can’t recalibrate yourself, nor your ordinary backyard mechanic. Official Lotus Insight tool is needed. You can confirm my suspicions using a regular OBD II reader, the code thrown will be exhaust related.
I recommend anyone with an Emira to get a reader anyway 😂

Thanks. Can this cause engine damage in any way? Safe to drive?

 

[EmirOfDenmark]

If it is intermittent, or catches occasionally, it will throw codes. In my experience with electronic flap valves on the exhaust, it can absolutely cause limp modes.

Thanks. Is this a loose connection issue, or more complex you think?

 

[KAR120C]

Thanks. Can this cause engine damage in any way? Safe to drive?

As long as the flap is actually open under load or at high rpm it should be fine. The problem occurs when you're pushing the engine and the valve stays closed. It's designed to open regardless of driving mode to prevent too much backpressure.

 

[EmirOfDenmark]

As long as the flap is actually open under load or at high rpm it should be fine. The problem occurs when you're pushing the engine and the valve stays closed. It's designed to open regardless of driving mode to prevent too much backpressure.

I see. So is this the ECU going “hmm the flap doesn’t seem to be reporting back properly, so just to prevent to much back pressure, I’m lowering the revs”?

Is there a way to just have the flap open all the time?

(Thanks so much for your explanations, much appreciated)

 

[Kimmax]

I see. So is this the ECU going “hmm the flap doesn’t seem to be reporting back properly, so just to prevent to much back pressure, I’m lowering the revs”?

Is there a way to just have the flap open all the time?

(Thanks so much for your explanations, much appreciated)

Yes, the ECU doesn't like what the flap is (or is not) doing, and since it belongs to a critical part of the engine - the exhaust system - goes into fail-safe.
I actually believe that in fail-safe/limb mode the flap is fully open at all times. At least it sounds like that when I hit limb mode. I have nothing to prove it tho
Too much back pressure can negatively affect emissions and overall engine performance, but it won't "damage" the engine realistically. I'd call up the dealer for an appointment and till then drive the car as you wish

 

[EmirOfDenmark]

Thanks again - very useful.

I’ve connected the ODB reader and it is showing code P1018. Anyone has an idea where I can look up ODB codes for Emira?

The pattern seems to be that first time it happens it throws the temporary (amber) P1018. This means limp mode and no engine light. Then, when it happens again in the same “driving session” it throws a red P1018, and the engine light comes on, but strangely no limitation.

I have two options, I think: 1) put on the stock and take it back to dealer (I suppose dealer would not like non- stock exhaust re warranty) or, 2) Get a Miltek valve controller which allows the valves to be open all the time

 

[ADC]

Thanks again - very useful.

I’ve connected the ODB reader and it is showing code P1018. Anyone has an idea where I can look up ODB codes for Emira?

The pattern seems to be that first time it happens it throws the temporary (amber) P1018. This means limp mode and no engine light. Then, when it happens again in the same “driving session” it throws a red P1018, and the engine light comes on, but strangely no limitation.

I have two options, I think: 1) put on the stock and take it back to dealer (I suppose dealer would not like non- stock exhaust re warranty) or, 2) Get a Miltek valve controller which allows the valves to be open all the time

You've already come this far with the modification... I'd go with option 2 if it were me

 

[Nova]

Thanks. Is this a loose connection issue, or more complex you think?

It could be a loose connection or a binding mechanical flap/actuator. I would get the shop that installed it to check: make sure no wires were nicked/cut, check that the flap rotates freely with no stiction or binding. Part of the challenge is that the valve needs to be able to rotate while under exhaust pressure, so while it may rotate freely at idle or off, it may bind while the car is running above some specific RPM.

Getting the Miltek exhaust controller may solve the check engine light problem - these systems typically are programed to tell the ECU what it wants to see even though the exhaust flap remains fully open. However, if the exhaust flap is actually having a mechanical problem and does not fully open, then you could have engine failures due to excessive back pressure.

 

[kitkat]

Thanks again - very useful.

I’ve connected the ODB reader and it is showing code P1018. Anyone has an idea where I can look up ODB codes for Emira?

The pattern seems to be that first time it happens it throws the temporary (amber) P1018. This means limp mode and no engine light. Then, when it happens again in the same “driving session” it throws a red P1018, and the engine light comes on, but strangely no limitation.

I have two options, I think: 1) put on the stock and take it back to dealer (I suppose dealer would not like non- stock exhaust re warranty) or, 2) Get a Miltek valve controller which allows the valves to be open all the time

why isn’t having the people who installed the exhaust fix the issue an option?

 

[EmirOfDenmark]

Thanks Nova!

That's what I concluded thinking about this as well. If the flap is physically constrained in some way, then the valve controller would not be able to report in time that it managed to open it. And the ECU would then limit the backwards pressure by reducing the revs.
Wouldn't the Miltek valve controller in open position prevent back pressure, as the valves would be open all the time?

 

[EmirOfDenmark]

why isn’t having the people who installed the exhaust fix the issue an option?

Of course! I am talking to them as well. That is my default option. But they still need to do something - the question is what?

 

[kitkat]

Of course! I am talking to them as well. That is my default option. But they still need to do something - the question is what?

They should be checking the exhaust valves — simple as that. They should check to see if any are broken, should be checking continuity, checking connectors and pins to see if any were damaged. The usual diagnostics one would run on them, they should be able to handle this, don’t think you need to spell it out for them — right?

 

[EmirOfDenmark]

They should be checking the exhaust valves — simple as that. They should check to see if any are broken, should be checking continuity, checking connectors and pins to see if any were damaged. The usual diagnostics one would run on them, they should be able to handle this, don’t think you need to spell it out for them — right?

You are right, and since yesterday, they took ownership of the problem, contacted Miltek, and are asking me to bring it in so they can do exactly as you suggested. I think this is either a valve controller calibration issue (i.e. it needs to operate slightly differently with Miltek compared to the stock exhaust), or the Miltek valve is malfunctioning at high pressure.