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Check engine - running rich


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Hi everyone. I've been battling a check engine light for a few months now and the dealership doesn't seem to get the grasp of it. My car is running rich. Replaced the mass airflow sensor, air filter, a leaking fuel injector, many ECU resets and a vacuum leak but the problem always comes back. My car has around 58K KM still on the factory spark plugs. Fuel economy is terrible in the city, slightly rough idle and a considerable loss of power on lower rpm. It stalled on me quite a few times on hard braking down to a stop. Any feedback is highly appreciated.

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Mine also has been running for a while with P0172/P0175 codes. Also replaced all the same things you did, in addition to the pre-cat O2 sensors. Idle is fine, and I don't really notice a huge hit to fuel economy, so I haven't spent too much effort resolving it. I did take it in to my indie shop and had them update the ECU with the latest code, which resolved it temporarily, but it's come back after a few weeks. They did indicate that if the update didn't fix it, it's likely fuel pressure related (which was a bit out of spec). I went ahead and ordered both a replacement fuel rail (comes with the fuel pulse damper that you can't get separately for some reason) and the pressure regulator found at the fuel pump. Haven't had a chance yet to install either (and my next inspection isn't for another 2 years 😂), but will follow-up once I do if this resolves it. 

 

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17 hours ago, Elmagnoon said:

I've been battling a check engine light

Do you know what the codes are?

88 Esprit NA, 89 Esprit Turbo SE, Evora, Evora S, Evora IPS, Evora S IPS, Evora S IPS SR, Evora 400, Elise S1, Elise S1 111s, Evora GT410 Sport

Evora NA

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On 27/10/2020 at 15:14, Elmagnoon said:

Hi everyone. I've been battling a check engine light for a few months now and the dealership doesn't seem to get the grasp of it. My car is running rich. Replaced the mass airflow sensor, air filter, a leaking fuel injector, many ECU resets and a vacuum leak but the problem always comes back. My car has around 58K KM still on the factory spark plugs. Fuel economy is terrible in the city, slightly rough idle and a considerable loss of power on lower rpm. It stalled on me quite a few times on hard braking down to a stop. Any feedback is highly appreciated.

Very similar issues to mine!

Sounds strange but changing the clutch pedal sensor did make a bit of a difference for me.....

I'm changing the plugs next....

I'm on 64k miles.

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On 01/11/2020 at 06:54, Hangar 111 said:

Is it a supercharged car? If so check the function and integrity of the bypass actuator.

Dave

Sorry, just to clarify, are we talking about the supercharger bypass actuator? How did you check function of it please?

Thank you!

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On 02/11/2020 at 12:02, Reindeer said:

Sorry, just to clarify, are we talking about the supercharger bypass actuator? How did you check function of it please?

Thank you!

Make sure that it can hold a vacuum - if the diaphragm is knackered, that's a potential unmetered air leak which would upset the mixture.

If it holds itself open at idle, that's a reasonable indication, but there is a decent chunk of vacuum at idle.  If you can vacuum test it, that's a better test.

If bypass is not operating correctly at low rpm then you will be getting boost when you shouldn't.

Dave

Edited by Hangar 111
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  • 1 month later...
On 28/10/2020 at 12:33, Bibs said:

Do you know what the codes are?

Sorry for the late reply, error codes p0172 and p0175. Also a quick update: got the spark plugs replaced as part of the 60K service but that didn't fix the problem. Left the car for 3 weeks at the shop. They did additional diagnostics, sending data back and forth to the factory. The factory came back that it's "probably" the cats that are throwing the codes. The dealership wants to charge me $6000 to replace the cats + labor, which is unbelievable.

Questions:

1. Is it possible bad cats will cause the issue?

2. Anyone aware of the Toyota replacement part for this? It will definitely be cheaper if it's a direct replacement.

3. Wouldn't it be cheaper to get an aftermarket exhaust? Note that we don't have emissions where I live, so I can get away with test pipes, just not sure what parts to buy, so I'd appreciate some help from the experts here if possible.

On 01/11/2020 at 10:54, Hangar 111 said:

Is it a supercharged car? If so check the function and integrity of the bypass actuator.

Dave

Hi Dave,

Yes it's an Evora S supercharged. One thing that I haven't mentioned in the past is that some bearings are getting very loud on hard acceleration. Not sure if it's the supercharger bearings or drive belt bearings. The drive belt has snapped on the previous owner and has been replaced around 20K KM ago.

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I can’t help with what the cause might be. But if it does come to replacing the catalytic converters then for that price you should probably get an aftermarket system.  Many options out there with sports cats giving sounds and power boost while passing emissions tests. Or if you don’t need to worry about emissions then you could even go for straight through exhaust too.  You have options available from 2bular, Hangar, Larini, Komotec and possibly a few more. 

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Get two 30GBP O2 simulators to screw in at the POST cat O2 bungs (so between exhaust and both post cat O2 sensors).  If the error code stays away, than indeed the cats are faulty.  They blow through, so you can call it a day then and run with these simulators in place (provided you don't need to pass emissions).  With an aftermarket exhaust and sport cat, you MIGHT need them too: the aftermarket sportcat sits a bit far down the exhaust path and might warm up a tad slow, triggering the P017x codes (cat below efficiency threshold), especially on the <200 cpi cats.   In that case you could also run without an aftermarket cat at all... the O2 simulators trick the ECU a cat is still in place.

Something like these (get the mini cat ones):

 

http://www.bigdaddiesgarage.com/mini-cat-cel-fix.html

Of course, not debating the environmental impact.

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