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Xisthos

Car misfiring and running very rich - need help

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Hey guys,
 
Wanted to ask for your inputs on what could possibly be the issue here. I'll try to make it as concise as possible.
 
Last September of 2017, I had my manifold & cat changed to Larini, which I use with my Lotus sports exhaust. Around December, I had a premature failure on my clutch, so I brought it to the dealer to have it changed. As many of you guys know, it requires a whole lot of work including removing the clamshell and pretty much all the electrical connections, and the engine itself. 
 
When I got back the car, I was still breaking in the new clutch and taking it easy, and it was running great, although I never really tried to rev it past 4k. The only strange thing is that I would always get a CEL with a P0140 and 0141 code, where the oxygen sensors have no activity detected, which is strange because it didn't get it when I removed my cat and used 02 extenders, and was driving it very spiritedly and tracked twice for a few months.
 
About 400kms in, when I had to brake suddenly one time, the car died on me despite being clutched, and would not restart right away. It took a few tries before it got up and running again.  When I would try to start the car, it would just click repeatedly and the dash lights would flash faintly. This happened on 3 more separate occassions, with a third time being the worst. During the last time, the car just would not start. It's worth mentioning that I always use the car, and when I don't always have it hooked up to a battery tender. At that time, I had to call the dealer for assistance and the car basically shutdown itself. It would not even respond to the car remote to open the doors, and when they checked the charge at the posts behind access panel while we were trying to charge it, the voltage was going up and down. Finally after about 45 mins, the charge just suddenly went up and we were able to open and start the car. During those times I was getting these codes:
 
P0685 - ECM/PCM Power Relay Control Circuit/Open
P0140 - 02 Sensor Circuit No Activity Detected Bank 1 Sensor 2
P0141 - 02 Sensor Heater Circuit Bank 1 Sensor 2
P0430 - Catalyst System Efficiency Below Threshold Bank 2
 
So off to the dealer it went to check what was wrong with the car, and they said that they inadvertently put back the sensors the wrong way. The main problem was that after this, the car would NOT run fine anymore. It was misfiring on 4 cylinders and running very rich. We have tried changing the plugs, switching out the injectors and the oxygen sensors to another car, and they were running fine. Of course you can imagine that the dealer is now blaming the fact that it's running without a cat, even if they know that it was running fine for several months without it. They're also pretty much at their wits end and personally because the immobiliser was involved in the previous incident, I am beginning to think that the ECU or the wiring might be damaged in a way. They have tried checking the plugs, coil packs, injectors and the MAF. They are still however, getting a P0134 code. 
 
Any help would be greatly appreciated guys. Thanks in advance!

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If you have the Larini manifolds you also must have O2 sensor extension cables. Maybe there is something wrong with the O2 extension cables instead of the O2 sensors.

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If the car just clicks away when trying to start, that sounds like a battery/earth problem to me, same with opening the door.

cheers

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Yes correct, we are going to check the current running through the extension cables soon. Re draining issue, when it was already at the dealer, all of a sudden it wasn't draining anymore, strange. 

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What/where are the post-cat O2 sensors connected?

Assuming your dealer has Lotus TechCentre, they can observe the live data for the O2 sensors, which will tell you straight away if they are working as expected.

The cars typically don't like running without a cat - if nothing else you are probably losing power but gaining noise.

Dave

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Unfortunately we don't have a TechCentre here, the dealership actually just started two years ago and we are their first customers. 

I am not completely sure where the post cat sensors are specifically situated, I was just assuming that they were around where the length of the cats previously were. 

You are right, I did notice that I lost torque on the low end, but it was noticeably quicker past 210kmh. 

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P0134  O2 Sensor 1 Circuit No Activity Detected (Bank 1)... so I'm with Dave, probably lambda sensor on bank 1 defective or something wrong in the cabling.  Shouldn't be a big issue.

Dirty test would be to switch the connector or sensor from the other bank; you should get a P0154: O2 Sensor 1 Circuit No Activity Detected (Bank 2) 

 

HOWEVER, you need to have a POST catalyst O2 similator (x2) for the lambda sensors or you'll trip P0430.  As to the reason why it ran fine for several months: more restricted intake air flow?  Hotter climate, air filter element getting dirty, airbox flap stuck?

I would stick in 2 O2 simulators post cat and replace the lambda on bank 1 pre-cat.

Edited by Kristof Thys

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Thanks for the inputs guys, we'll be checking these out soon and hopefully find the culprit. 

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As per Kristof - you can't just stick the post-cat O2 sensors back in and hope for the best, you will get post-cat codes in that case.

An unresponsive O2 sensor code would usually be accurate, so would recommend checking the extension leads and connectors.

In our past experience, the Larini headers are restrictive (they may have changed the design now?), and a de-cat will usually cause issues.

Dave

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4 hours ago, Xisthos said:

Thanks for the inputs guys, we'll be checking these out soon and hopefully find the culprit. 

If you do find the O2 extension cables or the lambda sensors itself to be faulty I have lambda sensors that allready have the correct lenght wireing so that you don't need extension cables.

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On 3/24/2018 at 01:29, rasasoufe said:

If you do find the O2 extension cables or the lambda sensors itself to be faulty I have lambda sensors that allready have the correct lenght wireing so that you don't need extension cables.

Thanks, will definitely let you know. 

On 3/24/2018 at 00:30, Hangar 111 said:

As per Kristof - you can't just stick the post-cat O2 sensors back in and hope for the best, you will get post-cat codes in that case.

An unresponsive O2 sensor code would usually be accurate, so would recommend checking the extension leads and connectors.

In our past experience, the Larini headers are restrictive (they may have changed the design now?), and a de-cat will usually cause issues.

Dave

I'm pretty sure it's the same design, unless they had a revision that I didn't know of. Please enlighten me though, what exactly happens with the de cat aside from throwing off the sensors? Living in a country where our regular temps are 35 degrees C, I was hoping to lower my temps as well. 

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