EGT Issues after decat
#1
Scooby Newbie
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EGT Issues after decat
Hey,
I recently swapped out the downpipe on my 2003 Blobeye WRX for one with a high-flow cat, also removing the cat pipe and swapping the uppipe for a cat-less STI one. I’m not sure if this is connected.
So I got a new EGT sensor and it is just reading either 200 or 365 (°C), nothing in between and nothing other than those two numbers. I’ve tried a different EGT sensor and I get the same result. Before I changed the cats, it was working fine.
I’d like to keep the sensor as a failsafe - especially as I’m running meth/water injection and want the added backup in case the meth system runs out/fails and I don’t realise.
I have CELs for slow lambda sensor response (due to the cats), and sometimes I get CELs for low EGT voltage. I’ve tried clearing these/resetting ECU and it doesn’t change anything. The EGT sensor is OEM.
Has anyone else had this EGT sensor issue? Or knows what it could be?
Thanks
I recently swapped out the downpipe on my 2003 Blobeye WRX for one with a high-flow cat, also removing the cat pipe and swapping the uppipe for a cat-less STI one. I’m not sure if this is connected.
So I got a new EGT sensor and it is just reading either 200 or 365 (°C), nothing in between and nothing other than those two numbers. I’ve tried a different EGT sensor and I get the same result. Before I changed the cats, it was working fine.
I’d like to keep the sensor as a failsafe - especially as I’m running meth/water injection and want the added backup in case the meth system runs out/fails and I don’t realise.
I have CELs for slow lambda sensor response (due to the cats), and sometimes I get CELs for low EGT voltage. I’ve tried clearing these/resetting ECU and it doesn’t change anything. The EGT sensor is OEM.
Has anyone else had this EGT sensor issue? Or knows what it could be?
Thanks
#2
Scooby Regular
Out of interest where have you fitted this EGT sensor?
#3
Scooby Newbie
Thread Starter
#4
Scooby Regular
That location would be where the A/F sensor would normally be fitted unless you've changed/modified the manifolds?
#5
Scooby Newbie
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#7
Scooby Newbie
Thread Starter
Also, that wouldn’t change the fact it’s not reading correctly, would it?
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#8
Scooby Regular
Just to be perfectly clear, you've moved the location of the EGT probe from it's old location at the top of the up-pipe to somewhere close to the O2 (A/F) sensor (Bank 1 Sensor 1) by welding on a boss, drilling and tapping the manifold and extending the wiring to suit?
Is the tip of the probe in the central gas flow?
How are you reading the EGT output values?
Referencing your CEL's which slow response one did you get?
P0133 O2 (A/F) Sensor Circuit Slow Response (Bank 1 Sensor 1)
P0139 O2 Sensor Circuit Slow Response (Bank 1 Sensor 2)
and EGT low voltage?
P0545 Exhaust Gas Temperature Sensor Circuit Low-Bank 1
P0546 Exhaust Gas Temperature Sensor Circuit High-Bank 1
Is the tip of the probe in the central gas flow?
How are you reading the EGT output values?
Referencing your CEL's which slow response one did you get?
P0133 O2 (A/F) Sensor Circuit Slow Response (Bank 1 Sensor 1)
P0139 O2 Sensor Circuit Slow Response (Bank 1 Sensor 2)
and EGT low voltage?
P0545 Exhaust Gas Temperature Sensor Circuit Low-Bank 1
P0546 Exhaust Gas Temperature Sensor Circuit High-Bank 1
#9
Scooby Newbie
Thread Starter
Just to be perfectly clear, you've moved the location of the EGT probe from it's old location at the top of the up-pipe to somewhere close to the O2 (A/F) sensor (Bank 1 Sensor 1) by welding on a boss, drilling and tapping the manifold and extending the wiring to suit?
Is the tip of the probe in the central gas flow?
How are you reading the EGT output values?
Referencing your CEL's which slow response one did you get?
P0133 O2 (A/F) Sensor Circuit Slow Response (Bank 1 Sensor 1)
P0139 O2 Sensor Circuit Slow Response (Bank 1 Sensor 2)
and EGT low voltage?
P0545 Exhaust Gas Temperature Sensor Circuit Low-Bank 1
P0546 Exhaust Gas Temperature Sensor Circuit High-Bank 1
Is the tip of the probe in the central gas flow?
How are you reading the EGT output values?
Referencing your CEL's which slow response one did you get?
P0133 O2 (A/F) Sensor Circuit Slow Response (Bank 1 Sensor 1)
P0139 O2 Sensor Circuit Slow Response (Bank 1 Sensor 2)
and EGT low voltage?
P0545 Exhaust Gas Temperature Sensor Circuit Low-Bank 1
P0546 Exhaust Gas Temperature Sensor Circuit High-Bank 1
That is correct. All apart from extending the wiring. Unclipping the EGT probe plug, from where it sits at the top left of the engine bay, gave enough length for it to reach the probe in its new position.
I have no reason to think the probe tip isn’t in the centre - it sits just as proud from the external of the pipe as it did in the OEM position (and to eye the pipes are the same diameter). Even if it wasn’t in the centre, I would’ve thought the readings would at least fluctuate instead of sitting at one of two discrete values.
I’m using a Tactrix v2 cable, reading through the ECU. I have used this to both log independently to SD and through RomRaider logger.
The CELs were for P0139 and P0545.
Thanks again
#11
Scooby Newbie
Thread Starter
Why would that stop it working entirely though? It’s only a k-type thermocouple. It will output a potential difference relative to the temperature experienced. I don’t understand why it’s only giving 2 discrete output instead of a quasi-continuous output
It almost seems like a short, and I was wondering if anyone had countered this before or could give me further insight
It almost seems like a short, and I was wondering if anyone had countered this before or could give me further insight
#13
Scooby Newbie
Thread Starter
Yeah, I can appreciate that. And I’m not writing off re-adjusting the position. I just feel that it should still read something, even if it’s only before the engine is running at full temperature - and it’s a fair bit of work to move it round so wanted to make sure I wasn’t missing anything obvious.
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#14
Scooby Regular
Did you look at the DTC pdf attached to post #8 ?
#15
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kwakman
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11
31 October 2002 08:41 PM