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Running lean; Exhaust temperature sensor MD116829?

Ali_6306

Active member
Joined
Aug 15, 2011
Messages
27
Location
Lahore, Pakistan
I have a 4G63 DOHC NA setup from 1988 JDM donor (SRGM2). The donor didn't come with exhaust high temperature sensor. Thanks to the forum members, I added a resistance (0.14 ohms) to address the instrument panel warning light. It is also relevant to mention that the setup has a single wire Oxygen sensor.

My car is running very lean so I introduced adjustable FPR. I reach the stoichiometric level if I set FPR around 58 psi. Which I believe is very high. So I suspect exhaust temperature sensor may be involved in setting AFR as the resistance is currently set at a constant, regardless.

Can someone suggest if this sensor is relevant at all to AFR. If so or not sure, does anyone know a replacement part for MD116829?

Looking forward!
 

tektic

Well-known member
Joined
Dec 19, 2012
Messages
1,497
Location
ronkonkoma, ny
None of that stuff ever shipped to the USA. Try over at the dsmecu.com forum. Many international members there.

Is that ecu matched with that harness and engine? If it's that far off I would assume not.
 

bigandbad

Well-known member
Joined
Sep 6, 2016
Messages
45
Location
Hamburg, Germany
This is a very rare part... It was only used in the 1800 EFI. The model code was E35, and I don't where it was sold - but not in Europe.
You may try it at Amayama in Japan, that still have a lot of NOS parts in stock...
At At MM EU it isn't even listed...
 

Ali_6306

Active member
Joined
Aug 15, 2011
Messages
27
Location
Lahore, Pakistan
Hello Tektic, you are right this may never have been shipped to USA. Although I've seen EGR temperature sensor in wiring diagrams for California versions. Although I am not sure if this is the same sensor. ECU and harness match as they were plugged out from a half cut from Japan. Verified from a wiring diagram as well. But I will try dsmecu.com. as suggested.

Hello bigandbad, thanks for confirming EU source. I am followup with Amayama.

Great that you responded. I had lost all hope - Cheers!

Regards,
 

slugsgomoo

Well-known member
Joined
Oct 16, 2003
Messages
3,776
Location
Tacoma, WA
I don't like exhaust temp unless you're also logging AFR and knock, because without those it's pretty useless. You can be wicked rich and have ridiculous EGT's just by having retarded timing. It's useful, but not by itself IMO.
 

misterfixit

Well-known member
Joined
Aug 4, 2004
Messages
1,596
Location
Midlands, UK
Hi Ali,

This is the thread where we fixed the sensor initially.
click
How are you getting on with it?

Rich
 
Last edited:

Ali_6306

Active member
Joined
Aug 15, 2011
Messages
27
Location
Lahore, Pakistan
Hello Rich! Great to hear from you. Been a while; hope you are well.

We fixed the light, but not the sensor. Used a variable and set resistance to 0.15 ohms.

Issue here is running lean. I am suspecting that this static 0.15 ohm resistance may be preventing ECM from setting appropriate AFR. Tried Amayama, Autopartmaster and many other sites, but none have MD116829 available.

Now considering a universal EGT. However, they come in different types. Would you know what type MD116829 is? I believe it is Resistance Temperature type with Negative Temperature Coefficient (NTC).

Regards, AP
 

kumfasa

Well-known member
Joined
Feb 28, 2015
Messages
125
Location
Tauranga, New Zealand
Is this the sensor that goes into the exhaust just after the catalytic converter?
I have a JDM VR4 and there is a temp sensor in this position in the exhaust, but it is purely to alert to an over-temp cat. It is not used in the fueling calculations at all.
 

Ali_6306

Active member
Joined
Aug 15, 2011
Messages
27
Location
Lahore, Pakistan
Its located around the same area. But since the donor half cut didn't have the sensor, I am not sure if it had a catalytic converter at all. Wondering if MMC connected it to ECM just to show a warning light /ubbthreads/images/graemlins/confused.gif

Anyways, I have ordered a wideband; expecting to get delivered by end of month. I intend to install it and then verify whether changing resistance (by variable) affects AFR at all.

Regards,
AP
 

kumfasa

Well-known member
Joined
Feb 28, 2015
Messages
125
Location
Tauranga, New Zealand
Yep, its purely for a warning light. If it were used for fueling purposes it would need to be much closer to the exhaust manifold/turbo outlet. In its stock position, which is after the Cat it would be far too slow to react to changes in combustion events.

I would look elsewhere for your lean condition. Vacuum leaks first.
 
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