correct value for warm CHT reading (ohms) Options

[brant]

so my CHT reading was 76 ohms - hot (at 180F oil temp)
I'm reading 2 different things.. on the Brad anders site


one saying that a warm reading should be below 100 ohms
but then the table shows this: for 210F

Sensor Temp = 39 deg. F Temp = 61 deg. F Temp = 210 deg F

0 280 130 003 6.10 K ohms 2.94 K ohms 199.3 ohms
0 280 130 012 NA 2.85 K ohms 191.2 ohms
0 280 130 017 3.63 K ohms 1.74 K ohms 124.7 ohms



I'd love some input from Djet folks about what numbers you see on a warm motor?

brant

[brant]

James,

super glad for your input.

I may be chasing nothing.
my plugs look a bit lean
and so far everything is testing spot on
car actually drove great (to santa fe and back to colorado for the RT66)

but my CHT gauge quit working and I pulled the thermo coupler to check it at the event.
noticed that plug was a bit lean... so pulled the other plugs and they are all the same.

I'm going to put the Innovate on it today and see what the actual AFR's are running at warm...

I'm guessing I might have to re-tune the MPS
however, it tested great last night and I see no reason for the car getting "leaner" as the plugs showed.

I will see what the AFR's look like
just seemed like the most likely thing could be a failing CHT sender... but it tests good hot and cold so maybe not....

[JamesM]

Usually when I have seen issues with CHTs or MPS failing things go RICH

Leaky MPS reads as higher load= rich
Increased resistance or BROKEN wire on the CHT circuit = rich

The CHT circuit SHORTED to ground could possibly cause a lean condition, but if that was the case you would most likely notice your car running like complete crap during warmup.


I have never been to confident in my plug reading beyond an engine being obviously rich or lean, Wideband is a good idea for accuracy however you may have a hard time getting the full picture with an instantaneous reading off a gauge as its most likely going to bounce around a bit, I prefer full datalogs to see what is going on over wider operating conditions, but either way should be better data than looking at the plugs

For some reason my gut is saying something with the fuel especially given it sounds like nothing else has changed and its running without noticeable issues....

Gas with any ethanol in it you want to run a couple points richer. Winter/summer blends can burn differently from each other as well as can different brands depending on the additives.

Have you checked your fuel pressure? Unless you have already opened up your MPS, bumping up the fuel pressure a bit may be an easier/safer way to get it slightly richer as MPSs can be a bit touchy, especially if you want to get it back to your prior settings.

Thats a bummer about the head temp gauge. I was going to say if its running good and the head temps are in a safe range I probably wouldn't worry about it. D-jet tends to float around a bit depending of if a fly happened to fart in your engine compartment on any given day (IMG:style_emoticons/default/tongue.gif)

My purple 1.7 car still has d-jet, I run it with zero gauges of any sort as to not obsess about how its running, otherwise I would probably go insane.