VEMS and EGT

[Billman]

New sensor installed and still seeing the same WTF???
I pulled the connector out and checked with a Multimeter and dont getting any readings at all? What can it be? Cant it be that a failure in VEMS ECU destroyed the second sensor also?

Can it be that the EM has bad ground or something?

Can it be that because it runs with other cables along that something interfeares?

[diesel des]

With my sensor disconnected vems reads 0. Try measuring sensor voltage on mv dc. the voltage is small but it should show a difference with engine running.

[GazzaG60]

lets face it. if the engine is running its producing heat and gas. the gas isn't 0 the over 1k in one go.

there must be a wiring or sensor fault. even controller.

if its a new pribe trace the wiring back. those connectors are only small.

if not you have vems gauge right? move the probe to gauge or ecu and test.

if not its multimeter time as stated by terry and co

[Billman]

I dont have VEMS gauge only ECU. Wiring seems ok. Probe with wire is new, came in yesterday.

I will check once again today with the multimeter.....i think after that is VEMS ECU service time.

[GazzaG60]

that would be a shame. i dont have a probe connected to my ECU though. gauge only.

ive never heard of a vems failure.

[A80Avant]

you could check if the wires are ok in the connector plug of the sensor. However when i had the cables mounted the other way around, i remember i wasnt getting any signal at all.

[Billman]

The wires are ok I double checked and it was ok!

[Billman]

Sensor is working. I have connected it again to the multimeter and when I heat the tip it works. So the problem is somewhere else! I also removed the connector that goes to the ECU and made the connection a bit better but didn't had the laptop to check. If it doesn't then I really don't know.

[Billman]

Still doesnt work. What can go bad inside VEMS so that it cannot show EGT? Is there any diagram or picture of this area in vems?

[GazzaG60]

gotta say id go for a wiring thing first.

can your multi supply mV also. if so get a reading for the probe at say 500c and feed that to the vems. if the vems gauge shows 500 jobs a good'n

[Val]

I've got similar problem.

egt faulty.jpg

With turned ignition on, it shows approx correct temperature in exhaust manifold.
When engine is running and sensor is in exhaust manifold, EGT temperature jumps to 1200C and stays there.

If sensor is put on top of engine (doesn't touching any grounds), temperature is about normal.
With sensor disconnected, VEMS reads 0.

Best thing to do is short the k-type wire as close to the unit as possible, this will create a thermocouple junction which will be measuring the temperature at the join,

Haven't yet soldered capacitator between egt wires. That's why temperature keeps jumping.
wire in vems egt connector.jpg

I have already stipped external insulation from EGT wire searching from wires shorted etc... nothing. Wire looks good.

Multimeter is my next step tomorrow.
What else I can do other than buying new EGT sensor?


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[Billman]

hey, take a look at this:

24.08.2010

EGT problems 0 to 1125 Celsius and again 0 changing every second on VEMS. The sensor is brand new and came in yesterday. Where is the problem? Can it be the controller inside VEMS?

yes, possibly. Try to short the EGT inputs, white and green wires.
also, try to disconnect EGT sensor, and short the EGT inputs, white and green wires. See what happens
you can also try with EGT sensor connected, but removed from the exhaust. Maybe some ground-loop causes this problem
make sure the EGT inputs don't touch +12V, not even for a split second

Answer

Removed sensor-no change
Short wires-no change
opened VEMS today and seen no wiring issues

-If i wanna change the AD597 do i need something special or i simply replace it like every SMD chip?

it can be replaced easily
it does not need extra calibration
however, test some mcp3208 analog input (EGT also connects via mcp3208). If the problem is from mcp3208, than changing AD597 won't fix the issue.
make sure to stay in 0-5V range (12V on mcp3208 input damages the board immediately)

It was the mcp3208

and also here

http://www.vemssupport.com/forum/index.php?topic=1385.0

[Val]

Thanks for answer.
Analogue inputs are working (configured them today earlier), so mcp3208 should be ok.
When I calibrated sensor, it showed correct temperatures - boiling water and ice.

I'm thinking about ground loop or some sort.

[Val]

Sensor was faulty. I borrowed new sensor and everything's working.

[ian4455]

Isn't the mcp3208 a programmable chip? Can i have it replaced and vems firmware re-programs it ? Been quoted £50 for replacing the chip, does this seem a ok price ?