Ficm Voltage

[SandawgK5]

Is it possible for the FICM to be going bad but not have voltage fluctuations? Reason I ask is my mileage is kinda sucky, only about 13 average with SRL loaded and no difference between that 8K or unlimited tow. Voltages are between 48.5-47.5.

Also even with it being 90 outside it cranked for over 7 seconds before it would fire. It has been doing this every time no matter how long I sit and let the glow plugs heat the cylinder.

Just looking for opinions.

Dik

[ZMANN]

you need to check the actual cranking voltage at the FICM
but after it fires and if it's up to those #'s it should not be effect mileage IMHO

ps I get the same MPG on a known good truck/FICM ,, the tires take a toll

[SandawgK5]

Cranking it didn't budge stayed right at 48. It just started doing it in the last month but mileage took a hit almost 8 months ago. Might just be programming and speedo cal.

Dik

[ZMANN]

the cts wont read fast enough to see a cranking drop at the FICM in My opinion

[SandawgK5]

even if I am cranking for more than 5 seconds?

[WarChild]

The CTS reads the ranking volts just fine if you start the CTS before you start your truck. You do that by touching the screen. To answer the OP's question No it can't be. But there are a lot of.things that can make your mpg suck. Are there at codes?

[SandawgK5]

Nope no codes not even non CEL codes "silent" codes I would call them. It isn't that bad but 16 for a full tank of highway driving was kind of a shock. In reality tuned on 35s it isn't bad. I am more concerened about the longer than normal cranking times but as I think about it, it might be glowplug controller or just glow plugs are getting old and need changing.

Dik

[elm302]

Yes it can be bad and still show good voltage. My bro in laws truck read a constant 47.5-48 volts while cranking and running. But it had a horrible cold start and running problem. I wrecked my truck that I had just put a new ficm in about 2 months earlier. We put my new ficm in his truck and it started perfect from then on. Put his ficm in mine and would run like crap.

[Country Mav]

Originally Posted by SandawgK5

Nope no codes not even non CEL codes "silent" codes I would call them. It isn't that bad but 16 for a full tank of highway driving was kind of a shock. In reality tuned on 35s it isn't bad. I am more concerened about the longer than normal cranking times but as I think about it, it might be glowplug controller or just glow plugs are getting old and need changing.

Dik

Well, 16 is top of the mark for my truck. And I'm at stock height with 285's... What were you getting?

[SandawgK5]

I was getting 19 highway and 13 city. It is down to 16 highway and 11 city. I don't baby it either.

Dik