Help low boost

[gonzo1949]

Hey guys I need some help figuring out this low boost issue. Was driving up 91 in Connecticut when I got the low coolant warning. Pulled over right away and noticed it was a little low. Filler her up and I was on my way. Noticed right away that I no longer had full boost. I don't know if the reason was the coolant light. Either way the rest of the day I only had about 20 lbs max. No check engine, or anything else out of the ordinary. The truck does have the @m*m^2 installed and the only thing I saw strange was that the ecm was commanding 5% for the actuator the whole time I was driving and logging? Any help is greatly appreciated

[dbl overdrive]

(02-23-2016 )gonzo1949 Wrote:  Hey guys I need some help figuring out this low boost issue. Was driving up 91 in Connecticut when I got the low coolant warning. Pulled over right away and noticed it was a little low. Filler her up and I was on my way. Noticed right away that I no longer had full boost. I don't know if the reason was the coolant light. Either way the rest of the day I only had about 20 lbs max. No check engine, or anything else out of the ordinary. The truck does have the @m*m^2 installed and the only thing I saw strange was that the ecm was commanding 5% for the actuator the whole time I was driving and logging? Any help is greatly appreciated

Hi gonzo1949. Have you determined where the coolant is going? I would look at turbo travel as well if the turbo only goes to 5% at all rpm's. You would need to pull the actuator though unless you use calterm to manually control it to see if it's moving.

[gonzo1949]

Yea I found a small leak in the hose that runs to the apu.I'm not sure if it's the actual turbo travel. Correct me if I'm wrong,if the ecm commanded turbo actuator position is 5 then it's gonna stay at 5. My question is y is it commanding 5 at all times.

[Hedley]

it should go up to about 58% at full boost depending on how you set up your tables.

[gonzo1949]

That's what I thought. So y is it commanding 5.

[gonzo1949]

Could it be some kind of silent derate? Is there a way to tell if it's derated?

[Hedley]

@m*m^2 should not have a silent derate in place but if it does it would come up on your fault codes.

[gonzo1949]

Oh ok. Well there's no fault code so I'm lost. I was thinking maybe a bad exhaust back pressure sensor?

[Marajin]

(02-23-2016 )gonzo1949 Wrote:  Hey guys I need some help figuring out this low boost issue. Was driving up 91 in Connecticut when I got the low coolant warning. Pulled over right away and noticed it was a little low. Filler her up and I was on my way. Noticed right away that I no longer had full boost. I don't know if the reason was the coolant light. Either way the rest of the day I only had about 20 lbs max. No check engine, or anything else out of the ordinary. The truck does have the @m*m^2 installed and the only thing I saw strange was that the ecm was commanding 5% for the actuator the whole time I was driving and logging? Any help is greatly appreciated

I know of lots of trucks that have that style of tuning in them that run around with low coolant all day long. they are a lot of old trucks with minor coolant leaks. It was not the coolant light or low coolant that can cause this. Something else must have happened to the truck as well.