I have an LLY with 180,00 miles on it. Its all stock - no delete and no tunes. I recently ran some balance rates on my injectors and noticed that they were all in spec but my fuel rate was low. This was at idle in park at 180degrees. My truck was sluggish and a bit smokey when pushed so I replaced all of the injectors with Bosch OEM remans. The truck seems to run better but my fuel rate is still low. It is running at about 2.5-3.5MM3. Any thoughts on what would be causing this to be lower than spec?
Low Calculated Fuel Rate
- Thread starter jbay
- Start date
What's your actual vs desired mm3? Not knowing what tool your are using, Calculated fuel rate is not all that helpful.
There are several other sensors such as MAF, MAP, fuel temp, and rail pressure that, if erroneous or gummed-up, can cause fuel to be limited.
There are several other sensors such as MAF, MAP, fuel temp, and rail pressure that, if erroneous or gummed-up, can cause fuel to be limited.
Your calculated fuel rate at idle is simply an average of how much fuel is being injected at idle through each injector. Your balance rates are how much fuel each injector is injecting +/- of the calculated fuel rate. Make sure your scanner is reading correctly as I know some apps do not read correctly. Even efilive only reads correct on one fuel rate and not the other. Depending on where you got your injectors, they may not be any better than what you replaced. Were seeing crappy remans in lly's+ now.
Don't think he's talking about being fuel limited. He's talking about it showing 3mm3 of fuel at idle when main fuel rate should be 7-8 for a warmed up engine.
I use a Launch 909E scanner and I think that I have it setup correctly. However, It is new for me. I bought the Bosch OE Remans through Industrial Injection. I did call them and I talked to one of their techs. He suggested that it may be a caused by valve lash out of spec. Another performance diesel company near me suggested that I may have a faulty ECM and that it might just be relaying incorrect data...They also both said that if the truck is running then why worry!
I understand what he is saying. He said the truck seems to run better now with new injectors. But is it actually running the way it should be? Gathering more data rather than taking advice based on subjective seat of the pants feeling would be the preferred approach, no?
I will run another scan with as much information as my scanner produces and then I will post those results for you to review. Thanks, Jesse.
Attached are the scans I ran this morning with as much information as my scanner will produce. My scanner does not produce a desired calculated fuel rate - it only shows an actual. Thanks, Jesse
So the truck runs like it should correct? The only concern you have is a low calculated fuel rate that’s in the scan data?
if the above is correct, stop looking at the scanner and drive it. The fuel rate shown is a calculation, not actual. Now it might say actual but it’s a calculation because there isn’t a sensor measuring how much fuel it actually going to the injectors.
if the above is correct, stop looking at the scanner and drive it. The fuel rate shown is a calculation, not actual. Now it might say actual but it’s a calculation because there isn’t a sensor measuring how much fuel it actually going to the injectors.