Monitor fuel rail pressure with a gauge.

dieselenthusiast · **Posted:** Tue Apr 22, 2008 12:47 am

Di-Pricol makes a Optix series 0-30,000 PSI common rail fuel pressure gauge. These gauges come with all the wiring and adaptors that will plug directly into the factory wiring harness. Now we can monitor fuel pressure after adding aftermarket pressure boxes and programmers. Currently, Di-Pricol has a kit for the Dodge Cummins. I’m sure it would be easy to make one for the Liberty CRD.

geordi · **Posted:** Tue Apr 22, 2008 1:08 am

Why would we need to make a different kit? Don't we have the same CP3 pump as the Cummins?

Sir Sam · **Posted:** Tue Apr 22, 2008 1:24 am

geordi wrote:

Why would we need to make a different kit? Don't we have the same CP3 pump as the Cummins?

yes, and we have the same plug on the CP3 for fuel pressure, and we likely have the same sensor on the fuel rail, if this product works by plugging in there then its likely that it could work with our vehicles.

gmctd · **Posted:** Tue Apr 22, 2008 1:29 am

Wow, dat's 'spensive, Lucy................

dieselenthusiast · **Posted:** Tue Apr 22, 2008 1:37 am

Sir Sam wrote:

geordi wrote:

Why would we need to make a different kit? Don't we have the same CP3 pump as the Cummins?

yes, and we have the same plug on the CP3 for fuel pressure, and we likely have the same sensor on the fuel rail, if this product works by plugging in there then its likely that it could work with our vehicles.

Well, you answered that question....................................So this might be a nice option for those of you who are looking to monitor your fuel rail pressure. :wink:

Uffe · **Posted:** Tue Apr 22, 2008 4:11 am

I'll be taking a closer look at rail pressure in my bosch book tonight, just to see what range the gauge will have to be in. I think I read somewhere that rail pressure is constant, but I don't feel too sure about it.

Uffe · **Posted:** Tue Apr 22, 2008 1:20 pm

Browsed and read for 20 minutes in the book and it is not written in stone, but clearly the pressure in the common-rail remains "constant" with very small fluctuations across operating points. Even at large injection quantities the pressure in the common-rail is virtually the same.

I can't find a diagram of rail pressure vs. rpm but I will keep an eye out while I read

gmctd · **Posted:** Tue Apr 22, 2008 1:47 pm

I thinkso the 'constant' adjective relates to not varying with rpm.............

Uffe · **Posted:** Tue Apr 22, 2008 2:34 pm

gmctd wrote:

I thinkso the 'constant' adjective relates to not varying with rpm.............

Yes I would assume so. But obviously there are different types of operating points. It could be fuel quantity, it could be rpm, it could be engine load.

Personally I'd go with a global operating point, which is a function of all of the above variables, as well as all those I forgot to mention.

In the book it also says that the rail pressure is "optimized" to a specific rpm. Again does optimize mean a negligible change or does it mean an important change compared to a human eye reading off a 270 degree gauge?

gmctd · **Posted:** Tue Apr 22, 2008 3:02 pm

Optimized means 4500psi at idle, 18000psi at 75mph, bursts to 22000psi WOT - doesn't vary with rpm, but may vary with extreme demand - I think we've eliminated any 'demand' inadequacies with aux lift pump - we may see some variation with a really good tune coincidental with improving software control of the 545RFE to handle the increased output - also, we can do verification of various techniques used in the insertion-type modules used to offset engine parameters for personal gain and pleasure - I seldom object to being the gunea pig, even if it turns out like breakfast with bacon and eggs, where the chicken is involved, but the pig is committed - too bad I don't have a KJ, meownself - this R&D stuff is really fun, even without latex gloves............

Sir Sam · **Posted:** Tue Apr 22, 2008 6:11 pm

gmctd wrote:

Optimized means 4500psi at idle, 18000psi at 75mph, bursts to 22000psi WOT - doesn't vary with rpm, but may vary with extreme demand - I think we've eliminated any 'demand' inadequacies with aux lift pump - we may see some variation with a really good tune coincidental with improving software control of the 545RFE to handle the increased output - also, we can do verification of various techniques used in the insertion-type modules used to offset engine parameters for personal gain and pleasure - I seldom object to being the gunea pig, even if it turns out like breakfast with bacon and eggs, where the chicken is involved, but the pig is committed - too bad I don't have a KJ, meownself - this R&D stuff is really fun, even without latex gloves............

Agreed, it would make this work easier, I'm getting closer though.

Monitor fuel rail pressure with a gauge.

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