Fuel Rail Pressure Issue

[tylerltr450]

Hey guys having a weird problem. Upgraded to 60hp injectors and I had this happen 2 different times on me now. What is happening is that when I push the clutch in the rail pressure drops like a rock to 5k or lower. Sometimes enough to stall the truck. I have change the duty cycle tables a little bit but nothing crazy. Any idea on what could be causing this. On my other tunes when I was dumping way to much fuel it worked fine and never did this. I data logged on my way to work so Im hoping I got the problem.

Note I dont think im maxing out my pump because i have FPA vs FPD is pretty much spot on but sometimes I noticed my FPA is more then my FPD.

Thanks

[2007 5.9]

Does this happen after a hard pull?

[tylerltr450]

Yes. the times the FPA vs FPD is different is after i let off the throttle. and when i let my foot off the clutch and it fp falls to 5k can be anytime. its also not very stable at idle it seems. Ill double check when I get in the truck after work but I noticed it when i was almost at work today.

[KhakiCummins]

What kind of delta and for how long are you seeing FPA higher than FPD when you lift off the throttle? It is normal for FPA to be higher than FPD for a short period when you lift, especially if you are hard into it and lift completely.

[tylerltr450]

What kind of delta and for how long are you seeing FPA higher than FPD when you lift off the throttle? It is normal for FPA to be higher than FPD for a short period when you lift, especially if you are hard into it and lift completely.

Not very long I cant remember 100% from last night but it was pretty short. When I get home I can check my logs and give you the correct time.

[2007 5.9]

Post the log, that'll be easier

[tylerltr450]

Here is the log file. I guess this has to do with the base duty cycle because I have one tune in the csp with stock base duty and it works good.
18226

[tylerltr450]

Note its also the same duty cycle as my one other tune and I ran that for weeks the way it was no problem.

[2007 5.9]

Duty Cycle at stumble and shutoff is lower than stock by quite a bit...I see -5% all the way to -15%...thats not calling for any FCA function....hence the stalling.

[tylerltr450]

How can 2 different tunes one that has higher pw and timing, has pilot and post timing not do the same thing to a tune that i cut post and drop pilot in the higher rpm range and less pw do this though. Just confusing thought running less would help. Plus trying to make a smokeless tune.

[tylerltr450]

Can this be the problem?
The only difference is the PW on the lower end of the fuel pressure.
Where it is circled is the only spot i really change the pw on the low end

18227

The 2 tunes on the csp that held prssure ok had pw tables like this.

18228

[2007 5.9]

Could be that when your FPA drops that low, the part of the table you modified does come into play.

Generally your engine should never operate over in that area...typically any pulse below 40MPa doesnt need to be changed unless your asking it to run on that low FP.

[tylerltr450]

The 2 tunes I have one with to much fuel the fuel pressure table is the same and the duty cycle is the same the difference from that tune to the other one is that I lowered PW, cut pilot after 2000rpm, and have no post. I put the other tune into the truck and I am going to data log that and let you know. I hate to run it because its way to smokey, and will probably post the log.

[tylerltr450]

Well it happens with the other tune if I push it hard enough. I guess I should increase fuel pressure down low to possible compensate? Or would increasing main timing help?

[2007 5.9]

Put your DC table back to stock

[tylerltr450]

Put your DC table back to stock

That will work also I guess haha.

[2007 5.9]

There are tables that simply don't need to be messed with until much later on, and DC table is one of them. As you have found it can be more of a bother than useful

[tylerltr450]

So what i probably should do is test those things with a dyno. :unsure: