SICK of the 70 mph surge

UNBROKEN

UNBROKEN

Ezekiel 25:17
Joined
Apr 21, 2006
Messages
17,158
What the hell will fix it?
My junk is almost undrivable at 1900-2050 rpms.
Do ALL modded FCAs do this ?
 
UNBROKEN said:
What the hell will fix it?
My junk is almost undrivable at 1900-2050 rpms.
Do ALL modded FCAs do this ?
Click to expand...

Mine does it on #7... Infact I forgot about the surge until I went to #7 for a little while... #5 and 9 are surge free.

I'll report for ya what John's pump does on #7 in the next few weeks vs Wickeds. I'm sure the FCA's are a little different.

But I believe you just have a software issues.
 
Mine stays on 9 but does it on all SW's

Next time you talk to John ask him about my pump...I sent him one to work over back in April.
 
What are you doing for pressure also? I had surge issues with a combo of problems, bad FCA and the pressure box turned up.
 
Smarty RP on stock. Surges no matter where the MP8 is set which is usually on zero.
Will running a stock FCA mess with anything if the rest of II's Bag of Parts is still there?
 
Mine is surging worse with the stock pump in. It does it in all switches now and would only do it on 9 with shanes pump. It does it at the same rpm range as yours does.

Joe
 
On sw 9 with II 85% mine surges at 1900 to 2200 rpms. Mp8 off n smarty rp off. If its turned down on sw5 it doesnt do it. Id like to knw a fix also.
 
Do any of you know the cause of the surging?

For instance, is the rail jumping up and down, or is pw running up and down? Since everyone is talking pumps I'll assume rail is getting out of hand? Anybody ever double up on the pressure regulators to compensate for additional pump displacement? That would get the duty cycles back in the range the ECM was designed for.
 
when i first modded my stock pump i did only the fca at first and it would surge once i modded the gear housing it stopped surging. it seems like the something is restricting the fuel flow int eh pump and the modded fca is having a hard time finding a happy medium.
 
Charles said:
Do any of you know the cause of the surging?

For instance, is the rail jumping up and down, or is pw running up and down? Since everyone is talking pumps I'll assume rail is getting out of hand? Anybody ever double up on the pressure regulators to compensate for additional pump displacement? That would get the duty cycles back in the range the ECM was designed for.
Click to expand...

If PW is jumping, rail will fall and need to compensate, causing and endless loop. It's seen in the rail gauge. I have nothing to monitoring PW.
 
UNBROKEN said:
My RP gauge bounces...5-6K psi
Click to expand...

Is it a situation where you're at the minimum duty cycle limit and the reg is still dumping too much, causing the DC to drop out of range to actuate the reg, then rail jumps way up causing DC to come back harder, then it dumps too much again, DC drops out again, rail jumps back up harder, DC comes back again, it dumps too much again......???

What does FCA stand for btw? I'm assuming that is your pressure regulator.
 
JasonCzerak said:
For me, it seems as if it's under super light throttle input. but not off throttle.
Click to expand...

Precisely.

That is the scenario for a very small fuel request. Something that is sometimes not easily granted by an injection system modified to move very large quantities of fuel. In the scenario of midrange rpm, and light load the engine needs very little fuel, so all of the systems will be running at the absolute minimum possible on a truck with large fueling ability. The pump is running relatively high rpm, yet the injectors need very little rail to meet the injection demands of the engine at little to no load. The result is probably a minimum duty cycle to the regulator. If your modified pump moves more volume for any given duty cycle, then you may very well have a situation where even at minimum duty cycle it still moves too much. Since the ECM isn't going to just let the rail run away, it will keep pulling DC down and down trying to control it. There may be a min DC where the reg stops functioning and closes off, or there may be a min DC where the ECM freaks out.

Sounds like you might need less flow from the pump, or more flow from the reg to get the DC back up in a friendly range where things aren't riiiiiiight on the very edge of the possible range.


On Edit:

I still don't know what you guys are even talking about. Is FCA the reg? What does FCA stand for? Is the DC percentage open or percentage closure? Everything I wrote above could be totally ass backward and useless because I'm assuming a lot here. If the part changed was a pump then what I wrote above is probably a good shot, if the change was to a modified regulator then not so much.
 
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Well, Rich'es bag of parts doesn't "flow" worth of crap in comparison to anything else. however, it may be a symptom of a badly/incorrectly modified fca for sure.. I've had one of these apart and there isn't much to them. A wrongly placed scratch would flow fuel to soon.

I wonder if a new FCA could be created that had more "resolution" per-say.
 
That is one of the very best explanations I have ever seen for this!!!

Thanks Charles
 
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