Jump to content

Flex Fuel Tunning Issues


JMSMotorsport
 Share

Recommended Posts

Im Coming across a few issues, While the Car was on 98 I got my Injector song very close on the dyno happy days 300rwkw on 11psi - Added some E85 and I am at E70 - 13psi Now Idle was OK little lean and Cruise was the same adjusted the Low Slope and moved the breakpoint and it’s back. So I adjusted the high slip to get WOT back - now the issue has arrived that at Tip In it goes super fat? Took some out of the Pump Shot Gain - hasn’t changed it. I then turned the boost up to 17psi but not instead of the nice flat fuel line at about 5200 starts to go lean again? Fuel pressure climbs with boost as it should. 
 

Light Blue (Boost) and Green (Lam) is at 13psi and Red (Boost) and Blue (Lam) at 17psi

image.jpg

Link to comment
Share on other sites

Update - Turns out fuel pressure is dropping after getting a higher boost run video of gauge - not sure if this is contributing to me using incorrect high slope to compensate at lower boost in turn causing the throttle tip in issue. 

Edited by JMSMotorsport
Link to comment
Share on other sites

50 minutes ago, JMSMotorsport said:

Update - Turns out fuel pressure is dropping after getting a higher boost run video of gauge - not sure if this is contributing to me using incorrect high slope to compensate at lower boost in turn causing the throttle tip in issue. 

You shouldn't need to touch the high/low slope for E85. A stoich change alone should have you within 1-2% of the original target if your injector scaling was on point. If you are running drastically different boost levels on E85 you might need some small adjustments however more than 5% suggests an issue with your original scaling or fuel pressure.

If you do not have flat fuel pressure at idle through WOT (make sure to do an extended 10+ second WOT pull to ensure there is sufficient return flow) you will be chasing your tail.

I recommend you have an inline fuel pressure sensor fitting you can quickly add into the feed line for all vehicles you tune. It should always be checked, not only if you have issues.

Pump shot gain is disabled from the factory, there is a multiplier for tip in/out it that is set to 0. If you have lean tip in this also suggests issues elsewhere.

Tip in is controlled by auF1156

Tip out is controlled by auF1303

  • Like 1
Link to comment
Share on other sites

11 minutes ago, JMSMotorsport said:

but even commanding 90% on the gate it only gets to 60%? 

0.7 / 0.85 = 82%

So you should be on 0.82 of the E85 map if you are using linear blend curves. If you have set up the boost ramp to use E70 == 1.0 then you should have 1.0 duty cycle.

First make sure you have added the duty cycle and desired boost to the boost blend ramp (and that you have modified the boost blend ramp, not one of the others).

Can you post your file up?

edit:

when you say "commanding 90% on the gate it only gets to 60%?" how do you know its commanding 90% ? As in the datalogger says 90%? How do you know what it is actually at, are you measuring it with a scope?

Are you running open loop or closed loop boost control?

Link to comment
Share on other sites

I adjusted the sensor based on the numbers in the how to guide. The supplied ones were out just. But there is certainly a fuel supply issue. Even now on the feed side the content drops from 73 to 65
 

Time to keep digging- 525 Walbro in a Sniper 1L Bucket, Upgraded wiring to a relay at the pump all feed side is -6 Teflon braid. What’s the consensus is that big enough lines? To make 450rwkw on E85 

Link to comment
Share on other sites

I don't know about the sniper bucket, I've only used the stock unit.

For the stock unit, the return system in the pot is one return restriction and another restriction is at the quick connect on the return line. If you look at the hole in the return connector, it is tiny.

I don't think a single 525 will warrant opening up the return line connector, but the only way to make sure is to at least have a gauge in the fuel reg and see what it does at idle.

I quickly went from 1x 460 to 1x 525 to 2x 525 with a fpr800 and I had already modded the pot from the outset. I only started further return mods and bigger reg when I fitted 2x pumps.

Link to comment
Share on other sites

Yeah getting it go go low enough is the issue you face with return restrictions.

If it will pull down to 3.5 bar with the vac line connected you're fine.

You can test the return limit now if you want by seeing how low it can go. Just bridge the fuel pump relay to keep the pump running with the engine off and turn the reg down until the gauge stops going down.

Low pressure at high load and WOT indicates a fuel supply issue, usually it's a blocked fuel filter or insufficient pump capacity.

Fwiw I've run several hundred kw more on a stock feed line.

Link to comment
Share on other sites

50 minutes ago, Puffwagon said:

There isn't a split in the reg reference line? A single 525 with a relay feed should be fine at that power and boost level.

It’s got me fucked. Just changed reference line no change, the bucket came with its own filter sock that I’m using as the one supplied with pump doesn’t fit as it hits the bottom of the basket. I forget when I pulled factory one out does the pump sock sit hard against the bucket base? Could it be that there’s no room for it to pull fuel in? I thought those socks were designed to allow fuel to get pulled in everywhere

Link to comment
Share on other sites

2 hours ago, JMSMotorsport said:

At idle vac line off I can set it at base 58psi and it’s steady and then fitting vac line pulls it down as should. So that wouldn’t cause a low pressure situation more so an unstable high pressure at idle. 

High pressure at idle is typical of the return flow being restricted. Normally you'd modify the return flow path for a 525 (we had to on our BF test car with the 525). To save yourself time KPM and many others sell full kits, eg wiring, modified swirl pot, everything is bench tested and warrantied for continuous E85 usage. Highly recommend just purchasing a kit like that purely on the time you save as you know it will hold flat pressure at idle/wot for your given power level.

Also there is a function to hold the E content at last value above a given TMAP pressure. It is set out of range by default, I recommend setting it to approximately 1.2 load (work out what this in inHG) so that the E content locks during a WOT run. This will also save the engine if you have the sensor in the return line and what you are describing happened after the vehicle has left the shop.

Link to comment
Share on other sites

26 minutes ago, Roland@pcmtec said:

High pressure at idle is typical of the return flow being restricted. Normally you'd modify the return flow path for a 525 (we had to on our BF test car with the 525). To save yourself time KPM and many others sell full kits, eg wiring, modified swirl pot, everything is bench tested and warrantied for continuous E85 usage. Highly recommend just purchasing a kit like that purely on the time you save as you know it will hold flat pressure at idle/wot for your given power level.

Also there is a function to hold the E content at last value above a given TMAP pressure. It is set out of range by default, I recommend setting it to approximately 1.2 load (work out what this in inHG) so that the E content locks during a WOT run. This will also save the engine if you have the sensor in the return line and what you are describing happened after the vehicle has left the shop.

This will be my go to next time.

Link to comment
Share on other sites

48 minutes ago, JMSMotorsport said:

Yep just seems odd. I just had pump apart again and fiddled around with socks and put it back in and it’s actually worse that’s what’s leading me that way. 

Is there a split in the fuel line between the pump and the top of the pot?

Link to comment
Share on other sites

Info from the Walbro site says a 525 is good for 100gph/378Lph at 78psi, the Raceworks calculator says the engine needs 359Lph for 700hp.

While myself and others have made over 500rwkw with this pump, undoubtedly with falling pressure and near zero return flow, I think we're seeing some data show us that the pump is only stable to around 450rwkw.

Edited by Puffwagon
  • Like 1
Link to comment
Share on other sites

Iva had a thought. Injectors should be good for it but in the software can I reduce the expected base fuel pressure to be at 3 bar then would the slopes just be a matter of reducing them by the pressure percentage difference or would it not be that simple? 

Link to comment
Share on other sites

I have used the Ryco filters but I swapped to a washable stainless filter from Goleby's.

When the pump is running out but the injectors have room, you can add fuel to the speed density table. If it starts going lean at 5000rpm, get in there and drop the cells it runs through at WOT by 500 to 1000 numbers from 5000rpm and up and it'll richen up.

I haven't tried dropping the base pressure but it should be as simple as changing the slopes and breakpoint to suit.

Link to comment
Share on other sites

30 minutes ago, Puffwagon said:

I have used the Ryco filters but I swapped to a washable stainless filter from Goleby's.

When the pump is running out but the injectors have room, you can add fuel to the speed density table. If it starts going lean at 5000rpm, get in there and drop the cells it runs through at WOT by 500 to 1000 numbers from 5000rpm and up and it'll richen up.

I haven't tried dropping the base pressure but it should be as simple as changing the slopes and breakpoint to suit.

Yeah the only issue I thought that doing the speed density on flex when it goes back to 98 will be pig rich.

I've used the ID spread sheet to find the difference between on 43.5psi and 58psi on there slopes and taken this amount from my current slopes. Hopefully this gives me a good starting point on the slopes. Might work out the percentage change also and try these numbers.

Link to comment
Share on other sites

Done some more testing this morning, Run even bigger cable to relay - found some voltage drop even between relay and pump due to cable size. Bumped my alternator voltage up so I’m now getting a solid 13.7v at the pump. Made little difference - lowered base pressure to 3bar - the high and low slope numbers were out by around 5-10% even after lowering via the same percentage and amount use be the ID calculator - still getting pressure drop. I’m leaning towards an actual pickup issue at the pump. 

  • Thanks 1
Link to comment
Share on other sites

That clip is cut too short to see much but glad you got it sorted.

Haha I was getting worried that my own dual 525's were going to run out 🤣

I've been looking for another gauge to add, I've got the advanced ethanol gauge but need one like the other one you've got there. Will be adding that in future to track oil and fuel pressure in the log.

Link to comment
Share on other sites

Jumping back in here for some info.

I put my ethanol content sensor in the return of my car, thinking that it would always have plenty of return. I've noticed it moving around at WOT which seems like it is running out of pump. I'm gonna pull the pumps out and make sure they aren't on the bottom of the pot and also invest in a fuel pressure sensor.

Link to comment
Share on other sites

Why not buy one of those adapters like Motion raceworks have that split the fuel at the ethanol sensor? Flows about dash 10 or more with it and I assume every company has ripped off the design by now... 

Isn't your swirl pot non existent (cut up) @Puffwagon?

Do you use the 40 micron filter in the Goleby's fuel filter or buy a 10 micron (Aeroflow have the same filter but sell a 10 micron separately, you can't select either/or)... 

Link to comment
Share on other sites

Yeah I'll look into it, I've gotta up-spec the whole system if I want to make more power anyway.

The swirl pot is mostly there, it has about a third of the base removed to accommodate the pumps. Last time I had it out I noticed the pumps weren't 100% level but cbf fixing it at the time.

I've got the 40 micron filter in there at the moment, I'll take a look at it because the car did sit around for a while.

  • Like 1
Link to comment
Share on other sites

I doubt a slightly skewed pump would make much of a difference but you never know.

Yeh mine rarely gets driven which is why I thought a cleanable filter could be done (and inspected) yearly with my oil changes (less than 3k km's a year). My 20lt jerrys I keep for the genset were full with what appears to be algae like what diesel gets and it's the same BP 98oct... 

Link to comment
Share on other sites

His was jammed in the bottom of the pot though with no clearance so that as opposed to not being 100% level are two different things, unless of course by level you meant jammed on the plastic base and not on an angle (skewed or one higher than the other). 

I'm making assumptions with your interpretation though. 

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...