Fueling problems with 720cc

[Mr. Y]

Hello.

Haltech E8 here installed on 7M-GTE (injectors are paired). Last summer I was running 550cc injectors in multipoint mode and everything were ok.
Now I've installed 720cc and got some problems.
I can't tune AFR in ANY injection mode. In batch/multipoint I can't tune any load above idle and free-revving. Enigne misfires badly and leans. Increasing injection time doesn't help.
Semi-sequential mode is better. Engine revs till 5500RPMs and can be tuned even under load but in 5400-5800 range still leans badly (and misfires). Besides that it runs very rich @idle (can't tune leaner than 12.xx)

I've converted fuel rail to dual-feed. Installed SS fuel lines (-8AN). Replaced walbro with bosch bosch 044. Nothing helps! Just moved "problem RPMs" a little.

Guys, please describe your setup running paired injectors... 720cc and larger.

I suspect that problem is in Haltech semi-sequential mode. It fires each channel twice per cycle (every crank rotation). Stock ECU (and p'n'p AEM too) AFAIK fires each channel once per cycle (every two crank revs). Am I right?

I'm very angry and disappointed. 550cc are too small for me. I already wasted lots of money (new pump, new lines, 720cc)... I don't know, if 680cc will work or it will be another 600$ trashed... What shall I do?

PS: injectors are good. I've checked them.
PS2: Bosch 044 in-tank, 10mm supply line (-8AN), new stock fuel filter under hood, T-fitting, dual-feed rail with drilled and taped return in the middle. Aeromotive AFPR then. Tried completely stock fuel supply with walbro in-tank - just the same (even slightly worse).

 

[figgie]

Here are a couple of questions that I did not see you post

What is your base fuel pressure?
What is the resistance of the injectors?
How did you wire the injector pairs (series or parallel)?

That lean spot might actually be a rich spot. Lean does not backfire Not enough fuel to backfire. Rich on the other hand will. Here is a real quick rule of thumb on the fuel table.

If it looks like a mountain range (in the graphics portion), then you got to look it over again as something is wrong. The fuel table along with the ignition table should be smooth not rough.

 

[Mr. Y]

Thank you for input!
I've tried different BFP - from 37 to 43psi. 43psi seems best to me because it runs leaner at idle (more pressure helps closing injectors sooner, I think).

Injectors are low-imp Denso's wired like stock (two in parallel via resistor pack).

Car doesn't backfire (no flame from exhaust), it misfires (I know how lean mixture feels).

As for fuel table... 550cc map is smooth (e.g. aprox. 2,5ms inj. time across all -63kPa load column). Map for 720cc is smooth too, but leans at 5500 badly. Increasing injection time (more than 1ms) at 5500 helps a little, but it is not right. I must eliminate problem, not compensate it.


PS: enabling Peak&Hold makes idle better (leaner and smoother) but doesn't affect 5500 problem :-(

 

[figgie]

BFP - more pressure does not help in closing injector faster. That is a function of your EMS. More pressure WILL inject more fuel per given pulse width.

have you tried taking away the resistor pack and having the haltech connect directly to the injectors in P&H mode? The P&H mode is used for low resistance injectors.

as for the misfire, it does not have to "flame out" from the exhaust. It still happens, so much so that would be my first guess and not a lean spot especially with 720.

I have to ask, have you tuned before? Eliminating a fueling issue IS compensating for it on a literal sense, in the fuel table. You have to increase/decrease PW and the surrounding loadpoints to achieve the required lambda at the load point. Otherwise you are not compensating for the error

 

[Mr. Y]

BFP - more pressure does not help in closing injector faster. That is a function of your EMS. More pressure WILL inject more fuel per given pulse width.
My idle inj. time is 1.5ms and AFR is 12.8. If i reduce it, I get 16.xx AFR. Increasing FP at idle from 25psi to 32psi and AFR becomes 13.5 @ 1.5ms injection. Can you explain this fact?

have you tried taking away the resistor pack and having the haltech connect directly to the injectors in P&H mode? The P&H mode is used for low resistance injectors.
Yes. But P&H can't be run without resistor pack. Paired injectors impedance is about 1Ohm, so current is 12Amps (at 12V) - too high for P&H. If I enable P&H in software, injectors will saturate.

as for the misfire, it does not have to "flame out" from the exhaust. It still happens, so much so that would be my first guess and not a lean spot especially with 720.
There is no reason for very rich mixture there. Inj times are tiny (on light load or free-reving). And _increasing_ inj time in problem area helps a little. So I'm sure it's not over-rich condition.

I have to ask, have you tuned before?
No. I even don't know what is injector... jk.. I've road tuned and sucessfully run my car with 61mm turbo on 550cc last summer. So I do know how maps should look. And I do know that 2ms injection time difference in neighbor points (5250 to 5500RPMs) is not ok! (and I'm still lean with that 2ms enrichment).

 

[figgie]

BFP - more pressure does not help in closing injector faster. That is a function of your EMS. More pressure WILL inject more fuel per given pulse width.
My idle inj. time is 1.5ms and AFR is 12.8. If i reduce it, I get 16.xx AFR. Increasing FP at idle from 25psi to 32psi and AFR becomes 13.5 @ 1.5ms injection. Can you explain this fact?

yes of course!

You say reduce "IT". I am going to gather you mean reduce Fuel Pressure as "it"? IF you reduce fuel pressure, you AFR go to 16.xx? Is that correct? Then it is working correctly and just as I stated! When you decrease FP for a given PW, you will go leaner (higher AFR #) and just the opposite if you increase FP for a give PW (lower AFR #).

16.xx means you are lean for the given PW + FP. Then you increase FP from 25 psi base to 32 psi base and you are seeing a mixture of 13.5 AFR @ 1.5msec. You are richening it up, again how it is supposed to work.

have you tried taking away the resistor pack and having the haltech connect directly to the injectors in P&H mode? The P&H mode is used for low resistance injectors.
Yes. But P&H can't be run without resistor pack. Paired injectors impedance is about 1Ohm, so current is 12Amps (at 12V) - too high for P&H. If I enable P&H in software, injectors will saturate.

think OUT of the box. Paired in parallel the injector resistance will be 1.5 ohms (3 ohm each). Run the injectors in series and you are up to 6 ohms per circuit. The haltech is more than capable of handling that resistance straight up.

as for the misfire, it does not have to "flame out" from the exhaust. It still happens, so much so that would be my first guess and not a lean spot especially with 720.
There is no reason for very rich mixture there. Inj times are tiny (on light load or free-reving). And _increasing_ inj time in problem area helps a little. So I'm sure it's not over-rich condition.

timing can be 1.0ms and you still can be rich. The issue is that you are using a bigger injector, so for ANY given PW you will inject MORE fuel than the same PW on a 550cc/min injector.

I have to ask, have you tuned before?
No. I even don't know what is injector... jk.. I've road tuned and sucessfully run my car with 61mm turbo on 550cc last summer. So I do know how maps should look. And I do know that 2ms injection time difference in neighbor points (5250 to 5500RPMs) is not ok! (and I'm still lean with that 2ms enrichment).

there are a couple of issues just from the posts.

You base map is not right (low numbers). You need to decide what your base fuel pressure is going to be and once you do, do not change it as it is an excercise in futility if you do. Then you can set base inj PW and scale up/down from there. Ultra rich at the bottom and lean in the mid point, but no way to take away more PW, then you need to lower the base FP and add inj pw per load cell for most of the fuel table. Most EMS will interpolate from surrounding cells if the load value does not correspond to a specific cell.

 

[Mr. Y]

I appreciate your help, but we are speaking different languages...

by "it" I meant injection time. Lowering inj time always leads to leaner mixture, but raising FP leads to leaner AFRs in my case too! (at very low injection time).

As for inj time value... 1.5 is not little. Haltech fires injectors every rotation, so 3ms (minus injector lag) every cycle.

As for P&H... I tried P&H with resistor pack. Do you think that P&H when injectors are connected in series will be different?

I'm not trying to run 550cc map on 720 injectors, I use it just for reference (inj time dinamic). 550cc map has not any bumps at 5500 area. So 720cc map shouldn't too!

My base map is good. Car drives well till 5500 rpms. Please don't try to teach me... Changing FP a little doesn't affect AFR much. Yes, running 12.xx AFRs at cruise is stupid, but it doesn't affect driveability.
May be my English isn't good enough to explain, but i'm sure that there is problem, it's not just stupid user that installed standalone and now trying to tune it.

May be opening two 720cc injectors at once every rotation leads to some king of fuel pressure pulsations? Or may be stock fuel filter isn't good enough for 720cc's? (can't flow fuel fast enough to compensate pressure drop at high RPMs)

 

[figgie]

As for inj time value... 1.5 is not little. Haltech fires injectors every rotation, so 3ms (minus injector lag) every cycle.

1.5msec is the lowest point for most EMS without going to an autronic (know to be good to .75ms) and MoTeC (.6ms). 1.5ms is usually the smallest you can go without affecting the spray pattern. Hence why I tend to like to start lower base and raise PW instead of lower PW. You can try 1.0ms but i highly doubt the haltech will be able to control the injectors reliably at that short a PW.

As for P&H... I tried P&H with resistor pack. Do you think that P&H when injectors are connected in series will be different?

I'm not trying to run 550cc map on 720 injectors, I use it just for reference (inj time dinamic). 550cc map has not any bumps at 5500 area. So 720cc map shouldn't too!

the issue is that the 720cc/min injectors have a diffenert "inductance" curve. What works with one will not automatically work with the other. Just from an electronics standpoint. Can you post your fuel map.. an image capture of it is fine.

My base map is good. Car drives well till 5500 rpms. Please don't try to teach me... Changing FP a little doesn't affect AFR much. Yes, running 12.xx AFRs at cruise is stupid, but it doesn't affect driveability.
May be my English isn't good enough to explain, but i'm sure that there is problem, it's not just stupid user that installed standalone and now trying to tune it.

Easy tiger! I am not teaching you. I am trying to go over all the starting points incase something was missed.

May be opening two 720cc injectors at once every rotation leads to some king of fuel pressure pulsations? Or may be stock fuel filter isn't good enough for 720cc's? (can't flow fuel fast enough to compensate pressure drop at high RPMs)

I have been chewing on this. The Bosch 044 flows a lot better than the walbro 255 lph fuel pumps. So I doubt that it can not keep up. On the fuel filter side. That might be an issue but can not say for certain as I usually go with aftermarket if going with aftermarket fuel pump so never tested to see what the OEM Fuel filter can flow.

 

[turbo joe]

You can have some pulse problems for sure...been there done that. I don't think that opening them two at a time will do it, but opening all six at a time could.

Not saying that IS your problem, only that it is a possibility. Mine ran fine to 5000, then it hit a wall...would not go further and the fueling went from really dialed to crazy. Switched it back to 720 mode and the problem went away forever.

 

[Mr. Y]

1.5msec is the lowest point for most EMS without going to an autronic (know to be good to .75ms) and MoTeC (.6ms). 1.5ms is usually the smallest you can go without affecting the spray pattern.
I'm with you.


Can you post your fuel map.. an image capture of it is fine.
I can't right now. But nothing special is there. Inj time starts from 1.5ms at idle (-63kPa) smoothly increasing with load (2ms iirc at -50kPa, 2.1 @ -42kPa etc)

I am trying to go over all the starting points incase something was missed.
Thank you!

never tested to see what the OEM Fuel filter can flow.
I'll try to get aftermarket filter in two days and report back then.

You can have some pulse problems for sure...been there done that.
Couldn't you describe your 'problem' setup and 'ok' setup please? I mean inj. size, injection mode etc...

 

[turbo joe]

You can have some pulse problems for sure...been there done that.
Couldn't you describe your 'problem' setup and 'ok' setup please? I mean inj. size, injection mode etc...

Like i said, I had problems running in 360 mode (AKA: batch). 4-banger with BIG injectors(160# times 8, 2 per hole), all firing at the same time.

The synch sensor had died and I hadn't replaced it...worked on the smaller engine setup, but that changed abruptly when I went up in displacement and re-configured the fuel system a little. It basically made a standing wave in the line that amounted to fuel cut at 5000.

When I re-installed the synch sensor and went back to 720 (sequential) the problem disappeared. Again...I'm not saying that it IS your problem, just that it is possible for it to happen. It was a bitch to finally figure it out...you wouldn't believe what we had to do...LOL...I don't really want to get into it here and take this off topic, but it was a nightmare.

Long story short, put it on an engine dyno and ran it with a mechanical fuel system (with EFI system running the timing) to verify the ignition side, then thrashed the fuel side for about a day on the dyno...swapped out the fuel supply system to a Hilborn-type return setup (high speed bypass and a pinch valve for boost)...problem went away (big hint for us), then did the sych sensor (smaller pulses, higher frequency) and it worked just fine.

I've also seen it on a lower output setup, running batch-fired injectors (4X 35#, running batched) Most batch-fired cars have a damper...and lots of people pull them off. It does happen. I put the damper back on this car and it solved the problem.

Nobody made a -10 damper for the other one. :evil2:

 

[Mr. Y]

update: Installed aeromotive fuel filter. Now car leans in 4700...5000 range AND 5700-6000. It proves that it's fuel-pressure/flow related (not tuning).

BTW, I'm bying AEM from member here and going full sequential injection soon. And stock 440ccs for now

 

[turbo joe]

40-ish pounds of fuel a hole should take you quite a ways (6 times 40# injectors is around 480 horse)...how much power are you planning on making?

 

[figgie]

Well double up on the Bosch 044 or go an 040 (external). See if that fixes the issue.

 

[Mr. Y]

how much power are you planning on making?
I'm going 550+ RWHP with water injection. As for 440cc.. I hope they will handle 11psi (my lowest boost).

Well double up on the Bosch 044 or go an 040 (external). See if that fixes the issue.
Great idea, figgie! But bosch 044 costs 350$ here and I've already low on budget... Can't spend 350$ "just to try" =(

 

[turbo joe]

how much power are you planning on making?
I'm going 550+ RWHP with water injection. As for 440cc.. I hope they will handle 11psi (my lowest boost).

Well double up on the Bosch 044 or go an 040 (external). See if that fixes the issue.
Great idea, figgie! But bosch 044 costs 350$ here and I've already low on budget... Can't spend 350$ "just to try" =(

Well...I wouldn't count on 550cc injectors to make that much power. That's pretty much at the far end of what they're capable of. You could stretch it somewhat by cranking up the fuel pressure, but how far you can stretch the capacity depends on the pumps you have and how much boost you need to get to the power you want to make.

As for whether they'll "handle 11psi"...the only way they wouldn't is if you think you're going to make >480 (at the motor) at 11psi. That would be one stout 7M from what I've seen of them. Roughly a 275 horse NA motor...or 1.5 horse per inch.

 

[IJ.]

550rwhp+440cc injectors just doesn't add up Yuri.

 

[Mr. Y]

Ian, I'm not going 500+rw on 440cc. I have 720cc's for that goal.

Update: Installed 440cc injectors and... Problem is still there =( To be honest, I'm totally messed up. I have only one perfectly working setup: 550cc, stock feed, walbro, stock FPR. I can't try stock feed with 440cc... (Already modified fuel pump hanger). Can't try stock FPR either (It can't handle flow of bosch and big lines, too much pressure).

I'm not even sure that it's fuel problem now... Anyways, I'm going to try stock ECU with stock MAF, injectors etc... If problem wil be there, I'll dig fuel supply... If it'll go away - wait for AEM.

 

[IJ.]

Yuri: Are you still running the stock return line?

 

[Mr. Y]

Yes, stock return line. With Aeromotive AFPR I can set 25psi at idle without problems, so I guess return line is not restriction. May be even lower but I don't need it.
When I tried stock FPR with big feed line I saw almost 50psi at idle.