Fuel Problem

[adv4nced53]

Related Mods:

Air:
o Evo3 16G Turbo

Fuel:
o 1G Fuel Rail
o AMS 680cc Injectors
o Walbro 255 High-Flow Fuel Pump
o Aeromotive AFPR w/ 6AN fittings

Other:
o HKS 272 Intake/Exhaust

Tuning:
o DSMLink
o Innovate LC-1 Wideband

Problem:
Running 18psi and I have to max out the injectors to not run lean. I've had this problem since I got the cams. At 95% duty I am making 11:1 - 12:1 range but that shouldn't happen until 25+ psi. I thought I was overflowing the FPR so I installed the Aeromotive AFPR. Set it to 43psi with unplugged vacuum. With vacuum it runs about 40psi and at boost I've seen it around 45psi (antilag). I do have a bit of a boost leak but still...these injectors are maxing out wayyy too easily. Voltage is fine. Any suggestions?

PS: Will fix the boost leak ASAP.

 

[dsmdragon]

WOW sounds like you have a bit of a problem here. Well with the afpr a lot of the problem should have been fixed. But with 650cc of fuel you might have problems with the 1g fuel rail holding up to the flow. Do some digging and findout what the rail's max is, also even at 25psi the injectors should be fine. Make sure that theres nothing in the way and that they are rated at 650. A sometimes they seen the wrong ones or something. also with the sizes of cams here it can answer some of your question, but you shouldn't be hitting insane lean numbers.
Just look into the rail it might be stoping the FP.

 

[2gGSX]

Post a log.

 

[steve]

You have a bit of a problem.

With a 43 psi base you should be see much more of a drop at idle unless you really only have 6 in hg vacuum and then I suggest you have a problem elsewhere.

Under boost the pressure should raise 1:1 with the boost pressure and I assume your seeing more than 2 psi boost when you were testing.

 

[adv4nced53]

Well yes...under antilag i hit about 10psi and this gauge is under the hood so i couldnt monitor both the boost and the fuel. What is it supposed to go to exactly at a maximum? Over 50psi of fuel? I know people who run 90% duty at 28psi and I am nowhere close. 1G rails shouldn't be a problem and they are actually shorter so I don't see how this can be the issue. DSM link is tuned properly for those injectors, so this is really weird. Anyone else have any ideas?

Also, it's hard to get the car to idle when it's cold. Not sure if that is related but I have to give it gas for about 15s then it takes over and still idles low (700-750rpm). I did make the idle higher but then after driving for a while, the idle would just go up to 1500rpm. Probably the IAC but who knows...it might help here!

 

[CROWN007]

hm...I ran fic650's stock fuel rail with aeromotive fpr and ran 38psi with vaccum line off for base pressure. Never overran my injectos at 23psi on a garret to4b v-trim. Ran around 70-80% wot. Before I had dsmlink i had them maxed out when i was using maft and afc and car ran like crap. Since u have 1g fuel rail should u run 1g base pressure?

 

[2gGSX]

No, the 2g ECU assumes that you are running the stock 2g base fuel pressure.

What rising 1:1 with boost means that, given base fuel pressure of 43 psi, then at 10 psi of boost you should have 53 psi fuel pressure.

How sure are you that DSMLink is set properly for these injectors? Are your LTFT's close to zero? Is your TPS properly set? Is your ISCPosition properly set? Is your FIAV/associated throttle body parts working properly?

Post a log.

 

[steve]

If your asking the "what pressure should it be or should I run" question then you should use the base fuel pressure for your model year car (ECU).

Once you understand that it boils down to how you tune then you can change the base pressure to better suit your needs.

The Max fuel pressure is dependent on your fuel pump. The all have relief valves that limit the max and on top of that they need to be able to flow enough fuel under pressure to keep up with the injector flow.
From the regulator perspective it must maintain a 1:1 ratio across the entire range of manifold pressures. The ECU expects that the FPR will maintain the pressure as FP = base FP + manifold Pressure. So at 20 psi boost you see base + 20 psi and under 20 in hg vacuum you see base + -10 psi (20 in hg = -10 psi)

You also have to keep in mind that there are pressure loses (Resistance) in the system between the pump and rail. So the pressure before the fule filter will be higher than at the rail and at the pump higher still.

 

[adv4nced53]

I'll post a log tomorrow...those DSMLink questions are hard for me to answer.

 

[adv4nced53]

I have a log here:

Index of /pictures/gst/logs

I took out the car for a drive and then i realized the battery on my laptop was basically dead. Could only get one and it knocked as you can see. Looking at it though I don't see how this can help with the diagnosis...what other variables should I log?

 

[adv4nced53]

bump

 

[2gGSX]

Just as a note, bumping will get you in trouble.

Why are you adding 24% fuel by redline? In essence you are pulling a net total of 6% fuel by 7000 RPM. Are you tuning with a wideband which is reading 11:1-12:1? If that is the case...

I think you have 450's. Given your airflow and your IDC, and assuming that you are indeed running between 11:1-12:1, the numbers make much more sense if you actually had 450cc injectors instead of the 680's.

Someone else can verify, but at t=7.04s your IDC is 96.6%, and airflow is 32.2 lbs/min. Metering looks to be close enough, so the airflow number should be fairly accurate. With 680cc injectors (closer to 650's actually), you'd be running an AFR of 32.2/(.966*650*4*.76/454) = 7.69:1, which would explain your knock as it would be rich knock (albeit that's not nearly as much knock as I've seen other people with rich knock). With 450cc injectors however, your AFR would be 32.2/(.966*450*4*.76/454) = 11.1:1.

There are some other problems as well, including your FrontO2 signal being dead. That shouldn't interfere with your open loop operations though (in fact, it should make you stuck in open loop).

 

[adv4nced53]

Just as a note, bumping will get you in trouble.

Sorry.

Why are you adding 24% fuel by redline?

So I don't run lean.

I think you have 450's.

Can't be. Even though I didn't buy them, it says AMS on them and I believe that they are 680s. I had no problems with fuel before the cams.

There are some other problems as well, including your FrontO2 signal being dead. That shouldn't interfere with your open loop operations though (in fact, it should make you stuck in open loop).

I don't see how this can explain the problems with the fuel. Could that give me a bad idle though?

 

[2gGSX]

So I don't run lean.

With your global correctly dialed in, no other fuel adjustments, and base fuel pressure verified, you should not have to add fuel in to keep from running lean. In fact, you should be running the stock fuel map at that point, which would mean your ECU be trying to run an AFR of 9.5:1. The fact that you have to add 24% fuel by redline to run 11:1-12:1 means that something is very very wrong with your global (which indicates an injector size issue)

Can't be. Even though I didn't buy them, it says AMS on them and I believe that they are 680s. I had no problems with fuel before the cams.

I don't know what to tell you. If you want to rule out the possibility of having the wrong injectors once and for all, then you can either get them flow tested, or fix your front O2 and tune your LTFTLo and LTFTMid to zero percent. My guess is that both of those fuel trims will be maxed positive.

I don't see how this can explain the problems with the fuel. Could that give me a bad idle though?

It's possible that this could give you a bad idle. Assuming my guess is correct, and given that I don't think you're entering closed loop operation (log "OpenLoop" and see if the value ever goes to 0 to verify), your ECU would not update STFT or use it in your fuel delivery. In effect, this should mean that you are running very lean during cruise/idle operation.

 

[adv4nced53]

With your global correctly dialed in, no other fuel adjustments, and base fuel pressure verified, you should not have to add fuel in to keep from running lean. In fact, you should be running the stock fuel map at that point, which would mean your ECU be trying to run an AFR of 9.5:1. The fact that you have to add 24% fuel by redline to run 11:1-12:1 means that something is very very wrong with your global (which indicates an injector size issue)

I know this and that's why I made this post.

 

[2gGSX]

That is why I am saying, verify your injector flow rate either via LTFT tuning or getting them flow tested.

 

[adv4nced53]

Unfortunately, I have to revive this post.

Nothing has changed, except that I replaced the front O2, so it actually reads correctly now. That didn't help with the idle though, which is odd. I have a vacuum/boost leak at the throttle body, which I need to fix and will within a week.

The fuel trims seem wrong but not terribly wrong. I am a newb when it comes to those, so someone please explain them to me.

Here are the readings:
LTFT Lo - 11.5%
LTFT Mid - 9.2%
STFT - 11%

Those are at idle with the car warmed up. I am yet to see what happens during a pull and I'll update with that tomorrow.

For now, can someone give me some fuel trim basics?

Thanks

 

[adv4nced53]

Made 2 more logs today...

Index of /pictures/gst/logs

1] Hitting peak boost and letting off
2] Idle

I seem to have lowered the STFT to 0% (±1.5%) but the long term is still off. Nothing has changed when it comes to maxing out the fuel but my AFPR's gauge reads no less than 36psi at idle. Is that normal?

 

[99gst_racer]

Anyone?

Rule #5. Please refrain from bumping your threads on this site.
Thank you for your cooperation.

 

[2gGSX]

Made 2 more logs today...

Index of /pictures/gst/logs

1] Hitting peak boost and letting off
2] Idle

I seem to have lowered the STFT to 0% (±1.5%) but the long term is still off. Nothing has changed when it comes to maxing out the fuel but my AFPR's gauge reads no less than 36psi at idle. Is that normal?

STFT should eventually level itself off to hover around 0, otherwise you've got some extraneous problem that the ECU can't correct, such as having injectors bigger than you're compensating for or base fuel pressure being very very off.

Unfortunately, I have to revive this post.

Nothing has changed, except that I replaced the front O2, so it actually reads correctly now. That didn't help with the idle though, which is odd. I have a vacuum/boost leak at the throttle body, which I need to fix and will within a week.

The fuel trims seem wrong but not terribly wrong. I am a newb when it comes to those, so someone please explain them to me.

Here are the readings:
LTFT Lo - 11.5%
LTFT Mid - 9.2%
STFT - 11%

Those are at idle with the car warmed up. I am yet to see what happens during a pull and I'll update with that tomorrow.

For now, can someone give me some fuel trim basics?

Thanks

Looking at the idle log...
1. You need to go to ECU-->Misc-->turn on Invert CAS
2. Verify that you have the plug wires switched correctly
3. Log ThrotPos and make sure everything is set correctly (RawThrotPos=32 without touching the pedal, 255 at WOT). The procedure on how to do this is in the user's manual.
4. Adjusting your BISS and pay attention to ISCPosition and get it close to 30 at idle, and LrndIdleAdj close to 140. It looks like you have to back out the BISS, which will cause the ECU to close the ISC and thus give you lower numbers.
5. Zero out your fuel sliders, that is not normal and your global fuel modification is obviously off. Also, those are your WOT tables and thus do nothing in closed loop operation. Due to the fact that your LTFT Lo and LTFT Mid are both very positive, your global fuel setting is too low. After you zero the sliders out, set your global fuel to -21% and start driving around until you get stable LTFT readings and then post another log. If your LTFTs are both closer to 0, then you're wrong about your injectors being 650's.
6. Zero out your airflow sliders.

I would post these logs up on the DSMLink forums as well since I may have missed something.

 

[adv4nced53]

I bought DSMLink used, so I don't have access to the link forums. I know I have 680cc injectors because I ran 26psi before the cams went in at 10:1 AFR. Since the cams went in I've been having these problems. I'll try the inverted CAS.

When it comes to throttle position, I do not get a reading! Might be the TPS but I have to double check.

 

[steve]

I bought DSMLink used, so I don't have access to the link forums.

If you have a real copy of DSMLink then Tom and Dave want you to have access to the forums. You should follow the process on the DSMLink web site (DSMLink user transfer) but if the seller hasn't and doesn't transfer ownership you need to contact them directly.

Make sure you don't have a bogus V1 counterfeit copy counterfeitcopies [ECMTuning - wiki] If you do you should let them know where you got it from and start saving for a real copy.

 

[2gGSX]

He has V2 since I can view the airflow tables and whatnot, which is supposed to be legit as far as Tom/Dave are concerned.

Post up a log of the car before the cams went in then including LTFT Lo, Mid, and STFT. Everything in your log is indicating that your global compensation is incorrect.

 

[steve]

He has V2 since I can view the airflow tables and whatnot, which is supposed to be legit as far as Tom/Dave are concerned.

Then I'm sure they will help him get signed up for the forums if he asks.

 

[adv4nced53]

Will do. I'll talk to the previous owner. I have old logs but none of them monitored fuel trims , which I know is noobish but oh well...

TPS works fine and I need to do a better log with a lot more variables that I can post up here. I installed a wideband gauge today and had to unplug the battery and since then the long term has obviously been 0% (driven very little). The STFT was around 13% at idle and went to 0%-ish when I revved it.

More logs soon. Thanks for the help!