too much fuel + w/i = bad timing???

[alex027]

My car was dyno tuned with pump gas for 20 psi with an o2 sniffer. I'm now tuning with a logger and an afc. I just recently installed a water injection kit, and with the same 20 psi my peak timing at 6600 was only 16*? I didn't change anything on the afc yet , but i thought that after installing a w/i kit you needed to lean out the afc settings. Wouldn't leaning it out cause more knock, and less timing advance. I'm still not too good at the whole tuning thing so any thoughts or help would be appreciated. Thanx.

 

[alex027]

I took my car to the track and was hitting fuel cut. Wouldn't the water injection keep knock down so as not to hit fuel cut. I actully had to richen up a few spots on my afc, to keep from hitting fuel cut. I am stumped, anyone with any help would be appreciated.

 

[Blue92]

The water injection should help prevent knock. Got any logs? Is your base timing good too?

 

[v8killerr1]

how much hp/torque did you get on the dyno?

 

[alex027]

I had a few logs but, while at the track I recorded one and when i went to take a look at it the palm froze. It would not do anything so I had to reset it and when i did this it erased the logging program and all saved files. So i do not have a log saved as of now, but i will most likely head out again today to give it another shot. My base timing is fine. My dyno runs were graphed with hp against a/f. I do not know my tourqe figures but my horsepower was 276 awhp on a dynojet.

 

[Joesmoke]

Yes, lean it out on the afc. You always want to run a lean engine more power (to a point of course) and the water injection will allow you to push back the knock threshold.

My recent WI install:
14b (18psi)
smic
450 inj.
little bit of extra fuel pressure.
As soon as ran with straight water, I took out 5% on the high tables of the AFC to prevent a bad "bog" I then mixed a little of windshield washer fluid in there and with the addition of the methanol in the wiper fluid, I could have gone a little leaner.

Then I went to straight methanol. Huge power, (and no knock) came when I leaned
out -10 @ 3400 and -15 from there on the hi table.

Your mileage will vary/depends on your car/tune with logger or wideband applys here, but yes, start leaning it out.

 

[alex027]

Im hitting fuel cut with the just the w/i turned on and my afc at the same settings. wouldn't leaning it out any more cause it to be more prone to hit fuel cut? I hit fuel cut once. Richened up the area where it hit, and then no problems. Turned up the boost a little and then hit fuel cut twice on a 3rd gear pull. All the research i have done on w/i has shown that you can run more boost without having to switch to race gas. The last time at the track I put in race gas, turned up the boost, and didn't touch a thing on my afc. Ran great. I ran w/i a few days ago at the track and I wasn't even able to take a run without hitting fuel cut, even at the same boost level. Just reading what i have just wrote makes me even more stumped, by putting it into perspective.

 

[Joesmoke]

The way you explained it is odd to me as well. Here are some basics that you probably already know, I just want to put them down so everything is clear:

1.Moving into the negatives further on the AFC moves you farther from FC (altered air flow signal) and produces a more lean running car.

2.When moving into the negatives, airflow is altered and you will end up with more advance

3. Running racegas and WI will usually allow you to lean WAY out! With racegas you can lean out and with WI you can lean out. Although I have not run both yet, I would imagine it is a cumaltive(sp?) effect
4. Ambient air temp and density have an effect on timing. Were there temp diffs?

3 questions:

What size injectors do you have?
Where are your AFC settings now?
What is your WI kit? Jet size, pump pressure etc.

If I were you, I would not bring racegas into the equation again until you have pump gas figured out. Wont do any harm, just harder to get things running well. One more variable.

Jason

 

[alex027]

i wasn't saying that i was going to run both race gas and w/i. I was just saying that when i ran race gas everything was fine, even without changing my afc settings. And when using the w/i I was having problems. I definitely wouldn't get into both yet. I have rc engineering 550's. My w/i kit is from aquastealth.com. It is a 140 psi pump that is set to activate at 10psi of boost. The nozzle is a .6 mm.
afc settings:

1-4000 -12%
4600 -11%
5200 -1%
5800 -2%
6400 +2%
7000 +5%
7600 -2%

 

[44pirate]

Are you running straight DI water?
You should be leaning it out.
Are you sure it's fuel cut and not just bogging. 10psi for the WI to come on seems a little too early. I'm new at the WI injection. I'm running 50/50 on mine. I have the WI to come on at 18psi but then I'm boosting 26psi.

 

[Joesmoke]

pirate 44, if your system can handle it, you gotta try straight methanol. Thats the good stuff. Be prepared to lean out pretty far!

Alex027, what turbo are you running? What intercooler? Those settings look like you could lean it out (but every car is different).

Fuel cut with settings like that seems odd

Boost leaks?
Jason

 

[alex027]

It is definitly fuel cut. I am running a 50/50 mix methonal/water. I have a big16g, and am using the dejon tool super big sidemount (10"x10"x5"). I felt the intercooler after every run at the track and it wasn't hot at all. And no boost leaks. The night before i went to the track i logged a run. I hit fuel cut at about 5200, but the logger didn't show any dip in timing. The only thing that i can think of is that maybe the car sees such quick timing advance because of the colder air, and all of a sudden sees some knock and then bam, just decides to stop sending fuel. I drove right through the fuel cut and it picked right back up without hesitation, and pulled strong through the rest of the gear. The only time i would ever hit fuel cut prior to the w/i was on a cold damp day. With the water injection isn't the ecu seeing a cold damp day all of the time.

 

[Joesmoke]

Sorry, Im stumped.

But quoting from your second post:

"Wouldn't the water injection keep knock down so as not to hit fuel cut."

This statement is wrong. Knock has nothing to do with fuel cut. You mentioned again in another post and that post is incorrect as well.

You also mentioned you "drove through it (fuel cut)" I assume you mean once you hit that brick wall, you lifted the throttle, then got back on it. Anything else would not be fuel cut.

If im going over things and oversimplifying or questioning issues that you are confident are true (like are you sure its the brick wall of fuel cut), its just because your problem has me curious and I want to make sure I'm on the same page.

 

[Sk8er07999]

fuel cut is a safety feature in the ecu which cuts fuel if it sees TOO MUCH AIR COMING IN. So what does an afc do? It modifies the airflow signal from the mas and sends it to the ecu. Then the ecu determines how much fuel to add according to how much air is coming in. So in order to push fuel cut back the you must go further negative with the afc. Because this tell the ecu less air is coming in. But heres where you must be careful. We all know that too lean and you will detonate. But if you go too rich on an afc you will cut. It's a very fine line...

 

[alex027]

It wasn't as hard of a hit into the brick wall, but i felt it. Maybe it wasn't fuel cut then. It sure felt like it though. Maybe it was just a very strong stutter. By driving through it i meant i just kept it floored and the car would pick right back up very strong.I'm going to go ack out tonight and see what i can do. I'll figure things out. I'll let you know what the cure was when i fix it. Thanks for all of the help. Just reading everything has given me a better understanding of how it all works.

 

[Joesmoke]

Fuel cut is like running into a brick wall. Its been described like that many times and I have personally felt it.

Fuel cut hits when you're doing a banzai run. Then all of a sudden, the engine essentially shuts off. Feels like a brick wall, or that something has broken in a big way! My natural reaction (Im sure others too) is to take your foot all the way off the gas. Its a knee jerk reaction to an situation. All's fine when you get back on to it. When you're not expecting it, it will scare the hell out of you!

I am almost positive you didnt have fuel cut because of your symptoms, and because you said you kept your foot in it and drove through.

I am glad you have learned from this post. I would look for other challenges, like you said, ignition stutter. Keep searching the boards (this and others) and youll come up with your answer. Remember, almost anything that has ever happened to a DSM has been covered somewhere in these boards.

Good luck.
Jason

 

[44pirate]

Try setting your WI to come on at a higher psi for onset. What your exeriencing is a slight bogging from the WI onset.

 

[Sk8er07999]

I could see the cut in my logges on the palm. Under wot when fuel cut occurs I would see a sharp down fall in the o2's. like a sharp spike pointing straight down. I would hit cut like three times as I went through third gear until I put in the injectors. So in the o2's you would see a steady line at like .91 then when the cut occured you see a shard spike dropping down pretty far. But I was able to drive through these as well. it's not like hitting a brick wall but it does give you a good jolt.

 

[Joesmoke]

How do you "drive through" (I assume you mean keep your foot to the floor with 0 lift) when the car cuts its fuel off? Only to give it back once you lift off the throttle.

Hitting a brick wall? Its been described like that for a long time and its a good description.

 

[Bohrn]

fuel cut is not related to knock or lack of it.

Fuel cut is simply the ECU thinking that there cannot be enough fuel for the amount of air flowing thru the MAF.

See, if you have a bigger turbo, full perf exhaust, and more boost, you ARE flowing more air than your ECU's fuel tables tell it that it has fuel for.

Even if you have a bigger pump and injectors, your ECU DOESN"T KNOW that and still assumes that you have the measly stock pump and 450's.

Enter the MAF hack/swap and an SAFC or other piggyback.

You hack away the lower part of your maf and add 510's and a bigger pump. And adjust it properly with your SAFC. NOW, you have enough fuel and your car is adjusted properly so you HAVE enough fuel for it, even though the ECU doesn't know it.

Buuuut, you have helped the MAF flow more UNCOUNTED air thru the bottom part, so that air can make you power but not go towards your fuel cut "debt". Also as you have taken out fuel on the safc, it is fooled into thinking there is less air thru it, again delaying the onset of fuel cut.


Or so I have been lead to believe anyway.

Jason, where you gettin your alkyhol at?? I've just been running water and cheap Smurf Piss.

Also, a couple of you are triggering your w/i at quite high boost. I have been running mine at about 4 psi. Givver a try guys, its nice to have a cool charge the whole time. Might not work for ya, but try it anyway. you can rig an LED off the solenoid wire that can be run into your cockpit to tell you at least when the solenoid is open.

 

[Joesmoke]

Good post John. I think we covered the basics in laymans terms and then you came in and got all uber technical.

Hey, last time I talked to you did I not say that I was going to trigger mine at 4 psi and you're like "Man thats so low, Im going to go at 15 psi"

Methanol source from hardware store. Wood alcohol, methyl alcohol, methyl hydrate,its all good. Was a little pricey @ 10.xx for 4 liters, but I didnt do any shopping around. Could probably find it cheaper. Just wanted to give it a try.

Now if I could just convince you that you don't need those fire hoses you call injectors in your car. What are they, 780's? 720's? Be prepared to lean way out with the straight stuff. Even with smurf piss im at -10 @ 3400 and -15 from there. Stock 450's baby. Cars moving and not complaining. Guess Ill save those 650's for when I have giant snail.

 

[sweet97]

VERY INTERESTING POST! I sent a PM to one of you guys and I want to learn more about this as I am going to need it. I am running a 50 trim because I got a great deal on a new, unused AGP RS49 from a tuners member saving me around $3. bills. I am going to have the Dejon Street FMIC which is not the big IC the turbo would like and this injection may be the ticket for a couple extra lbs. of boost. I will check out aquamist and their site and any more info here, either general or technical would be appreciated. Mark

 

[44pirate]

I'm using "denatured alcohol" with 50/50 water. I had to lean it out about 8%. I'm gonna try and run straight methonal when the weather gets cooler here in FL. I prefer the water mix for the cooling properties that the provides.

 

[sweet97]

Where can I get the equiptment to install on my car? Does anyone have pics of their installation?
www.aquamist.com was a site for hydroponics. Mark

 

[alex027]

This is a link to a tech article showing how to make a DIY w/i kit.http://dsmtuners.com/forums/showthread.php?t=81892.
Although i bought my own kit from www.aquastealth.com i found this to be very helpful. There are other sites devoted to water injection also. I found a google search on water injection to be very useful.