Ok as some of you know me and LS1Queen have been fighting a dry n20 problem for a while and here we go again the dry is leaner now than it was before the new tune, The car was running very bad and we took it back to jeremy at revextreme he retuned it and now the motor is running very good but the dry shot is worse What needs to be done to get more fuel on the dry only? we have place the nozzel just about every where with the only changes was the closer to the maf the harder it hit but still went lean if you look at the wide band play back it will move rapidly from 13.1 to 12.4

 

may be a problem with your MAF sensor.
Have you tried another one just to rule that out?

If it's okay, then it's not acting "normal" at all.
Whenever it's important for you to run the dry shot ( I don't know, maybe that's all the time ), then I suppose you could just modify the section of your MAF table in the tune that applies when you are using the N2O.

A full diagnostic scan when your hitting the dry system could be helpful.
You could monitor your MAF output in particular.

If everything looks good on the scan, then that sort of points to other odd-ball type problems like your fuel pressure dropping or something like that.

Don't give up. You'll figure it out.

 

It moves from 13.1 to 12.4 over the course of the run??? If so it is adding fuel...

 

Ya beat me to it, that's goin richer.

 

What's your N/A a/f? what's your fuel pressure at wot under full demand? What's your wot pe multiplier? Have you logged your IAT on a run? Do you know where your long term fuel trims are at? What rpm does your wot PE start at? what is your ws on rpm? It never surprises me anymore on how many tuners do not know how to tune a dry hit, or be able to tell where the problem is? Ask your tuner about fuel adder vs IAT.
Robert

 

I know its getting richer but 13.1 on n20 How long will that last? I am looking for more like 11.8, I am 100% that its not fuel pressure related car has a racetronix system with a booster fuel pressure never jrops below 58psi on the spray,

 

Those numbers are from a wideband in real action on the track, right, not on the dyno?

Cuz I heard that what it shows on the dyno is about 1 point richer than what it would be on the track, so maybe it's actually 12.1 to 11.4? I don't know if that's the case, can anyone verify for me if there actually is a 1 point difference on a dyno with a wideband and real world drag racing with a wideband?

 

The MAF has been changed and i have efi live and looking at the MAF during a run it looks good, the only thing that i can see is the iat will be at around 33c and falls to -1 as it gets colder during the run it gets leaner

 

N/A afr is 12.8 fuel pressure 58psi, I think the long terms have been turned off I dont know what wot pe is, IAT will go to -1C on the spray

Is there anyone in Florida that knows how to tune a dry kit?

 

On the track I know that if i stay in the trottle I'll burn off plugs before the 1/8 mile

 

How long does the 13.1 last? might just be a lean spike which if under 1 second no worry. How big of a shot?
Robert

 

No its pretty much the whole time but the longer you stay in it the leaner it gets well atleast i think so i dont like staying in it when it in the 13's and its a single 55 pill, when the car was first tuned it put down 188 to the wheels on a single 61 pill and would pull the 1/4 staying at 11.8-12.0 and then a few days later it wouldnt go 500ft and two tunes later still same problem.

 

While I agree with you that you want to be in the mid 11 range on a dry shot if you are burning the end off of plugs before the 1/8 you may be getting detonation from to much spark advance or to little fuel octane. ya your running a little lean but not lean enough to burn good spark plugs (tr6) off.
Back to the fuel thing if you have good fuel pressure, your injector duty cycle is good then just increase the fuel PE table its not as complicated as its being made out to be

 

I don't think we're getting the complete story here.

How can you not know if you have LTFT's or not?
Is this a speed density tune? or is it running in MAF-fail mode?
Not running through CATs are you?

If you have EFI-live then yes you can simply boost the fuel delivery in the PE vs RPM table. Test and see what happens.

 

Also, stop saying your going leaner as the run goes on, if you r actually going richer. Its two different worlds of troubleshooting and expected outcomes.
You say your starting at 13.1 and ending at around 12.4. Compare the PE from where at 12.4 to the 13.1 and shift your multiplier tables, to start around 11.x and slightly lean out from max torque towards max hp rpm ( I am not saying lean it out, just get a little leaner, like 12.5 on track not dyno), and then richen it back up after peak hp til lshift/redline. I dont rely on the IAT mutiplier since my logs show quite a delay from the time dry nitrous enters the engine to the PCM seeing the temp drop. I have stuck with MAP/MAF areas and tune according to rpm vs airflow @ WOT. Agree'd spark pops plugs long before leaning out will, which it sounds like your richening up anyway, just not soon enough or rich enough. I would seriously look at your Fuel Trims if they are on, I would think the trims are not locking at 0. I had similar issue until the trims fell in-line.

Devon.....Dyno will read richer than track/street not leaner, so if his readings were on the Dyno he would be running somewhere around 13.8 at start to 13.2 near end on street, or vice versa if his wb was on the track then on a dyno he might be 12.4 start to 11.6 ending on a dyno. Unless he was using a loading dyno, then its not an issue. Using my LM-1 compared to a shop WB I seen no difference in readings. On the dyno I was at 12.5:1, on the street I was 13.3:1. That was NA. Same applies to Jucie. This was on a Dynojet, not sure model number but not a loading type.

 

My EFI-live version doesn't even let me see the IAT fuel multiplier!
I can only change the bias between the IAT and the CTS.

I agree the original problem didn't seem to be described accurately enough.
Listing out some results of the scanning and WBO2 log would be helpful.

 

Ok i did a wot run on the dry, At wot the afr was 13.1 the i sprayed it droped to 12.6 and then moved up to 13.2 as the rpm went up and the 1/8 mile it was 13.2 It did not burn any plugs and this is the info i have No KR during the run timming at 23.5 injector duty was 71% IAT went from 41c to -1c Map 98kpa MAF 409g/s and car was very lazy at end of run fuel trims where 0 but as i said before i think they are off the last time i had it at the tunner he said the fuel trims was effecting my wot performance and he was going to turn them off due to this

 

So you never burned any plugs.
Okay did you say there were CATs on the car?

Next question: Did you take the screen off of your MAF?

 

Oh here's where the big confusion is. This isn't true at all.
I've run 14.0 AFR on the bottle for 1/8 mile and no burning of the plugs.

I'm starting to think right now that your problem may be that the MAF still has the screen on it, in which case you were never in any danger.
Just simply get rid of the screen and problem solved.

 

I am sorry but that was something we forgot to say the times it burnt plugs it had a screened MAF, the last run Greg reported was with a descreened MAF.