My car has as stated in the subject, a slight hesitation on a part throttle takeoff and now that I have AFR gauge notice it idles around 15.5 or so then when I take off it drops to 14.xx then during the hesitation jumps to 18.xx then back down to 14.xx when it gets going? What should I be looking at as far as tuning to help this? I do have HP tuners. TIA

 

Can you post a log and/or tune?

 

Here it is.

 

Going through the tune, but it would be very helpful if you had a log to go with it, so we can see what it's doing.

 

So there are a few things I've noticed. The first is you have a 2 BAR SD tune, but you are not running any type of boost, from your description. I also saw that your MAF fail freq is still 14k, and all trims and stuff is still on, but you have the p101, 102, and 103 set to no error reported and the light is off in the tune. This makes me think that perhaps the MAF was throwing codes.

You don't need a 2 bar OS for NOS. The hesitation can come from a few things, but hard to say which just looking through the tune without a log to compare.

 

You're right, no boost. I'm not running a MAF anymore and the tune should be setup for that. I'll get the car out later today and get a log for you to look at. You just need a part throttle, normal driving log correct? I also have to get my shift points raised for part throttle too, I can't stand how fast it shifts. lol

 

Do you have a stock tune? You should really go back to the 1 BAR OS so all your MAP offsets are correct. You can copy everything over from your current tune as far as VE and other tables. For the VE, copy only rows up to 105 kPa, as that is 1 BAR, or 1 atmosphere.

 

Crap, gonna have to look for it. I'm sure I have it somewhere here on a thumbdrive. Would you know why my tuner went with a 2 bar setup?

 

I have no idea why he would do that. The only thing you need that for is boost. Pretty odd honestly, that he would change it. I don't see the advantage.

 

Listen to Doc he;s right and I totally agree, you don't need to be 2 bar OS. The maf should be failed to 0 as well. Your tuner is corn fused.

 

Can you look at this one also and see if it's also 2 bar? This was my tune from the tuner and another guy looked at it and changed a few things for me to try. I don't know if maybe he changed it?

 

I’m at work right now, so I can’t look at the tune at the moment. It’s easy to see if it’s 2 bar. Go to Engine>Airflow>General>Main VE table and check the MAP values. If they go over 105, it’s not a 1 bar VE. 2 bar = 210, 3 bar = 315 etc. Yours should STOP at 105, aka 1 bar. Kpa is just a different unit for pressure. 105 kpa = 14.7 psi, or atmospheric pressure at sea level (bar/barometric pressure). No NA car can exceed baro. What your tune is saying is that your engine can go up to 29.4 PSI, or double the baro, which is physically impossible without boost.

 

Yep that's a two bar map as well.

 

Is there any chance you can contact your tuner? You should really get the STOCK tune file from him, since it should be licensed to your VIN. I would hope he would have kept it, since I just put them in a folder just for this purpose. It takes almost no computer memory of effort, really.

If not, then you will need a new stock tune file from the repository and you will have to spend credits to license it (probably will anyway if you haven't licensed it though your HPT sofware and MPVI), then fix that interesting version of a "speed density" tune because there is a lot going on there. Still trying to figure that one out.

Check my guide on setting up and tuning for speed density, but DO NOT get into the NOS. There's more to that. I will say though, I'll bet it fixes your hesitation issue.

EDIT: SEE BELOW...

 

Alright, so I did some research into why someone would run the 2 bar. It's for fueling, and the actually is an advantage, if your controller doesn't take care of that for you.

The question is then, is the MAP sensor wired on a relay to your nitrous activation circuit? Needs to be a 5v supply. Should be the on the same with the WOT circuit. It tricks the MAP into thinking it's 105-210 kpa by tagging out the signal, which makes it easier to tune for the nitrous. That I can see as an advantage.

Question 2: Does your controller pull timing? Because it is still in the 28* range WOT, with an interesting "dip" right through the middle. Even with the dip, it seems still pretty high for nitrous, depending on how much you're talking though.

Question 3: What shot, how big?

Looking through your tune, I do not see the use of the IAT or ECT sensor resistor/ground being set to anything to indicate pulling timing there either.

We can work with this provided that the MAP is in fact getting an additional 5v applied when nitrous is activated. If the controller is doing this though, like many can, then I don't see the need for the 2 bar. I would recommend testing this with the scanner but activating your nos (not actually spraying though, just checking wiring/bottle off) but seeing if it does indeed jump to 105-210.

Cool, so I learned a new trick today, thanks lol.

 

No, the map sensor isn't wired to the nitrous. I'm just running a window switch/wot switch, no controller. It's a wet kit that will not see over 150 shot. My tuner did know I was going to be spraying once in a while so maybe this is the reason he went with a 2 bar setup He did tell me not to try it with this tune or I'd blow it up. I was supposed to take it back for a nitrous tune but winter/snow came and I never made it back.

I'm gonna watch your tuning guide now and try to learn a few things.

 

Okay, well I can see what his plans are now, and assuming he is going to wire in a 5v power source to the MAP signal on a relay, then the 2 bar makes sense. That's the only way this will work. The hesitation is most likely a result of spark or fuel. You do have a weird dip in the middle of your spark table, so this is probably more likely than fuel, and is always more pronounced and noticeable. The lean spikes are most likely a result of a "rough" VE tune since it sounds like he planned to finish it later and got it "close enough." I can't blame him there really, as VE can take some real time to tune out, perfectly. That and he thought he would see the car again. I can't say I haven't done this myself. Just had VERY strict instructions to the owner, DO NOT test WOT until you bring it back. He brought it back the following weekend and I finished the tune lol. Sounds like he gave you some instructions too lol.

 

Yeah, as far as not using nitrous until he gives me another tune for that. Guess now that the weather is better, I'll just take it back to him and have him "touch it up" I just figured it might of been something simple. Thanks for looking at it and the advice also!