I'm having a problem with a lean spike with a small increase in tp. Say I'm cruising at 10% tps and increase to 15-20% my afrs will spike very lean 17-1 or so. Same thing happens when I shift gears, sometimes so bad that I can feel the car hesitate. I have played with tip in trim with no luck. If I increase the tip in trim I still get the lean spike followed by a rich AFR for a couple seconds until it levels off again. I believe its not a tip in issues since its happening at lower tps %. The car runs perfect other then this issue. I currently have it in open loop all the time and my afrs stay pretty on everywhere in the map. Cruising and idle is about 14.7-15 afr tapering down to 13s at 0 vacuum to 12s for 1-4 psi then lower 11s up to 15psi.

Info on my setup
B18b mostly stock block with simple turbo setup
Walbro 255 fuel pump
Bosch 600cc injectors
Stock fpr
Tuned on Neptune rtp

Any insight on what might be causings this is appriciated. I have searched for hours and can not seem to dig up any info on this particular issue. Let me know if I need to provide anymore info. Thanks.

 

MAP or TPS based fuel map?

 

MAP

 

You can see in the graph section of these data logs exactly what happening. The second pic I was trying to induce the lean condition so I could see it in the logs. Black line is afr and white line is tps %. Any ideas are appreciated.

 

Just try adding more to the TPS Tip-In trim value under Injector Calibration and see if that helps at all.

 

Here is a data log with -10 in the tip in trim box. With my injector size Neptune calculated it at -60. I have added a lot of trim and it does not seem to make it any better. What else could it be?

 

Is ur tps calibrated correctly?
Slow response from the tps maybe?
Or offset enough to cause off readings?

 

Yes the tps is calibrated or at least extremely close. It reads 1% closed and 101% full throttle. I don't think 1% of will make it lean spike like this.

What offset are you referring to that could cause off readings?

I appreciate the suggestions.

 

Offset on the tb itself like its position but if it reads fine I guess that's not the problem then

 

This exact setup was previously tuned on crome gold and did not have this lean spike problem. Since then there has been zero changes to the setup except switching to Neptune rtp with the demon 2. So I believe its a calibration problem, I'm just not sure what else to try. The injector battery offsets are set the same as the crome tune.

 

Do you have idle tables? It could possibly be a setting where you have fuel being trimmed in idle and it not stopping the trim value because of some setting that you might have missed where the trims shut off at a certain throttle percentage or load value.

 

I understand what you are saying, but I don't think Neptune has that. The only thing I can think of is maybe fuel cut, witch is more of a tip out setting. I have looked at the fuel cut perameters and they are deffinity not met when this is happening.

Maybe I'll try to add more tip in trim and log it again. Just weird that I've went from -60 all the way to -10 in the tip in trim box without improvement.

 

I went out and did a little more data logging. These two logs I have +25 in the tip in trim box. That's 85% more then Neptune estimated it should be! The lean spike seems to be the worst after a quick shift around 1/2 throttle or so. The second pic is a 2nd 3rd 4th gear log and you can clearly see the black AFR line spike after shifts. The fist pic is a 3rd gear pull with no spike but the AFR go really rich on tip in before it goes back to target indicating too much tip in.

I also double checked my fuel map by looking up everywhere I have spiked leans in the logs and then hitting those load cells while cruising and they are all on target. So I'm pretty sure its not a problem with my fuel map.

I'm just completely stumped as to why my afrs are spiking like this. I don't think its normal to spike lean in between shifts like this. And I know with 600cc injectors +25% tip in trim is just way too much. I've never heard of anyone running that much tip in trim with 600cc injectors lol.

Any ideas are appreciated. Thanks guys.

 

possible vac leak, or improper injector offset.

 

Thanks for the input. I was hoping you would chime in. I will check for vacuum leaks, but I'm pretty sure I don't have one as I've looked the whole car over pretty closely. And idle is on target.

I just set the injector offsets to what they were set to in my crome gold tune that did not have this problem. If it was incorrect injector offsets do you think they are too short based on the logs? (I have read your crome tuning guide FYI thank you very much for that!) During to spike I noticed the duty cycle does not change so they should still be spraying fuel...

 

Submit tune and datalog of the event via email. It's likely in your fuel map or settings.

 

Thank you very much! I will get it sent this evening when I'm off work.

 

No problem.

 

Make sure to post the results if you get it figured out. If the offsets are too low the dead time will create a delay, resulting in lower fuel volume. If your fuel pressure regulator is faulty you may also get that problem, but typically you'd experience more issues.

 

I will post up my results when I get a chance to drive it again. I hate threads that never have a resolution, nobody learns anything from that lol. I appreciate all the input so far.

HRTuning looked over my tune and data logs and gave me a few pointers. I must say I'm super impressed with their customer service! He got back to me hours after I sent him an email. This is why I decided on Neptune rtp over the other options. Their customer service is second to none.

 

I got the lean spiking issue take care of thanks to help from hrtuning. During my shifts I was hitting low load cells that I never hit any other time and I did not notice it in the logs due to my wideband having a slight delay. I was making the problem worse by adding tip in trim causing irratic lean followed by rich problems lol. Now with fuel added in the right area and tip in trim back to normal setting shifts are smooth with out hiccups. Thanks again for the help guys. Big thumbs up to hrtuning for great customer service!

Now after getting that working perfect I think I'm having an ecu problem lol. I'm getting a solid cel and the demon can't communicate with the ecu. So I'll be trying to fix that next.

 

No problem. Let me know if you figure out the other issue.

 

I see that problem quite a bit. One of many good reasons to use a load-bearing dyno.
HRTuning has the best customer service of all tuning companies I correspond with, including standalones and non-Honda tuning systems. He puts up with my sh*t all the time

 

So I'm not entirely sure how I fixed the solid cel problem but its fixed now lol. I was having the same problem with 2 different ecus. I ended up just going back threw the demon install process and triple checking all the connections and now it works perfectly. The demon must not have been fully seated in the ecu or something lol.

Thank you again everyone for all the help. I appreciate it!