Tuning an LS1 with unknown camshaft

[#0 Ounce]

I have an LS1/T56 that I am trying to tune after installing it in my Datsun Z. The previous owner passed away before I could find out what camshaft he had put in. He did say it was a "midrange" cam. What I can see is Scat rods, Mahle piston, ARP bolts everywhere, dual valve springs with titanium retainers, ported 853 heads, FAST 92/92 TB,FAST fuel rail with (I think he said) 42 lb injectors, 85mm MAF, and I put on Hawks Third Gen 1 7/8" headers. After tuning the VE tables and Idle tuning several times it runs a lot better but at cruising speed it stumbles and hesitates. If it were carbs I would think it's a bit lean. Reading through all the info here it seems I might need to compensate for my O2 sensors being so far away from the stock location. Is there a calcualation for this or instructions somewhere I just couldn't find? Here is my tune and log. Do you see something that I need to fix?

[DrLoch]

To do this correctly you need to get a wideband and add it into your logs so you can really see what's going on. Trying to do it with the NB's can be done but it's a longer process.

[#0 Ounce]

Think I'm pretty close to a final tune (for now). Drives really nice, stumbling is almost gone, changed a lot of things and redid things several times: It has LS2 coils and was using LS1 dwell and Dwell Modifier, I redid those to match the LS2 tables. Can't just copy and paste because the tables are different. Did the VE tables several times and the MAF too. Anyways, here's a log and my tune. Let me know if anything looks wrong or could be better. Thanks!

[matty b]

Just looking at the NB O2s, you are nowhere near commanded under WOT. Commanded is 12.9 and you are at 455mV where it swhould be easily in the 900mV range. Hell you dont even have Fuel trims on to figure it that way.

Your VE doessnt look anywhere near correct.

Get a Wideband, youll probably notice you arent anywhere close to correct anywhere.

[#0 Ounce]

Thanks, matty b. That is what it wants for VE. I went over them until they were within -+2%. I need to order a Wideband, already have the extra bung for it. Can it be logged with the MPVI2 ?

[matty b]

Thanks, matty b. That is what it wants for VE. I went over them until they were within -+2%. I need to order a Wideband, already have the extra bung for it. Can it be logged with the MPVI2 ?

IF you are going over 100% VE by more than a percent or two, the fuel data you have is wrong or your measuring equipment is inaccurate and narrowband are just that anywhere outside of lambda 1 ie ; stoichiometric. VE follows torque fairly close, so unless your motor is really making peak torque at 7000 rpm, its wrong.

You need to put the car on the back burner till you have a wideband in place and can tune it properly, there is too much non-stock equipment on there to safely tune that motor the way you are doing it.

Regarding using the wideband with the MPVI2, you can go the analog route through the AC pressure sensor or EGR sensor inputs and there are uite a few youtube videos on how to do that. The easier way is to hook up the wideband to your laptop via serial and not have to wire the wideband to anything except the USB port of your laptop. IF you get a popular controller, even the maths are done for you by HPTuners already. That is the best way to do it.

[#0 Ounce]

Thanks. I started with the LS1 VE tables and they are 100% at one corner and 50 something at the opposite corner so me not doing any WOT stuff it was just left like that. I did have a few runs that asked for 100+% when driving with the MAF and everything turned on so I bumped it up there. I did take it to get tuned at a dyno after I installed it in my car but he did WOT stuff and did a few adjustments here and there. I was really disappointed in the drivability so I decided to tackle it myself. My peak torque was at 5500rpm and the midrange was seriously lazy. It is no longer lazy and throttle response is excellent now. I did not do any wide open throttle tuning myself because I don’t have a wideband. Here’s the graph from that dyno session.