Nistune Forums

Hi, I really thanks for help me with my problem.

1987 Z31 VG30ET , Twin Garretts GT2860RS, JWT stage2 cams, 750ccm Siemens Injectors, Ford Lightning MAF, Greddy E-01 Boost Controller, Walbro 255lph fuel pump, Aeromotive Fuel Preassure regulator, NGK BCPR6E, Magnecore R100 ignition cables

When is engine running on stock boost 12psi, engine is running nice and smooth, but when I try rise the boost to 15 psi or more, engine starts producing massive detonations. Not only little ones, complete lost of power, there are only two stages, one engine is running nice, second massive detonations. I was trying change amount of fuel, higher-lower ignition advance, I checked every ignition component and nothing help. I am without ideas what can be wrong.

Logs and Binary files included, if anyone can check this and tell me, what I am doing badly, I will be very thankful.

And is possible that two GT2860RS can hit without problem 5,1V MAF reading? It is normal?

If you need anything to know, please ask. I will be very thankful for any ideas, what can be wrong.

What are your AFRs like throughout the rev range? Do you have a dyno AFR curve or can do a log with AFRs so we can trace it?

Maximum MAF voltage I see in this log is 4.019 volts @ 00:22:24.104. It idles about 0.08 volts so offset is displaying correctly in the log player

Also noticed your timing map is higher than stock. When you increase boost this will increase pressure inside the cylinder, so you may need to pull much more timing out to compensate for the increased boost

Start with getting your AFRs right and let us know what they are then focus on pulling out timing to avoid detonation. As long as you dont have to pull too much out

Basically tune for the most boost you intent to run and tune around that. Obviously running more boost will increase combustion pressure, hence temperature and cause detonation if it was on the edge previously

Hi Matt, thank you for helping me.

So dyno AFRs reading is really hard to do for me. Which AFRs logs can help to you?

I am now using Ford Lightning MAF, previously I was using Cobra MAF and AFR curves from nistune for them. So It is bad using them?
I dont know where I can found correct VQ maps for this AFMs.

Jason sent to me some bin files from his 430rwhp car which are working for him correctly and when I use them car have same problem with detonations.
I found that, when I am using his bin files, ECU dont read speed of car and is showing 60 speed all of time.

So yesterday I was playing with car of my friend. He has only modified exhaust, intake, intercooler, and we were changing AFM for Cobra MAF.
I was change only VQ Map, adjusted K value for right one and little tune for fuel injection map because we rised boost to 15psi on stock turbo and car is running
without any problem with AFR 12:1 in full boost. It is normal that, stock T3 turbo when is pulling 12-15psi, Cobra MAF read out can reach 4,4V?

So I tried using original bin from his car in mine, I changed only VQ Map for Lightining MAF, K value for bigger injectors, and my car have still same problem max boost
12psi, than if i try 15psi, massive detonations and lost of power.
I was trying bin which I sent there yesterday, only lowered timing on full boost and nothing helped, everything is same.

I know that two GT2860RS turbos are flowing much more air in 15psi than stock T3, but I cannot find way how make run engine little better, to find out where start
changing anything in maps. Every change makes no differents in engine behavior.

Can it be ECU related problem?

Or any other ideas, what can be wrong?

I discovered only one thing, when I try setup timing for full boost to higher values 40-50, engine have low power but detonations are not so massive, but this isnt helpful, I was only trying if will be there any difference.