Stock 84T and 88T tune on 84T Comparisons, More Dyno Results

[bemis]

84T

84T ECCS

88T

88NA ECCS with 88T tune

With each pull, the timing was set to stock according to each ECCS.

The boost was set to a max of 18lbs, but it would spike at 18lbs and then fall off to about 15lbs as the RPMs increased.

Meth/water injection was used during each pull.

Basically, we tried to keep the pulls the same for good comparison.

The most obvious difference is the HP.
As notice the difference in the AFRs. Because of the leaner conditions with the 88T tune, I had severe detonation after about 3500, but as the mixture started to richen, the detonation stopped, around 5000.

The AFRs on the 84T tune started dipping into the 11s around 4000. The AFRs on the 88T tune started to dip into the 11s around 5000.

Also, the AFRs on the 84T tune dip past 10, but the AFRs on the 88T tune never clear the 10 mark.

After about 3 pulls on the second tune, we (Stinky and I) decided to modify the fuel pump at the ECCS so that it would run at 100% duty all the time. We thought this would help richen the mixture earlier in the RPMs, but it didn't make any difference in the AFRs.

My next step is to pull the tune off the 84T ECCS and put it into the 88NA ECCS. Hopefully that will give me a better, and safer place to start tuning.

Please feel free to "chime in", as long as it makes sense. :wink:

[Jason84NA2T]

Wow, I knew there was a difference, but never figured it to be that staggering. The peak at 5000-5800rpm is just gone. Looking at the shape of the curves instead of the peak HP... I'm now wondering what it would be like at stock boost with no water/meth injection. I would also be interested in seeing to torque numbers so I don't have to reverse calculate it.

I'd wager a guess the TP and fuel maps for the 88-89 cars was truly set for a very low boost application.

I also never noticed any difference in AFR's from re-wiring the fuel pump, and my car is a little more modified.

[Stinky]

One thing to keep in mind is that the afrs resulting from teh 88 tune didnt come close to what the 88 tune had in the fuel maps. In other words, something wasnt right. Had things been working as they should the afrs would have been much richer much earlier. I think a maf swap and some more testing needs to be done before any real conclusions can be made.

[Jason84NA2T]

Stinky wrote: One thing to keep in mind is that the afrs resulting from teh 88 tune didnt come close to what the 88 tune had in the fuel maps. In other words, something wasnt right. Had things been working as they should the afrs would have been much richer much earlier. I think a maf swap and some more testing needs to be done before any real conclusions can be made.

I see. If you had a nistune board installed in both ECU's you could probably quickly determine what "wasnt right". It seems to be it could be as small as the k value being off? Which z31 MAF was in the car?

[bemis]

Stinky wrote: One thing to keep in mind is that the afrs resulting from teh 88 tune didnt come close to what the 88 tune had in the fuel maps. In other words, something wasnt right. Had things been working as they should the afrs would have been much richer much earlier. I think a maf swap and some more testing needs to be done before any real conclusions can be made.

Keeping this in mind, I have always had problems with detonation and lean conditions when running the 88T tune on my 84T. In fact, detonation is much more prevailant on the road than on the dyno because the load conditions are much higher and presistant, even with a larger meth/water injection nozzle. The 88T tune may be good for a T3 turbocharged Z31 under low boost, but from my experience, I'm not confident with running it at higher boost. These dyno runs only reinforce my position, while keeping in mind that correlation does not mean causation.

[G-E]

after discussing some stuff with a knowledgeable nissan guy, seems it's highly possible that nissan decided to lower the sampling rate for the o2 sensors in later ecus, possibly only for one type of o2, possibly both

the ecu and the tune would have a completely different fuel delivery curve, it would ramp slower as it is reading the event later, so you wouldn't be running as rich as quickly, but does the fuel and timing in the tp scales work to fix it at low boost?

has anyone compared timing maps 84T vs 88T ?

[Jason84NA2T]

The sampling rate of O2 sensors is indeed faster with the titania sensor, but that information is meaningless in regards to this test. It has no impact on open-loop operations.

[G-E]

hmm maybe not.... maybe it was the fix for the lean surge though

we need more data, give us data, errrrr

[bemis]

I'm working on pulling the timing and fuel maps off an 84T ECCS right now, and then transplanting them into the 88T software. Just have to figure out how to get my Willem programmer to read the chip. (I don't have too much experience with these things programmers)

[bemis]

I've released the 84T BIN on my website, as well as Jason84NA2T is going to put it up in his BIN Archive. In it, the 84T timing and fuel maps have been inserted into a 88T BIN, so all other 84T scales are not represented.

I think this is a better BIN to use for those that are switching their 84-87 eccs's over to the 88-89 models, since it has been shown that the 88T tune on a 84T engine is less than desirable.

To help prove this even more, my next step is to run my 84T on the dyno with this modified 88T bin in a 88NA ECCS. This will show whether it is the ECCS or the 88T tune that is the culprit.

[simply86T]

can it just be the difference in compression ratio between the 2 turbo engines? which the 88 tune is trying to compensate? i know higher compression will require more fuel to prevent detonation, but if running 88t tune in an 88t engine, maybe the lean problem will go away......?

[bemis]

I've just installed the 88NA ECCS with the 84T software into my 84T and took it for a spin. The boost was set to 15lbs, and thanks to the helper spring on the wastegate, it stayed there until redline. The outside temp. was 90degrees F with a relative humidity of an armpit. I heard NO detonation through a fourth gear pull on the highway. I'm feeling very confident about this simple modification that has been seriously overlooked. Now, I'm gonna put it on the dyno and see what the AFRs are looking like and compare those to the stock 88T software ran on a 84T engine.

[bemis]

Just got back from the dyno. I ran the 84T with 84T timing and fuel maps on an 88NA ECCS. I also ran the 84T with a stock 85T ECCS, and a stock 88T ECCS.
For the run on the 85T ECCS, it had be be ran with dropping resistors since I couldn't remove them from the lines without taking too much time.
For the stock 88T ECCS, the O2 sensor was disconnected.
The boost was set to about 15lbs and the timing was set to stock base timing.

pink = 88NA w/84T tune + meth 50/50, 13lbs boost
burgandy = 88NA w/84T tune + meth 50/50
teal = 84T ECCS + resistors + meth 50/50
blue = 88T ECCS + resistors + meth 50/50








Most noticable difference was that the boost held steady all the way to redline. I acheived this by using a helper spring on the wastegate and no boost controller. I just tighten the spring until I get the desired boost pressure. I will NEVER go back to boost controllers again.

Second most noticable difference was no detonation on either of the three ECCSs.

Also, look at the AFRs from the run with the 88T ECCS. Its balls rich.

Conclusion, if you're gonna run a later ECCS on your earlier turbo engine and crank up the boost, use my 88T tune embedded with the 84T fuel and timing maps. Otherwise your gonna lose power and ping your engine to death.

Oh ya, thanks goes out to Ellis AutoWorkZ for letting me use their awesome dyno and the extra ECCSs they had lying around. If you live in the area and haven't stopped by the shop, then you SHOULD. :wink: