**DONOTDELETE**
(Unregistered)
09/05/10 10:50 PM
help understanding the effects of ecu/injector change

I decided that I'd finally reinstall my keydiver chipped ecu and 750 cc injectors. Before hand I was running a stock ecu and stock injectors, stock maf, 14 lbs of boost, 3-inch exhaust, stock engine, big fmic, and that's about it. I'd see knock all over the place, any rpm and load range. But the car ran pretty good and was pretty fast. I put the keydiver stuff in and the bigger injectors and I turned up the boost to 18 psi. That's all I changed. My knock count is practically non existent now. Is that just because of more fuel? The fuel trims are now 81% low, 100% mid, and 82% high. The other question I'm having relates to turbo response now. The car seems to almost be on a switch. There is a moment where it seems to load up, almost bog, but not quite. It will pop once or twice through the exhaust, and then it takes off like a rocket. Almost as if it flicks a switch. I don't really know how else to explain it. I drove for about sixty miles tonight trying to let the ecu learn. Was that not enough? Most of the miles were highway miles. A few other notes here, 37 psi fuel pressure, b16g, 2g exh mani (self-ported), recirc'd bov, tps is adjusted correctly, 5 degrees base timing, 255 walbro rewired, afpr, stock fuel lines, kinda long i/c piping 2.25", no safc, or other fuel control. I think I probably need one of those. Thanks guys.

Terry Posten
(Old Balls)
09/05/10 11:45 PM
Re: help understanding the effects of ecu/injector change

You are running rich at idle and high. Do you have a AFPR or is it the stock unit?

If it is the stock unit, that is why you are rich (walbro 255).

With a proper chip (set for the injectors you are using and the MAF) your timing maps will be correct and that is why your car is like a rocket when boost hits.

The 16g is a journal turbo and they hit all at once. If you go to a ball bearing unit your power curve would be much smoother. So the "big hit" is normal for your setup.

If you have an AFPR then lower your base pressure 1-2 psi and your idle trim should go up to a more normal setting. And that would also help the "loading up" condition you are feeling. But don't go too lean, watch the trims. If you lean it out too much you can do major damage (but the knock sensor should protect you a little bit).

Have fun - a 16g properly setup is the best street turbo around for our cars.


**DONOTDELETE**
(Unregistered)
09/06/10 10:56 PM
Re: help understanding the effects of ecu/injector change

Well I do have an AFPR. I bought it used, I think its a china bay special. But it works. If it isn't a china bay, its a weapon R. I'll try to turn the fuel pressure down a pound or two. I think I'm also going to have to investigate an afc and some tuning. This is the farthest I've ever gone into modding a 4g63t powered vehicle. I'm chasing my buddies "store bought" 402 whp 2G. But he sucks at driving. So I think I can beat him, with far less power.
On another note, for all of you with B16g's, when are you hitting full spool? I think I'm coming in a little late. I hit 18 lbs in second gear around 3600-3800 rpm and around 3300 in fourth gear. I've had an issue blowing out manifold to turbo gaskets in the past but that was with a different exhaust manifold. It hasn't blown out since I changed it.


Terry Posten
(Old Balls)
09/07/10 12:07 AM
Re: help understanding the effects of ecu/injector change

What cams are you running? That will make a big difference on spool. I really good set would be 264s. The stock cams spool quicker but fall flat around 6200.

Get some 264s and you lose about 200 rpms of spool but can pull full boost past the 7K mark.

If you get an SAFC, you can fine tune the trims. But don't go too far. Fooling the ECU with a big change will take you out of the timing maps.

In order to really fine tune everything, you need to get a WBO2 so you can see exactly what your burn is at each rev.


**DONOTDELETE**
(Unregistered)
09/07/10 07:27 AM
Re: help understanding the effects of ecu/injector change

Thanks terry! A little food for thought. The cams are stock btw.

mitsuturbo
(Banthony )
09/07/10 10:49 AM
Re: help understanding the effects of ecu/injector change

If you're running piggyback devices, i cannot endorse the S-ITC enough. I honestly think this is MORE important than a S-AFC. It was the single best tuning mod i did to my car years and years ago. They're not very common, and are of a 5 knob variety rather than the fancy schmancy technological-wonder-screen type of device, but they are totally indispensable when dealing with tuning issues without Link or something similar.
If you've got a keydiver chip, your fuel is probably pretty close to in line. Being able to adjust your timing to fit your fuel curve is better than lying to your ecu about airflow in order to meet your timing demands. As you decrease airflow to ecu, the timing will go up. NOT what you're looking for at WOT, usually. It becomes a constant battle to find the middle ground.

Ebay link


**DONOTDELETE**
(Unregistered)
09/08/10 11:03 AM
Re: help understanding the effects of ecu/injector change

I turned the fuel pressure down about 1.5 lbs and the butt dyno says it helped with the loading up feeling I was getting. I haven't had much time behind the wheel yet, only 10 miles, and I haven't logged it yet. But as soon as I do I'll post the changes it made.

MITSUTURBO- this is the first time I've ever heard of the S-ITC. I totally agree with you that with the keydiver chip my fuel ratios are pretty damn close, the car drives too well for them to be off much. I am really only having issues in the 3k-4k rpm range, and with the minimal time I've had after the fuel pressure adjustment it seems better.
Both you and terry got me thinking and this S-ITC seems like a good deal. But before I do this I think the first thing I need is the WBO2. Then an EGT. Then maybe this S-ITC. I don't really feel comfortable "street" tuning using either an S-ITC or an S-AFC so I'd take it in for dyno time any way.



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