Slo_crx1

100% correct. It's a very elusive problem, car runs fine cold and fine full throttle and fine on the highway. As soon as I jump off the highway though and head into my town where it's part-throttle situation it starts to stutter and bog. I can watch the rice-gauge drop into the red/lean zone when it happens too, and now when you floor the gas it makes it stutter even worse for a few seconds and then clears up and goes back to the stoich/rich area. I really need a wideband for this. :P

widebody93

Here's a thought, I was workin on a friends car that was doing the same thing. He had a D16A6 block with D16y8 intake ,the D15 CX head and trans. It was a junkyard built motor he said, something he pieced together just to have transportation I started with hooking up a wide band to make sure the FAZE narrow band A/F was reading correct, and it was. When the motor was under full throttle or more than say 50% car was ran great. But under that value it done as you described. When it done this I instantly turned the key off and let it coast with the clutch in and we trailered it back to my garage. I took off the intake manifold and "LOw and Behold" The issue was there. The intake manifold Ports are larger than the ports on the head. So when under low throttle and not alot of air going into the head fuel puddled up"Lean" then spit and sputtered"Rich" from it finally just pouring into the intake and as you gave it ,more throttle it eventually vaporized/used up the escess fuel. I put the D15 intake manifold on with the D16Y8 injectors and problem solved. Just my experience with a HYBRID JUNKYARD WARRIOR.

Slo_crx1

I'm wondering now after looking over the .bin file I modified if it's doing this because I forgot to remove the checksum routine. I'll find out soon enough, I did replace my IAT and ECT sensor along with redoing the map for no checksum since I did change a few things in it.

ososlohatch

that could def casue it, what are your afr's when it happens ??

E-b0la

When I burned my first stock map on my chipped ECU in my 98 EX w/ d16y8, I didn't remove checksum either. The car ran fine WOT, till it heated up and went into limp mode. It also ran rough on light throttle. Try reburning w/out checksum routine, I'm more than willing to be the problem is something with the chip.

Octanox

play with map cut and resume settings.

Slo_crx1

Map cut? Lol...dude I'm in stone-age obd0 land, and not to mention the fact that I'm running n/a on a basicly stock n/a obd0 pr3 map via BRE for tweaking purposes.

So far I replaced the IAT and ECT sensors today, and removed the checksum in BRE, guess what...still no luck. I paid really close attention to it tonight on the way home, and pretty much anything under 30% throttle does the leaning bog/stutter routine...just not as noticeable when you're cruising at 70mph and 32-3400 rpm. My fuel pressure gauge still bounces around like crazy, and the adjustable regulator (or the stock one for that matter) doesn't change ----. I'm going to reburn the .bin so it runs with no o2 sensors and see what it does closed loop, and if it still does it I guess I'll be yanking that walbro pump back out and tossing it in the garbage.

Guy-Fast

sounds like fuel delivery issue. Either the pump or you have a clog in the lines

Slo_crx1

That's pretty much the only thing I can think of...it never did this with the stock pump. Maybe the walbro sock?

Slo_crx1

Ok, maybe got a few issues taken care of today. I read through the b16a EF service manual, and it says TPS reading at closed throttle should only be around 0.3v, so I reset it to that. Throttle response is much better, although I don't have the full 4.5v that it should read at WOT (even tried a 2nd TPS sensor and that one doesn't hit 4.5v either, the throttle plate just doesn't move far enough to allow it). Also took care of my fuel pressure problem, I guess the regulator just didn't have enough spring pressure to hold back the fuel, so I turned it almost all the way up and got a rock steady 43psi at idle and climbing to 48-50 at wot. Warmed the car up and drove it, didn't really hesitate this time around or stutter, although once or twice there was a very slight hiccup but at least so far it's bearable. I also reburned the map that I'm running to disable the bit check for both o2 sensors and the vss, so that might help a little as well. Guess I'll find out the final results tonight on my way home from work, and then can get started on my ITB project. Thanks guys!