I'm having stupid part-throttle issues...HELP!!!! Need help bad!!!
 

I'm having some stupid part-throttle bullshit in my obd0 b16 swapped hatch, anytime the engine's warmed up and I'm under 2500rpm's the car bogs down at part throttle. I can hit the gas to the floor and it doesn't want to clear out, I actually have to let off the throttle and then lay into it and it picks up fine again. I've checked the tps sensor, set it at 0.45v closed, checked my chipped obd0 pr3 and even reburned the basemap and still nothing. Plugs are good, o2 sensor is brand new (put it in last week), run a minimum of 93 octane, and have correctly set the base timing at the dizzy to the specified 16*btdc. Anyone else have any ideas or things to add, please post 'em up. It doesn't do it while the engine's cold, and I can watch the shitty narrowband a/f gauge go from the rich section down towards the lean area and hover a little when it starts bogging, and when you let up and get back in it shoots back to the "green" section again, so I know it's leaning out for some stupid reason. Even tried jumping the fuel up with my vafc just to see what it'd do and nothing. WTF?

Obd0 is a pita, time for an obd1 swap and some Crome tuning. :P

Re: I'm having stupid part-throttle issues...
 

I would check your internal on your dizzy make sure there isnt any corrision


also spark plug wires how old?

Re: I'm having stupid part-throttle issues...
 

I'll pop the cap off tomorrow and check inside and see, it's an old dizzy so it's possible. Wires are some set of Accell 8.5mm or something around that size, maybe 6 months old tops.

Re: I'm having stupid part-throttle issues...
 

the crusties inside a dizzy are known for odd ignition problems atleast from personal experince. Alot of the JDM used dist I have seen have alot of build up inside of them

Re: I'm having stupid part-throttle issues...
 

make sure your tps isn't wandering its position

Re: I'm having stupid part-throttle issues...
 

It's not, I've set it at least 3 times so far in the past week just to make sure. The only amount it seems to differ over time is 0.005 volts, which really isn't ----. I kinda boned myself in the long run, I have an msd cap for an external coil, and today when I went to order another one they said they can't get them in any more, and nobody local can get one either. :P
Either way I'm converting over to obd1 so I can run Crome (the version 1.4.5beta gives me a stiffy ;D) so I don't see the purpose in special ordering a $60 cap just to never use it again. :P

Re: I'm having stupid part-throttle issues...
 

Well, figured I'd bump this for some more possible answers. So far I've replaced the o2 sensor with a standard bosche 1-wire, replaced the cap and rotor, replaced the plugs and wires, replaced the map sensor, set reset and set the tps again, replaced the fpr, replaced the piece on the other end of the fuel rail (almost like a shock setup for where the fuel enters to smooth it out), burned and reburned .bin files for the ecu and a few other things and still no luck. Each day it seems to get worse and worse, starting to get to the point where it bogs and starts to buck off the line if you slowly press into the throttle. Only time now it doesn't do it is when the car's cold and still warming up. Granted it's dog rich, but once it warms up and leans out it starts to do it consistently. Only thing I haven't replaced is the walbro 255lph pump that I have in the tank, and even with a new adjustable fpr on the rail I still can't get the pressure to drop below 38-40psi. Unfortunately, the most I can get it to raise is about 55psi and at idle with vacuum to the fpr it only drops maybe 2-3psi at most. I'm about 2 seconds away from just replacing the pump with a stock unit, since all of my problems with this car started after I changed the pump. :7 Any one else have any more ideas?

Re: I'm having stupid part-throttle issues...
 

map sensor?

Re: I'm having stupid part-throttle issues...
 

Changed and tried 3 different ones...absolutely no difference at all. :P

Re: I'm having stupid part-throttle issues...HELP!!!! Need help bad!!!
 

is cam timing correct?

Re: I'm having stupid part-throttle issues...HELP!!!! Need help bad!!!
 

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

Re: I'm having stupid part-throttle issues...HELP!!!! Need help bad!!!
 

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.

Re: I'm having stupid part-throttle issues...HELP!!!! Need help bad!!!
 

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.

Re: I'm having stupid part-throttle issues...HELP!!!! Need help bad!!!
 

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

Re: I'm having stupid part-throttle issues...HELP!!!! Need help bad!!!
 

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.

Re: I'm having stupid part-throttle issues...HELP!!!! Need help bad!!!
 

play with map cut and resume settings.

Re: I'm having stupid part-throttle issues...HELP!!!! Need help bad!!!
 

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. >:(

Re: I'm having stupid part-throttle issues...HELP!!!! Need help bad!!!
 

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

Re: I'm having stupid part-throttle issues...HELP!!!! Need help bad!!!
 

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

Re: I'm having stupid part-throttle issues...HELP!!!! Need help bad!!!
 

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! :)

Re: I'm having stupid part-throttle issues...HELP!!!! Need help bad!!!
 

Well, the results of the drive home tonight aren't too much different than previous results. :P It still bogs, although not as bad now (perhaps due to getting the fuel pressure set for once). I'm going to set the TPS back to .45v where I had it before, in general it feels like the car isn't getting enough fuel through the entire rpm range now. I'm also going to disable both o2 inputs and try closed loop to see what it does. This is really starting to piss me off. :7

Re: I'm having stupid part-throttle issues...HELP!!!! Need help bad!!!
 

I assume that you changed the fuel filter too?

Re: I'm having stupid part-throttle issues...HELP!!!! Need help bad!!!
 

Yeah, I changed it about 3 weeks ago thinking the problem might've been due to that. I had a discussion with an old mechanic at work earlier today, and he said to try the fuel pump...maybe I just got a bad one for some reason. So it looks like it's time to go buy a new stock pump again. :P