Hey guys I've been fighting with this issue for a while and can't seem to figure it out.
2000 honda prelude
H22a
11.1 pistons
Pro 1 cams
Ported head, manifold 70mm tb
FIC 525cc injectors
Wal Boro 255
HA motorsports p28/S300

After build it had a slight hiccup sometimes but was barely noticeable. On warm days after start up it would idle up like normal but when it came down it would lean out and try to die. I passed it off as being bad iacv and wasn't to worried because it would catch itself and idle normal after warm. I unplugged the iacv one day to mess around idle and noticed it still did the same with iacv unplugged. Now it's gotten alot worse it's idling rough and cutting out throughout entire rpm range. I've recorded and datalogged many times and everything looks normal.
Things I've replaced
Plugs/wires
distributor cap, rotery button
Coil, ecm
Fuel pressure regulator, fuel filter, fuel injectors
Tps, map sensor
Battery, battery ground
Things I've checked
Crank sensor,cyp
Fuel pressure, fuel injector pigtails
Valve adjustment
Compression and spark
I'm normally pretty good at diagnosing these things but I'm to the point I'm throwing parts at it. So if anybody has any ideas please help.
I just don't get why it's cutting out and jerking. It does it worse at a low load and steady rpm.

 

What’s the afr that it’s cutting out at? Have you Richened up that section of the map to help it? Misfires are generally caused by two main issues, #1 is weak spark, think of the spark as essentially the suspension for the tune, the weaker the spark the more the car will act up under lean condition or too rich condition. #2 would be a improper fueling. If its leaning out adjust the afrs and see if that fixes it. Mid 14’s for part throttle should run great, if its still acting up post a video on here and I can give you a better idea what’s going on.

also make sure your tps is calibrated in the s300 since you replaced it. Closed should read close to 0% and wot should be close to 100%, if it reads 0 at closed and 60 at wide open throttle when calibrating the tps the tps isn’t in the throttle body spot that actuates the sensor arm.

 

Afr is steady 14.5 and it doesn't move during the cutout.I've tried adding fuel through out map but no difference. It's crazy I've spent alot of time on the tune it's close to perfect and everything is reading how it should when datalogging. Im gonna go through wiring harness today and check continuity. I just don't get why it's not throwing a code. I've got a tuner friend that's coming by today to help. My laptop lags pretty bad so hopefully his will show it doing something.

 

My tuner friend came over and checked it out. We tried his ecu and uploaded my tune and it ran really lean part throttle with his ecu but wot was fine. Which is real crazy considering we both got ha motorsports ecu and hondata v3. So we riche'd it up and found it ran better rich 12-13 at part throttle but still had a miss/hiccup. Anything over 14 part throttle and it jerks pretty bad. It acts just like a injector is cutting out but it's not throwing any codes and looks good with noid light. I double checked fuel pressure and grouNds. Lol I'm out of ideas I've checked and replaced everything I can think of. I was wanting to start another build but this has had me hung up for a while. Any ideas or suggestions welcome.

 

On a 2000 prelude where does fuel injectors get power from. I was gonna trace down wires and test for continuity. They all get good volts but one may be cutting out. It should throw a code but idk. From schematics it looks like main relay to injectors/ ecu but is the a junction some where?

 

I was looking over schematics and it looks like power goes from main relay then splits and one goes to ecu and one goes to connector c112. Then feeds injectors and iac. I'll tear into it wed and see what I find.

 

All yellow/black wires at the fuel injectors should have 12v+ when the key is on.

 

Thanks for the reply. I've tested them several and got 13.5v but I'm thinking there maybe a break in the wire somewhere and it's cutting out. The schematics showed a connector between main relay and injectors. I'm gonna check continuity and hopefully find something.

 

I may have figured out the ecu either that or I got another gremlin. My afr gauge goes dim sometimes. I've checked ground and power a bunch. Today I lost power to fuel pump and gauge so I checked relay. The relay had no power so I checked ecu and it had no Main power. I tried to splice in another ground but no luck and I checked eat ecu fuse. So tomorrow I'm gonna run a new power wire to ecu and hopefully it'll fix all my problems. Hopefully it was barely shorting out causing my issues. It's just crazy it's a power issue. Anytime I've dealt with wiring it's ALWAYS been ground problem.

 

Check your power at the keyswitch electrical switch... specifically, at the IG2 position. The only ground that could be causing the ECU to lose power to the fuel injectors would be the engine harness ground just forward of the thermostat housing.

 

I've got power at the actual ignition just not at ecu at the ignll position. It's got power at pins for evap and o2 I think but no Main power.

 

Well I ran a new power wire to ecu and got the car running but it's still doing the same crap. Im out of options I'm going to go through it again this weekend then take it to a shop. This is really eating at me I've never had to put a car in the shop.