Prembird

1997 Civic
LS B18B1 Swap
5 speed swap
Dont remember which harness (Has v-tech plug - B16y7 or something)
OBD2 to OBD1 jumper harness
P75 ECU

Ok here is whats going on.. Its gonna be a long read cause I have tried a ton of stuff.. Hopefully someone here has an idea for me to chase down..

First things first.. The guy who built my car kinda butchered it if you ask me.. I have spent a ton of time and money putting everything back to way it should have been built the first time, everything from tucking wires to completely rebuilding the suspension (they used heated springs to lower the car).. That being said...

A few weeks ago I started noticing a hesitation when you barely touch the gas. Didnt matter if you where parked or driving. Push on the gas pedal and nothing till you depressed it about 1/8 inch then it applies the throttle at that position and jerks the car. It didnt do it every time, some days not at all and others it wouldnt stop. Consistently has gotten worse till it was doing it everyday..

Searched online and came up with that it was probably my TPS causing it. I know I should have tested it but since I was already at the parts store I just bought one. Got home and installed it according to numerous guides on this forum and others. No issues except I didnt have a chance to set the closed position correctly. Closed it was reading .6 ohm and WOT was 4.5.

Hesitation was pretty much gone but barely still there. Thinking that it being at .6 instead of .5 or .48 might be causing this, I went ahead and went back a little later and pulled the throttle body so that I could go ahead and clean it to get rid of any deposits and hopefully make the whole setup better running.

Came off fine.. Took everything apart without issue.. Cleaned it up and without thinking grabbed a fine grit paper to help remove deposits.. Not that big of a deal but guess I nicked some of it up and ended up modifying the butterfly so that it would close completely (Completely screwing it up) .. Before you flame me I wasnt thinking straight and was tired.. I can now see that I screwed up my TB completely and will have to replace it anyways..

So went ahead and put it all back together and bench calibrated.. reinstalled it. Started up and it jumped to 3500 rpm and held... shut down.. checked everything over and couldnt find anything. Went back and restarted.. Back to 3500.. Checked the TPS and its reading where all over the place.

Gave up for the day..

Went back next morning.. Double checked all wiring, connection, etc.. Everything is connected correctly. Pulled new TPS off and bench tested.. Ratings where all over the place. Took TPS back to store and warrantied it. New TPS shows .5 ohm at closed and clean sweep to over 4.5 off the car.. Install TPS again. (I did have battery disconnected when doing all of this)

Set it all up again this time I noticed that with the TPS installed, car in on position and not running, that it was registering 2.8 ohms at closed position. Barely moving the throttle and it increases quickly and then blanks out beyond its range. Took the plug off and retested just the TPS while on the car and it shows .5 ohm closed and 4.9 ohm WOT.

So now it seems from what I can gather is that something is adding around 2 ohms to the signal feed causing to to read as though im at half throttle.

Other things Ive done and outcome...

Unplugged MAP while running. Idle drops to 2500 with slight hunting
Unplugged IACV while running. Car hunts between 1300 to 3200 rpm.
Blocked off IACV using tape trick. No change, Idle 3500
Sprayed everywhere using carb/choke cleaner looking for vacuum leaks. Nothing changes

I have had people suggest that the TB butterfly being screwed up with major light being seen around it is the issue but I dont see how that would effect the Ohm load when the car is just in the ON position and not running. I wouldnt think it would effect the TPS sensor itself when calibrating.

I will be getting another TB and putting it on but where is the extra OHM load coming from to tell the ECU that im at half throttle when closed? Could it be the ECU causing the issue? Reason I ask about the ECU is that since I bought it, it has had an issue of every now and again going into limp mode out of nowhere on me... Quick cycle of the key usually corrects it. Maybe happens once every 3 months.. Sometimes a couple times in a row and goes away completely for long periods (Months)...

Im completely at a loss at this point...

Thanks in advance for any help and I will answer all question that I can...

Greg

B_Swapped93

why haven't you tried a new ECU yet if you've done all that and this is still happening I would highly recommend that. since obd2 to obd1 via jumper i'd also be willing to bet it has some shitty chip.

Prembird

From my understanding it isnt chipped at all.. They used the p75 obd1 cause it was for an LS B18B1. Where im located I have not been able to find another ECU to try with either. Im in southern missouri. I went to springfield today and went to every junk yard looking and no one even has an interga on there lot. Craigslist has been a complete bust for me as well.

Prembird

Also if im going to be looking for another ECU.. Which OBD2 ECU can I use with this setup. I would prefer just to get rid of the jumper harness altogether if I can.

ZenkaiRacer

You don't have your TPS and IACV plugs swapped by accident do you?

Prembird

no i dont. The harness they used in the car actually has different plugs for the TPS and the IACV. The plug to the TPS has been modified along with the outside plastic of the TPS to allow them to plug together. If I can find the correct harness at a junk yard I will swap the plug over to be the correct plug.

Prembird

Another thing I just remembered... Tested the wires at TPS... Ground of DVM on ground terminal of battery, Positive to ground (Green wire) of TPS shows 1.5 ohms when key is on.. This i figured is normal due to loop back through the system.

Red wire shows nothing when not connected to TPS

Yellow wire shows 5.01 Volts with key on...

If that info helps any...