B16A hesitation low rpm light throttle

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hatchedlsvtec

Large Member
I have seen many threads about this problem but I have not really found an answer for my situation. I have a 91 civic hatch with jdm obd0 b16a. I am using one single wire o2 sensor at the main collector on aftermarket headers. No cel. When driving at a steady speed below 3k rpm, when I try to accelerate just a little bit, it slows as if I'm letting off the throttle until I push the pedal more than half way down, then it kicks, and runs perfect. No problems at heavy throttle and idle. Do I need to get and wire in another o2 sensor to fix this? If so, does it wire into pin C8? btw I am using these NEW parts:
-distributor.
-spark plugs
-1 single wire o2 sensor
-spark plug wires
 
Try to advance the timing a little (like 2mm move of the distributor). Not sure how OBD0 timing is done but my OBD1 needs the service plug jumped with a piece of wire or paper clip which turns my CEL on and allows me to manipulate the ECU for a minute. Try to advance it a little and drive it. I had a Slight hesitation at low rpm and found out my timing was at 12 degrees. Advancing it made it go away. Try it...cant hurt. Just make sure you run it at high rpm in first and stick you head out the window to listen for pinging. You need to be driving to put a load on the motor (least thats what I was told years ago) a 2mm move shoudln't hurt anything....its roughly between 1-2 degrees movement of the timing.

TPS check for volts wouldn't hurt either.
 
I did forget to mention I had an extra throttle body laying around that was on another motor I used for a while, and that was the first thing I did was swap in this known good tps and T-body. I checked voltage coming from the tps Key On Engine Off and it read 0.25vdc at closed throttle and 4.45vdc full open with a steady increase in voltage as I slowly opened throttle.

I checked the timing with a light and the service port jumped with a paper clip and adjusted the ignition timing to be at 16 degrees BTDC. Basically it lines up with the middle mark of the three marks close together on the crank pulley.

Engines like on a del sol I believe have 2 o2 sensors, each reading from two cylinders. On this engine, using only one o2 sensor would throw a cel... Correct? It also sounds to be what my engine is acting like, two cylinders too rich, the others too lean. But, this engine has the obd0 computer used in 88-91 civic in Japan... Did this Japanese vehicle use two o2's?
 
Only one O2 on your set up...it should be a 4 wire? Maybe not though. Sorry....I know more about OBD1

Advance the timing 2 degrees and try my theory. What TB did you use? You said you had one...which one? You need a Bseries TB and it shoudl have a Fast Idle Thermo Valve (FITV) on the bottom of the throttle body. You may have a OBD2 TB with no FITV on it. Or maybe a D seires.....measure the in sdie diameter in metric (mm) should be 60mm
 
obd0 ecu's really only have one pin used for (1) single wire o2 sensor... c8 is for a secondary single wire o2 I believe.

The throttle body I'm using is off of a 91 teg ls. It all looks pretty much exactly the same. It does have a FITV. Inside diameter of throttle body is 60mm. The TPS is mounted with rivets so there should be no calibration issue.

This hesitation is not 100% consistent with low rpm. It only happens between 2k - 3k but accelerating through that range is no problem. It chokes only when I'm cruising at a steady speed in a higher gear and give it just a little gas to speed up. If the ignition timing was off enough to affect performance this bad, this problem would be extremely apparent every single time. For example, I had the wrong part number distributor installed on this engine, and the most advanced setting I could put it at was firing 8 degrees BTDC. It had a similar hesitation, but it was through all rpms, consistently all the time. It ran like total shit. The book calls for 16 degrees, I got the correct dizzy and put it at 18 and drove it around, I felt slightly less power and still a hesitation.

I'm thinking about leaving this 1 o2 sensor how it is and just splicing a second wire from it to go to C8 as well as C16 for the normal o2 pin. We will see
 
Ok after a little reading I see splicing one sensor to read as two is no way to fix this. So with aftermarket headers that have an o2 bung at the main collector for reading all four cylinders, then another bung at the end of the cat conv or (test pipe) still reading from all four... From what I gather, I need to stick a sensor in each one and wire them 1 to c16 and 2 to c8? They both read all four so fundamentally it's exactly the same as splicing one sensor to two pins. WTF I do not want to go cutting and welding and crapping out these headers.

stumped.
 
obd0 ecu's really only have one pin used for (1) single wire o2 sensor... c8 is for a secondary single wire o2 I believe.

The throttle body I'm using is off of a 91 teg ls. It all looks pretty much exactly the same. It does have a FITV. Inside diameter of throttle body is 60mm. The TPS is mounted with rivets so there should be no calibration issue.

This hesitation is not 100% consistent with low rpm. It only happens between 2k - 3k but accelerating through that range is no problem. It chokes only when I'm cruising at a steady speed in a higher gear and give it just a little gas to speed up. If the ignition timing was off enough to affect performance this bad, this problem would be extremely apparent every single time. For example, I had the wrong part number distributor installed on this engine, and the most advanced setting I could put it at was firing 8 degrees BTDC. It had a similar hesitation, but it was through all rpms, consistently all the time. It ran like total shit. The book calls for 16 degrees, I got the correct dizzy and put it at 18 and drove it around, I felt slightly less power and still a hesitation.

I'm thinking about leaving this 1 o2 sensor how it is and just splicing a second wire from it to go to C8 as well as C16 for the normal o2 pin. We will see

Had the same prob lol

One 02 sensor per pair of cylinder..!!

Just switch your 02 wires around and it should be okay =)
 
I took my headers to a meineke (only because I don't have oxyacetylene torch/welder) and they cut and welded an o2 bung on the headers where the pipes for cylinders 1 and 4 come together, and another bung for cyl. 2 and 3. two brand new o2's in each, and the old o2 i cut the wire off and just use it as a plug for the bung at the main collector just before test pipe. Now it runs great at all rpm's and at any throttle change/setting. 1 o2 sensor signal split into two ecu pins will simply not run correctly.
 
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