aeon117

Obd0 to obd1 conversion on a b18b non vtec motor in 91 integra DA coupe. Only 2 CEL is for speed sensor and intermittent crank sensor.

The distributor is obd1 non vetec, converted with a jumper harness to obd0, then at the ecu another harness converts obd0 to obd1 running hondata s300 ecu.

So the car drives great, but if you WOT smash on it 1st, 2nd, 3rd, by around 5-6k rpms in 3rd, it will just fall on it's face till rpms drop below 3k, which it will then stutter hard anytime above about 3200 until the CEL comes on for the crank sensor (it's either crank angle or position, I don't remember this exact moment).

Tested the distributor connectors with multi meter, and the wires aren't grounding out, and read between 350 and 420 ohms at distributor, the first jumper, the ecu jumper, and ecu.
Replaced 3 distributors now, although problem is less frequent, still comes up.

So finally just ran 18 guage wires straight from the distributor to the ecu.

Still messing up!!!

If I clear codes while idling (with hondata), it will usually work fine until hitting the upper rpms again. Turning off and on motor will usually work too.

So my question is what else could it be, just a faulty ecu? What can I look to do to troubleshoot this next?

TIA

aeon117

The 2 wires I replaced were the blue and blue/yellow from the distributor and ecu side ( pins b15 and b16) btw.

Is it possible the sensor is picking up the wrong signal? Like in obd0, the crank angle sensor is the orange and white wires which would correlate to the cyp sensor pins b11 b12 on the obd1 ecu.

Also, someone else said the igniter is going bad which could lead to the issues, but curious why it would show crank sensor as the problem. Maybe because the igniter going bad relates to misfire, which sends a bad crank sensor signal?

muellersfan

For code 4, you need to do three electrical tests using a multimeter.
Turn key OFF and unplug ECU connector B. Set multimeter to read resistance/Ohms.Post the three Ohm readings.

aeon117

Ok, I didn't measure resistance between the pins and ground, but I did continuity test. Tests done at the distributor plug, the distributor jumper harness, at the ecu jumper harness, as well as ecu. Tests all showed between 370 and 420 ohms, and no short to ground.

One thing I didn't do was unplug the ecu connector during the tests. I will do this test again when I get back to the car sunday or monday night and post the results.

Out of curiosity, If the problem is intermittent, wouldn't the tests also be intermittent for failing too?

muellersfan

When code 4 is thrown, have you ever reset the ECU and code 4 quickly returns after starting engine? If so, that is when you should do the three Ohm tests.
If the intermittent problem continues without obtaining any abnormal Ohm readings, then swap in a known good ECU. Then go from there.

aeon117

It's never come back after resetting, unless I try and clear it with hondata while datalogging and maintaining rpms. If the car is idling, it will remain cleared usually until WoT again. Sometimes it will come back just cruising around 4k rpm (tranny only has 4 gears).

If the car is shutoff and back on while still driving, it's 50/50 if it will come back instantly.

I'm planning on testing the car most of Monday. Need to figure this out if car is being kept, or if it just needs a new ecu.

Would test other ecus, but only have vtec ecus or single cam, so they all kind of run like crap on the motor. The vtec ecus limp mode because of the speed sensor, the single cams I'm assuming it's just the tune. Main reason for running hondata ecu was for ability to read the engine lights to determine why it was limp mode-ing. Couldn't figure out the cel light jumper with the jumper harness from obd0-1

The hondata ecu was working properly the past 2 cars it was in, but I know that doesn't necessarily mean much.

Thanks for the info

aeon117

Set multimeter to 2000 ohms, disconnected the ecu connector B, and did the tests with key off

Resistance between b15 and b16 was 372-378. Resistance between each pin and body ground was 1, which is what my multimeter reads on 2000ohms default.

This is without the ecu throwing the code.

Waiting to get the right key to drive it, roommate only left me the key to unlock it lol.


One thing I've been curious about is that it looks like the jumper harness at the ecu is splitting pin b15 at the obd1 side to pin c16 on the obd0 side.
Wouldn't this be sending b15 (crank positive) to the o2 sensor, or vice versa, the o2 sensor to crank sensor? Is that supposed to be normal? I have the o2 sensor disabled and even depinned c16 on obd0 side of the harness a while back, but if I remember, the car wouldn't even start like that.



Edit:
Finally able to drive the car. It won't mess up till around 5k rpm in 3rd or 4th gear. 1st and 2nd seem to rev to 7k fine. Once it messes up, it won't let you rev or anything until the revs drop below 3300 ish then it will rev limit at 3300. Didn't throw any engine codes besides speed sensor (was already on), and seemed to fix it self after driving under 3k for a minute or so to where I could rev out to 7k again until 3rd/4th gear.
Took maybe 6 times of doing this until it finally threw code 4 crank angle sensor (on hondata smanager), it throws crank position sensor on the hondata android mobile app. Car would not rev past 3300 after this. Parked it turned the car off and checked ohms on connector b for b15 and 16.
Reads 455-460 ohms this time, still no change while testing each to chassis ground (multi meter shows 1)

aeon117

Just to update:
The car hasn't been driven since my last post, until just now. Went and de-pinned the C16 (obd0 side of the ecu jumper harness) wire, which is spliced into the B15 obd1 ecu side. Hondata android mobile app shows 2 codes, 1 for speed sensor (previous code), and TDC no signal. I noticed sometimes the TDC no signal code would go away as I would mess with the ECU jumper harness (like: moving it around, repositioning the ECU, and ensuring the plugs are fully pushed in). In the end, I wasn't able to get the code to remain off, and was on the whole time I drove it.

Car revs out fine now, in all 4 gears till red line, no issues for at least 20 minutes of driving after fully warmed up. Went to the store after testing, and just parked it back home afterwards, and now writing this post.
Not sure why I have a different code for unplugging what should be the o2 sensor (obd0 side, which splices into the b15 ckp positive on obd1 side), nor why a TDC code isn't throwing limp mode either, but as long as the car runs fine (which it seems to be doing now), I could really care less, as emissions or CEL aren't issues for this car.

Just wanted to update on new information. If I don't further post, assume that the issue was solved by basically verifying the pinouts on the ecu jumper harness. If problem comes back, I will have to assume it's either a faulty/loose connection in the ecu jumper harness, or faulty ecu. My next step would be to source another OBD1 ecu that would be capable of running this motor to test.

Either way, I appreciate any support received, and hopefully if anyone else has similar issues, this thread could help them out in some way.

muellersfan

Repeat the Ohm tests on ECU pins B13 and B14. Set your multimeter to the lowest Ohm range for the tests.

aeon117

Will do it today. I'm going to be testing the car today and tomorrow to make sure if any problems occur anyways. Lowest ohm setting I have is 200, next above that is 2000. I have the cheapy centech 7 function meter, that is usually on deal at harbor freight.

Also going to see if I can clear this vss code too so that way I don't have to constantly check hondata for new codes since the light is basically lit 24/7 haha

muellersfan

Use the 200 Ohm setting for testing the circuit for an open or short.

aeon117

Been a while...

The next day, I went to try and test the connections, still read the same as before, b13/14, b15/16, reran the speed cable from the transmission to the gauges to try and fix the vss code.

VSS code seemed to clear 90% of the time (the gauge still doesn't work, though), unless you rev out really fast, then it seems to pop back up, but once cleared, will usually stay cleared for a good while under normal driving.

No other codes popped up that day for the whole day, drove it to work, to lunch, and back. Around maybe 30 total miles that day. No issues, car didn't stall, revved out fine, no limp mode.

I'm guessing the harness splitting the o2 sensor to the crank positive was throwing it off, and possibly loose connections in the jumper harness, as after I put everything back together after testing both sets of wires, didn't have any problems over 30 miles of rough driving.

Would have done more testing, but, transmission crapped out as soon as I got back home. It's a cable clutch, and the pedal went straight to the floor right as I was parking it. Owner thinks the (already crappy transmission that was in it, which was grinding in 3rd, and also missing 5th gear) finally crapped out, especially considering how I've been smashing on it so much trying to test this issue. Been parked since, as the spare transmission that was on hand turned out to not be a B series transmission. Have a clutch kit on hand, but owner wanted to put in a transmission with all good gears, including 5th, so been waiting on that.

All in all, seems like verifying connections and pinouts in the jumper harness was the issue. Will update at some point if car gets back and running soon.