Car: 91 hatch with a Z6 and OBD 1 swapped in, new distributer, fuel filter, and O2 sensor,cam and ignition timing was recently set, no CEL's. Also has O2 meter installed and fuel pump controlled by a toggle switch (long story).

Problem: When I first start it and drive it around town, it's just fine. If I were to take off down a highway and hold it at a constant speed, it will be fine for a mile or so, and then almost like someone flipping a switch, the O2 meter will go super lean and the engine will start to bog down and chug terribly and not want to rev past 3k. If I were shut off the engine for only a few seconds and then re-start it, it will act like nothing ever happened until I go a few more miles at a constant (higher) load (as in on a highway) and then do it again. Another (and quicker way) to induce this is to do a wide open run through the gears. While I'm going wide open and shifting it will be proforming just fine, but as soon as I take my foot out of it, it will be super lean and bogging down again, requiring a re-start. Because of the suddenness of it, I would tend to think that it might be some sort of sensor or something electrical, but there are no CEL's. Another thought that crossed my mind is that the fuel pump is on the way out....but then wouldn't it be doing the "bog mode" almost at random instead of after the engine being under load? Any ideas?

 

******* bump for my car doing the same thing with my obd1 b16 swap...


driving alog the highway and all of the sudden bam!


no throttle. and it wont rev past 4k, i just put it in nuetral and back into 5th and its fine.

 

Dizzy?

 

Dizzy is brand new....but even if it was the dizzy, then there would be no spark. No spark = nothing to ignite the gas, which doesn't explain it leaning out.

 

if tried changing my dizzy with 2 brand new ones. and nothing for me.


im thinking that the fuel pump is the culprit.

 

I had the same problem when it was my dizzy.

Since you guys have swapped or brand new I have no idea.

I was getting spark with mine too, just not enough, and only to 2 cyls.

I took my cap off and it was like a copper brillo pad.

 

cram-before-finals-bump

 

UPDATE *insert Unsolved Mysteries theme*

Shortly after this post I installed a fuel pressure test gauge and did some runs with the car. Following the FSM, the entire fuel system checked out ok. During the tests it finally threw me a CEL, and it flashed me a code 43...fuel delivery system. According to the FSM, code 43 usually means the O2 sensor. I reset the computer trouble codes and did some more runs, and now the only code it will throw me is a code 1, which is the O2 sensor. I've checked, double checked, and triple checked the wiring on that sensor. The signal wire is going to the right place and isn't grounding out, the sensor ground wire is properly sent back to the ECU's sensor ground pin (I want to say pin D22 off the top of my head, don't quote me on that). One of the guys from a local shop suggested disconnecting the O2 sensor and seeing what happens. It basically resulted in how its acting right now, but exaggerated. It would run fine just to putt around with almost no load on the engine, but as soon as I put any sort of load on it, it would go into the dreaded "bog mode". The heater control wires were even checked and they were ok. I'm about 5 minutes from soldering everything back up again (everything was soldered up before this all began). Seeing as how turbocharging/running Crome was in the scope of this project in the first place, would skipping ahead and running Crome to disable the O2 sensor solve this problem? Any thoughts on what it might be? (note, that O2 sensor is brand new)

 

i have crome, and im going to try and disable my o2 and see if it helps, ill give you an update tommorow.

 

bump cuz i have the same problem....b16

 

bump

 

update: Ive replaced the fuel injector wiring (very questionable MPFI swap was done) and replaced the 02 sensor...and it still does it. Out of desperation I threw a multimeter on the TPS and MAP sensor to see if they would tell me anything when it decides to bog down, and they both checked out ok and didn't fluctuate at all. Considering the previous owner had an AFC installed, what are some common problems that have arose from bad SAFC installations? Also, after the wiring was replaced there are no more CEL's or trouble codes being thrown, but still bogs after a constant highway cruise or after a WOT run.

 

disabling o2 does not fix it.


ive disabled everything. VSS , ELD, o2 and it still cuts out..

i have a code 17-vss and a code 36 which isnt even a code sooo i dunno..

 

I have some what of the same problem. If I were you guys I would change out the fuel filter. When I was bogging once I change the fuel filter and it did wonders. But now Im starting to bog again at random times, mainly when im at constant even throttle.

And my girl friends car, the gas cuts sometimes when trying to speed up to 70mph (the speed limit in WA). It cuts at 70 and wont respond at all but it will rev to 3k but it wont speed up. Then the gas will come back on at 62 mph and speed up like nothing happend, then at 70 again it will cut and do it over and over again. No idea why.

 

I'm interested too, i've got an obd1 z6 mini me that will act similar, just not as bad. Mine will start to bog on and off after a while of driving. I've been throwing a code 1 occasionally, first week after the swap it was fine, but since it throws the code every so ofte(been a while now though). I have a bosch universal we put on with butt connectors, but i'm getting strange voltages out of it from the signal wire when the code is on. OP: what kinda o2 sensor are you running and how is it wired in?

 

Fuel filter was just replaced less than 400 miles ago...but the thing is a physical fuel supply problem (pump, lines, regulator, filter) couldn't be fixed by simply flipping the ignition off and on in a split second. With that sort of "recovery time" it would have to be something electronic. On a similar note, I probably should have mentioned that the P28 was swapped out and found to be ok.

O2 Sensor is a brand new AC Delco universal part # 213-1536, signal is wired right to the ECU via the OBD1 conversion harness, signal ground is wired directly to D22 (sensor ground), both heater element wires are wired via the conversion harness.

 

The plot thickens. While on a test run I discovered that while idle and partial throttle act like crap when its doing it's bog-down routine......but WOT acts normal.

 

bump

 

So, the mysterious bog mode that was at first looking like a fuel problem infact turned out to be a cooling issue. Unusually low resistance values for the coolant temp sensor (around 180-190 ohms) sent up the red flag that the engine was running a little hot. The previous owner had installed a non-ac Neon radiator. Anyways, after making an aluminum block off plate for the wide open half of the radiator support and drilling a few holes around the edge of the thermostat (yes I know its a band-aid fix, but done more as an experiment) the ECT's are down to more reasonable levels....but I'm thinking that the holes in the thermostat may have been overkill and now it's running a little too cold. Regardless, the "bog mode" tuned out to be the computer trying to compensate for a friggin hot ECT's. Right now the way everything is setup its a bit laggy from idle (idle is especially lean) to 3k, but thats just the way projects tend to go. Thanks for the suggestions and hopefully this info can help someone.