Engine Trouble.. Stumped
- Thread starter Corprin
- Start date
Update:
My dad sent out his spare OBD2 reader and I pulled the codes. Turns out I had codes that showed issues with o2 sensors at B2S1 and B#S2. Ordered up a new sensor to replace the dead one at B2S1 (S2's don't do anything with mixture) and replaced it. Once everything was back together I found the plug was wrong. I went with the VIN differences between SELS and AELS, and found that really doesn't tell you what you have... it's all about what the under-hood label says you have. Since all was installed, and the o2 was now not returnable I started hunting down if I could just swap the plug. Answer... yes.
When I pulled the plug out of the truck I found the wires were baked, insulation was brittle and missing in large chunks. The titania type sensors our trucks use function on resistance rather than voltage output. Since my issue seemed to be temperature dependent this makes complete sense. The hotter the exhaust, the hotter the exposed wiring, the higher the resistance in the wiring, the leaner the read, and the more fuel is dumped into the chamber.
This accounts for the unbalanced readings I was getting during a live pull with the OBD2 reader, values on B2S1 were higher than the B1S1.
Wife is headed to Twilight with the girls, so I will fix and test the o2 to see if that worked.
Report to follow.
My dad sent out his spare OBD2 reader and I pulled the codes. Turns out I had codes that showed issues with o2 sensors at B2S1 and B#S2. Ordered up a new sensor to replace the dead one at B2S1 (S2's don't do anything with mixture) and replaced it. Once everything was back together I found the plug was wrong. I went with the VIN differences between SELS and AELS, and found that really doesn't tell you what you have... it's all about what the under-hood label says you have. Since all was installed, and the o2 was now not returnable I started hunting down if I could just swap the plug. Answer... yes.
When I pulled the plug out of the truck I found the wires were baked, insulation was brittle and missing in large chunks. The titania type sensors our trucks use function on resistance rather than voltage output. Since my issue seemed to be temperature dependent this makes complete sense. The hotter the exhaust, the hotter the exposed wiring, the higher the resistance in the wiring, the leaner the read, and the more fuel is dumped into the chamber.
This accounts for the unbalanced readings I was getting during a live pull with the OBD2 reader, values on B2S1 were higher than the B1S1.
Wife is headed to Twilight with the girls, so I will fix and test the o2 to see if that worked.
Report to follow.
Not ignoring you at all, just have been busy. I am entering finals and family holiday crap, so my auto-work time is very limited at this point. Before I started shotgunning at possible issues, regardless of how logical they may be, I wanted to fix the absolutely known problems in the truck to eliminate simple variables, thus the o2.
The o2 did not fix the main issue, but did fix others. The problem persisted and I believe you are correct with the CKPS going south based on the difference between tach and ECU RPM readings during the bucking/hesitation. Fail point is temperature and RPM dependent
When I found the issue was persisting, and now having an OBD reader, I began to watch live data while the issue was going on, not just saved values on code trips. With the engine warmed, and recently returning from a 20min drive where I am seeing the issue, I can get the hesitation to occur in park and neutral (transmission issues ejected). As I increase RPM the ECU (via OBD reader) and tach are showing equal values. When I hit 2k, the engine starts to buck/hesitate and the ECU rpm value drops to about 870 or so, while the tach sits at 1800. I can then let off the throttle and the truck returns to normal idle, wash and repeat. Since the engine is rotating 1k faster than the ECU thinks it is, the fuel and ignition maps are that far off possibly causing the issues.
Now just need to find time to get it swapped out before it starts to snow... don't want a sloppy walk to the bus stop.
The o2 did not fix the main issue, but did fix others. The problem persisted and I believe you are correct with the CKPS going south based on the difference between tach and ECU RPM readings during the bucking/hesitation. Fail point is temperature and RPM dependent
When I found the issue was persisting, and now having an OBD reader, I began to watch live data while the issue was going on, not just saved values on code trips. With the engine warmed, and recently returning from a 20min drive where I am seeing the issue, I can get the hesitation to occur in park and neutral (transmission issues ejected). As I increase RPM the ECU (via OBD reader) and tach are showing equal values. When I hit 2k, the engine starts to buck/hesitate and the ECU rpm value drops to about 870 or so, while the tach sits at 1800. I can then let off the throttle and the truck returns to normal idle, wash and repeat. Since the engine is rotating 1k faster than the ECU thinks it is, the fuel and ignition maps are that far off possibly causing the issues.
Now just need to find time to get it swapped out before it starts to snow... don't want a sloppy walk to the bus stop.
speed sensor, it is a known defect in the 96 to 98 vintage. it kills one cylinder bank thus emulating a misfire...
it is land rover's way to govern speed on and off road vrs other manufacturers governing rpm...
it is a cristal piezo sensor whick develops tiny break thus loosing the tune.. there is / was a tsb in reference to it...
it is land rover's way to govern speed on and off road vrs other manufacturers governing rpm...
it is a cristal piezo sensor whick develops tiny break thus loosing the tune.. there is / was a tsb in reference to it...