vipmiller803 Posted March 18, 2015 Author Report Share Posted March 18, 2015 The ignition switch was on for just a second before recording commenced. Engine firing followed a few seconds later. If the weather is tolerable tomorrow, I might rewire the manual switch with a relay. If the SES light comes back, I will check tunerpro for codes. Quote Link to comment Share on other sites More sharing options...
vipmiller803 Posted March 19, 2015 Author Report Share Posted March 19, 2015 Alright, some interesting developments. Between yesterday and today, I have gotten the SES light 4 times. I checked it 3 of those times and the only code now up is the 134, I am thinking the O2 sensor is misbehaving intermittently, given the past few data logs. With the cold front we just got, I do not think the fans have been needed at all, so that would explain the lack of the 670 code. It is peculiar that through many long drives it has misbehaved only a handful of times, all of which while I did not data log. As much as I love to warranty items at advance, I think I might replace the connector first. When I replaced the sensor in December, the connector seemed fine to me, but that is obviously not definitive. My worry with connector replacement there is the solder temperature limit. I was thinking I would take away more of the wiring to overcome that, but that might become a PITA if I run into the bigger wire bundles. If that does not solve it, I think I will go to the sensor then. After that, wiring? Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted March 20, 2015 Report Share Posted March 20, 2015 you may find these helpful: http://imgur.com/DnN0sJU,k3UzDj2 Quote Link to comment Share on other sites More sharing options...
vipmiller803 Posted March 20, 2015 Author Report Share Posted March 20, 2015 I think I caught it in the act! After a 30 min trip on the freeway (where the SES light came on), I stopped and hooked up the computer. Upon restart, the light was off and it only took a couple of miles to come back. There are some definite dips in the O2 signal where it goes well below 200mV. I still have not looked at the connector or the sensor to check for any damaged wires. Here is the link for the xdl: https://drive.google.com/file/d/0B6AKqXKswy6VeS1DTUlPYnRNaEU/view?usp=sharing Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted March 21, 2015 Report Share Posted March 21, 2015 in that log, around 2:08 until about 6:15, the sensor basically quit responding and hovered around the 450 mark, which can certainly set the O2 lazy code. Quote Link to comment Share on other sites More sharing options...
vipmiller803 Posted March 21, 2015 Author Report Share Posted March 21, 2015 I see that now. Not something damaged wiring or connector would do, so I will be replacing that sensor shortly. It is interesting how that was so intermittent, with some other long data logs being flawless. I cannot come up with even a bad explanation for it, but I swear the warm weather made it better. Maybe I am just high. Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted March 22, 2015 Report Share Posted March 22, 2015 if some wiring got jostled, I could see it making an intermittently open wire appear good for a long period of time and then appear bad suddenly. Quote Link to comment Share on other sites More sharing options...
vipmiller803 Posted March 22, 2015 Author Report Share Posted March 22, 2015 Yea I can see that, but wouldn't that be a straight up open circuit? As in 0 mV, not 450 mV? I figure if a connection/wire was the problem, we would at least see some total drops in the voltage, not just inactivity. To update: I replaced the sensor yesterday. Just the trips to get and return the socket for it took 4 times as long as the actual replacement, which was a breeze. I did drive it some last night. So far so good. Will update if the SES light comes back. Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted March 22, 2015 Report Share Posted March 22, 2015 the way the O2 sensor's sampling circuit works, the signal is biased to ~450mV when no sensor is connected or the sensor isn't producing a signal. once the sensor starts warming up, it will start moving away from 450mV. the ECM doesn't attempt to control fueling based off of O2 sensor data until the signal rises above ~600mV or drops below ~300mV as a way of making sure the sensor is up to temp before attempting closed loop control. Quote Link to comment Share on other sites More sharing options...
Twinpilot001 Posted April 9, 2015 Report Share Posted April 9, 2015 OK ill venture a guess!! Try putting a vacumn hand held pump on the MAP sensor-where engine vacumn attaches =to test & see if that map sensor holds vacumn?? I have a code readedfor obd1 cars .they are available on u r local craigs list-just advertize for one!! Cheapo! Now - if vacumn wont hold steady? replace the map sensor!! Id also test - when idleing for any vacumn leaks by spraying brake clean or carb clean around the intake , areas & see if idle characteristics change?? if so locate the leak 's?? & fix! be sure to check all vacumn lines as they willget old & some will leak (carb spray!!) when running. Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted April 10, 2015 Report Share Posted April 10, 2015 a 95 3800 doesn't have a MAP sensor. the only ones that do are the L67 cars with a boost guage(Bonneville) and those aren't in any way connected to the PCM, only to the instrument cluster. the early OBD2 implementation F-body applications might. Quote Link to comment Share on other sites More sharing options...
vipmiller803 Posted April 19, 2015 Author Report Share Posted April 19, 2015 Something of a reviving here... Got the code again today so the wiring is now suspect. First time since I last posted in March. I will be doing a visual inspection first, then I will do a more direct continuity/resistance test on the wires. I have a Haynes manual that I might be able to pull the pinouts for the ECM connectors from. Assuming that moving the wiring around is what "cured" the problem for that while, the wiring at the sensor end (as opposed to the ECM end) is the culprit. There is a chance that I have another connector laying around, so I will look for that today. OK ill venture a guess!! Try putting a vacumn hand held pump on the MAP sensor-where engine vacumn attaches =to test & see if that map sensor holds vacumn?? I have a code readedfor obd1 cars .they are available on u r local craigs list-just advertize for one!! Cheapo! Now - if vacumn wont hold steady? replace the map sensor!! Id also test - when idleing for any vacumn leaks by spraying brake clean or carb clean around the intake , areas & see if idle characteristics change?? if so locate the leak 's?? & fix! be sure to check all vacumn lines as they willget old & some will leak (carb spray!!) when running. Considering that the code had nothing to do with any pre-engine air sensors, I do not think I need to give any attention there. Also, 94's and 95's are different. Most stores do not have readers for that. There are some out there, but all out of my budget for this car. Quote Link to comment Share on other sites More sharing options...
vipmiller803 Posted April 23, 2015 Author Report Share Posted April 23, 2015 Alright so the code is back to pretty much every drive now. I will be replacing the connector momentarily. I am still worried about solder melting and running off. I was thinking of doing a crimp connection without the plastic outer part followed by a soldering. That way, even if the solder melts, it is more likely to stick around and the physical connection is maintained. Thoughts? Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted April 23, 2015 Report Share Posted April 23, 2015 60/40 solder has a melting point of ~360*F. the lead-free junk is a bit higher still. I imagine the insulation would be doing interesting things before/around that temperature. if it bothered you enough.... you could make an effective radiant heat barrier for a couple of pennies. I imagine that is what GM was intending by using loom, with some effectiveness. Quote Link to comment Share on other sites More sharing options...
vipmiller803 Posted April 23, 2015 Author Report Share Posted April 23, 2015 60/40 solder has a melting point of ~360*F. the lead-free junk is a bit higher still. I imagine the insulation would be doing interesting things before/around that temperature. if it bothered you enough.... you could make an effective radiant heat barrier for a couple of pennies. I imagine that is what GM was intending by using loom, with some effectiveness. Hmmm... Electrical tape only good for ~200*F, so I guess that should be the primary concern. I do have some lead free stuff but I hate soldering with it. It is a pain and most times does not work well. Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted April 23, 2015 Report Share Posted April 23, 2015 perhaps stuff some fiberglass insulation inside of some loom(and around the wires) and call it a day? that's far more than what most people would do for the same job. Quote Link to comment Share on other sites More sharing options...
vipmiller803 Posted April 24, 2015 Author Report Share Posted April 24, 2015 (edited) Found the culprit! I looked up the schematic and this is one of the sensor wires (as opposed to the heating element wires). Unfortunately, this is the most focused I could get the camera on it. It had a section that had two kinks and this break. This was the only break in insulation. All of this was hidden under the plastic wire wrap covering it, which had some minor unindicative cuts. All this was about an inch out of where the wires diverge from the main wire bundle. So, I did not replace the whole connector. I just spliced in a piece of wire to replace the damaged section. perhaps stuff some fiberglass insulation inside of some loom(and around the wires) and call it a day? that's far more than what most people would do for the same job. I do not have loom or fiberglass, but I will keep that in mind for next time. I found some electrical tape I had that was good for 266*F so I just used that, along with the regular leaded solder and the crimp connections. We shall see how it holds up. My biggest issue with soldering all the wires was that if the solder fails, the heater element circuit might have enough juice to start a fire if it shorts. With the correction I made, that is not a concern since I did not have to mess with the heater element circuit. Edited April 24, 2015 by vipmiller803 Quote Link to comment Share on other sites More sharing options...
vipmiller803 Posted April 27, 2015 Author Report Share Posted April 27, 2015 Took the buick upnorth this weekend. About 5 hours of driving, some heavy city parts included, and the wiring still looks nice and neat. SES has not reappeared since the fix. I think I can call the fix a success at this point. Quote Link to comment Share on other sites More sharing options...
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