Electrical gremlin

Mattyp77

About a year ago I started getting my first trouble codes involving the TPS. (P2101, P2176, P1515). I don't remember if it was one or all of those codes at the time but I tried cleaning the carbon in the throat as people said it can prevent the blade from opening/ closing. Didn't help. I bought a new throttle body so together. Helped for a while. Months later the code came back. I forgot I had already replaced it once and ended up just buying another one. Mind you this was an original gm product from another trailblazer at the junk yard with only 42k miles on it. It may have again helped for a while but things only got worse from there. Once in a while like every few weeks during summer I would start the car in the early am for work and It would run terribly rough. I would also have a check engine light with those TPS codes and sometimes others indicating a problem with the gas pedal sensor. It would also be in limp mode with that check engine light with a downward arrow. Basically undrivable. But usually it would only take one restart of the key to get it to start right. No more codes no more limp mode no more running rough. Other times maybe 2 or 3 restarts. I was beginning to associate it with colder mornings. I heard that grounding issues could cause problems like this. I ran some new ground straps to the frame and engine block and also tried going back to the previous throttle body. I tried switching at least twice. By the way I have had other electrical problems. Light bulb connectors melting and hvac/ blower motor module connector melting. 3 out of 4 12 volt dc outlets mysteriously don't work. Still haven't figured that one out. As weather started getting colder the problem got much worse. Now it's every morning and can take over an hour to get it to start right. I can't find anything that particularly does the trick. Just a matter of repeatedly restarting it. And it spews gas out the back when I run it like this btw. It's running extremely rich hence the running so rough. So I hate to run it like that. But when it starts right. Everything is perfectly fine after that. Occasionally it will turn on me in middle of driving. Say for instance if one morning it started good the first time. It will often wait until I'm down the road somewhere then boom goes into limp mode and running rough and all. The other day I decided to have a look at the live data with my cheap Zurich scan tool while it was doing this and I was amazed at what I saw. Fuel sys 1: O/L - Drive. Calculated load is showing over 70%even though I'm just idling in my driveway. Fuel trims are basically just showing 0%. Spark advance in the negatives?? TPS is pinned at 30%. What gives? I cleaned the MAF sensor with proper cleaning solution as well as map sensor and electrical connections to those and TPS connector. I haven't messed with the gas pedal yet. Maybe that? Bad computer? Can I run a ground wire directly to computer and/or TPS? But I checked grounds with a probe light and multimeter on the block, grand, and electrical connectors abs they all looked to me. I'm not seeing resistance unless in doing it wrong idk I'm not an electrical expert but I think I have a pretty decent understanding what I'm doing. P.S. I would like to upload pictures of the scan tool but I guess you can't do that on this forum huh?

Kirstie_H

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Mattyp77