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2007.5 Gmc Sierra 5.3 Recently when driving, when letting off the pedal my rpm's drop dramatically. From 1400-2000 to 500 then spike back up too higher rpm's. Ive also noticed that acceleration is very boggy. Another crazy thing it's doing is when Im barely pressing the throttle to maintain speed the afm kicks in. When it kicks into v4 mode its like the truck instantly slows down like Im hitting the breaks then spikes back when returning into v8. The truck started these problems a month ago. What could be going wrong with it?
My plan is to bring my truck to a mechanic's house that works at dealerships to get inside of the computer and find out the problems. @swathdiver my engine is the non flex fuel. But i was wondering if i could swap to the 2010-2013 flex fuel engines. As far as the oil leak it seems to be coming from the rear main seal leaking where the engine bolts to the tranny, but the whole bottom of the engine and tranny is covered in oil so hard to determine the leak.
If I were to do an engine swap. What motors would be the best out of the 07-13 models ? And as far as the the the problems with the TPS, could it be the ECM that is going bad. Again it only does it after a rain.
i have a 2007 (newer) Gmc Sierra SLT with the 5.3 AFM and has 207k miles. I have a variety of problems I'm dealing with and wanting to know what the best solution to these problems. I bought the truck used and had it for over a year now, the first problem i seen was a small oil leak started a couple months after i bought it. Thought it wasn't a real big deal. A month or so after a very bad lifter knock started, and the oil leak seemed to get worse. The lifter knock threw codes and had a very rough shake and very hard gear shifts and lots of smoke on start ups and low oil pressure sensor began to fail . After this happened i parked the truck for about two weeks, changed the oil and added an additive for the knock. Soon it seemed to run a little better but didn't stop the random lifter knocks, rough running, and hard shifts. After a month or two it got better, then came the misfires. I then replaced all plugs and ignition wires and oil pressure sensor. The rough idles began to go away and the lifter knock fadded away also. A few months later i started to get engine power reduced codes after it would rain. Truck wouldn't start unless the codes were cleared. If it did let me turn over the truck, it sounded and felt like it was going to blow up. Then started it: still wouldn't let me use the throttle, so clear the codes again. The codes read TPS sensor and TPS correlation . I then changed the sensor and still had the same problems, but would start and run , but still the pedal would not work. In the last month it started the misfire again on #6, pulled the plug and the tip was completely shattered and covered in oil. i Changed the plugs the were less than 9 months old, then two weeks after came #8 misfire with the spark plug looking the same as #6. i replaced the plug again and then did an oil change. Now my oil pressure sensor is failing again and throwing a performance issue code. The oil leak is now bad and having to poor about 2-3 QT's every 1-2 weeks. Now Im asking what should i do with this engine, and I've delt with the these problems for over a year now. One day it runs fine then the next it starts with a new problem hopping it doesn't leave me on the side of the road one day.
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