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Hello, I recently inherited a 1999 Tahoe LT 4x4, 5.7L Vortec, Auto, 194K miles. Codes are P0300 and P0304.
cylinder 4 has no compression. Fuel pressure is 55psi, Spark is steady and strong on all wires as indicated with an inline spark tester and timing light. 120-125psi on all other cylinders to include 2 and 6. No milk in the oil.
I have not not taken off the valve cover yet to see what’s going on with valve springs yet.
My question is “what sequence should I try to see if it’s springs, valves, seats, rings, pushrods, lifters, etc?”
Dave in Abq.
How's it going, I have a 2000 single cab 4.8 Silverado 1500 that has a misfire, gradually revving up the engine you can tell the engine is missing and causes truck to vibrate, and vibration is worse while driving. Has following codes: p0300, p0137, p0141, p0157. I believe these are codes for random engine misfire and various 02 sensors? If someone could point me in the right direction I would really appreciate it thanks
I have a 2001 silverado with the 5.3. It has about 153,000 miles and I have been having an issue that I haven't been able to track down. At idle it has a miss at idle, whether it is cold or warm. My knowledge says it is a vacuum leak somewhere that I cant find. There is no miss at any other rpm than idle. Recently as it has been getting colder (sub-30 degrees F) when I first start the pickup it shakes violently at idle, but after it warms up for about 30 seconds it runs as normal. Today when I started it and was warming it up my SES light started blinking, even though it was idling as normal. I shut the truck off because I knew that meant a multiple misfire code. I tried to start the pickup and it would not start. I plugged in my code reader, and I found the code P0300, or multiple misfire. I cleared the code and it started up and ran just as normal, with no issues. I drove it around 30 miles, shutting off an turning it back on numerous times to try and duplicate the issue but the code never came back. I have checked the intake gasket, which seems to be very intact. Where should I look next? Thanks for the help in advance.
I did a search on here for replacing the engine computer and was surprised for not finding much !
We have an 05 Silverado with a 5.3 in it. The other evening, my wife went to see a friend and when it began to storm, she decided to leave. She went out and the truck was dead, no click, no crank. I went to get her and tried to jump start it (while it was still storming) and arcs came off of the negative terminal when the cable touched it. I stopped and decided to disconnect the battery till morning. Next day I go over there and reconnect the battery and the engine fans start running with no key in the ignition (probable reason why the battery arced the night before)! Battery voltage was down to under 11 volts so I took it to get checked since it was 5 years old. Got a new one, connected it, the truck fired up, and all seemed well. Took the truck home, parked it and 2 hours later I go to leave in it and the engine fans are running again ! When I drove away, I got about a mile from the house and the check engine light started flashing. Codes that came up were P0300 and P0480, random misfire and engine cooling fan code error.
So..... I checked what I could, but then on Monday took it to an automotive electrical guy. He ran his diagnostics and while it was there, the fans came on by themselves again with no key on. He check his schematics, ran his checks and suspects the computer has some kind of fault. He said to get a salvage computer and he would re-flash it for my VIN.
I checked around and found one local, but also looked online and came across "All Computer Resources" in Miami FL that sells reprogramed ECM / ECU / PCM automotive computers.
I wasn't sure what to do, so called another electrical repair guy for another opinion. He said it could well be the computer, but would run his own checks before just replacing it. He was adamant about not using a salvage or reconditioned computer. Said he has been there, done that, and will now ONLY install new OEM replacement GM computers and flash them.
Anybody out there have good or bad luck with a reconditioned computer ? Any thoughts or suggestions ?
Gonna get right to the point by stating the facts that I do know. I have a 2001 Tahoe with a 5.3 Vortec with 165k miles. Check engine light has been coming on the past four winters. It started out a temperatures <10 degrees, and now has gradually gotten worse to <35 degrees. Same codes every time, P0171, P0174, and P0300, Lean bank 1 and 2, and random misfire. Most noticeable is rough idle, the colder it gets, the worse it is. After reaching operating temperature, it idles smooth, with plenty of power and never misses a lick. Last winter fuel pump, filter, and all lines from tank to manifold was replaced.( Due to pump quit working) Also plugs and wires was replaced. After asking around, and doing a little research, I was hoping for an easy fix by replacing the MAF unit, which also contains the IAT sensor. I have to tell ya...it didn't help.
Thank you for the add, and any help you can provide.
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