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I have a 1994 Chevy C1500, 5.7L engine.
My truck idled high and I finally got around to replacing the idle air control valve. This didn't fix the problem and it continued to idle high. I determined the issue to be a vacuum leak, so I replaced my vacuum hoses and checked connections. I tested by spraying carb cleaner and the engine still bogged down at this so I cleaned the throttle body and made a new gasket for the throttle body because that one was falling apart. After doing this, the truck began idling extremely low. It threw the EGR code, so I have since replaced the EGR valve and EGR solenoid. Neither of these fixed the problem. Next on the list is to replace the throttle body gasket along with the distributor cap and rotor. Additionally, my truck will also struggle to accelerate.
The confusing part is this- there seems to be no rhyme or reason as to the low idle. Sometimes, the truck idles in park at 800-900 RPM and is able to adjust the idle to the load of the AC being turned on. Other times, it idles in park at what is most likely 300-400 RPM because it doesn't even register on the gauge. It does not seem to have any consistency as to if the engine is hot or cold- it just seems to be whenever it feels like it. This evening, while working on it, it started straight up once and idled great at 800 or so RPM and handled AC and headlight load. While the AC was running, we unplugged the wire that makes the AC compressor run- this dropped the RPM down to around 700 and it never recovered from that. The truck was turned off and started again. This time it idled around 700. Truck was turned off and started again- this time it idled around 500-600. The truck was turned off and now it had to be given gas to start and idled low, around 400-500.
Any ideas to explain what is causing this? We are all going mad trying to troubleshoot this and figure it out. We've checked so many things and nothing seems to be causing the problem. Any help would be greatly appreciated.
By scott willman
Okay I have a random misfire code 300 302 304 307 replaced already o2 bank 1 upstream and down stream,new plugs,new wires,new coils, new injectors,maf and map, truck will idle fine then it won’t,check engine light will blink and then stay on,if it’s idling ruff and I take off it stumbles till I hit 25 or 30 mph and then I punch it and it runs fine for an hour down the freeway, then when I stop it may idle ruff or fine what is going on with this truck and it has a lot of power,help......gas engine no flex fuel
By Chris Lee
Just replaced e driver side engine mount. After the install, my idle/park started rough idling specially it has more vibration and noise during Reverse. Any idea what could cause this?
Hey guys, first post on here and I've got something that stumped me 100%.
I have a 2005 silverado 1500 flex vin code Z. It Idles rough it has terrible acceleration, wide open throttle it takes off like nothing is wrong. It misses on 7 every time, misses on 2 every other time, every other cylinder misses here and there. No misses when in park and rpms are kept about 2500. CEL flashes most the time when accelerating (except WOT) otherwise the light is on solid. It has 220k on it and I have replaced alot of parts.
All 4 02 sensors OEM
Fuel pump OEM
Throttle body cleaned
3 stage fuel system cleaner BG Brand
Air filter believe it or not OEM again
New transfer case (unrelated issue)
I have covers the base of the intake with brake cleaner multiple time, no signs of leaks. I've had the smoke machine hooked up 3 to 5 times and again no signs of leaks. At this point what is the best route to take? Remove intake manifold so it's easier to get to and replace the main grounds behind the heads and replace gasket at the same time? Replace the pcm? Replace throttle body maybe? Any other suggestions or recommendations would be greatly appreciated.
I am a long time GM customer and currently own a 2009 GMC Yukon Hybrid truck. It has been an ok experience but just recently the truck started to do some strange and unsafe things. It started out revving up without pressing the pedal or hesitant to accelerate after stops and then moved on to stalling in the middle of driving and would give me a warning of REDUCED ENGINE POWER, SERVICE STABILITRACK AND SERVICE TRACTION CONTROL but would only do it every blue moon. Here recently I was leaving somewhere and the car begin to shake and shake and then stalled out after those codes popped up. I called the dealership and set it up for an appointment. They got me in and the day I was taking it to them it gives me the reduced engine power warning and I noticed the car went from a rough idle to an even rougher idle increasing more and more as I'm driving. Finally I hear 'CLUNK' and then all of a sudden its not just a rough idle, the engine is shaking VIOLENTLY. I turn the car off. Other times when the car would give me the warning of engine power being reduced, I could turn it off and wait a second and turn it back on and it would magically reset for a random time period before it did it again. I was about 2 mins out from the dealership so I made my way there and as I'm pulling it the engine starts to do that crazy shaking thing...everyone literally stops and stares at me, probably trying to figure out if I'm about to blow up! They get it in and the tech is super alarmed by that shaking and said he had never seen or heard anything like it. They pull the codes and replace the throttle body position sensor under an extended coverage offered by GM. After they fixed it, I'm notified that one of my engine mounts broke and I now have to produce $1,000 to fix it!!! The engine mount is what broke during the engine freak out during the 20 minute drive to the dealership because I heard it! When I get my car back it now wont go into hybrid mode anymore and its idling super funny... up and down...up and down and I can now feel every shift the engine makes and the start up and turn off even rattles now and my engine ran so smooth before this you could balance a penny on the engine! I'm so upset because GM says this is my out of pocket expense. However this only occurred because of their defective part! I'm taking it back in whenever the dealership calls me back(been waiting for hours) and they will see why the engine is idling unevenly and "recheck their work". I'm so sad and after talking to a GM rep who so rudely informed me that they did their part on fixing the throttle body and to just shovel out $1,000 that is not not their problem, it s actually a point of frustration. My husband and I have own 6 GM cars that were a pleasure to buy and drive but we will never buy another GM car again!
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I installed a new 6.0 motor with high volume oil pump on my 2008 6.0 LTZ suburban. It has only 500 miles on it at the moment as of 9-5-2019. I installed a new intake, new throttle body, (relearned) new radiator, new plugs, wires, injectors, fuel pump and new heavy duty motor mounts, I have this slight shake at idle and you can feel it in the performance of the truck when driving down the freeway as if something is holding it back, Its not throwing any codes, engine light is not coming on. Had a guy that all he does is reprogram cars and trucks with his computers and when he hooked his high dollar stuff to the truck, the rpm went to zero while it was running and said it was a cam position sensor but when he disconnected it it went back to normal. my regular mechanic hooked up his diagnostic computer (Zuess) right after and it had no codes and we cant find out what is up. Maybe the guys high dollar stuff was messed up. Some guys are saying its the trucks computer but its not showing any codes, it runs fine but it should be absolutely purring like a kitty cat and there should not even be the slightest movement. The guy with the computers said that it has the fuel efficiency program on it that drops to 4 cylinders from 8 to save on fuel, he said the system was on and asked if I wanted it turned off for 250.00. I didn't do it. something is up and its driving me nuts. anybody have an idea at all? the #1 cylinder failed on the original motor and the traction control code came on and said it needed to be serviced. After the motor was replaced it did not come on again and there was no code for it as well. just for some history. Please help
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