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Hey everyone so I am really confused here. I have this 2003 Impala LS with a 3.8 v6. The car will sometimes not start unless I press the gas pedal. This usually occurs when its hot but not always. It will crank but sometimes will not tun over unless I just so slightly tap the gas, and I mean put the slightest pressure on it. fuel pump is new, fuel filter is new, fuel pressure regulator is new, MAF is new, IAC is new, Crank sensor is new, fuel pressure is great. the car has 110% power no hesitation and will fire right up as soon as I hit the gas. The only noticeable difference is a slight decrease in occurrence since I added some injector cleaner to the fuel tank. but the problem still persists. No vacuum leaks either, I have smoke tested every hose under the hood. Air filter is also new. Every sensor is sending signals, no check engine light. The car also has spark whenever this occurs. All I can think is that the engine is not getting any air but I just don’t understand how that is possible. Or clogged injectors, but I also don’t see how that could be possible either. The car sat for a year but I have ran at least 3 full tanks of gas through it so far. I just don’t understand how moving the throttle plate just the slightest bit will get it to immediately fire. once it is running it also idles perfect right at 800-900 rpms
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Would the leak in the injector be noticeable? Cause when I had the fuel rail off yesterday to change the intake gasket, I left it pressurized and they weren’t leaking, and they were actually clean, so I don’t know what its deal is. I was actually thinking the computer is going bad, and I actually have a second one, but I can’t justify taking it to the dealer to have the security programmed so that the engine will start. I just want the car gone at this point to be honest.
[quote=”Durango8766″ post=114324]Would the leak in the injector be noticeable? Cause when I had the fuel rail off yesterday to change the intake gasket, I left it pressurized and they weren’t leaking, and they were actually clean, so I don’t know what its deal is. I was actually thinking the computer is going bad, and I actually have a second one, but I can’t justify taking it to the dealer to have the security programmed so that the engine will start. I just want the car gone at this point to be honest.[/quote]
No worries. Let us cleanse our self of this POS 🙂
That’s quite a journey you’ve got there. The whole time I’m reading I’m thinking there’s too much fuel for some reason. I was not expecting the PCV. If that doesn’t pan out, then I would be checking the fuel psi to see if you have any leaks or other issues that might cause too much fuel to go into the engine. It could also be that it’s not getting enough air so we have to consider that possibility as well. For now let’s just call it fixed and hope for the best.
Keep us posted.
Hi Eric,
Well the PCV ended up not working of course, I think its fixed because it will start fine 5 times in a row then all hell breaks loose. So the car has horrible fuel pressure leak down after i shut the car off, like it drops to 20 psi almost immediately. So I put a used fuel rail, and set of injectors on it today with my new fuel pressure regulator to no avail. So I don’t understand where it could be leaking? the fuel pump is new, the fuel pressure regulator is new, and the injectors aren’t leaking, because the leakdown rate was the same with both sets of injectors. so what does that leave me with? The other thing to note is that when it doesnt start its not like it just cranks, it cranks acts like it has started but doesnt start its just as though you got to start the car and it cranks the normal time and the starter cuts off but the rpms are at 0. Also the rpms peak at 1500 when it is cranking just as an FYI i guess. but basically the fuel pressure does not hold after shutdown. And I did check that all of the wires have continuity between the connectors and the computer.The other strange thing is that the intake makes this sucking noise like its starved for air, and you would think that the IAC would be allowing more air into the engine, but I took it out and it was in the closed position, so I dont know what that means.
Wonder if the new fuel pressure regulator is a dud? Crazier things have happened. I’ve bought bad brand new parts before, coils, thermostats, etc.,
but I don’t think the old one was bad to begin with, I have had three on the car so far, including a new one, and it doesn’t have any affect.
well I don’t have a vacuum gauge, but it seems strong if i take it off and put my finger on it it clings to it. It seems to have great vacuum, it has no leaks, but its running rich and seems starved for air during 50% of start ups. because if I open the trottle plate the slightest bit it will fire right up. Heck even If i take the pcv o ring out it will start, or if I take the vacuum line off the brake booster it will start. Also When I look at my live data and compare it to normal start vs no start there are no differences. Its damn frustrating.
I hear you…I’m a bald man, or would be pulling my hair out over this one. So, when you take the air duct assembly loose right at the throttle body, will it crank right up like it should? I sure hope you let us all know when you get it whipped…
No it still wont crank if I do that, but I spoke with a chevy technician, and we troubleshooted some stuff and he said the pcm is bad, so I actually have one, but I have to get it programmed so it will run the car. That should fix it, I will let you know.
Well the dealer pit in the new PCM, and it didn’t fix it, so now I’m having them diagnose it at $90 an hour.
Ok so I thought I would update everyone and put the mystery to rest. After I spent an afternoon at a chevy dealership, $250 later I was told that the pcm was not at fault, and that my wiring was bad. The car ran but barely at this point. And while the car was in the techs bay it sprang a major oil leak from the pressure sensor which they tried to charge me $80 to replace. So I drove it home oil leaking, and went on the search for a wiring harness the next day. It took me 5 hours to find one that had only been cut in a few places, but I got one and put it in the next day. Once again the problem persisted, but voltages that were skewed prior were now fixed. So I began some very in depth diagnosis for the next week when I figured I would unplug the MAF to see if it would run. And to my surprise the car immediately started without any hesitation. So today I put another brand new one in and the car is fixed, including the fuel trim numbers. Now I just have to sell it. I just couldn’t sell it the way it was, I mean it started fine when it was cold, so I could have in theory pulled one on someone, but that’s just not right. So stay away from ebay sensors I guess is the moral of the story. The sad part is that both new sensors were providing the same output, but I guess the ebay one had another issue.
What a journey, man!… Glad you were able to get this fixed. Thanks too for posting the results on the forum…
That was quite a journey, thanks for the updates.
A couple of notes. The fuel pressure dropping was likely the check valve in the fuel pump. I know you said it was new, but if you got it from the same place you got the MAF sensor, well, you get the point. That said, many times the fix is only as good as the parts you use. I always suggest quality parts, don’t ‘bargain hunt’ for parts because you often get burned in the end. I don’t have to tell you that however. I’m just putting it out there for others that may read this thread.
Thanks again for the updates and for using the ETCG forum.
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