It’s I have a 2010 Chevy Impala LTZ with the 3900 motor, my car has 108,2XX miles on the clock.
I am having an issue when Idling in drive or park, my car is supposed to idle around 600rpm. I have been noticing that my rpm will slowly drop to 500-550 rpm, the air conditioner really comes to the rescue when I turn it on. Because the Rpm will sweep up and down from 900 rpm to 500 3-6 times rapidly and then it’ll sort its self out and run perfectly even after shutting the air conditioner off.
I will be going back to the Chevrolet Stealership, to have them check fuel pump volume, and makes sure fuel injectors aren’t malfunctioning. also check for vacuum leak because I couldn’t find anything
Is there something I’m forgetting here? There’s no idle control valve, egr valve and fuel pressure regulator
Ive been told pcv inside my intake
thsnkyou
- changed the plugs twice
- Ran top end cleaner through throttle body and replaced the plugs a second time.
- new wires
- new coils
- cylinder 5 fuel injector (fixed cyl 5 misfire)
- Replaced maf and map sensor (helped alleviate)
- new serpentine belt
- I use high quality gas
- compression test done in all cylinders (around 120psi)
- idle relearn at Chevrolet dealership
- no pending or stored codes
- checkled vacuum lines
Have you checked the fuel filter? If you've never changed it out, it's probably clogged at that mileage.
Fuel filter is internal and built into the pump inside of the tank, will volume test rule that out on Thursday? I’m trying to do as much as I can, because I hate bringing out the checkbook.
Ah yes that's right. Yeah if you get good volume then your filter is ok. I'd guess you'll find the volume is low and the filter is clogged, BUT because it is in tank I would do the volume test first. Sorry, forgot that model was in tank.
Sounds great Thankyou, everything I have done has me believing I’m being led to a fuel issue. I’m not a professional but I’ve take my car to 8 different mechanics after doing most of the work myself to narrow it out and I have no answers yet. So I’m requesting the dealership to step in and do the work I’m requesting to rule out that fuel issue.
I’ve changed the cylinder 5 fuel injector because of a misfire without a cel and that caused it to resolve the issue now it’s just tracking this idle issue and I’ll have nothing wrong with my vehicle I’ll basically have a new engine after all said and done.
If it’s not a fuel issue then what would you recommend next, I don’t think there’s any vacuum leaks but I’m having them check that too. Could it be a crank position, cam position or oxygen sensor? Maybe something is dragging on the drive belt? All my pulleys look great and move freely except the crankshaft pulley of course.
I'm leaning heavily towards a fuel issue honestly. It has all the classic symptoms.
If that isn't it, I'd almost think PCM next more than a sensor, but it is hard to say.
I appreciate your input! Thankyou very much. I got more feedback from you than going to a shop in person. I’ll update you Friday sometime. I’m thinking fuel issue too, because it slowly gradually loses rpm when at a stoplight until it reaches the 550 mark and it’ll intermittently touch 500 and bounce back up to 550 and at the same time I get different variations of vibrations felt and heard throughout my vehicle. I can even do that fuel pump myself too , the gas tank is plastic luckily for me I’ll run it down to E before replacing if that’s what’s needed It could be a mixture of fuel injectors as well. But I’ve floored my car a few times and added extra cleaner to the gas tank every oil change. so I feel like it would have cleared itself out by now if it were those.
I'm happy to help man! Yeah if you've cleaned the injectors, it is probably the pump/filter. I'll keep an eye out for your update Friday. Hopefully the issue will be solved for you.
Well I got my car back from the Chevrolet dealership, appointment was 8 am Thursday morning and got it back 2:45 pm. They looked at the intake system to make sure no vacuum leaks and hooked up a big fancy computer to look at the fuel pump and injectors… he couldn’t give me a positive confirmation if it was the pump or injectors at all. I’m at a loss here. I was basically told to “drive the $hi+ out of it until something breaks”. I don’t know how they can tell me if it was a positive confirmation or not. Luckily they didn't charge me for the diagnostics for it. But I’m still upset. How hard can this problem be to find?
At this point I’m just going to keep up with maintenance and I’m not looking further into this issue. If it breaks I’ll honestly be happy. However. If this car can last me another 2 years the way it is. I’ll be even happier. It’s almost done being paid off. I made a huge mistake. My grandfather told me to not get this car or it’ll come back to haunt me. A month later he passed away. I think he’s up to all this nonsense lol