My 2001 Buick Lasebre is not starting properly. I have to pump the gas several times before it will start; then when it is started at low speeds or idle it wants to stall. As long as I can some how keep pushing the gas peddle it wont stall. On the other hand when I am driving at higher speeds, anything above 40 or so it runs perfect. The check engine light was on and shows EGR valve stuck open. I have replaced the Mass airflow sensor, fule filter, and the EGR valve. I had the code cleared and a short while later my check engine light came back on with the exact same reading. I bought this car only a week ago and was not expecting to have to fix a car I just bought and ran fine while test driving it. I have read may diffrent forum that say that it could be anything from my fule pump to vacume hoses, to some other sensor. I really can not afford to put to much more money into the car and really need to know from one who has had this problem what the cause is and how do I fix it. Someone please help I am at my witts end with this issue.
What is your exact code? - format: “P1234” There is no stuck open code for the EGR. Do you mean “excessive flow?” That’s P0402.
EGR is a whole system - not a single part. You need to learn the whole system and check it all. It involves a feeder from the exhaust manifold to the valve, normally some kind of flow sensing device, sometimes an actuating solenoid, and the valve. I think your might me electronically controlled which would leave out the actuating solenoid. In any case, those codes don’t tell you that parts are bad. Look at all parts as part of a system.
Its possible that an EGR problem could cause your symptoms. Its also possible for it to be something else. The first thing I would have done would have been to clean the idle air control valve.
This is a good overview of EGR systems: http://www.aa1car.com/library/egr.htm
Remove the vacuum line going to the fuel pressure regulator and check for the presence of fuel/ fuel vapors. The fuel pressure regulators on these GM vehicles are notorious for blowing the diaphram and leaking fuel into the vac line causing it to run extremely rich. Of course it could also be a chunk of carbon holding the pintle open on the EGR valve causing it to run lean which would be more likely as you never stated that it smelled rich. If this is the case then remove the EGR and start the car. Rev it up a few times to blow any chunks of carbon out and put EGR back on. Of course you’ll also need to remove carbon from valve as well. Otherwise pintle will not close and it will still be lean.
The OP stated that the EGR valve was replaced. As far as I know the pintle & seat are fully internal - which means there’s no carbon build up yet. Old EGR valve = excessive flow (still waiting to hear on that) and new EGR = excessive flow (?) - means the problem is almost certainly not the with the valve itself.
It sounds like a bad temp sensor. The egr seems a red herring. As often occurs. It takes just a multimeter to check the cold and hot range on the sensor. Depending on the state I would say take the car back and give me the money back. It could be a worse issue like wires that they could not fix.
I do not know what the actual code wsa but I saw it for my self it said EGR Valve stuck open. I will check a few of these things and see if I can get any results. Thanks for the help and if there are any more suggestions I would greatly appricate it.
What you probably saw was one of the possible causes for whatever the code was. The text that gets attached to codes is incredibly imprecise. But none of the standard descriptions include EGR stuck open.
If you want to check it again, many auto parts stores read these for free.
If the EGR is indeed stuck open, it would cause the driving symptoms you report. But as mentioned above it might be open when it shouldn’t be , but not actually be “stuck” open. The EGR is controlled by several gadgets that decide whether to open it or not depending on coolant temperature, manifold vacuum, throttle position, etc. It could be open because one of the associated sensors or controls is faulty and making it open when it shouldn’t. In that case replacing the EGR itself wouldn’t fix the problem.
Also, as mentioned above, the symptoms you report could be cause by problems unassociated with the EGR system. Vacuum leaks are also a common cause for idle and low speed symptoms.
I tried what Pete Peters said to take the EGR Valve off and reve the engine a few time and then put it back on. Well my check engine light is now off, but the problem still continues. And yes it did say “EGR Valve stuck open” I read it with my own eyes when I took it to oreilly’s and to the machanic and paid $50.00, both times it said it. But again I am still haveing the same problmes. I am going to check the vacuume line to the fule presser regulartor next since that does not cost anything to check. Keep the advise comming, we will get there eventualy.
Idle and low speed problems are often caused by an incorrect fuel/air mixture. At idle, very little gasoline is being injected, so a small error in the amount of air coming in makes a big difference in the fuel/air ratio, and how the engine runs. When going faster, more gasoline is being injected, so a small error in the air intake isn’t important. The EGR system injects air and exhaust gases into the intake manifold, and is designed to be closed or almost closed at idle. If it is open too far, it allows to much air and exhaust gases to flow into the intake, which affects the fuel/air ratio adversely at idle. One other common problem affecting the air intake is the PCV valve. If this part fails, it can cause similar idle symptoms. It’s easy to check, so that might be something to look at. Vacuum leaks are the other common thing and are usually fairly simple for an experienced mechanic to check. If your mechanic has an exhaust gas analyzer, that would be a useful tool to determine if there is in fact a problem with the air/fuel mixture at idle. Everything I’ve talked about is with the air, but of course the air might be fine, but the problem is the fuel . It looks like you are looking into that. Given your EGR code, I doubt it is the fuel system though.
Other things that might be bad are the idle air control valve and O2 sensors.
Where is the PCV Valve on the engine and how do I check it?
My husband knows where it is and how to check it. Doing that right now. It does sound like it is either being starved for gas or over loaded with oxxygen. Just one sure which, Thanks for the heads up.
Ok my husband was not able to find it. Can someone please tell me where the PCV Valve is?
We got the PCV Valve off how do we tell if it is bad?
Just shake it. If it rattles its fine. But this isn’t from a bad PCV valve.
Get the actual - very specific code. Perhaps it was a P1404 - which, I believe is an EGR pintle stuck open. But I’m telling you - asking people for advice on some kind of “text” you got associated with a code is a bad strategy.
And clean your IAC valve.
Like @cigroller says, if the PCV valve rattles when its shaken, that’s a sign it is ok. The other test a mechanic would do is to remove the PCV from the valve cover, leaving it connected to its hose (on most econo-box type cars the PCV/valve cover interface is just a friction fit and it just pulls out). While the engine is running, the mechanic would put his thumb over the open end of the PCV valve and see if he could feel a vacuum. If he did feel the vacuum, that means the PCV is probably working correctly.
As mentioned above, because of the code discussed above, the PCV isn’t the most likely culprit. Checking the PCV is pretty easy on most cars, so no harm done to check it. Most home driveway mechanics check the PCV every time they change the oil. But to get the most help here for your specific problem – and there’s some pretty knowledgable mechanics who chime in here from time to time so it’s worthwhile to seek help here – you’ll have to post the actual check engine code(s).
We checked the PCV Valve and it did not rattle very much so we changed that, no results. We then tested it again and said something about MAP sensor so we changed that. It now so far it starts like it is suposed to and the check engine light went off; but it is still dyeing and the engine is serging. I am now waiting to see if the check engine light comes back on to see what it says next. I will post tomorrow what the next set of codes are and issues.Thank you for all of your help.
OK, I have driving the Buick around for a couple days not and the check engine light has not come back on after changing the MAP sensor. But we are still having the same problems and they are starting to get worse. So not sure where to go from here.
Did you clean the IAC valve or not? A car that won’t idle well/stalls unless the gas pedal is pressed is classic for an IACV problem. Your “gas” pedal is really and “air” pedal.
Check the fuel pressure.
Checking the air and coolant temp sensors, as euryale1 suggested - though without saying which - is a very easy thing to do and could also matter.
hmmm … sorry @Kathiren you are having so many problems with you car. It seems like it has to be one or more of the
- EGR valve, & associated sensors, and actuators
- IAC (Idle Air Control valve)
- PCV valve
- Vaccuum leak
- O2 sensor(s)
I wouldn’t have guessed the MAP (manifold absolute pressure sensor) as a culprit, but it sounds like you’ve replaced it anyway.
Given what you’ve already done, I think @cigroller is on the right track with the IAC and the air and coolant sensors. If the IAC goes bad it can cause surging at idle but when you step on the gas and get it off idle everything runs fine. A vaccuum leak is the more common cause for that symptom though. I’m assuming your mechanic has already checked for vacuum leaks and checked that the O2 sensors are functioning correctly. As already mentioned , you should post the code numbers to enable the experienced mechanics here to be the most helpful.
The only other thing I can think of is that somehow in doing all this the engine idle speed screw has been adjusted out of it’s normal range. That can cause surging problems even when everything else is working correctly. This is often done by home mechanics in attempting to fix a more serious component problem by simply adjusting the idle speed. It never works. It just causes the car to surge and stall all the time. Has anyone adjusted this screw setting? If so, first mark where it is now so you can return it to the current setting if need be, then make sure the mechanic resets the idle screw to its factory setting (usually the factory settingn is a certain number of turns from completely closed). Hopefully it hasn’t been changed.