Mechanics

ENGINE HESITATION AND STUTTERING PROGRESSIVELY GETTING WORSE...

2000 Saturn L200 • 172,000 miles

To begin, this car is a 2000 Saturn LW2, not a L200. The website did not allow me to choose LW2. It is the 3.0 V6 model. I presently have 195,000 miles. Over the last 30,000 miles or so, the engine has been hesitating/sputtering a little bit at low rpms (probably 1,000-2,000 rpm range). Over time, this has been getting worse. The hesitation/sputtering feels as if my foot was very unsteady on the gas pedal, even when holding it completely steady. The engine will sometimes feel like it is struggling, then surge sometimes. Just very unsteady. When this happens, you can see the tachometer go up and down accordingly. This does NOT happen when switching gears, but while in gear. In order to narrow it down, I tested it in Neutral with the E-brake on, and the hesitation/sputtering does happen. If you do not press the gas, the car idles perfectly at about 700-800 RPMS. However, the hesitation only happens when you lightly press the gas.

Here is a list of things I have tried over the last year or so:
1. Replaced the spark plugs
2. Replaced the front and rear ignition coils
3. Used high quality fuel-injection cleaner
4. Replaced air filter
5. Replaced Fuel Filter
6. Cleaned the MAF sensor
7. The fuel pump is only about 12-18 months old (though I'm not sure if the problem was before or after the new fuel pump.

For the most part, I have not had any check engine lights. I had some a few months ago, but they were due to a failing ignition coil. Last week, I got the check engine light, and after getting a free scan at the parts store, it revealed a whole slew of error codes:
p1811 - Maximum adapt and long shift
p0402 - Excessive EGR Flow
p0405 - EGR Position Sensor Low Voltage
p0171 - Fuel System Too Lean (Bank 1)
p0174 - Fuel System Too Lean (Bank 2)
p0051 - H02S Heater Control Circuit Low Bank 2 Sensor 1
p0152 - Oxygen Sensor Circuit High Voltage (Bank 2, Sensor 1)
p0300 - Cylinder Misfire Detected – Random Cylinders
p0303 - Cylinder #3 Misfire Detected

After receiving these codes, I have replaced the rear ignition coil, the air filter, and cleaned the MAF sensor. After doing this, the check engine light went off. I think this may have resolved the P0300 and P0303 because the front ignition coil failed not long ago. However, yesterday, the check engine light came back on. This time, the ODB scanner only revealed 1 error code. This code was a P0050 (H02S Heater Control Circuit Bank 2 Sensor 1). After doing a little research, we thought it may have been a faulty Oxygen sensor. I believe this car has 2-3 sensors, so I tried to determine which one I thought may be the problem. After a little research, I believe the bank 2 sensor 1 was the oxygen sensor near the front of the engine (cylinders 2, 4, 6) near the exhaust manifold. We replaced that today, but the problem persists. The car drives fine at highways speeds. In fact, sometimes the car accelerates smoothly. The problem seems to come and go quite regularly.

I have tried to be very thorough in explaining the problem. Please let me know if you can help. I am hoping to fix the problem myself without spending too much money, if possible. Thank you!
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Jeremyb777
July 15, 2013.




Wow you have a lot going with all those codes for the surging I would suspect your egr maybe carboned up and sticking open cause the car to surge. Next time its doing the surging unplug the egr valve and see if the surging goes away.I have used that to find egr issues on those engines. Also you have a egr code for egr excessive flow so that would make sense the egr is sticking open sometimes. It also set miss fire codes. As far as the P1811 that is most likely a bad line pressure actuator in the transmission. I have replaced tons of those on those cars for that code.I will look up where that o2 sensor you have the code fr is supposed to be.

Saturntech9
Jul 15, 2013.
Bank 2 sensor 1 is in the exhaust manifold facing the radaitor.

Saturntech9
Jul 15, 2013.
Thank you for responding. I was hoping that you would see my post. Your second answer confirms that I replaced the proper O2 sensor (well, assuming that there was a problem with it). I will try the EGR test that you have suggested. I tried it a few minutes ago, but unfortunately, the problem was not present at that time. So, let me ask a few questions about this test to make sure I understand.

When I test the EGR valve, do I simply unplug the electrical connection that goes to it? Do I do this while the engine is running? If the EGR valve sticking open can create a vacuum leak, that would make some sense out of the other codes. Also, I saw a video on youtube where a man was testing a EGR valve. He cut a custom gasket out of a coke can. There were no holes in the middle, and the idea was to block off the valve all together. Is this necessary, or is just unplugging it sufficient? Anyways, I plan to test this very soon. I've just got to find the right time when the problem is present.

Tiny
Jeremyb777
Jul 15, 2013.
I wouldn't block the egr valve simply unplug it when its hessiating and see if the hessation goes away?If it does you will need a new egr valve. You can't leave it unplugged or the check engine light will stay on. The codes P0171 and P0174 is most likely a vacuum leak or a bad mass air flow sensor.

Saturntech9
Jul 15, 2013.
Thanks again for your response. I agree, when I look at the list of possible causes for p0171 and 0174, it seems that vacuum leak would be a strong possibility. Especially considering that a leaky EGR valve or one that is stuck open can cause that. I have never done this before, but I used some MAF sensor cleaner spray the other day to clean the MAF sensor. I guess it could still act up if it is bad. I'm going to try the EGR unplugging trick in a little while, so hopefully I will find out more soon.

Tiny
Jeremyb777
Jul 16, 2013.
Give it a try when its acting up.
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Saturntech9
Jul 16, 2013.
Well, I took the car out to run some errands today, and there were 3 different times that I put the car in park and saw the problem with the rpms fluctuating due to engine. Each of these three times, I unplugged the EGR valve while the car was running. Then I got back in the car and tested it and the problem was gone. Then, I plugged the EGR valve back in while the car was running to see if the problem came back. Each of these three times, the problem failed to reappear until I turned off the engine for a little while. So here is a summary: 1. Engine gave hesitation and RPM fluctuation in Neutral
2. I unplug the EGR valve, and problem goes away.
3. I plug EGR valve back in, and the problem does not return.
4. I turn off the car for a while, then come back and turn it on, and the problem is present again.

As mentioned, the problem is sporadic and is not always present. Because of this, I am not 100% sure that it is the EGR valve, but so far, it seems like it might be. The only thing that I do not understand is the problem fails to reappear when I plug the EGR valve back in. If there is any rational explanation for this, please let me know. Otherwise, I will try it a few more times over the next day or so and tell you what I find. Thanks!

Tiny
Jeremyb777
Jul 16, 2013.
All I can say is keep trying sounds promising though.

Saturntech9
Jul 16, 2013.
Well, here is an update. Today, I tested the "unplugging the EGR valve" trick a few more times and got the same result every time.

1. Engine gave the hesitation and RPM fluctuations.
2. I unplug the EGR valve and problem disappears.
3. I plug the EGR valve back in, and problem stays gone.
4. After turning off the car for a few minutes and restarting, the problem returns.

So, after getting this same result about 7-8 times over the course of two days or so, I thought it was worth buying a new EGR valve and giving it a shot. So, I bought it and installed it. So far, so good. I have driven it a few miles, through parking lots (which is when problem is most obvious), revved the RPMS in neutral, and even restarted the car a few times. So far, the problem has not reoccurred since then. However, the check engine light is still one. If the problem does not return, then I am assuming 1 of 2 things will happen: 1. The check engine light will be cleared after driving the car around town a bit -or-
2. The check engine light will remain on and indicate an error for something else (perhaps the P0050 Oxygen sensor light again).

We shall see. I will keep you posted and let you know if the problem stays gone or comes back. Thanks for all the help thus far!

Tiny
Jeremyb777
Jul 17, 2013.
Its funny you say that its mostly noticeable in parking lots. The first time I came across this issue when I worked for saturn. The customer brought the car in I drove it didn't really notice anything wrong. Went for a ride in the parking lot she should me the surging.I turned the engine off unplugged the egr and it was gone. Then turned the engine back off plugged it back in the surging came back. Did this three or four times same results. So I replaced the egr valve and the customer never came back from with the problem again.

Saturntech9
Jul 17, 2013.

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