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Old 07-26-2010, 01:47 PM   #1
BennySL2
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Default Jerky Saturn problem narrowed down to EGR valve. What next?

The problem: Our Saturn (1999 SL2, manual) would occasionally jerk at higher speeds and other times it was working hard (eg going up a hill). It started about a year ago (rarely, and difficult to reproduce) and slowly became worse. The jerkiness feels like an intermittent loss of power and would happen at inconsistent frequency, about once a second. It would happen at different speeds on different days, maybe 55-60mph one day, or 70mph another. Changing speeds would sometimes solve the problem, at least for a little while. The jerkiness is now problematic and reproducible enough that I decided it needs to be fixed.

What fixes the problem: From similar problems in past forum posts, I thought I'd try troubleshooting the EGR valve. I used RichPin's youtube video ("Exhaust Gas Recirculation Valve (EGR) Checking"; those videos are always an incredible resource) to put a homemade gasket between the valve and the rest of the engine. That fixed the problem immediately! The car feels like it has a little more power, and with about 1.5 hours of driving has not jerked once.

Interestingly, this improved another problem our car has: the Saturn would sometimes jerk when stopped and in gear (like at a stoplight). Put it in neural and back into first gear, the jerking would sometimes go away. Since I blocked the EGR valve the car only once, and very slightly, jerked at a stoplight.

What next?: I picked up a new EGR valve and gasket at Autozone, but before I put it in (and void the money-back return policy), I want to make sure that the EGR valve is in fact the problem. From my limited understanding, the EGR valve could be fine, but a sensor could still be the problem. From another site (sorry, can't post links yet), I learned that the EGR valve receives information from the following:

Engine coolant temperature
Intake air temperature
Manifold absolute pressure
Throttle position
Vehicle speed

What would people recommend? Eliminate certain sensors as the problem? Or is the problem most likely the EGR valve itself?

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Old 07-26-2010, 01:48 PM   #2
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Default Re: Jerky Saturn problem narrowed down to EGR valve. What next?

By the way, I have used Saturnfans.com countless times to do some of my own car maintenance. The posts I used often too old to comment in. But this site has saved me 100s of dollars and several trips to the mechanic. So thanks

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Old 07-26-2010, 02:19 PM   #3
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Default Re: Jerky Saturn problem narrowed down to EGR valve. What next?

It seems that it's 'EGR valve' day here. There's another EGR valve thread (thread number 156772) from a few hours ago. Some of the information fdryer posted might be relevant.

Some more information from me:

My SES light hasn't gone on recently. I haven't checked to see if there are any codes generated (if no light goes on, can I assume there are no codes?). Since adding the blocking gasket, the SES light came on.

My engine idles at the correct RPM.

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Old 07-26-2010, 03:05 PM   #4
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Default Re: Jerky Saturn problem narrowed down to EGR valve. What next?

It sounds EGR to me, since it got better with the blocking gasket. Before slapping the new one on, it'ld be worth trying to clean the old one with some carb cleaner. There's a richpin on this too

Even if there is not a code set (light on), there could be codes pending (has almost reached the criteria for a code, but not quite...computer isn't sure yet). For example, it detects a misfire, but it hasn't happened enough times to worry about. The computer remembers it, is ready to go, but the final misfire hasn't happened.

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Old 07-26-2010, 03:57 PM   #5
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Default Re: Jerky Saturn problem narrowed down to EGR valve. What next?

None of the sensors directly affect egr valve operation. All sensors output their signals to the pcm that controls the egr valve and uses the egr valve's feedback position sensor within it to tell the pcm pintle valve position. A dirty sticking pintle valve can cause driveability issues so cleaning is the first try before replacement since they're so costly. Its also been the experience of some members that OEM seems to be the better than aftermarket. If your old one won't work after cleaning, try the new one. And if the new one doesn't work because its an aftermarket one, get your money back for an OEM one. Some have tried junk yard egr valves with some luck.

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Old 07-26-2010, 11:13 PM   #6
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Default Re: Jerky Saturn problem narrowed down to EGR valve. What next?

Super. I'll give it a good cleaning and see where that leaves me. Thanks!

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Old 07-27-2010, 03:37 PM   #7
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Default Re: Jerky Saturn problem narrowed down to EGR valve. What next?

I took out the ERG and gave it a good cleaning with Carbo cleaner. There wasn't too much build-up inside. (The car has 170,000 miles on it).

I noticed that the pintle would stick when pushed in all the way. Tapping it would get it to pop out, but it would just stick again. No cleaning or twisting would get get it to not stick. I tried WD-40 (which might not be a good idea), and that got it to stay unstuck.

Alas, when I put it back into the car, the jerking and poor performance started immediately. Having driven it without the jerking, the difference is HUGE. It's like another car. (I haven't taken the ERG back out to see if the pin now sticks again).

I haven't decided if I'm going to put the autozone ERG valve in, or try to find one at a junk yard.

quantumech, I'm in Seattle too. Would you recommend a junk yard? "All West Coast" and "Affordable Auto Wrecking" come up on top of my search engine searches.

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Old 08-19-2010, 07:24 PM   #8
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Default Re: Jerky Saturn problem narrowed down to EGR valve. What next?

Here's an update. I've tried a number of things but none have fixed the problem. The problem is getting worse, especially when trying to cruise (but not accelerate) at highway speeds. What I've tried:

1) Cleaning my EGR valve (the pintle would still stick)
2) Installed a used EGR valve.
3) Tested the MAP sensor (a la RichPin). It seems to work. Voltages stepped down from 4.87, 4.07, 3.11, 2.2, 1.3V for every 5lbs of pressure.
4) Replaced the ECTS with a brass one. The car still had an 11 year old plastic sensor in it.
5) Ran the car for a few seconds with the EGR valve off. It revved up to 4K RPM as expected.
6) Confirmed that blocking the EGR valve completely fixes the problem (it does).
7) Hooked the car up to a scan tool. The car has a pending code: P0401 EGR Flow insufficient.

Here's the data from the scan:
Quote:
FREEZE DATA
fuel sys 1: "OLCL using HO2S"
fuel sys 2: N/A
load %:11.7
cooland F: 171
STFT RM1 (%):18.7
LTFT RM1 (%): -14
MAP (inchHG): 5.32
RPM: 2533
Speed(mph): 60
IGN ADV: -
air intake temp(IAT) F: not given
throttle pos(ABSLT TPS %): 0
OS211: not given
OS2S12: not given
Second Air: ERROR

LIVE DATA(idling after driving)
fuel sys 1: "OLCL using HO2S"
fuel sys 2: N/A
load %: not given
cooland F: 205
STFT RM1 (%): varies 0-3
LTFT RM1 (%): -14.8
MAP (inchHG): 9.45
RPM: 850
Speed (mph): 0
Spark advance/IGN ADV: varies 10 to 20
air intake temp(IAT) F: 98
throttle position(ABSLT TPS %): 0.3 (pushing the gas all the way down gets 90%)
OS211 :varies .1-.8 (0-3%)
OS2S12: varies .6-.8 (n/a%)
Second Air: ERROR

On the highway, when I accelerate even slowly, the MAP jumps from 30kpa to 100kpa. I'm thinking this is normal.
These are fairly close to cjc1966's forum thread 157622 and RichPin's youtube video. The Short Term Fuel Trim (STFT) is higher than cjc1966 (1.6%), Richpin (0.8%). But BadgerW says +/- 40% is okay.

Anyone have any recommendations on what to try next?

A question: I obviously have a problem with the EGR valve not behaving. And the car knows this too. But what data is the car looking at to generate the P0401 code?

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Old 08-19-2010, 08:52 PM   #9
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Default Re: Jerky Saturn problem narrowed down to EGR valve. What next?

if your cat is getting clogged the excessive back pressure could be going into the engine via the egr valve and cause a rich condition (its a non combustable gas) and cause it to trim fuel (your LTFT -14)

Just theory though. can you pull the cat and install a test pipe and see if its any better with the egr?

OldNuc I think posted the back pressure specks somewhere.

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Old 08-20-2010, 01:55 AM   #10
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Default Re: Jerky Saturn problem narrowed down to EGR valve. What next?

Quote:
Originally Posted by 1996SL11.9L View Post
if your cat is getting clogged the excessive back pressure could be going into the engine via the egr valve and cause a rich condition (its a non combustable gas) and cause it to trim fuel (your LTFT -14)....
HUH? Any exhaust flow back into the engine simply leans out mixtures, not richens it. How can it be possible to richen air/fuel mixtures when exhaust gases are already combustion byproducts?

BennySL2, either try a junk yard egr valve or buy an OEM one (unless the A-z one works) since you've proven several times that blocking works to eliminate egr valve interference. The egr valve is causing all your issues at this point. Emissions data is after the fact when a before/after blocking of the egr valve ports shows immediate changes in engine running.

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Old 08-20-2010, 04:02 PM   #11
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Default Re: Jerky Saturn problem narrowed down to EGR valve. What next?

It was good thinking, fdryer. I just tried your suggestion. Unfortunately, when I installed the Autozone EGR valve, I get the same exact problem. Well, at least that definitely rules outs the EGR valve itself.

Two more things I can think of:

1) When I removed the MAP sensor I noticed that there was some oily grime/dirt around the sensor. I wiped it off. There was also this oily dirt inside the hole into the manifold. I could scrape some out with a paperclip. I don't know if this is normal or not. And I'm unsure how to clean it further. Related, I could also try cleaning the throttle body, for no other reason than I haven't done so.

2) Maybe I have leaky hose /pipe somewhere. I just recently started hearing this faint hissing/whining noise when I'm accelerating (and happen to be driving by something that reflects the sound back to the driver-side window). I can't find where this sound is coming from. The sound could also be coming from a spinning belt, though. So I'm not so sure.

Well, I might just have to knowingly fail my WA State emissions test so I can then go to a mechanic.

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Old 08-20-2010, 04:50 PM   #12
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Default Re: Jerky Saturn problem narrowed down to EGR valve. What next?

Too many people become overly concerned about gunk/grease/oil/carbon deposits inside the intake manifold. Its there because of positive crankcase ventilation, the pcv that recirculates combustion blowby gases escaping past the piston rings that are vented back to the intake system as part of emissions controls. When someone remarks about their intake being greasy, its from recirculating all this back to clean up emissions otherwise this would have been vented as another exhaust port instead of coating our intake manifolds. All normal; if the engine doesn't care why should you? Fuel economy won't improve one bit and I dare anyone to prove it. Its cosmetic that's all. If you feel the need to clean you can do what everybody else does; inject seafoam directly into the intake system and create a cloud of mosquito repellent in your driveway. Whether it cleans out the intake system is debateable. It won't improve on emissions inspection but most feel good about doing it. By and large every intake manifold is covered in this gunk and still passes emissions inspection. When I removed my intake (to replace a thermostat) and saw the build-up I spent a few minutes cleaning any wet areas but didn't obsess over it as I pass NYS emissions all the time.

Your egr valve is causing the emission failure if it still turns on the SES indicator. Your only choice is either a good junk yard one or OEM.

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Old 08-20-2010, 05:09 PM   #13
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Default Re: Jerky Saturn problem narrowed down to EGR valve. What next?

Well, I'm not looking to do any extra work, trust me.

As for passing WA state inspection: I think they just plug a code reader into the computer and if it has trouble codes, you're in trouble. My SES light is NOT on, but I do have a P0401 code. I presume I'll fail because of that. I'll then have to fix it, or spend a certain amount of money trying to fix it.

I've had 3 different EGR valves in the engine (the original, a used OEM, and one from Autozone). They all do the same thing, so I'm running on the assumption that the EGR valve itself isn't the problem. Fdryer, are you thinking that it still might be the problem?

I don't know what exactly is tripping the P0401 code either. It seems that all my sensor data is okay, so I'm at a lose... Recently, the jerking also happens when accelerating from a full stop, and that makes it unless the EGR valve is blocked.

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Old 08-20-2010, 05:28 PM   #14
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Default Re: Jerky Saturn problem narrowed down to EGR valve. What next?

Here's a reprint from the FSM for your car.
Attached Files
File Type: pdf 99 SL2 P0401 part 1.pdf (111.1 KB, 291 views)
File Type: pdf 99 SL2 P0401 part 2.pdf (53.5 KB, 94 views)

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Old 08-22-2010, 10:14 AM   #15
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Default Re: Jerky Saturn problem narrowed down to EGR valve. What next?

Excellent fdryer, that's for posting that, it's exactly what I was for.

For others, the pertinent information is:

Quote:
The EGR flow insufficient test is checked once per ignition cycle during deceleration.

DTC P0401 will set if a calculated value compared to an engine speed vs barometric pressure
determines there is a restriction in EGR flow when:
* Engine speed is between 1,350-2,000*RPM.*
*The VSS is greater than 48 km/h (30 mph).
* The throttle is closed.
* The engine coolant temperature is greater than 70°C (150°F).
*The vehicle is in top gear.
* No EGR pintle, TP sensor, MAP, VSS, IAT, ECT, or IAC DTCs have been set.

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Old 08-22-2010, 05:37 PM   #16
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Default Re: Jerky Saturn problem narrowed down to EGR valve. What next?

Since worsening, I've noticed something else: The car won't jerk during the first minute or so after starting it after it's cooled. Then it starts jerking whenever accelerating from a dead stop. Gunning it, or very slowly accelerating ameliorates the problem. This is, of course in addition, to the jerking on the highway, which occurs during cruising, but not acceleration.

Just throwing that out there, in case it helps with the diagnosis.

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Old 08-23-2010, 11:16 PM   #17
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Default Update, details

First: I brought the car to its WA state emission test. The car had no SES light but still had a P0401 code. My code reader said it was a trouble code (not a pending code) which would fail the test. But Washington state disagreed, and the car luckily passed the test.

Second: I then brought the car to a shop. Their diagnosis:

The Catalytic converter is very clogged. Exhaust is being pushed back into the engine (probably causing the EGR valve problem) and also leaking through a hole in a pipe (causing the wheezing noise). The shop drilled hole before the Catco to release the blow back, and the car runs much better, and much much louder (I don't need to honk anymore).

They quoted me $605 parts and labor to replace the Catalytic converter ($356) and rear oxygen sensor ($170). Plus I'd need to replace the busted exhaust piper for $380 parts and labor. So $913 total. It's tempting to buy the tools and try it myself, but my thinking is that I might be extending myself.

It's the original Catco (171K miles), so I understand it's not too surprising that it needs replacing. There's always a chance something else is the root of the problem though. Or that the clogged Catco has now damaged other parts of the engine. But nothing indicates that so far, so fingers are crossed.

Thanks fdryer, 1996SL11.9L, and quantumech for your help. I'll post if anything changes. Also, 1996SL11.9L was spot on, so gold star there.

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Old 08-24-2010, 04:13 PM   #18
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Default Re: Jerky Saturn problem narrowed down to EGR valve. What next?

My take: if it ain't broke (not getting a code for the O2 sensors), don't fix it. Yes, $900 is a bit of a ripoff (could be worse; I was once quoted to overhaul the whole exhaust (catcon, muffler, piping, and both sensors) for $1200 ). Needless to say, I went to car-x that day, got a new catcon, muffler, and piping, all for $605.

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Date Obtained: 5/30/07
Status: Alive, 1/2 exhaust

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Status: Alive, no heat

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Old 08-25-2010, 06:06 AM   #19
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Default Re: Jerky Saturn problem narrowed down to EGR valve. What next?

Quote:
Originally Posted by fdryer View Post
HUH? Any exhaust flow back into the engine simply leans out mixtures, not richens it. How can it be possible to richen air/fuel mixtures when exhaust gases are already combustion byproducts?
Exhaust gas is already burned. nothing more left in it to burn. O2 all used up or most of it anyway. hence non-combustable. It is used to lower combustion temp because it dilutes the combustion air some and displaces the O2. Less O2 means richer condition. You answered the question yourself. That in turn lowers the NOX.

The EGR's pintle is spring loaded.........any back pressure great enough to overcome spring pressure will lift the pintle and burp EGR into the intake. Do not believe me? take an EGR valve and use a pen or pencile and see how easy it is to push the disk back.

OBDI Mopars use to test the EGR by energizing its solinoid and freezing fuel trim and look for a rich condition. If no rich condition it coded.

There is more then a few guys out there with roughness and bucking that probably have this very same problem with a CAT clogged enough to effect the EGR operation or they wouldn't give back pressure specs.

EGR problems screwed me in the past so I learn what it does. In older cars that do not monitor EGR, roughness of any type at light throttle loads is the first thing to look at.

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Old 08-25-2010, 07:29 AM   #20
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Default Re: Jerky Saturn problem narrowed down to EGR valve. What next?

Quote:
Originally Posted by 1996SL11.9L View Post
Exhaust gas is already burned. nothing more left in it to burn. O2 all used up or most of it anyway. hence non-combustable. It is used to lower combustion temp because it dilutes the combustion air some and displaces the O2. Less O2 means richer condition. You answered the question yourself. That in turn lowers the NOX. ...
I beg to differ here. How does the overall air fuel mixture become richer when exhaust gases are deliberately ported in during acceleration and cruise? If the O2 sensor is operating correctly and fluctuating between slightly rich to slightly lean, the overall a/f mixture is towards ideal stoichiometric (14.7:1). Deliberately adding exhaust/spent gases into this mix would tend to lean out the overall mixture since the system is naturally aspirated and cannot draw in any more air/fuel/exhaust gas than physics allows.

If what you say is true then fuel economy will tend to drop even more as your supposition is to continually run a rich mixture.

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