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2002 SC1, 5 speed, 1.9 L Rough Idle

Tiny
SAMUELRODGERS
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  • 2002 ALL OTHER MAKES ALL OTHER MODELS
I sprayed carb cleaner into the IAC bleed hole and around the butterfly, then replaced plugs and wires, coolant temperature sensor. Runs smooth for 15-20 seconds on a cold morning, then rough high idle about 1300 - 1600. It seems to stick in one place or another, occasionally as high as 2500-3000 rpm and will increase when I push in the clutch to shift, even though I already took my foot of the gas. This afternoon it was warm so I turned on the AC on the way home and the idle dropped to normal (1000 with AC on) and smoothed out. I get vacuum to the orifice in the EGR vacuum line, but at idle no vacuum through the EGR solenoid. Could this be the problem? When should I be getting vacuum to the EGR valve and how can I check this out? I don't want to just keep buying parts til I get lucky.
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Wednesday, February 21st, 2007 AT 6:31 PM

19 Replies

Tiny
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You didn't waste any money on what you replaced, so don't feel bad about it. The egr valve can be cleaned and may be the cause. Make sure the passageways are clear after you remove the valve.
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Wednesday, February 21st, 2007 AT 6:50 PM
Tiny
SAMUELRODGERS
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I took your advice and decided to take apart the egr valve and clean it. Went to the parts store to buy replacement gaskets first and they can not match my EGR valve. I looked everywhere I could find on the WEB and the picture of the egr valve for my 2002 saturn 1.9 L, SOHC, does not match the connector or anything else. Mine has a part number 21210000 on the top of the diaphragm, is more square, doesn't have any electrical connection on the top, and the connection to the exhaust tubing is in the horizontal. No idea how to figure this out.


https://www.2carpros.com/forum/automotive_pictures/60510_P1010002_1.jpg

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Thursday, February 22nd, 2007 AT 7:40 PM
Tiny
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Before anyone blows a hole through me, I am a meager service writer. :)

I'm throwin this out here anyway:


https://www.2carpros.com/forum/automotive_pictures/30961_satvac_1.jpg



Are we looking at the right part?


https://www.2carpros.com/forum/automotive_pictures/30961_sategr_1.jpg



https://www.2carpros.com/forum/automotive_pictures/30961_sategr1_1.jpg

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Thursday, February 22nd, 2007 AT 8:17 PM
Tiny
SAMUELRODGERS
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Boy do I feel stupid. My EGR valve is just where you said and looks just like it. Thanks so much. I think the "valve" I was looking at is part of the AIR system during engine warm-up. I'll give it another try. What should I look out for when I try to clean the EGR valve?
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Thursday, February 22nd, 2007 AT 9:32 PM
Tiny
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Any black carbon build up. Get a good intake cleaner to spray it out. Anywhere the air flows through should be looked at and cleaned as well. Use rags, pipe cleaner etc. On the engine side. On the egr there is pintle that may be sticking spray it out good. A google search on cleaning egrs may expose a little more.
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Friday, February 23rd, 2007 AT 5:25 AM
Tiny
SAMUELRODGERS
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I pulled the egr valve and it was pretty clean. A thin film of fine carbon, but no chunks. The pintle (has a little torx head in it) was moving freely. It has some light spring pressure that I could push in with a small screwdriver. If I shake it it rattles a little. I sprayed it with carb cleaner, but I want to check it out before I put it back on. How do I go about testing it off the engine? Can I apply some voltage to it to make it move in (open)? If so, how much and which contacts? It has 5 electrical contacts in the connector.
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Tuesday, February 27th, 2007 AT 7:53 PM
Tiny
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By chance did you check for any codes in the computer?
Here's the connector view:


https://www.2carpros.com/forum/automotive_pictures/30961_satcon_1.jpg



I can't say that a rattle should be present, short of a piece of carbon in there, but if you cleaned the pintle, That's about the best you can do on those as I understand.
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Wednesday, February 28th, 2007 AT 3:54 AM
Tiny
SAMUELRODGERS
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The only codes so far have been cyl 1/4 misfire and 0507 high idle. I replaced the cleaned egr with no change. I replaced the IAC, which did not appear gummed up, but still no change. I replaced the PCV just for kicks, no change.

The engine will still jump up to 2500-3000 rpm with the clutch in after driving for a few minutes and when this happens the car will maintain speed in gear or even speedup. I have plenty of power and it seems to rev up fine without a flat spot or top-out.

If I turn it off when the idle is that high and restart it immediately, then it starts running at close to about 1500-1600 RPM. This might mean there is a timer involved. It also will rise by itself if I just let it sit in idle.

I still did not replace the Throttle position switch, MAP, or O2 sensors, but I'm not getting any codes for them.

Help!
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Wednesday, February 28th, 2007 AT 6:10 PM
Tiny
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Misfire code?

Po301 and po 304?

What code # (s)
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Wednesday, February 28th, 2007 AT 6:54 PM
Tiny
SAMUELRODGERS
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Sorry, yes P0301 and 0304, then 0507. Nothing else so far.
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Wednesday, February 28th, 2007 AT 8:10 PM
Tiny
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The procedure calls to go after the misfire codes first.

I believe the ignition coils work 1-4 and 2-3, not saying they are bad.

The idle fluctuations sound like a vacuum leak or sticking throttle.

Somewhere along the way, I read about a fuel injector balance test to be performed on the coupes when a po507 is noted.

I know I'm not being much of a help, but.
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Thursday, March 1st, 2007 AT 4:45 AM
Tiny
SAMUELRODGERS
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I measured 7500 ohms across the secondaries of the igntion coils (not including the wires) which I believe is in spec. Does it make sense that P0301/0304 would show up first if the TPS was intermittently not reading zero at idle, thus allowing EGR valve to function as soon as the CWTS heats up. Then maybe when the exhaust O2 heated up it would not know the throttle was closed and start calling for more fuel and the idle climbs to 3000? Would then turning off the engine reset a timer for exhaust O2 to take over so it didn't immediately return to 3000 rpm?

Can I safely start and idle the engine with the connector pulled off the egr valve and see if the misfire goes away? Without power the egr should be closed and is supposed to be closed at idle, right?
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Thursday, March 1st, 2007 AT 1:08 PM
Tiny
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If there was a egr or tps problem an accompanied code should be present.

Can you do a compression test on the bad cylinders?

You can pull the connector on the egr and see, I would expect an egr code to then appear.

I am wondering if the idle and misfire codes are not related. Check the vacuum hoses for any that may be soft

I am not aware of any timers involved anywhere. Just sensors.
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Thursday, March 1st, 2007 AT 6:11 PM
Tiny
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One more shot at a possible vacuum leak.

Spray some carb cleaner, brake clean throttle cleaner etc around the intake manifold gasket, especially #1 cylinder area.


https://www.2carpros.com/forum/automotive_pictures/30961_satin_1.jpg

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Friday, March 2nd, 2007 AT 6:03 PM
Tiny
SAMUELRODGERS
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After spraying some more carb cleaner it seemed that at least the #1 injector might have a seal leak. I changed all of the manifold seals on the injectors which didn't make any change. Also put the socket on the intake manifold bolts, with no effect except not getting P0301/P0304, but _0507 instead. Put a cover over the egr gasket and idled it so an egr leak would be stopped. No effect. Still idles rough and get P0507 codes.

Cleared the codes and drove it. Sitting at a stop light with the clutch in, all of a sudden the idle jumped to 2500 rpm. Pumping the gas wouldn't make it go back down. Turned off the car and immediately back on, and the idle went back to 1500 on restart.

While intake manifold leak has been talked about as a possibility, I don't get how turning the car off and immediately back on would make the high idle go away if it were due to heating the intake.

The freeze frame picks up 20-30% engine load at idle when I get the P0507 at 1300-1500 rpm. MAP is 7-9 in Hg. Is this typical to have such a high indicated engine load at idle?
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Sunday, March 11th, 2007 AT 3:15 PM
Tiny
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This mis fire codes had to be eliminated first, which you did. It may not feel like you accomplished anything, but you did. This is part of the fun of auto repair.

It is not typical to have a high engine load at idle as you describe. However that is one of the symptoms of the problem that is happening.

Conditions to set the code po507 include:
-vehicle speed at zero mph
-tpangle at zero %.
-BARO is greater than 70 kPa.
-Ignition voltage is 9-18 volts.
-IAT is greater than -13degrees f. (-25 C)
-Desired idle speed is 650-875 RPM.
-ECT is greater than 140 deg. F (60C)
-No ECT, EGR pintle, MAP, misfire, vehicle speed or TP sensor DTCs are set.

Notice the last one makes refernence to the misfire DTCs that you just solved :D

Looks like we need to check the IAC terminal resistance next.
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Sunday, March 11th, 2007 AT 8:07 PM
Tiny
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Try tapping on the tps or wiggle the connector to it and see if idle changes. IF not take the connector off the TPS and check for corrosion. Leave it unplugged and see if idle still goes high.
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Monday, March 12th, 2007 AT 4:37 PM
Tiny
SAMUELRODGERS
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I have been driving the car 6 or 7 highway speed trips now and the CAT and EGR diagnostics have not run. Something has to be preventing that. I have P0507 code.

While out driving the idle shot to 2900, so I pulled over and unplugged the TPS. The idle immediately dropped to normal, not sure what RPM, but a lot lower. Then I plugged the TPS back in and the idle shot up again.

Is this conclusive that the TPS is the problem, or should I take it out and try to clean or check something on it? Hope this is it!
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Thursday, March 15th, 2007 AT 9:22 PM
Tiny
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Replace it. Check for corrosion on connector as well.
Congrats!
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Friday, March 16th, 2007 AT 10:20 AM

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