EGR valve issues

brtnstrns · Dec 27, 2010

So I'm pretty sure based on the symptoms described in my manual that my cars problems (running/idling incredibly rough until the engine is at normal operating temperature) are due to a screwy EGR valve. I'm wondering what all I need to check to determine the source of the problem as I know that the EGR valve is regulated by various systems. Anyone got any ideas on what all to check and how to go about repairing the problems that might exist? I'm hoping its just the valve itself that needs to be replaced/fixed.

trinity_gt · Dec 27, 2010

Start by pulling the vacuum line off the EGR valve at idle. First check for vacuum at the line. If you've got vacuum there and/or the idle quality improves, you may have a problem in the control solenoids.

If the idle doesn't improve it's possible the EGR valve itself is stuck due to carbon buildup internally.

Before tearing into the EGR though, have you checked all other sources of possible vacuum leaks? Checked the inlet duct between the MAF and the throttle body? Checked the vacuum hoses connected to the plenum? Checked the PCV valve? Has the MAF been cleaned lately and if not, do you run an oiled (e.g. K&N) air filter?

wmburns · Dec 27, 2010

+1 on above. Especially check the vacuum lines to/from the DPFE sensor.

If high mileage, consider replacing the EGR value. Be sure the throughly clean all EGR passways while there.

GDawg · Dec 28, 2010

Is your car not throwing any codes?

brtnstrns · Dec 28, 2010

It is but they're saying rich/lean fuel mixture and related issues, which could mean various things. But based on the symptoms it seems very much like the EGR valve.

wmburns · Dec 28, 2010

There are 1000's of DTC codes. Each has a story to tell. You are doing yourself and the ppl trying to help you a dis-service by not posting the full DTC codes.

If asked to handicap this thread, my vote is exhaust or vacuum leak.

brtnstrns · Dec 28, 2010

wmburns said:
There are 1000's of DTC codes. Each has a story to tell. You are doing yourself and the ppl trying to help you a dis-service by not posting the full DTC codes.

If asked to handicap this thread, my vote is exhaust or vacuum leak.

Alright my bad. I'm going to have to get them again, I forgot what the actual numbers were, I was just recalling the information on them.

GDawg · Dec 28, 2010

Your computer has a lot to say about it's own running condition. Get all the codes past and present and list the codes themselves not the description.

My vote goes toward vacuum leak...

brtnstrns · Jan 4, 2011

Well according to the codes, I'm wrong about the EGR valve as its saying there's a misfire in cylinder 6 and its too rich in bank 2:

Codes Thrown:
P0306
P0175

The P0306 wasn't thrown the first time I got the codes checked a few weeks ago. I'm also confused as to how the symptoms could be worse when the engine is running cold and then get better as it reaches normal operating temperature as I would assume a cylinder misfire would have the same effect no matter what temperature the engine is at. Anyway, where is a good place to start trying to fix the problem? Thanks for your help

trinity_gt · Jan 4, 2011

Pull the plug on cylinder #6 (driver's side, 2nd from the front of the engine). What does it look like?

Try swapping the COP from cylinder #6 with that from, say, cylinder #2. See if the problem follows the coil pack or stays with the cylinder.

The fact that you're getting too rich on the same bank that has a misfire may mean that the PCM is detecting the raw fuel coming out of 6 but it could also indicate that way too much fuel is entering 6 and causing the misfire. You may need to check the fuel injector for that cylinder too: It may be stuck on (or the driver in the PCM is stuck on) or you may have a fault in the wiring (e.g. chafing of the wiring has produced a short that causes the injector to turn on all the time...)

wmburns · Jan 4, 2011

IMO, ignore the P0175. It is the result of a constant misfire from cylinder #6 (P0306). Fix the misfire in #6 and go from there.

This demostrates why it's important to post all of the DTC codes.

As for the causes of misfire, start first with ignition. Swap the COP with another cylinder and see if the problem follows the COP. Use a "noid" style to confirm the firing pulse.

Confirm that the fuel injector is firing. Use a "noid" style tester or listen with a Mechanic’s stethoscope.

If the problem is not found check the base engine starting with a compression test.

>>
P0175 - System to Rich (Bank 2)
P0301 through P0310 - Misfire Detection Monitor

brtnstrns · Jan 11, 2011

Read the codes again today and I'm getting the P0175 but also a P1151. I have not started repairs yet but I am about to right now. I'm getting no indication about which cylinder is having a problem. Should I still approach trying to fix the possible ignition problems of cylinder 6?

brtnstrns · Jan 12, 2011

I replaced all the spark plugs and the PCV valve. Don't notice any vacuum leaks with a quick lookover. Still running crappy and throwing the 0175 and 1151 codes. What should I do next????

wmburns · Jan 12, 2011

If you look at the FULL list of what COULD cause this, you will see that there is still alot of work to do.

Consider getting a propane based vacuum leak detector. A quick seach of Amazon for an example of an affordable unit.

If high mileage, consider replacing the front O2 sensors. This would at least give you known good ones to work with.

Note, fuel pressure is listed as a possible cause. Is the fuel pressure vacuum reference line connected and leak free?

This could also be a clogged fuel injector. Consider an injector cleaning flow test service such as injectorrx.com.

If asked to handicap this thread, since the lean conditon is being reported on a single bank (left), IMO an exhaust leak on the left side of the engine should be high on the list. Check for leaks especially around the EGR system and DPFE sensor. Exhaust gases are hard on rubber parts. Any leak in the lines to/from the DPFE sensor will be hard to see because the sensor is slow close to the firewall.

A MAF problem would affect both banks. As well as a vacuum leak early in the induction system would affect both banks. If this is a vacuum leak, look for something that would affect only a single side. Valve covers, oil dip stick, or fuel injector O-rings for example.

>>
P1151 - Lack of HO2S-21 Switch, Sensor Indicates Lean

Electrical:
Short to VPWR in harness or HO2S
Water in harness connector
Open/Shorted HO2S circuit
Corrosion or poor mating terminals and wiring
Damaged HO2S
Damaged PCM
Fuel System:
Excessive fuel pressure
Leaking/contaminated fuel injectors
Leaking fuel pressure regulator
Low fuel pressure or running out of fuel
Vapor recovery system
Induction System:
Air leaks after the MAF
Vacuum Leaks
PCV system
Improperly seated engine oil dipstick
EGR System:
Leaking gasket
Stuck EGR valve
Leaking diaphragm or EVR
Base Engine: Oil overfill
Cam timing
Cylinder compression
Exhaust leaks before or near the HO2S(s)

brtnstrns · Jan 12, 2011

So I decided to go ahead and check out the EGR valve itself and in the process of removing it I noticed that the sleeve of the metal hose going from the exhaust manifold (I think) into the bottom of the EGR valve was not even finger tight. So I removed the assembly and cleaned it up just for the hell of it and made sure that the sleeve of the metal hose was screwed in snuggly to the EGR valve base and after a 15 minute drive or so the rough idling, sluggish acceleration, and stalling problems seem to have been fixed. The check engine light is still on which I assume will turn off after driving for a while (if the problem is fixed). Now I know this was a short drive so its very possible its just a fluke that its running like its supposed to and I won't know for sure until I drive it again but could the loose collar be enough of an exhaust/vacuum leak to cause such a problem?

wmburns · Jan 12, 2011

Consider for a moment that one loose connection is BOTH an intake leak AND and exhaust leak.

The check engine light normally won't go out on it's own (it will after enough drive cycles). The normal action is to reset after a repair is complete. Remember, the idle will be rough until the PCM re-learns new idle trim values.

Are you a "glass half full" or a "glass have empty" sort of guy? Just wondering because you get advice saying to check the EGR system. Low and behold a problem is found. As an added bonus, the condition immediately improves. Why not take a moment to enjoy a sucess?

brtnstrns · Jan 12, 2011

Well I was enjoying but it still seems to be acting up and has actually gotten worse as I've gotten to my third drive in it after fixing the EGR problem. But if you say the PCM is still configuring the idle that might be it. Otherwise, guess I'll be going back in to try to find more vacuum or exhaust leaks.

wmburns · Jan 12, 2011

Check this out:
Amazon.com: Thexton (THE382) VAC LEAK DETECT: Automotive

Because the car has been operated for an extended period of time with a leak, the idle trim values will be "different" from the current values. It will take time for the PCM to re-learn. As stated before the usual action is to re-set the PCM with an ODB2 reader or by disconnecting the battery. This does give the advantage of turning off the check engine light.

Trouble shooting is a "process". Evaluate the symptoms. Make a "guess". Look for problems. Find and repair. RETEST. (wash, rinse, repeat).

Post the DTC codes and symptoms once the car has been driven enough to establish a new base line.

EGR valve issues

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