Sticky EGR

[Phoenix127]

My engine has exhibited an odd miss which occurs only after warm up. Once warm it results in a rough idle but otherwise normal operation. I have tried distributor caps and insulators, wires but never found a clear solution until now.
The EGR valve is sticking open! I placed a momentary vacuum on the EGR valve and it would stay open causing the roughness. The engine stumbled and struggled to run. After cleaning up the valve with solvent and reassembling the problem has disappeared. I guess it stuck open during the first operation of the day after warming up. Might resolve a few mysterious idle problems believed to be ignition related.

 

[sheward]

Interesting. Thanks for sharing that. It's likely something being ignored. I've read very little about the egr valve here.

drew

 

[gsxr]

Was the rough idle persistent? And otherwise drove normally, just had a rough idle? Great info, btw - thanks for sharing!

Drew, you are right, we rarely hear about EGR issues.

 

[Phoenix127]

Was the rough idle persistent? And otherwise drove normally, just had a rough idle? Great info, btw - thanks for sharing!

Drew, you are right, we rarely hear about EGR issues.

It was only on the first start of the day. Once fully warmed up the rough idle would begin. it would barely run at idle but give it more gas and it drove normally. My routine was to hit Starbucks and it would stumble through the drive through line but after driving a few more miles on the highway it smoothed out. I think repeated opening and closing the EGR during the drive loosened it up. The idle problem has gone completely away now with a clean egr valve. I had read and read believing it was moisture, or ignition or vacuum related. I hope this helps someone else. I’ve learned so much about my car here it feels good to give back.

 

[nocfn]

what solvent did you use, describe your process for others if you can briefly.

 

[Phoenix127]

what solvent did you use, describe your process for others if you can briefly.

Brake cleaner or Chemtool B12 works well. The EGR valve is conveniently located on the top front of the M119 engine. It is a simple matter of removing the vacuum tube and unbolting the valve. There is a gasket which should also be replaced. Exhaust gasses are dirty and this valve and passageway may become clogged with oily carbon buildup over the years when this valve opens. For me the problem was a sticking valve. Previously I had roto rooted the passageway using a length of small diameter stainless steel cable chucked into a drill. You can splay out the buisness end into a brush shape and do a fair job cleaning that passageway this way. I also used Chemtool B12 here. Be careful because the cleaner is very strong.

To clean the valve I used a length of clean vacuum hose on the valve and applied vacuum to operate the valve either with a mite vac or you can use your mouth. Cycle the valve open and close while spraying cleaner in the valve until it is clean. Replace the gasket and EGR valve, tighten the bolts, reattach the vacuum hose and start the engine. You can tell if it works by applying vacuum to the valve while the engine idles. Vacuum applied at idle should choke the engine down if the EGR valve is working properly. Releasing the vacuum should return idle to normal. In my case the valve stuck open causing a continuous rough idle.

 

[dionphaneuf]

@Phoenix127 were you getting a CEL, blink code 5 as well? I've had a much less severe version of your stumble or misfire along with code 5, but it is a slight hiccup every now and then that drives me insane and distracts from the otherwise smooth M119 idle (and light free dash!). I've replaced the vacuum lines and elbows but not rooted the passageway (speedo cable) nor cleaned the valve and replaced its gasket.