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Old 11-27-2018, 05:50 PM   #1
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shoestring's Avatar
Join Date: Jun 2009
Location: Swampscott, 01907
Default '91 240 w/EGR: idle quality

Ok, so my '91 245 idles like it's got a huge cam when it's cooler than say 50 degrees outside. Smells super-rich. It runs like this for about 35 seconds and then it kinda smooths outs, but is never really smooth. Drives fine, reasonable fuel economy, no DTCs of any kind, etc. It's got an M47, and the only mods are an A cam and 0.040" off the head. I have at times done internet searches on this trying to see if there's a solution. I've found threads describing what I've got exactly, and the only common denominator is that all the cars have EGR. Of the multitude of B230F(T)s around me, it clearly is the worst, I would say it's non-OEM quality.

Looking to the group to see if anyone else has experienced this and if you were able to fix it.

Like I said, it doesn't seem detrimental, it's been this way for 75k. I really just like to fix stuff.

Thanks in advance.
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Old 11-27-2018, 06:26 PM   #2
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Join Date: Nov 2002
Location: California

Doubtful. You could just block the port at the intake manifold and recheck. A stuck open EGR valve could cause problems, but I haven't seen it happen often on these cars.
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Old 11-27-2018, 06:34 PM   #3
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Join Date: Jun 2002
Location: S NJ, a suburb of Phila.

Well with the overlap of an A cam plus higher compression. Each cylinder firing is going to hit a bit harder. So it shouldn't idle as smoothly as the stock cam. Do a careful check for vacuum leaks. Use a vacuum gauge to see where you are at with intake vacuum at idle. Typical four cylinders are around 18-22 inches at idle but with a higher overlap cam that can be lower. The A cam is pretty mild so it should be in that range. You could try advancing the cam to see if that helps it be a bit more smooth. I suggest at least four degrees advanced to try it out.

EGR operates at cruise. If it is affecting the idle which it can if something failed. You can remove the stuff altogether and get non egr computers or there are ezk chips which will eliminate the egr function.
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Old 11-29-2018, 07:55 PM   #4
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Join Date: Nov 2015
Location: South GA

When doing the PCV system in my 90 240 with EGR, I noticed that the pipe that comes from the exhaust to the EGR valve looked fine on the top surface, but rusted away in a few spots underneath. It was causing some issues as well as the rubber vacuum hose section to the unit was cracked.
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