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Old 11-27-2018, 05:50 PM   #1
shoestring
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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
ZVOLV
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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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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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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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Old 07-06-2019, 11:51 AM   #5
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Hey just as a follow up to this:

I swapped the LH and EZ116-K modules for non-EGR -561/-169 non-EGR units and the results are improved (what I would call "proper") cold start idle quality and driveability and improved fuel economy, maybe 2ish mpg on both highway and combined. I can't tell you if it's because there's a problem with the design and function of the EGR system, if there was a problem with either one of my original modules, or what. I don't believe there was an issue with the mechanical aspect of my EGR system as the only check engine lights I ever got were repaired with a replacement EGR solenoid.

I'm not a fan of deleting emissions equipment if so equipped, but the results in my case are pretty cut and dried. I'd like to know if any of you out there with 50-state cars experience the cold start "this thing sounds like it has a huge cam" idle. As I stated in the original post, after 30-40 seconds (closed loop?) it drove totally normally.

I do like over 30mpg (barely) highway at 75 with a V cam though!
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Old 07-06-2019, 04:30 PM   #6
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Glad you got an improvement from the ezk ecu swap. Both my kjet turbo and the 93 wagon with LH2.4 start lumpy. You can clear it by holding revved up for a little bit. then they are fine. Both have a V15 cam and have started like that when it's cold since the cam install. A lh2.4 951 ecu was slightly better in my experience than a 561.
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Old 07-06-2019, 04:39 PM   #7
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Agreed about the 951. Would be my choice but 561 was on hand.
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