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I have a 2002 Edge with the 4.0 liter engine with just under 170K miles on it. Let me start at the beginning, I came out of the store and had a crank no start issue, a very rough cranking too. I waited and tried a few more times and if fired up and ran well all the way home. I was way overdue for a tune up so I replaced the plugs and wires and a few other things. It did not help. I still had an intermittent crank no start issue. I checked spark and no issue there. I did replace the fuel filter and it seems to start every time now but the problem now is that it idles really rough and only at about 500 RPM's. if I hold the throttle at a higher RPM, say about 2000, it runs nice and smooth. I took off the IAC and cleaned it really good and stuck my power probe on it and it does actuate so I don't think that is the issue. I do hear a high pitched whistle which makes me think there might be a vacuum leak. I did pull the vacuum line off the top of the EGR valve and there was no change to the idle, not sure if that means anything though. I will be damned if I can find a vacuum leak. I might rent a smoke machine. I also unplugged the MAF and it made it worse so I am sure that is not it. At one point I changed the Crank Position Sensor as well and that did not help either. No CEL and no codes with the OBDII reader. I did check live data on O2 sensors and fuel trims and all appears normal. Any ideas? Thanks all! I really appreciate the help!
Update, I You Tubed how to test the PCV valve and the EGR valve and they appear to be good. I did spray carb cleaner around and no change so then I tried starting fluid and no change. I ordered a cheap smoke machine off of amazon which will be here on Tuesday. I will update.
Okay, I got a cheap smoke machine off of Amazon, And I found a leak around the TPS, Took the TPS off and it is coming out of the side of the throttle body where it mounts. I am not sure if there is supposed to be a gasket on the TPS, I would assume so. Anyone had this issue? My questions is, should the TPS seal this off at the throttle body and I can just add RTV or replace the TPS or do I need to replace the Throttle body itself? I am leaning toward the RTV as that will be much cheaper than a $300 reman Throttle body.
Last edited by Onenuttman; Feb 19, 2025 at 08:32 AM.
Reason: Upate to diagnosis
smoke machine works great, you can try with WD 40 or starting fulid and spray around hoses. listen for the rpm's to rise.. with motor warm and running unplug the IAC see if the motor almost dies.. if so it working.
Include year / model / mileage in posts so we don't have to click around for your particulars.
You've a 2002 with the 4.0l SOHC.
Check the PCV valve for operation and the large, plastic "L" pipe which carries the vapors across the back of the engine and forward to the intake.
These split with time.
It's harder to get a look at than you might think as it's against the firewall and buried among other hoses as it reached forward.
I thought if that info was in my profile it would automatically show up, sorry about that! I have added it now, thanks!
In regard to the PCV valve, I did inspect the hoses but I did not pull out the actual PCV valve and shake it. I was told if I clamped off the hose to it and it ran better it would be a sign that it is bad. I clamped it off and it did not change anything. Is this a legit test or do you think I should still fully remove it and the pipe and hoses and inspect? I did order a cheap smoke machine off of Amazon so I am hoping that will reveille a leak. Thanks for the help!
Only the elbows are rubber.
The rest of the large L is hard plastic and will break if clamped.
Also, posters here have reported that the bottom of the L pipe is where it cracks. Take that for what it's worth.
Also, I think anything 1/2" ID you can make fit is OK to replace said L pipe.
A guru here said to replace the PCV valve every 3rd Winter in northern climates and every 4th in the South.
How long has the current PCV valve been in service? They're cheap enough to replace.
Be careful "1/4 turning" the PCV valve out of the valve cover.
You don't want to break the female receiver part. It's built into the valve cover and replacements are no longer available.
A careful repair would be required.
Thanks for the response! I pinched the elbow on the front of the engine where it was easy to get to. I will completely remove the PCV, the tube and elbows and inspect and while it is out I will replace the PCV valve too.
