I hate to start off with questions, but I am at a loss on this one. I have owned this Jeep for a long time and have crossed many items off the check list. The Jeep has over 200,000 miles on it but a lot of things have been done. Timing belt, water pump, radiator and fan and so on. Long story short. Last week my wife and I were on a trip and the engine developed an intermittent loud tap from the engine and a misfire. I of course thought fuel injectors and replaced all four with rebuilt units from AutoZone. 1240.00 dollars worth. I just knew that would solve the problem but not so much. The darn thing still does the same thing. Runs fine for miles and then taps bad misfires cylinder for few seconds or less later runs fine again. The tap sounds just like an injector hanging open. That loud and horrible sound. I am at a loss. My mechanic son says it may be a bad rocker but I am not sure. Any advice would really be helpful. Thanks from the new guy.
The new guy with a problem, Go Figure.
- Thread starter My05CRD
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KalleXX
New Member
An intermittent problem is likely not a mechanical one. I would think it has something to do with with the fuel delivery as you already have guessed.
Not seldom the camshaft- or the crankshaft position sensor is on the way out (or both). The fuel rail pressure solenoid is also in the equation. It could explain the intermittency.
I had a fuel delivery problem that ended in a crank no start. It was caused by a faulty cranskshaft position sensor. But the engine ran for a while before it gave up. Seemed intermittent in the beginning. The noise you hear can be an effect from intermittent stuck fuel pressure solenoid.
Connect a scanner where you can monitor the fuel pressure live and check what happens when you have a misfire. If you have some fault codes they can give some hints too.
Not seldom the camshaft- or the crankshaft position sensor is on the way out (or both). The fuel rail pressure solenoid is also in the equation. It could explain the intermittency.
I had a fuel delivery problem that ended in a crank no start. It was caused by a faulty cranskshaft position sensor. But the engine ran for a while before it gave up. Seemed intermittent in the beginning. The noise you hear can be an effect from intermittent stuck fuel pressure solenoid.
Connect a scanner where you can monitor the fuel pressure live and check what happens when you have a misfire. If you have some fault codes they can give some hints too.
Well thank you for your reply. I had my son hook his scanner up to the Jeep when we were trying to figure out the problem. He did notice the fuel pressure go down about 1000 lbs when it had the misfire and knock once. It did it again and no noticeable fuel pressure drop. No codes come up and stay. I am at a loss for what I am searching for. I have put over 300 miles on the Jeep since it started acting up but the misfire and knock come and go.
KalleXX
New Member
I think it is fuel delivery related. I had no codes for faulty cranskshaft sensor.
It's so darn weird. Honestly, I wish it would just miss and make the noise all the time so I can chase it down. I drove the Jeep around 30 miles today to get it inspected and it ran fine for 90% of the trip. On the way home it started knocking and missing, clear up run fine and do it again. It's really driving me crazy wondering what it is.
I have not checked that. I don't know enough about the EGR system but would it make one cylinder misfire and knock that bad?
JMichael2006
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Delete the EGR, it only gums thing up. Check for a sticking fuel pressure solenoid. They have been know to get an intermittent stick.
Thank you. I will check the fuel pressure solenoid. I have the Mapp sensor unhooked because I heard that would bypass the EGR. Am I correct?
I ordered a new fuel pressure solenoid today from ID Parts. It wont be in until the day after Christmas. I sure hope that helps. I drove the Jeep today and I did notice the miss and knock come more often if you stand on the pedal. If you drive it normal it does it a lot less often,
JMichael2006
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I have noted on mine, if I come off the throttle then tip back in the knock goes away and the turbo spins up normal.
Sometimes it is just a quick misfire and knock with mine and sometimes it seems to last for quite a few seconds. Never knocked over 30 seconds but when it does it feels like a lifetime. LOL. I thank you and everybody else for the direction. I sure hope this does the trick. I really don't want to have to pull the engine apart unless I know what is going on for sure.
Okay , Help !!!! I replaced the fuel pressure solenoid and put the rail back on with everything tight. Did the pressure pump to make sure fuel was getting to the rail and tried to start the jeep. Nothing , primed it a few times more and it leaks fuel around the fuel filter from too much pressure I guess. I won't hit at all. Any ideas? Have the battery charger on it now because it was running it down.
KalleXX
New Member
Hi!
You might get some ideas behind the problem using the attached file. It explains how our system works and what to do if it does not.
br/KalleXX
Thank you for that information. I did finally get it running but had to really wing on the starter to get it to light off. It ran fine for a little while but went right back to the intermittent misfire and knock. I drove it a while and the knock got worse and now it makes the noise all the time. I am in the process on pulling the engine out and finding what in the heck it is. At least now its making the noise all the time so I should be able to find it if I dig deep enough. What a pain in the rear it is to pull this engine out so far.
KalleXX
New Member
Good luck!
It would be interesting to know the cause.
I would replace all solenoids. The solenoid (FCV) on the CP3 is a bastard to change when engine is installed.
There is a site I used that have Bosch original parts, even though they are no longer produced: https://www.kevadiesel.com/
br
KalleXX
Thank you for the info. I am not going to let this thing kick my old rear end. My wife is looking in the garage going " Oh my God " LOL. More of her Jeep lined up against the walls than on the Jeep so far. I haven't even got to the mounts and bell housing bolts yet. It will be quite an experience.
Update, Got the engine out and torn down. What a pain. Anyway, finally found the problem. The very rear exhaust rocker arm roller bearing was shot. The bearings were completely out, and it was just flopping around. I guess it rolled okay for a while and then would stick and make the noise and missfire. What a crappy design. I went ahead and pulled the head while I have it apart to replace the head gasket and studs. Of course two exhaust studs were broken. I guess I will have to drill and tap them out. I needed to replace the oil pan due to Jiffy Lube cross threading the drain bolt. I am getting somewhere with it though. My garage looks so bad.
On your new oil pan, don't use the drain plug anymore. Get a Fumoto Valve. It is a small brass ball valve with a spring lock on the lever. You install it once and never chance messing up the oil pan drain threads again. Google it or check Amazon. The are worth the money. Also, you can get one with a nipple on it to slide a hose on so when you drain the oil, it doesn't splash everywhere.
