John_S

Hello to all,

First time posting here. I changed my oil pump on a 2002 Grand Cherokee 4.0L. I tried priming it with the coil pack off for awhile but decided the starter and the battery couldn't handle it.

I removed the camshaft position sensor and used the post I saw about a drill and a slotted blade to turn the pump from up top. This worked well and the pump was primed. I then reinserted the sensor and then started the engine. I have good pressure now and it idles well, but it will not allow the throttle to be given to it. It starts to misfire and I receive primarily code PO352 and sometimes PO353.

I've narrowed this down to 2 things (I think) possible that I may need to resync the sensor or the coil pack. On the sensor when it was removed no cranking of the engine was done, only the oil pump was spun.

If I do need a resync could someone explain why and how this would be done?

Thanks

dave1123

The best I can do is refer you to page 6-18 in the Haynes repair manual for Jeep Grand Cherokee 93-2004. It is an involved procedure and I might get it wrong trying to explain it to you. The most important point is to make sure you set it at TDC on the compression stroke, not the exhaust stroke.

John_S

Dave,

Why would I need a resync if I did not move the cam or the crank while I was spinning the oil pump to prime it?

Also, the code I'm getting is PO352, which would seem to be the coil pack, any thoughts?

Thanks

dave1123

You had to pull the oil pump drive unit out to spin the pump, right? That has the gear on it that is driven by the cam. It has to be resynced to the cam now, especially if you didn't set the crank to TDC before you pulled it. IDK why you're getting a code for the coil pack unless the connector isn't fully engaged.

John_S

Wouldn't I get a different code for the cam and crank not being in sync, I believe that would be P1369? So even if the cam isn't moved or the crank while priming the pump a resync is required?

Does anyone out there have hands on experience with this priming of the oil pump by using this method? if so, could you chime in as to how you did this?

Thanks

dave1123

IF you got the oil pump drive gear back in on the very same tooth, okay, but chances of that are very slim. The cam and crank sync is controlled by the timing chain. Resyncing the oil pump drive gear is easy but critical because it positions the cam sensor in relation to the proper cylinders, much like the older distributor. The sensor only fits into the oil pump drive one way. When the drive is installed properly. the holes in the base and pulse ring should be aligned and the body of the unit should be parallel with the engine centerline. DO THE RESEARCH!

I think I'm done trying to explain this to you.

John_S

Geez Dave,

As a first time working on a Jeep you could have provided better information.
Here is what I found:

The Camshaft Position Sensor (CMP) on this engine is bolted to the top of the oil pump drive shaft assembly. The sensor and drive shaft assembly is located on the right side of the engine near the oil filter.

The CMP sensor contains a hall effect device called a sync signal generator to generate a fuel sync signal. This sync signal generator detects a rotating pulse ring (shutter) on the oil pump drive shaft. The pulse ring rotates 180 degrees through the sync signal generator. Its signal is used in conjunction with the crankshaft position sensor to differentiate between fuel injection and spark events. It is also used to synchronize the fuel injectors with their respective cylinders.

When the leading edge of the pulse ring (shutter) enters the sync signal generator, the following occurs: The interruption of magnetic field causes the voltage to switch high resulting in a sync signal of approximately 5 volts .

When the trailing edge of the pulse ring (shutter) leaves the sync signal generator, the following occurs: The change of the magnetic field causes the sync signal voltage to switch low to 0 volts .

On top of that you did not explain any of the above, also I corrected it by sound without the DRBIII tool, and I believe I am within 1 degree of being correct. Purring like a kitten now.

Dave ,

Please do not respond to this post, to anyone else out there that has an issue (and I've read a lot of people with this issue) with priming the oil pump via the drive gear of the cam sensor I have a quick way to fix your issue.

I hope future responses from others are more cordial than Dave's

Thanks to all...

dave1123

Not trying to be a putz, but didn't I tell you where to find the information and to do your own research? I may have been a little short with you, but I got frustrated.

chadwick82

Please Help....I just pulled the oil pump drive( but didn't place at TDC before I did), replace the camshaft & crankshaft sensors, got to TDC then put oil pump drive in, then camshaft sensor....still running rough...got to be a timing thing....whats the easy fix.

John_S

Chadwick here is a URL that will help:
http://www.jeepforumz.com/showthread.php?t=1847

If this doesn't work let me know and we can try an alternate approach.