I've got a 2001 jimmy 4X4. I just got it back together after replacing the intake manifole gasket. While I was at it i gave it a full tune up. It crunk up ok, but now it's missing badly. I'm getting the po303 code and if I listen on the driver's side where cylinder 3 is it almosts sounds like there is an exhasust leak. I'm sure my gaskets where all put on properly and I've checked the distributer cap and to make sure I'm getting spark on #3. Could the miss and sound be from not getting the timing set back properly? I set it by marking the distributer where #1 spark plug goes and had the rotor point to it, but it was hard to tell if I got it back pointing exactly how it originally was. I've looked up the DIY thread and will set it properly, but does that sound like my problem? Ideas???

I just wanted to say that it sounds more like the valves with the air sond than it does an exhaust leak. And I have checked the plug to make sure it is tight. Thanks, any help would be appreciated.

 

come on guys anybody!

 

I just got done putting my 2001 4.3 4X4 jimmy back together after a new intake manifold gasket and a full tune-up. Now it's idling rough and I can feel a miss in the motor. The check engine light flashes and I keep getting PO303. I've checked the plug, wire, cap. The only thing I can think of es I didn't get the timing spot on. Could this cause this? Wouldn't I be getting a PO300 if that was the case?? Please Help!!

 

If I try to get the pointer to line up with the 6 the last 1/2 inch of the distributer won't go in. One the timing thread in the DIY forum it says align the oil pump with the distributer, but it doesn't say how to do it. I have put a long screwdriver down the hole, but how do I align it. It's not like you can see down there!

 

1. Verify the firing order. (Could be you crossed a plug wire at the cap)

2. I would rotate the distributer a little each way to obtain the best idle.

3. Verify that the plug wires are fully seated at the cap and plugs.

4. Is the egr valve seated in the manifold and not leaking by.

5. Is the TBI gasket leaking by. (Spray some gumout at the base of the TBI and if the idle changes or improves you have a leaking base gasket)

6. Check all vacuum lines for leaks. (Plug all vacuum sources and see if idle improves.)

7. Is the IAC valve plug fully seated in the connector on the TBI.

 

There is a thread specifically on timing your truck in the Tech Article (DIY) section entitled EDI Engine Timing. Go through that step by step...

You cannot manually turn the distributor on the 96+ engines. It is held in one fixed position by the retaining clip.

And PLEASE do not bump a post after waiting only 7 hours. Give people a chance to respond on their time.

I have merged your three separate threads into one since they all seem to pertain to the same issue.

To align the oil pump shaft, you have to go by feel or get a junk distributor and remove the gear off the end of it... You have to look at the orientation of the blade in the end of the distributor shaft when it is properly aligned as stated in the writeup. Once you have done this, things should go together. It may require some tinkering to get it properly aligned. Just be patient and do not get frustrated.

 

I've gotten everything worked out except I'm still having a bad miss in cylinder 3. If I try to drive it the check engine light blinks almost constatly. I've gone through the whole electrical and timing system making sure everything is pluged in properly including the plug wires. It's getting fire to cylinder 3. What should I check next? If it has fire it's almost got to be a fuel problem? Do you think I messed up the fuel spider somehow when I did the intake manifold gasket?

 

New update. I had pretty much ruled out the electrical system from the misfire, but today I turned the radio on while I had it running and I could hear what sounds like the timing of a plug firing through the radio. I have never heard that before so I guess something is grounding out on engine or frame. Other than a cracked plug or a bad wire (both of which are brand new and have been checked) is there anything else that could cause this? Thanks

 

If you have somewhere where you can turn out all the lights with the engine running you should be able to see if any of the plug wires are arcing against the engine or body. Could the number 3 plug wire be touching the exhuast manifold and burnt the wire creating a short? If you have a spare plug wire, try swapping one plug wire at time to verify that you do not have a faulty wire (even though the wires are new). Did you put in resistor plugs as replacement? Resister plugs suppress ignition noise.

 

OK so I couldn't figure it out and finally just took it to a shop. The said I had a leaky injector and they are going to have to synchronize the timing and the fuel sysem. Anyone ever heard of having to synchronize those together?