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Misfire help after rocker install

t24moore

t24moore

New member
I just replaced some springs and rockers for a friend of mine. When I finished the install I started the car up and it ran okay but made a real loud tapping noise. I let it idle for a bit to see if maybe a lifter had not pumped up however the tapping continued. I removed the front valve cover and sure enough 3 of the rockers were not getting oil. So I loosened them up and re-torqued them. Then I started the car up to make sure they were getting oil. All but the one under the coil pack bracket on the exhaust side started getting oil. I moved the bracket back and retorqued that one again and when my helper went to start the car the engine would not fire. I checked the wires that go behind the coil and the ground was exposed along with a yellow wire that goes from the cam position sensor to coil pack bracket connection. I removed the harness striped everything off of it and fixed the two damaged spots and did a continuity test on all of the pins to make sure it was okay. Reinstalled it and now the motor seems to be running on three cylinders (2-4-6) only. To get the motor to fire I have to hold the throttle open and crank it for a few seconds. The motor will run as long as you give it throttle but shakes really bad. The only code in the PCM is the multiple misfire code. All cylinders have spark. The injectors have constant power. I dont have a noid light set yet but I used my tester light to see if the PCM is sending ground. I never seen the light come on. I also pulled the rail up to see if it fuel would shoot out when the engine is cranked and none came out except a tiny bit on cylinder three. I did a leak down test on all three of the cylinders and they check out good. I havent checked fuel pressure yet because my tester is missing. Im wondering if that yellow wire going to the cam position sensor shorting to ground damaged the injector driver somehow. I unplugged the cam position sensor to see if it would run fine and it still didnt. I dont have a pcm yet was just wondering if anybody has any other ideas or anything I might have missed. Sorry for the long story and thanks in advance.
 


What wires were damaged? There are two wires that have yellow. Yellow that goes from CKP to the ICM and a yellow/black that goes from the CKP to the PCM.

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I see two possibilites.

1. Some fluke caused those to not get oil. And once you reset them most have oil?
2. Those wires have caused you to go into limp mode.

My first thought on it. You installed ZZP modded rockers and that's why one bank isn't getting oil and it's running only on one bank. When GM designed limp mode, I'd bet it was a way that would keep the engine running reasonably. Not well..but at least running. ZZP modded rockers require modded pedestals, because they move the position of the pushrod to rocker closer to the pivot point. This requires more clearance in the groove where the rod lays in that groove of the pedestal. Swiggles and I saw this on an install we did with a friend. When he bought the rockers used, one of the pedestals wasn't machined for the rockers. If you take that front pedestal off and look at the grooves for the rockers, you should see that it's been machined. If not.. take even a dremel with a sanding drum and make all those grooves a bit deeper. I measure about 10mm from the edge of the bolt hole.
 
Rico said:
What wires were damaged? There are two wires that have yellow. Yellow that goes from CKP to the ICM and a yellow/black that goes from the CKP to the PCM.

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Click to expand...

The yellow going to the ICM, it touched ground. Thank you.

Bill
I think thats exactly what it is. I will grind the pedestal and reinstall it. Ive installed cams and roller rockers a bunch of times but never dealt with ZZP modified rockers. Ive spent two days trying to track this problem down and was about to replace the PCM. Thank you guys again. I will let you all know how it turns out.
 
I have seen this oil problem on a small handful of motors.... Never found a solution to it....

All the lifters manage to die on one bank of cylinders, due to some blockage or something somewhere.... that typically shows up after doing work on it only.... to my knowledge I have never seen this issue pop up randomly while the car was assembled and running.

I also have never had a chance to troubleshoot this problem personally, it was all over the internet/phone every time I have ran across it.
 
I almost guarantee it's that damn ped. Especially if they weren't brand new. The guy that pulled them off didn't realize it and reinstalled one by mistake on his own engine.
 


I remember that happening. Pain in the ass to figure out. But once the pedestal was fixed or swapped with the right one, he was golden. He's still running them in his turbo setup now although he barely drives it lol.
 
It was the pedestal, I put the stock one on by mistake. Now I'm having an issue where two rocker arms aren't getting oil. One gets it if I loosen it up. I hate this modified ****. I've installed countless cams and roller rockers and never had something like this happen. I still think it's a pedestal issue.
 
I said screw that pedestal zzp sent and just modified an old one. She purrs like a kitten now. Thanks for your help everyone.
 
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