Cam and Crank sensors have both been replaced. The vac signals are stable at throttle, it's at idle where they bounce just a bit. I know it's that IAC working in and out that's doing it, it just won't steady out.

Fuel pressure under load is the only thing I haven't personally checked, the shop told me it was holding well at 52psi.

 

and what was the fuel sync set at?

If you replaced the cam sensor you must get your fuel sync set.

edit: I think you mentioned that you swapped the o2's... just in case you didnt... it could be possible that one of them is slow to respond which will also cause it to ping.

 

Steve,

Why would fuel sync need to be set to swap the cam sensor? It's a simple magnetic device that sits in the distributor and watches the notch on the shaft go round and round. The distributor doesn't need to be moved or loosened to install it. Pop the cap, take off the rotor, and lift out the pick up and unplug. The new one only goes in one way.

I have a guy that has an Auto Xray 6000. He's going to help me diagose it with the scanner and hopefully that'll tell me what's going on.

 

tolerances are not going to be identical from 1 part to the next (made in different locations at different times).

the thing to remember here is the cam sensor tells the pcm where the cam is in its rotation. if it's off a few degrees and sprays too late or too early you COULD (not 100% sure) have a pinging problem. At this point you dont know for sure where it is, you swapped manifolds which also would be a reason to know where it is (because tweeking it 1 way or the other will make it run better or worse... research the ideal setting for it).

It sounds to me that the fuel sync is the only thing you havent swapped or checked and I'm hoping that if you have that dialed in, your pinging will go away.

if that does not take care of it, I'm out of ideas...

 

I'm wondering of installed the headers was just enough scavenging to lean out a cylinder.

That or the Cloyes Timing chain I installed stretched just enough.

 

I still think it's your a/f leaning out or your advance curve is not correct for the new manifold. Did you contact your tuner (Hemifever?) about it?

 

yeah, he said he could pull timing no problem. My problem is that this tune worked for a while, then stopped working. That's the one reason I don't want to blame the tune. If I have a problem with the engine, I need to find it and fix it, not disguise the problem
with a tune.


I will say this though. I do still have a ping, but I'm certain that the old intake manifold was faulty. There was A LOT of oil in the intake, and the catch can I put on the PCV isn't catching near that amount of oil. I even had oil DRIPPING from the IAT when I pulled it out. I'm going to try to call my buddy with the scanner and see when he's available. He owns his own small business and works all the time. In the mean time I'm going to run a ton of cleaner through the engine and see how that works.

 

i wouldn't think either of those is the culprit.

do you think an injector (or two) could be bad, leaning out 1 or 2 cylinders ?

be careful with cleaners, some of them can do more harm that good.

how do the plugs look ? anything unusual there ?

 

Funny you should ask that:

When I pulled the plugs to do the compression test, there was more carbon on the bottom of the last few threads than there should have been for plugs that were only in a week. number 7 looked blacker than all of them but not by much.

 

How black were they? If the insulator, electrodes, and cavity were all black, then you aren't running lean, obviously.