One thing you guys might want to consider is to evaluate fuel pressure since that relates to fuel trims and possibly this starting problem. Besides the usual static pressure/leakdown at KOEOff you can travel with the fuel gauge on the windshield to make sure that there are no dramatic pressure changes as well as look at pressure during a hard start.


George

 

Thanks George and Les, so I have briefly looked at the other sensors that come into play in closed loop, I think it's in one of the videos above, they were all seeming to operate as expected though. I'm not sure of the specific readings of the MAF, MAP and other sensors with what they should be reading, but they appeared to be in check. I have done a leak down test and my fuel pressure seems to check out, in post 50 I have a video of the fuel pressure while idling and snap throttle, also the leakdown test. And in post 32 there is a video where I actually caught the hard start and got a reading of the fuel pressure while it was cranking trying to start, it was at 50 psi cranking. I'm excited to do the running compression test here in the next day or so now, maybe it will turn up something, what's weird is I had the P0507 code before the rebuild and it stayed after as well, could I have missed something during the rebuild? I'm mainly thinking of the intake valves and how they didn't get lapped in or anything they remained the exact same as when I pulled it. But the thing is I remember all the cylinders held the compression pretty good when I did a compression test before putting it in, I guess I will see if I have a problem soon enough. I don't have the P0507 code anymore since I adjusted my set screw but I know now that is just a bandaid to what's really going on, my fuel trims are going way positive when I'm driving telling me it's getting too much air still somehow.

 

Ok guys, I just got done with the running compression test, results are below. I didn't do cylinder 3 because it would require some serious trickery to get the compression tester in there if it's even possible LOL. Anyways, I may have found my problem right off the start, and I wouldn't have found anything just by doing a static test so thanks again Les. Cylinder 1 idle and snap compression is way high. I have read 80% of the static reading is the max the snap reading should be? The other cylinders are all in check with this but #1. The first run I also had my tablet connected and watched as the misfire counts went up, now with the compression tester on #1, it was reading misfires on cylinders 1 and 2, is this normal? Also at the end once I was finished I connected my tablet again to clear the codes and also had a look at the misfire counters again, cylinder 1 was up in the 500s with the rest being 100-200, any idea why this could be? It was running for about the same time as all the other cylinders. Once clearing the codes and starting it up normally misfire counters are all 0. Do you guys think whatever is going on with cylinder 1 is causing my rough idle? What do you guys think it could be that's causing this? I'm having a hard time thinking the exhaust is clogged or something like that because #5 was looking good still. Video of cylinders 1 and 5 while doing the running compression test below also.

 

I am sure that Les will have his thoughts but no its not likely an exhaust restriction because the bank is OK. I would say its an exhaust valve problem and if thats right hopefully its the lifter being partially collapsed. Good work on this more sophisticated test, good stuff.

I Hope to spend some time looking at your LTFT issue tomorrow.

George

 

Thanks George, I wish I understood what a 'collapsed' lifter was more, my understanding is it's incapable of remaining pumped up with oil pressure but how would this affect anything other than lubrication to that rocker? I am confused about how them not pumping up fully makes excessive clearance, when I had mine out I remember thinking about this and I couldn't really figure it out because they seem like one piece that doesn't expand with oil pressure? Please explain if you can George. Also, when I had all the lifters out I was thinking about replacing them all as I got them out of order and a bit dirty, but then decided not to and just cleaned them up really good, I want to say if it is the lifter there's a good chance the lifter in #1 exhaust right now originally came from #6 exhaust before the rebuild, that was the cylinder I had a bent valve on. My only other thought would be the camshaft lobe itself as the pushrods and exhaust valves are all brand new. The running compression test definitely took me a while lol, after the first time I started it up with the compression tester attached I almost crapped myself, I was just a bit worried about how I had the spark ground set up, and also all that unburnt fuel, and the sound of a dead miss isn't very reassuring either LOL. It worked out in the end though just as I planned and I got faster as I went on, and I'm happy I did it because I wouldn't have found this by only doing a static test. Picture below of my spark ground set up.

 

Lets pull that valve cover and compare rocker arm action on #1 to that of #5. Wonder about a flat cam lobe or bad lifter. There is something definitely going on with #1 and its not fuel injection or ignition.

 

The basic idea is that you have high dynamic compression because the exhaust gasses are not clearing #1 properly which implies an exhaust valve that does not open properly. This as you said can be from a bad cam lobe, the lifter, pushrod, valve, etc. The hydraulic lifter gets pumped up with oils and takes up the valve lash providing a sort of running auto valve lash setting if you will. A collapsed lifter is one that does not pump up completely. Do you have any valve ticking or tapping? When my LIM gaskets started to fail my first clue was pushrod tapping from water in the oil.


George

 

I see that Les is back up with the same ideas, I will let him guide you on this since the test was his idea.

George

 

Thanks Geroge and Les, feel like I'm finally getting somewhere with this rough idle after all the diagnosing. There's no excessive valvetrain noise that can be noted here that I have noticed George. I should be able to take the valve cover off tomorrow, I honestly thought you needed to slide the PS bracket forward to take the cover off on that side but looking at the manual it appears you don't! What should I be looking for with the cover off? Just how much each exhaust valve rocker pushes down? Do I need to have it running while I do this so I can test the lifter's functionality? I've been thinking here, and in the test cylinder 1 was about 40 psi above the others at idle and snap, that's quite a bit of pressure that cylinder 1 is holding back right? So I'm thinking the difference in rockers or how far the exhaust valves are opening should be fairly easy to see with that much of a pressure difference.

 

I would do a visual comparison first (while running). Yes its messy - you could stand some cardboard on the exhaust manifold side of the rockers to deflect oil back in. We're looking specifically at a problem with #1 exhaust so compare action of #1 exhaust to #1 intake. Also feel and shake rocker with engine shut off. Also can you compress internal plunger in lifter by hand pressure when valve is closed?

It's the intake that won't come off without sliding the PS bracket forward.

Typically these problems do make some noises but we will have to see.

If a lifter/rocker doesn't lift all the way due to excessive clearance, the starting point where the valve is actually lifted off it's seat (as well as when it closes) is different. So valve timing gets screwed up as well as any restriction the lower lift of the valve would happen to add. Probably valve timing is bigger issue as the duration valve is open is likely reduced a lot with just a little change in lift.