AFM Issues / Misfire

[Peter Tremonti]

looks to me like you need to do a crank position relearn

This is what happens currently when I try to relearn the crank position. It says test is running but then it just sits there thinking until I restart the scan tool.

 

[Doubeleive]

does your scanner tell you to set the parking brake and turn off the ac?

 

[Peter Tremonti]

does your scanner tell you to set the parking brake and turn off the ac?

I know the AC was off but I'm sure the parking brake was not applied. I will try again when I get to work this morning and hook up the scanner.

09:50am - So I tried again after driving to work with the parking brake on and it finally cleared out after 3 tries. Seems like an unnecessary thing to have on, but I guess not. Thanks for the help!

 

[Peter Tremonti]

Found my issue with cylinder 7. The front rocker isn't rocking. I started it up just to see what it looked like. There is some pressure pushing up on the pushrod when the engine is running but not enough to move the rocker. After shutting off the engine, it took about 15 seconds before the pushrod fell back down out of the rocker pocket.

Aside from deleting the whole AFM system like most people do. Would you recommend replacing just the bad lifter and see what happens or swap the whole bank of lifters while it is apart? And at that point would it be worth replacing just the AFM lifters or all i on the one bank?

Lots of questions. Going to order parts tomorrow so I'm looking for recommendations before then.

 

[swathdiver]

View attachment 249547Found my issue with cylinder 7. The front rocker isn't rocking. I started it up just to see what it looked like. There is some pressure pushing up on the pushrod when the engine is running but not enough to move the rocker. After shutting off the engine, it took about 15 seconds before the pushrod fell back down out of the rocker pocket.

Aside from deleting the whole AFM system like most people do. Would you recommend replacing just the bad lifter and see what happens or swap the whole bank of lifters while it is apart? And at that point would it be worth replacing just the AFM lifters or all i on the one bank?

Lots of questions. Going to order parts tomorrow so I'm looking for recommendations before then.

You'll have to decide how much money to spend and how long you want it apart. If you just pull the head on that side, replace all the lifters and lifter trays. You can also get the new valve cover to reduce oil consumption and it is SOP to replace the VLOM as that is what usually causes the lifters to fail. The latest parts are far more reliable than the originals.

 

[Peter Tremonti]

Time apart doesn't matter at this point because I bought it to flip it once it runs well enough, and decide if I like the body style enough to get a hybrid. This one was less than half the price of the one I was interested in and I'd rather get familiar with one that's going to be sold before I trade in my 2005 Suburban.

I'm fixing things as I find them to be a problem. So far, there have been some switches bad, weather stripping for the doors, tail lights and harnesses (one of which I think has a bad ground pin again), completely filthy inside, missing quarter glass, and a few other issues to name a few. If I can make a couple dollars on it and get familiar with the new body style, I'm all good.

 

[Peter Tremonti]

Decided to take the head off and throw a set of AFM lifters from ebay into it and see what happens. I'll take out the oil pressure sender and check the screen while I'm there. If everything works out fine after that then I'll be happy. Otherwise, the intake and VLOM are easier to take back off and do afterwards compared to taking off a head. Should have all the parts here by next week.

 

[Peter Tremonti]

Finally got around to swapping in a new set of AFM lifters. The misfire is gone but it's clattering like crazy still. I took off a valve cover and let it run and only saw oil flowing freely out of the front and rear lifters (only 2 of the 8). The oil pressure is around 40psi at a cold start and drops slightly down to around 30 when it warms up. It does stay at or over 40 while driving 30mph depending on load.

I've already taken off the pan and replaced the pickup tube. The pan had the least amount of sludge I've seen in one of these engines so far at maybe 1/4" in the corners only. I seem to be finding differing opinions about which oil pump goes into an AFM motor. Advance auto says it takes a melling M295 or M296. Melling's website said a 10355 would be needed for an AFM engine and the original oil pump is already a high volume pump based on the additional flow required by the AFM parts.

I have not bypassed or plugged the relief valve in the oil pan even though I had it off to do the o-ring on the pickup tube. I am wondering if it would be worth it to port and shim the oil pump and see what happens before swapping in a new one. I haven't seen any videos of before and after porting or shimming a pump on an LS. I've only seen videos of how it SHOULD help after doing so but no direct comparisons of before and after.

It is going into V4 mode with no issues at the moment and it doesn't seem to drop oil pressure like I've read it could when that happens. There are no more misfires at this time just ticking and lower than I'd like oil flow from the lifters.

Thoughts?

 

[George Owens]

I’m just starting to get the tick as well, did you replace all the lifters or just the AFM ones?

Finally got around to swapping in a new set of AFM lifters. The misfire is gone but it's clattering like crazy still. I took off a valve cover and let it run and only saw oil flowing freely out of the front and rear lifters (only 2 of the 8). The oil pressure is around 40psi at a cold start and drops slightly down to around 30 when it warms up. It does stay at or over 40 while driving 30mph depending on load.

I've already taken off the pan and replaced the pickup tube. The pan had the least amount of sludge I've seen in one of these engines so far at maybe 1/4" in the corners only. I seem to be finding differing opinions about which oil pump goes into an AFM motor. Advance auto says it takes a melling M295 or M296. Melling's website said a 10355 would be needed for an AFM engine and the original oil pump is already a high volume pump based on the additional flow required by the AFM parts.

I have not bypassed or plugged the relief valve in the oil pan even though I had it off to do the o-ring on the pickup tube. I am wondering if it would be worth it to port and shim the oil pump and see what happens before swapping in a new one. I haven't seen any videos of before and after porting or shimming a pump on an LS. I've only seen videos of how it SHOULD help after doing so but no direct comparisons of before and after.

It is going into V4 mode with no issues at the moment and it doesn't seem to drop oil pressure like I've read it could when that happens. There are no more misfires at this time just ticking and lower than I'd like oil flow from the lifters.

Thoughts?

View attachment 262252 View attachment 262253 View attachment 262254 View attachment 262255

 

[Peter Tremonti]

I’m just starting to get the tick as well, did you replace all the lifters or just the AFM ones?

I only did the AFM lifters on the odd bank. It fixed the misfire but not the ticking.

I have since bought an OE higher flow oil pump and cleaned up the casting while I was waiting for an opportunity to install it. Hopefully I'll get it installed before the end of the year.

Something I've found out according to Melling and Advance Auto Parts is that my engine takes an M295 pump. Everything I've read elsewhere says that the AFM and VVT gen 4 engines use a higher volume pump so that's what I bought.