Hello everybody. Unfortunately engine trouble has brought me here but hopefully y’all can help me out. This is my wife’s car and she loves it so I really want to figure it out instead of just dumping it.

We have a 2017 Chevy Suburban 5.3 liter. 6ish months ago I did a “soft” dod delete by modifying/plugging the Vlom and deleting through tuning. I did that because I was hearing a knocking that sounded like a stuck lifter but it actually freed itself I believe before doing the delete. After that everything was good for awhile.

More recently a new tapping/ticking type sound started, along with rough idle/engine vibration/poor acceleration. I used my code scanner and saw that there were high counts of misfires on cylinder #3, but it hadn’t thrown a check engine light or anything like that. I went ahead and replaced spark plugs and wires since it has 130,000 miles and I hadn’t done them since buying it at 50,000 miles but that didn’t make a difference. I checked spark on that cylinder and it was there. I swapped fuel injectors with cylinder #1 but the misfire stayed on cylinder #3. Even though the spark was there I also swapped coils with cylinder #1, with no change. Compression on #3 was 150-175 psi. What else can I do or check before giving in and taking it to a shop?

Thanks in advance!

 

you could check for vacuum leaks in the intake manifold, but this is sounding a lot like stuck lifter.

 

But aren't cylinders 1, 7, 4, & 6 the ones with the dod lifters that can collapse? Or can the regular lifters also get stuck? When I pulled the valve cover I didn't notice anything unusual in the valve train travel, and intake/exhaust push rods for cylinder #3 were straight.

 

AFM technically (DOD was the pre-2007 system)
I'm not an expert on this topic (don't have an AFM engine, so never needed to be), but from what I hear, "soft" deletes don't really fix the problem. Plus you did it later in the vehicle's life. (My brother's threw a rod at 60k)
Cyl 3 might be unrelated , or a side effect.

"Any time an engine has failed AFM lifters the lifter guides must be replaced, the lifter bores
must be measured, and the VLOM must also be tested for proper operation, or replaced. In
addition the VLOM oil filter must be replaced as well... it has been reported that it is common to find the
VLOM oil filter plugged and needing replacement on high mileage engines with miss-fire fault
codes."
https://www.melling.com/wp-content/u...s-3.1.18-1.pdf

 

I see what you’re saying. Thanks for explaining, I’ve hand blinders on with only looking at cylinder 3.

I think I’ll stick with my plan of going ahead with a full dod delete (cam, lifters, rockers, etc) since the wife wants to keep this vehicle for the long haul. It needs some reliability.

 

If you guys want to keep it a long time, and the rest of the vehicle is in pretty good shape, given the miles on the current engine, it might be more economical to get a remanufactured engine with AFM already removed. Rebuilding can get expensive. I haven't priced it out, but something to consider.

 

I got a quote to rebuild was $3500, but that’s bottom and top end. I can get a decently low mileage engine for 1500 and do the delete myself for another 1000 in parts.

I’ll have to look around and see if anyone offers them with Afm already deleted.

 

https://products.jasperengines.com/g...-iii-iv-engine

 

A few more checks you can make, if you haven’t already:

1) Check compression on at least cylinders 1 & 5 - compression sounds good initially but the PSI on #3 has to be compared to known goods (aka the cylinders that aren’t misfiring). 150 to 175 PSI isn’t good if the neighboring cylinders are producing 190 or more. Test #3 again at the same time - engine temperature can affect compression readings so you should test them all while the temperature is the same.

2) Carefully check for the valve springs to be fully in tact and not cracked. It’s not uncommon for them to break near the ends without shattering the spring completely or breaking apart, and enough tension can remain on the valve to keep it closed, but it still affects valve movement enough to cause misfiring.

3) The AFM lifters are certainly a weak point in these engines, but the non-DOD lifters are still hydraulic rollers and prone to collapse and damage. Check lifter state by manually rotating the engine until the valve is fully open (or close to it) and watch for the spring to push the lifter back up. A good lifter will hold the pressure for several hours - one that’s collapsing (or beginning to) will lose it quickly. The longer the bleed down time, the better condition the lifters are in.


I’ve installed about 4 Jasper reman engines that I can recall off the top of my head - only one of which was a DOD deleted engine. It was 2-3 years ago for a 2007 Silverado 5.3.

The install kit came with a tuner that would only accept one VIN without needing to be completely wiped before it could be used again on a different vehicle.

We’ve serviced that truck every oil change since and it seems to be doing well so far - I’d have to check to see how many miles it’s seen since the install, but it’s a workhorse for a carpenter so it gets plenty of mileage and pulls a trailer.

I’ve seen true quality from Jasper so far (been doing business with them for 7 years now).

​​​​​That said, the average cost of their engines is on the high end (again I’d have to verify what they were - I don’t want to provide false info) and any DIY’er capable of doing a top end rebuild could probably come out well under their prices, even with machining costs for the heads.

 

I checked cylinders 1 & 5 for pressure increase while inducing pressure in cylinder 3 (to check head gasket) and saw no change. I should probably do a full compression test and a closer inspection on springs. Sounds like my long term plans with a afm delete should still resolve any of the issues suspected in my situation. I would get a separate engine to do the delete on and swap in. Then use the old one in a project truck, so I'll have time to see what the failure was.