Hello all. Long time lurker and reader, first time poster. I'm posting this because it's an issue I haven't seen anyone else post anywhere and maybe this can help someone in the future.

I have an 08 40th Anniversary with a manual, so 6 port. Let me preface this by stating that a compression test has been done and it yields "middle of the road" results, meaning yes at some point in the future it'll need a rebuild but it's not quite hit that point yet, and there's also not any hot start issues either. Yet.

I have been dealing with a weird issue that I'm confident I'm close to ironing out. Storytime.

Be me. Have fun on road trip to car show. Doing pulls. Life is good. At the end of one pull, come to a stop and car stalls. Starts back instantly and immediately stalls again at idle. CEL. Work my way down to a local parts store and pull codes to get a cylinder 2 misfire code, lean code, and random misfire code. Check for spark at plugs, all is well. In a need for it to not stall, I attempt a 20 stomp reset and EUREKA it no longer stalls at idle. Now I have no CEL/misfire codes but I have big loss of power. Car is completely gutless after about 3500-4500 rpm. At 5k and up, you can hear a difference in engine sound and then at 7k rpm UNDER LOAD ONLY, the engine cuts completely with a "bang" sound and thick smoke exits the exhaust (and exhaust only, it looks like something out a Bond movie) and car comes to a stop. No oil or fluids on the road. No CEL. Car starts back instantly and sounds like before. Drives down the road just the same. My only guess at this time is something is preventing it from going to high RPM under load. When not under load, it will rev above 7k rpm.

After some extreme cautious testing and checking, I decide to drive it 6+ hours back home and and keep it at low RPM. It does fine and I make it home with no further issue and begin diagnosing.

The issue is a weird one to say the least. I started by running injector cleaner through in case one was possibly clogged. No bueno. I check fuel pressure at idle, which seems fine but slightly low. I decide on a new fuel pump since it's possible that pressure is tapering off at higher RPM. New fuel pump installed yields an extremely mild improvement, but does not fix the issue.

After more deliberating I come to the theory that when the engine cuts at 7k, what I'm seeing is excess injected oil being burned off, and the engine is not flooding since it starts back instantly. The theory is that it is leaning out to total fuel cut beginning at roughly 5k rpm. I decide to replace all 3 solenoids on the back of the UIM since I have spares laying around and was checking for vac leaks. No obvious leaks, solenoids replaced and no change. Time to clean the MAF. Check the engine air filter. Both are clean and ready to rock, yet no dice.

I'm certain I'm skipping over a bit but that's the gist of it which brings me to now. Current theory is that I have possibly a primary injector stuck closed or not properly flowing on rotor 2. I have new spark plugs and ordering new coils and wires, even though I have spark where I should, I'm gonna go ahead and replace it all while I'm in there pulling injectors to bench test and swap to see if there's any difference.

Since I know someone will ask, mods are TurboXS catless midpipe and catback. That's it.

This weekend I'll be pulling the intake manifold and checking the injectors and I'll replace all the ignition bits once I get everything in. I'll update here with results or changes once I have more information. If anyone else has come across something similar, please feel free to share as this is definitely a new one by me.

 

Clean MAF?
Oil in intake?
Lower intake manifold service ports not left uncapped or the lines broken/disconnected anywhere?
VFAD in place or removed? Are the lines for that in place and intact?
SSV opening/closing smoothly?
Hear the APV's actuate open/closed when you turn key off?
Check valve in the vacuum line going to the vacuum chamber oriented in the correct direction and functioning to keep vacuum in that chamber?
Start with those and report back

 

MAF is clean, no more oil in intake than otherwise normal for 100k mile car. I'm actually trying to find the resistance values for the MAF so I can test to see if it's in limits. Nothing spotted out of the ordinary as far as intake ports or lines, everything is hooked up properly and I haven't found any vacuum leak thus far. VFAD should be in place considering I certainly haven't removed it but I'll have a second look since this car wants to pull it's current circus act. As far as hearing the APV's and the check valve, what exactly should I be listening for or looking at?

 

High rpm stall + puff of smoke sounds like oil barfing due to blowby. 2008+ cars route crannkcase ventilation into the lower intake manifold, so it barfs there instead of the intake where you can see it. No amount of oil in the intake is normal, so if you have any at all, that's a clue. The blowby is due to worn side seals.

The oil injection system isn't capable of injecting thr amount of oil that could cause this.

What exactly does middle of the road compression mean? What are the numbers?

 

Compression numbers are in the 7s, so like I said, not great, but not numbers where I'm running to a builder either. And please don't mistake, this is not a "puff of smoke." It quite literally looks likes a smokescreen out of a Bond movie when it happens. That is not a puff. Also don't forget that this issue started with a lean code and inability to idle. That doesn't necessarily point to oil barfing from my experience. I'm not saying it's the healthiest engine on these here magnificent forums because it most certainly isn't, but based on the things I'm seeing and experiencing, I don't believe compression is the issue at hand. Hot starts are fine, numbers in the 7s, but seems to be leaning out at higher RPM.

 

Also worth stating, I got some new red primary injectors in yesterday that are known good so I'm going to check resistance and compare but I'm understanding that the reds operate from idle and max out a little under 4k RPM. If anyone can confirm, that'd be great. It's definitely a unique issue and now that I don't have codes, it's difficult to track.

 

What was the compression tested with? 7's at what rpm? Compression loss manifests differently but the big red flag here is the smokescreen. There's only really one way that happens: large amounts of oil in the combustion chamber. All signs point to oil barfing.
I'd recommend putting a catch can in the oil neck vacuum line to see what you catch.

 

Interesting. I'll look into the oil barfing more, but it isn't that something that would happen gradually not suddenly? When this started it was very sudden. Went from running good and no issues at high rpm to not even being able to idle until I reset the ECU. Obviously if it's determined to be the issue, I'm gonna shell out for a rebuild or say "YOLO" and start the rew swap. The question is, is there a way I can definitively confirm that barfing is my issue?

 

Well for starters I was gonna say stop listening to people on here till I saw the only MF I trust here. Loki you like an admin or some?
anyway. I’m not here to argue because what Loki is referring too isn’t something I’ve had to deal with beside after purchase. Since then all good. I hate to be this guy but are you sure you’re not overfilling and you are using a long neck funnel?
I just dealt with this same issue of power loss in certain ranges. Idle hunting. I noticed a thick buildup of grime on my single exit hks tracking it forward I ended up under my driver side rear passenger seat. Apparently my 8 thought she needed a highly flammable mister system for added risk factor for my 120 mile round trip to work in phx heat. 2 solid streams of fuel right at the elbow. After replacing the fuel pump I cleaned up my rear speed sensors from gas grime was all while my battery was charging for my 20 stomp reset. Oh and eccentric shaft sensors since I was cleaning sensors and it was jacked up.


also maybe before you do all that. Go out for a good drive around the neighborhood till problem starts. Park it kill it and take off your front bumper check your to see if your vfad is holding on to vacuum. But I don’t see it being a possible culprit as mine is currently holding vacuum and she’s pullin like she was reborn. Loki keep an eye out for that post soon please lol