[SOLVED] No power, enters limp mode on acceleration

So the vacs control solenoid just wasn't connected I may have knocked it off when installing the downpipe but I put it back on and the code hasn't come back
Im at a loss, I don't want to keep dumping money into it I want to enjoy it. I did a compression test this morning and 180-165-160-140, yes this is a problem but it shouldn't cause this problem It should still be able to boost as i had done a compression test 3 months ago and it was 145 in cylinder 4 and its been boosting fine.

Its getting too much air or not enough fuel when I repeat the issue trying to accelerate, I have an extra set of spark plugs lying around so maybe Ill gap those and throw them in. I really don't know what to do and any help or guidance would be appreciated
before anyone tells me to check for vacuum/boost leaks, I have

@Enki @Awafrican @StreetSpeed6 @L337TurboZ please help me out

 

You have very low compression in one cylinder. More than 10 percent is an issue and you're around 20-25% difference between 180 and 145.

You really need to do a leak down test and if that tests fine look at rebuilding the motor.

 

This it runs its self test and moves freely and your good to go

 

Ive had low compression in that cylinder for months now though why would it be worse all of a sudden, and it still has compression should it be "fine"?

I have a feeling it's more complicated then just VTCS a problem

 

Low compression is not "fine"

It eventually gets worse and worse and worse. Think of it like the High 5 that eventually turns into full blown motor. There is a reason it is low and you need to find that out.

A leak down test will tell you where the loss is at. If you get a leak down tester and hear air through the intake then you need to check the intake cam timing or bent valves, if you hear it in the exhaust it's the same, if you hear it in the crankcase through the oil cap or dipstick tube then it could be a cracked piston, cylinder etc. Or if you even see bubbles in the coolant it could be a bad head gasket.

 

I know it's not fine but a new motor is expensive, I understand the concept but if I can run it till it dies I'd prefer that.

Do you think a problem with pcv/OCC could cause lean conditions?

 

If there is a vacuum leak of any kind, low fuel pressure into the HPFP, of low pressure from the HPFP you'll have a lean condition.

I know a new motor is expensive but I'm just being real with you about what you need to do about the compression and what it probably is. I wouldn't even look at the lean condition until I had the engine compression concern fully diagnosed.

 

Wouldn't low pressure into the HPFP show up in the logs as low rail pressure? The HPFP is a positive displacement pump, so really just needs to be "fed."

 

I personally did this with my engine not knowing it had a bad ring. I'm not saying you should do it but I understand the $$$ side of it.

So after hooking up the vtcs vacuum line the code went away but the problem persisted and has been test drove again? Can you take another log and post it? I am wanting to see your LTFTs at idle and driving. A bad exhaust leak can cause this sluggish boost feeling and it honestly doesn't have to be some major noticeable thing.

My CST4 lagged terribly and didn't make the power I thought it would and come to find out I had a bad turbo manifold to turbo gasket that was missing a bit of it.

 

I understand my motor is on its way out, but it has been on its way out for months. The lean condition is what's causing my problem
If my engine was at that point wouldn't I be burning a bunch of oil? oil consumption is very minimal. It also idles perfectly and drives normally under low load. when I did compression test in june i got 175-160-140-145 and now its 180-165-160-140.
Something is causing a lean condition which when i reach about 0.65-0.7 load which is right around when I build a little boost the check engine light starts flashing and when I drive it on light load for a about 20-30 seconds the light stops flashing and the only code that pops up is p0300 which means its multiple cylinders getting the lean afr and not just cylinder 4 with the low compression.

I checked for leaks using water, i need to get my hands on a legit boost leak tester. Maybe my vented catch can is failing and its pulling air through because the check valve failed? I really don't know and i don't know where to start. Im going to take it to a garage and see what they tell me.

 

If you are seriously wanting to look into something else other than the obvious low compression issue then I would check exhaust gaskets. I did a turbo swap and thought everything was good and the cst4 had blown out my copper gasket 1/2" chunk lol

I see. Well a lean condition under demand for higher fuel flow sounds like the issue which could be a number of things. This might sound dumb but possibly run some fuel system cleaner in the tank. The most concentrated that the product suggests is how I would run it. There could be something stopping up your fuel lines or something or possibly even in/around the ITFP. Let me know and feel free to DM me

 

Yes after hooking up the VTCS the issue persisted but maybe my VTCS solenoid is faulty, but if it was restricting airflow I would think I would be running rich right?

My accessport is outside in my car ill post some logs tmr, but my LTFT prior to the issue would always be negative, about -8,0. Now when i cruise around under light load LTFT are -7,-5 ish (Id have to look at the logs to confirm), But when I put it under enough load to reinstate the issue it starts to run lean (about 15-16 afr) STFT are at +25, LTFT +6 ish and then when I let off the gas LTFT goes to +10.

For the exhaust, I don't hear any hissing or anything from in the engine bay but the CPE downpipe doesn't fit into the magnaflow CBE properly so there's a leak at that flange but that's after both o2 sensors and its not a super loud leak.

Ill go get some fuel system cleaner tomorrow, also my ITFP hits about 55 psi in KOEO and my hpfp pressure is where its supposed to be at
I just don't understand why im not getting DTC's and it only happens under x conditions and not all the time which is why I think the engine is "fine" for now. When i need to accelerate I go to about -4psi and it pulls well and AFRS r good but once i go to -1 or higher its bad news

 

If the vtcs is stuck in the closed position your engine won't be able to flow nearly enough to run boost. I still think that it could be in the closed position. I would honestly just try deleting it but cut the rod to where you can keep the actuator. Everything would still look stock at that point and you will gain flow in the IM if nothing else if it turns out not to be the issue.

Removing the intake mani isn't fun I understand but if you remove it and it fixes it then that would be awesome. Have you looked at how the vtcs works? So then you'll understand why it is super bad to have it fully in the closed position. That would basically close off about 75% of your intake mani runners lol

 

If i was to just find a way to have the little metal piece that swings the actual butterflies stuck on the open position would that be beneficial? I still don't understand how it would cause the lean AFR tho
Also just to put it out there the highest amount of boost ive hit is 8lbs

 

Well yes but I don't think you can do that without removing the IM to fool with it probably. Confirm the vtcs actuator is working or constantly open and let me know what happens then.

8psi for a ko4 isn't much at all as mine ran like 2-4psi just going up small hills lol

 

Yeah I know its not a lot of psi lol I usually hit 22psi Im just saying what ive managed to hit since the issue started
How would I be able to diagnose if the actuator for the VTCS has failed?

 

Not sure but probably somehow with unplugging it and using some small leads off the battery to touch the pins and see if you hear or feel it do anything. @L337TurboZ tell us the ways of diagnosis please lol I am terrible with that crap.

 

What tune are you running?

Edit:
Put the PCV system back to stock but check to make sure the check valve works first.
Otherwise, cap the intake and intake mani PCV ports and add some hose to the others (PCV plate and valve cover) so that any blowby you get dumps under the car; should help keep the engine bay cleaner if blowby is huge.

 

its a new revision from freek tune, I flashed it onto the speed when I finished installing the DP yesterday

 

Did he say anything about why it might be running lean?