When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
@vtec_ I think you might be overthinking things...
You had a big boost leak (#16 check valve), you fixed it. Now it's holding pressure with a normal amount of leakdown on a pressure test and hitting 1.1 bar on boost. That is pretty normal for a tuned engine, so my guess would be that despite what you are interpreting from your tune loader device, you are running a tune.
You can check the connections to the N75 valve. There are three vacuum/pressure lines connected to it and one 12v connector. The "output" of the N75 T's and goes down to the two waste gates, you can pull the line off and use a handheld mightyvac type pressure tester and ensure the wastegates are opening evenly and at an appropriate pressure. One "input" of the N75 connects to the Y-pipe with a little elbow tube that sometimes gets kinked or cracked. The other "input" goes over near the diverter valve where there is no boost pressure.
Essentially the N75 valve switches between supplying ambient pressure to the wastegates (allowing the wastegate spring to be overcome fairly easily and limit boost) and supplying boost pressure to the outside of the wastegates (helping to hold the wastegates closed at pressures beyond just the mechanical wastegate spring). The ECU switches between the two inputs rapidly when 12V is applied or removed from the two connectors (duty cycle) and allows the ECU to modulate exactly what boost pressure it wants the wastegates to hold against.
You can bench-test all of this pretty easily, but the N75 valve itself is also pretty cheap, so if you bother to remove it to bench test it, I'd probably just throw a new one in there. 996-605-155-00, under $40 from OE parts discounters.
If you had a bad N75 valve, I think you would be getting much less or notably more boost, not right at that 1.1 bar which is a very common pressure on a tuned motor. If your waste gates were tightened down, so be it. 1.1 bar is fine for these engines. I doubt you will have much success having someone "read" your tune unless you just go ahead and pay a tuner for a completely new custom tune. Apart from the expense, we are lucky to have several very respectable tuners in our community and if you have concerns, working with a tuner, loading a new custom tune and running some data logs is the way to go.
My advice? Drive and enjoy the car. Sounds like you did a good job sorting out some previous problems with it.
The oil in my car is coming up on a year old. I have only driven it about 1000 miles since then due to primarily working on it instead of driving. Mostly minor items. Is it really worth it to change based on age alone? The limited service records I have show years between previous changes. Car has ~95k miles.
Presumably you are running a top quality A40 approved synthetic? Oil degradation is certainly not going to be an issue at 1K miles, the only concern might be condensation and moisture build-up if there weren't any/many trips long enough to get the oil hot enough to burn off the condensate. I'd probably just spend the time it would take to do an oil change and take it out for a drive long enough to get the oil fully up to full operating temperature, and keep it there for a while to cook off any moisture.
Presumably you are running a top quality A40 approved synthetic? Oil degradation is certainly not going to be an issue at 1K miles, the only concern might be condensation and moisture build-up if there weren't any/many trips long enough to get the oil hot enough to burn off the condensate. I'd probably just spend the time it would take to do an oil change and take it out for a drive long enough to get the oil fully up to full operating temperature, and keep it there for a while to cook off any moisture.
This is what I would do as well. I just went three years on an change because I've barely driven the car the last couple years. But on the occasions I did drive the car it was for 50+ mile trips to burn off any moisture in the oil.
@vtec_ I think you might be overthinking things...
You had a big boost leak (#16 check valve), you fixed it. Now it's holding pressure with a normal amount of leakdown on a pressure test and hitting 1.1 bar on boost. That is pretty normal for a tuned engine, so my guess would be that despite what you are interpreting from your tune loader device, you are running a tune.
You can check the connections to the N75 valve. There are three vacuum/pressure lines connected to it and one 12v connector. The "output" of the N75 T's and goes down to the two waste gates, you can pull the line off and use a handheld mightyvac type pressure tester and ensure the wastegates are opening evenly and at an appropriate pressure. One "input" of the N75 connects to the Y-pipe with a little elbow tube that sometimes gets kinked or cracked. The other "input" goes over near the diverter valve where there is no boost pressure.
Essentially the N75 valve switches between supplying ambient pressure to the wastegates (allowing the wastegate spring to be overcome fairly easily and limit boost) and supplying boost pressure to the outside of the wastegates (helping to hold the wastegates closed at pressures beyond just the mechanical wastegate spring). The ECU switches between the two inputs rapidly when 12V is applied or removed from the two connectors (duty cycle) and allows the ECU to modulate exactly what boost pressure it wants the wastegates to hold against.
You can bench-test all of this pretty easily, but the N75 valve itself is also pretty cheap, so if you bother to remove it to bench test it, I'd probably just throw a new one in there. 996-605-155-00, under $40 from OE parts discounters.
If you had a bad N75 valve, I think you would be getting much less or notably more boost, not right at that 1.1 bar which is a very common pressure on a tuned motor. If your waste gates were tightened down, so be it. 1.1 bar is fine for these engines. I doubt you will have much success having someone "read" your tune unless you just go ahead and pay a tuner for a completely new custom tune. Apart from the expense, we are lucky to have several very respectable tuners in our community and if you have concerns, working with a tuner, loading a new custom tune and running some data logs is the way to go.
My advice? Drive and enjoy the car. Sounds like you did a good job sorting out some previous problems with it.
Thanks, I bought a mityvac today so I am going to test the wastegates and make sure they are cracking properly.
Originally Posted by QwikKotaTX
The oil in my car is coming up on a year old. I have only driven it about 1000 miles since then due to primarily working on it instead of driving. Mostly minor items. Is it really worth it to change based on age alone? The limited service records I have show years between previous changes. Car has ~95k miles.
Do you live in Texas? If so..Id just drive it as its pretty warm there year round. IN the northeast where we have big temperture swings and condenation is a thing here when things frost over.
Thank ya'll. I will probably let it go another year. I definitely let the car get to 180F or so before I give it any hard throttle. After 15 minutes or so of driving after that it's plenty warmed up, especially with our climate. Yes, Texas, but we have high humidity. Just letting a car idle for years on end does not do it any good. You have to drive them. Better for the rest of the vehicle as well.
It is holding it and it is on the stock map according to the device UMW provides. It will hold around 1 bar and sometimes spike to 1.1. It should hold a solid .7 bar on a flat road in 3rd gear (tiptronic)
I still need to 100% confirm its on the stock map but I am pretty sure it is.
Datalog (1) setpoint boost (2) manifold pressure (3) n75 duty cycle (4) afr and find out for sure.
Datalog (1) setpoint boost (2) manifold pressure (3) n75 duty cycle (4) afr and find out for sure.
Thans..will give it a whirl tomorrow. If the setpoint and manifold pressure are close to one another, its most likely tuned right?
If it were targeting .7 bar and the manifold pressure were @ 1.2 something would be wrong/broken.
I tested the wastegates individually and they 'crack' at 7 psi and are fully extended/open @ 10 psi.
Remember target boost and creep, spike are all different. Creep is not good, but these cars don't seem to get it, spike is fine, it should hit above and taper back to the target. Sounds like the car is running 1.0 bar tune. Log it, make sure no issues, minimal knock sums, and just drive it.
Picked up this boost leak kit from a friend who sold his car, but never used the kit. Never even assembled it! I put the caps together, it comes with 4 silicone couplers, I need to get my car on the lift to see which pair fit...
Started the car to go for a drive before the day's heat set in and as I engaged the clutch as the car idled, I merely engaged the pedal to the floorboard. Always an unwelcome occurrence. Slave, master, accumulator all under two years since my last 098/764/dmfw clutch R&R and let's see.. Did I replace the hydraulic line? Probably only thing I didn't. We shall see, it's one of those connected items I'm betting. No warning, no clutch behavior different. Checking later for visible Pentosin etc. Terrific! I needed something to do.
06-12-2024, 01:15 PM
