Julian's '91 200 20vt

[88a5tq]

Redacted

[88a5tq]

Hey everyone, need some help here... Keep in mind I haven't checked the vacuum lines from the n75 to the wastegate yet. Heres a log from today. With 100% DC on the 220-240 kpa range of boost DC vs rpm table, my boost still tapers to 174 kpa by 6k RPM. Take a look at my log and the table in question and you will likely be scratching your head like I am right now. Ill check the hoses tomorrow morning but seriously how is this acting like this if everything is proper? Bad N75? I have another but I hadn't noticed any problems for sure since my boost control tuning only concluded today. Thanks for looking!

[chaloux]

Put refDC to 0 across the board and take another log. If it's the same something is bad in the boost control system ie hose or n75 or wiring

[chaloux]

Oh. You also have it set to boost target based. Usually I use RPM/gear/speed based (in Boost Control, PID settings, about 2/3 of the way down). Try refdc vs rpm/gear/speed based and change the table to 100% for the first few cells (say up to 3500rpm) and then go to say 30 from there on and see what happens.

WHat turbo is this?

[chaloux]

Your VE table also needs some work. It's pretty lean when building boost.

[88a5tq]

Thanks man. Lots of good info to get me moving in the right direction. I haven't gotten any feedback on this stuff yet. This is just a lowly k24... I should be able to boost it into oblivion if I want but I can't lol. I'll look all of those over.

[chaloux]

Yeah I'd say it's just on spring pressure because it should be peaking at like 3krpm not 4krpm. There may also be a boost leak which can be hard to detect in VEMS due to not having a MAF. No flat on your face bucking or anything. It just works with how much air is going into the motor regardless of leaks etc

[88a5tq]

Will make some reforms and check back after I look things over

[88a5tq]

Ok So I did some playing and some looking. My filter's ducting hose came off and the inlet was resting against the fender so that likely restricted flow to an extent. Here are my log and config after doing some more tweaking. Also I forgot to mention that this is all logged with my meth injection turned off so things will be getting further rich soon. Just waiting to tune both boost and fuel completely

[chaloux]

Still weird. The good news is that by fattening up your fuel on boost onset you gained 100rpm in spool! And you did build more boost and hold more boost to 6krpm, but it really should be overboosting like crazy and spooling way earlier on a k24. Are your cams perfectly timed? 7 links up on each and 10 links across? Did you open the motor or swap cams or anything or was it basically untouched?

You also still need more fuel from 3700-4700rpm in those boost cells. TQ peak is a pretty important area not to be lean in.

Did you try setting refdc values to 0? If you do that and there's no change you're on spring pressure. Very easy way to check. You could also unplug n75 and again, if no change, spring pressure.

[88a5tq]

Motor has never been apart. Only did the timing belt job and the rest is untouched except for the steel dizzy gear and strapped intercooler. I never tried the "0" refdc but I'll unplug the n75 tomorrow and take a pull. all I did was crank the stock spring waaaay down. The hoses looked in one piece on the n75 but they're original. May replace. I'll try removing the K&n also and do a pull just in case its restricting the upper rpm flow. That's just a hunch of mine. Thanks again. More updates to come

[chaloux]

That boost curve is pretty much inline with what a cranked down stock spring or higher pressure spring would produce.

[88a5tq]

lol that's what I was afraid of. Jesus I hope its not ECU related . I guess ill be swapping that valve out for the spare and testing the valve for voltage output period. Something is wonky here no doubt

[chaloux]

I highly doubt it's ecu related but I can see why you would have that fear, lol

[loxxrider]

You said you did the timing belt job... you sure it isn't a tooth off or something?

[loxxrider]

You should work on learning to stab the throttle at low RPM (100% tps at 2k RPM) and hold on for dear life until redline unless you see it go lean or way too rich, or hear knock. If you do that, it will make it much easier for someone here to help you tune it.

If it were me and I was trying to diagnose boost, I'd set boost vs TPS to 100% everywhere and same with boost refDC at 800 RPM (it can't hurt). You should see 100% duty cycle as soon as you go 100% on TPS regardless of other conditions. Your spool will surely improve. Your fuel looks OK. If you do a full pull I'd be happy to try and help clean it up. It's been a long time since I've tuned on VEMS so I'm getting back in the groove here

Also, your boost is dropping off so much at high RPM because the boost refDC and boost vs RPM are set that way. The reason someone has set it that way is because of your stock injectors. You can see they are at 85% duty cycle already! Still, you can squeeze more out of them until about 5500 RPM. You should be able to hold 20 psi until then at least.

When you're working on these kinds of issues, put boost DC and boost target in your graph so you can see what they are doing. See attached. Also, PID boost control will really help keep the boost up in the higher RPM when you get this sorted out a bit more.

Finally, you don't have to post a log and a config. The config is already contained in the log file.

[Aktapod]

Chris and Matt, you guys are the best! I'm kinda following along so I can get some exposure before I actually install VEMS, so this has proven very informative! I'll keep my eye on this as it progresses.

[loxxrider]

Kevin,

Install VEMSTune and play with some logs! You will be able to learn a lot that way. VEMSTune is now a lot more complete and the help section in the boost control drop down is pretty good (Press F1 while in the Boost PID settings). I just read it for the first time in a long time and I see they have added a lot of nice features as far as closed loop control goes. I'd like to see everyone here using it! You will have no problem following along with that Kevin, and it will help you tremendously in controls class when you get to it.

I will try to see if I can dig up some things I've written about PID and tuning in general (I know you just sent me the tuning thing I wrote recently). I really need to archive this stuff better.

Oh, and I can't wait to see more of your build

[88a5tq]

Anyone ever wake up Sunday morning thinking its Monday and they're an hour late for work?? Uhhh I did hah.

Matt, Chris are you guys not on the payroll yet? I find it difficult to believe your usernames aren't red and you are not the weekend help . Seriously you are both being soooo helpful I greatly appreciate every post! Since its Sunday it looks like I have most of the day to track these issues down. I will get started since im already up.

Kevin this is a perfect opportunity to learn about the software. I didn't figure out everything I could mess with until after I got the ECU installed. If you open the sample config files the software provide on the main screen you can start editing the layout of the gauges and make new tabs with what's important to you. Also you can start making new profiles on the log viewing screen to show only what you want and save them for use with you logs later. I waited to my own detriment. I am glad you are able to benefit from my trial and error though. I like knowing I am helping a fellow wrenches

[88a5tq]

Ok so I did the 0 refDC test and got 160 kPa across the board. The log is below. After that I went through and replaced all the vacuum hoses going to and from both the wastegate and N75. I wasn't taking a dam log though lol! In my autotune page it showed it tuned fuel VE cells clear up to 280 kPa (IRCC around 3500 to 4500 RPM) though haha so that got better. I bet its my k&n Apollo filter is too restrictive or something. I still didn't look into that. I took a few more logs but Ill put up my most recent with some refDC tweaks on it that I didn't have a chance to re-log but that can be another day. Been beating this car silly trying to diagnose high boost/rpm conditions. ... actually no, no police involvement yet

[loxxrider]

Happy to help as much as I can.

I am writing up a document on boost control right now that I think you'll find useful. Keep an eye out for that soon. I should have some time later to take a look at the latest logs.

[loxxrider]

What autotune page are you talking about? I thought you had the ego correction turned off when I looked. Are you talking about something else? It's best to leave any auto corrections off while tuning if possible. That way you have complete control over the tune and aren't relying on the computer to correct.

[88a5tq]

Excellent I'll watch for that. Im still quite new to this software and what completely baffles me still there is what function exact ly that each performs of PID. Those values remain zero for me for now. Im referring to the VE autotune page under tools. I've been relying on it too much im sure . I do keep EGO correction at zero as well even though it says its on sometimes on the top of the screen. I mainly keep it off so it won't reduce VE while running meth, well for the future I guess. Once in a great while I'll hear a clattering during mid range on high boost but it makes me think my wastegate is doing it. Anyone experience that before? Chris I would be extremely grateful if you took a look at my logs. That's would be great. Just a reminder that I changer refDC slightly in high rpm for my next log but never logged it. I changed the timing belt about 8 months ago and it was perfect at the time and perfect performance while using the IA chipset so unless it jumped a tooth when VEMS destroyed my flywheel, I can't think of a reason why it would be off now. Thanks for your insight

[88a5tq]

Here's the filter in question, its about 3/4" smaller diameter than stock turbo inlet hose. Its HP restricting on turbo cars somewhere below 400. If anyone else out there has VEMS tuned for the k24 please let me know! I since removed the crappy heat shield I made so that's not rattling. I really need help on my ignition table too. Thanks all

[loxxrider]

Easiest way to find out of its being a restriction is to just take it off! You wont hurt anything doing that. As ricer as it looks, I dont really believe it is restricting anything.