HB280ZT Posted February 1, 2008 Author Share Posted February 1, 2008 Hi All, Well after talking with KTM I decided to go back and take a look at a few items. I decided to just go back to an older program that worked very well with my car and go from there. Well I drove it to work this morning and it is still fluttering and what I mean by fluttering is that I get a momentary hesitation that shows up in my boost guage as a bouncing guage, like a miss and then fire then miss again, causing the car to buck. So now I am really pulling my hair out! I am really not sure what could be causing this issue. So lets recap: Rebuilt lower end of motor, stock 83 turbo lower end, with rings and bearings. Put on different intake manifold, turbo vice P82 Put on new BOV, Tial 50mm Nothing else has changed! I have done nothing else to the car that should have caused this. So I guess I am going to just back up and punt and ask people if they are running the newer MS1 extra code with a turbo can I see a copy of your msq file to see if I have something drastically setup wrong. Will also look in the code thread to see what is there. Thanks for the help, hopefully we can get this fixed as I have other work to do on the car before some needed track events! HB280ZT Quote Link to comment Share on other sites More sharing options...
z-ya Posted February 1, 2008 Share Posted February 1, 2008 Have to tried to disconnect the BOV? Remove the vacuum line and plug it on the manifold side. Note that now you will have a new sound, the sound of all that pressure slamming against the throttle plate when you let off the throttle after boost. My BOV flutters a lot at part throttle when the manifold pressure is around atmospheric. Quote Link to comment Share on other sites More sharing options...
HB280ZT Posted February 1, 2008 Author Share Posted February 1, 2008 No I have not tried blocking off the BOV, but will give it a try later today. Thanks HB280ZT Quote Link to comment Share on other sites More sharing options...
z-ya Posted February 1, 2008 Share Posted February 1, 2008 No I have not tried blocking off the BOV, but will give it a try later today. Thanks HB280ZT Keep it installed, just disconnect the vacuum line and plug it at the manifold so you don't have a vacuum leak. Quote Link to comment Share on other sites More sharing options...
HB280ZT Posted February 2, 2008 Author Share Posted February 2, 2008 Well I disconnected the vacuum line to the BOV and it still fluttered. So what to try next? So who here has a working 29v or y series code that is working on a turbo motor? I need to see what you are doing so that I can see if I really have something messed up. Here is my last msq file: Thanks for the help. HB280ZT megasquirt200801312116.zip Quote Link to comment Share on other sites More sharing options...
Nigel Posted March 6, 2008 Share Posted March 6, 2008 As Clifton said, your turbo is probably not matched perfectly to the engine, so you're getting surge. I'm experiencing a similar problem (but mine is even worse!). You didn't notice it before because your old BOV did what it was supposed to do and vented the surge. The only problem from the sound of it is that it was leaking under boost. It doesn't surprise me that the lower gear didn't help. You're loading the engine more, but the flow is the same, so more surge (I hope that makes sense. I'm really tired, so in my state of mind, it makes sense to me right now ) I'll bet the new Tial is set too stiff, so it's not venting with low boost surge. The spring isn't really what keeps the valve closed under boost. The manifold pressure supplied by the vaccum line is what keeps it closed. It balances out the pressure against the valve in the intercooler plumbing that the BOV is attached to. The spring is really in there to keep the valve closed when you're not boosting. But if it's too stiff, it won't react to low boost surge. So, run a softer spring in the bov. You're not recirculating so it's not a big deal if the valve is open at idle. You will be drawing in some unfiltered air, but unless you're idling in a sand storm, so that shouldn't be a big deal either. I'm running a soft spring in my Greddy Type RS, with the tension backed almost completely off, and it holds 15lbs no problem. That helped tremendously. I still have some surge, but only a new turbo is going to solve that at this point. Nigel '73 240ZT Quote Link to comment Share on other sites More sharing options...
Clifton Posted March 6, 2008 Share Posted March 6, 2008 You didn't notice it before because your old BOV did what it was supposed to do and vented the surge. A BOV only vents on closed throttle. If the turbo isn't matched and it surges under load (WOT), no BOV will help that. Maybe you meant that but just wanted to clarify. Quote Link to comment Share on other sites More sharing options...
Nigel Posted March 6, 2008 Share Posted March 6, 2008 A BOV only vents on closed throttle. If the turbo isn't matched and it surges under load (WOT), no BOV will help that. Maybe you meant that but just wanted to clarify. Yeah, you're right. Like I said, I was really tired when I wrote that . But when you try to hold part throttle/low boost, you are backing off the throttle a bit. With a mismatched turbo, just lifting the throttle a bit can cause surge. A soft BOV spring will make the BOV far more responsive to smaller throttle changes like that. It doesn't get rid of the surge, which ideally you wouldn't have in the first place if the turbo is matched properly. However, a softly sprung BOV does make it far more livable. Believe me, I've tried it! My Z went from being undrivable under any boost except full throttle, to at least being somewhat enjoyable until I can replace the turbo. BTW Clifton... it was you who clued me in to the reality of part throttle/low boost surge in a post of mine last year. Thanks for your input! I couldn't figure out what was going on prior to that, and I was blaming it all on my BOV. But I've gone on to doing a lot of reading about surge and BOV's, and I've learned a lot. Nigel Quote Link to comment Share on other sites More sharing options...
Evan Purple240zt Posted March 6, 2008 Share Posted March 6, 2008 Is the surge under full boost? I had very simaler symptoms on the dyno last saturday and it turned out I was running enough boost to force the bov open. Evan Quote Link to comment Share on other sites More sharing options...
Bernardd Posted March 6, 2008 Share Posted March 6, 2008 I've got the same turbo and have the same problem. It's really bad with the .63 turbine housing. I switched mine to a .82 and take my wastegate reference right out of the turbo. It reduced spool up a bit but I now get very little to no flutter. Another option for you is to try a bleeder type boost controller. Quote Link to comment Share on other sites More sharing options...
proxlamus© Posted March 6, 2008 Share Posted March 6, 2008 this might be wayy out there.. but how about an intake front fire?! not a backfire.. but a front fire.. Ive noticed this sometimes on start ups on cold days.. small little intake pops and my boost gauge flutters.. Ive fixed this by adding more fuel and allowing proper warm up Quote Link to comment Share on other sites More sharing options...
HB280ZT Posted March 7, 2008 Author Share Posted March 7, 2008 Guys, Great information. To start with I only get this under part throttle low boost above 3500 rpms. I have been playing with the timing and almost got rid of it yesterday. But I tried something new and now it is partial back again. As for the turbo being a mismatch could be, but there are people on this web running turbos much bigger then mine and not having any problems at all. So?? If the weather premits I will work on the timing some tomorrow and see where it leads me. Also you can check on my other post about spark tables: http://forums.hybridz.org/showthread.php?t=131045 Thanks for the help! Quote Link to comment Share on other sites More sharing options...
Clifton Posted March 7, 2008 Share Posted March 7, 2008 Guys, To start with I only get this under part throttle low boost above 3500 rpms. I thought it was WOT. Is it steady state part throttle, just cruising with no change it TPS? Quote Link to comment Share on other sites More sharing options...
HB280ZT Posted March 7, 2008 Author Share Posted March 7, 2008 Clifton, As far as I can tell it is only happens when I am at part throttle cruising getting into boost. That could be just below, at or slightly into boost. When I really get on the throttle it does nothing but get up and go! Also when it does turkey (surge) my rpms are still increasing but my foot is not pushing on the throttle anymore just maintaining a steady state throttle. Thanks Quote Link to comment Share on other sites More sharing options...
Bluto Posted March 7, 2008 Share Posted March 7, 2008 edit! Quote Link to comment Share on other sites More sharing options...
Clifton Posted March 7, 2008 Share Posted March 7, 2008 On line 3185, you are at 3300 rpm, 180 kpa but it looks like your TP is only 33%. On another one you make 200 kpa with 33% TP at 5200 rpm. Is your TP % correct? Quote Link to comment Share on other sites More sharing options...
HB280ZT Posted March 7, 2008 Author Share Posted March 7, 2008 As far as I know my TPS is good to go. How can I really check it to see if it is running through its paces without any problems? Quote Link to comment Share on other sites More sharing options...
Clifton Posted March 7, 2008 Share Posted March 7, 2008 You should have set it on megatune. Check it though, should be 0% without touching it and 100% at wot. If your TP setting is set on megatune then it's right, but 30% throttle isn't much to make that kind of boost. If you open the throttle more the surge goes away and the boost needle stabilizes right? Quote Link to comment Share on other sites More sharing options...
HB280ZT Posted March 7, 2008 Author Share Posted March 7, 2008 Clifton, I set the TPS via megatune when I setup the program. You know at no throttle and at wide open. I will go back and look at it again. Quote Link to comment Share on other sites More sharing options...
HB280ZT Posted March 11, 2008 Author Share Posted March 11, 2008 Well I had a chance to check the TPS and it checks good, as far as I can tell. Also plugged the BOV and it still flutters. Have tried several different timing maps and it really did not help at all. Here is a quick datalog that shows just a flutter sequence. One of the items that is concerning me is that the Map and boost is dropping at the rpm is increasing, is that normal? Also you can see how the boost and map are bouncing around. If it is the turbo what to change? T3 turbine AR .63 stage 3 T04B compressor AR .70 hi-fi intercooler 8"H x 20"W x 3.5"D 3" in/output intercooler piping 2.25" Hope this helps narrow down items to try next. datalog200803102036.zip Quote Link to comment Share on other sites More sharing options...
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