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That is a good idea. My Saab 9-3 ‘daily’ overheated today (lol I’m an automotive masochist) soon as I get a minute I’ll upload that tune. Feel like I’m ‘fighting myself’ somewhere..
I got mine much better from when I posted. The IAT was moved to the intercooler pipe in front of the radiator and my ASE and Taper curves look like this. Not very elegant but I think the basic curve is similar to what others have done. It's not perfect but the car starts better and after 30 seconds of driving it's all good. Will continue to tweak it, just have not had much time after the charger was installed.
Hey guys I would like to bump this thread, I’m running a BP05, Wallbro 255, 60psi return rail w recent addition of Flowforce 640’s. I run MSPNP, MX3 chassis but same issues.. The injector upgrade was part of a DIY package upgrade ending in the installation of the smaller machined pulley That will push my M 62 up to factory limits or about 1500 RPM at redline. Currently i push about seven psi and the stock injectors were fine but I have a feeling they’re going to max out by the time I get to 11 or 12. I actually experienced a mild version of the hot start issues with the stock injectors running lean to about 16 but rarely stalling. I moved my IAT to the intercooler. Tuning has gone surprisingly smoothly for me to this point but this hot start issue with these 640s is really starting to frustrate me. I have been all over several threads and I can make the issue better with aggressive ego control But the car may still stall. Anybody else had any breakthroughs with this issue? How did you solve it? I’ve been all over this for weeks now it’s driving me nuts LOL
FWIW, I have a MSPNP2 (99-00 model) on a BP05, Walbro 290, non-return Radium rail. My GM IAT is in the outbound tank of the IC. I have experienced the hot-start problem (probably more so because of my non-return fuel rail), and I've gotten it to the point where hot restarts are tolerable...not perfect. Here are my ASE settings;
ok here be my tune.. saab demanded my non work attention over last few days, so i haven't driven mx3 or 'prettied up' my tune since my last attempts at solving this issue on my own.. so here it is warts and all...
Uh huh.. this is my current setting, I haven’t done any tuning since entering this thread.. seems like I’m going in the right direction, maybe no ‘majic bullet’ for the issue..
Good. OK. This is an MX3 with Kia Swap, If I understand correctly. MS2 PNP.
I'm not going to address simply hot re-starts because that is like discussing paint color of the living room of a house with a failing foundation. Tuning is iterative, but it still builds on some fundamentals; and trims from there.
1) A 1995 Miata comes with sequential injection. If your harness / engine is wired for sequential, that is what you should be running.
2) If you have 640 cc injectors, then the Req'd Fuel should be set up accordingly. Is this not a 1.8L engine?
3)WUE should be at 100% at around 185 - 190F. There is no reason to offset your entire curve to be offset by 5% at 205 CLT, which is normal operating temp.
4) These days, most people run "Incorporate AFR".
5) Don't set Flood clear at 100%. If your TPS calibration gets off, you won't get clear when you want it. Set it at 70%
6) On your VE Table, the area 35-90 kPa and 500-1100 is out of line with rest. Realize that the engine goes through that area immediately after starting. I tend to make 80-100kPa, low RPM a bit rich, rather than lean.
7) I cannot find where to set ASE as cycles or 0.1 seconds per cycle. It has been found to work well, with the times you show, when tenths of seconds is chosen.
8) I suggest using Idle Adaptive Advance Timing.
9) Your EGO should be set to PID, not Simple.
10) Go to Trubokitty.com and download the basemap for your Engine / Megasquirt. Look it over and get a feel for a good tune (but realize you will need to adjust for the injector size).
10) Your MAT corrections are not bad, though you should later tune that while running about 100kPa or higher. That is not an issue with your hot restarts, as you have set to ignore MAT corrections during ASE.
EDIT: Also check the “calibrations” of thermistors and AFR (wideband).
DNM
Last edited by DNMakinson; 08-25-2019 at 07:27 PM.
Knew this was coming.. lol Yup i started with a ‘B6D’ basemap.. runs okay But I need to back the trailer up before I pump the boost LOL. I will apply this logic and then re-post results, thank you for your reply
Actually that brings up an interesting point..Kia BP looks like MM95 motor, (besides mounts, water pump & ignition) but I’m using B6D harness. Timing looks good but should I run sequential injection on this motor? Sure I can figure the wiring out if necessary..
I don't know how well a motor runs with random injections on multi-port system. Seems like a waste to have multi-port and not run sequential, but I have no real experience there. Sequential vs wasted spark ignition is polish, but I envision sequential vs non for injection to be of value.
One other thing... Go to the Meet and Greet and join the community in a more formal manner. Then folks will know who you are, what you have, where you live (that can be put into your Profile to display beneath your Join Date).
Ok, they say ‘Knowledge without application is null and void’, so I applied ALL of the advice in DNMakison’s reply, with these results.
1. Hot start issue - without ego correction, leans to about 16/1 when ASE tapers off, but does not stall. I have idle VE at about 13.7. I consider this a success.
2. My fuel table was jaggy because of lazy base settings and VEAL tuning. Easy fix. Cross referenced Trubokitty & DIY maps
3. (The big one) sequential fuel injection. My car originally shipped with this feature, and so did the MSPNPMM9495. A simple software change made a world of difference in the running of my car. Smooth as silk and way more responsive. Naturally I had to do a general re-tune after making this adjustment. AE still needs a little tweaking but she has never run this well
I struggled for about 2 years with hot restarts, like you, on my '95 running an MS3. For the record, I also observed lean AFRs when the engine was hot.
Folks like DNMakinson, Curly, and Rev were very helpful but we couldn't really get it figured out. Playing with corrections of CLT, ASE, and MAT didn't make a lot of difference and I observed starting issues even when CLT was ~150*, which the MS wouldn't consider a hot restart. So that led me to investigate when else it could be.
Cutting to the chase, I found my problem was hot fuel, including vapor lock when really heat soaked. I figure the fuel gets heated as it sits in a hot rail, substantially lowering its density and therefore its energy for a given volume. Since the MS is operating on time (and therefore volume) the lower energy per volume of fuel was causing lean conditions. The problem was largely mitigated by adding a Conti flex fuel sensor and correcting fueling based on fuel temps. I called BP asking for fuel density values for the 10% ethanol blend sold by Arco here in Washington and calculated density changes based on temperature. I eventually discovered the engine wanted more fuel than the math predicted so I simply adjusted the curve based on observation.
I wondered why these hot restart problems would show up after installing an MS when I never had this trouble with the OEM ECU. I recall there's a little valve on the fuel rail that's invoked by the OEM ECU but is removed with a Megasquirt because it's considered no longer necessary. To be clear, I didn't completely investigate this path so I'm not sure if it's correct.
A couple of notes:
It's important to install the flex fuel sensor on the return line so it reads post-rail temps. My sensor is downline from the rail via ~2 feet of hose because that was the most convenient way to mount it. I need to move the sensor closer to the rail because it seems fuel cools a bit in the hose so the sensor is reading a bit cooler than what's actually in the rail. I suggest you mount the sensor as close to the fuel rail outlet as you can.
The Conti sensor takes ~30 seconds to accurately read temperatures once it's been turned on. When I first start everything, the sensor reads -30F even when the fuel is hot and will actually cause the MS to *remove* fuel instead of adding it. I've mitigated this somewhat by turning the key to On, waiting 30 seconds, and then starting the engine. This is only necessary when the engine is really heat soaked. I wonder if Conti has improved responsiveness of their sensor with a newer version...
I swapped out Flow Force 660s for ID1000s based on suggestions the injectors dead time behavior changes when they get hot. I found that didn't make a difference though. I contacted ID, Bosch, and an ECU engineer friend from a major car OEM. They all said heat technically causes a minor change but it's not enough to notice, and certainly not enough to account for hot restart issues. This led me down the fuel temp route.
I wondered why these hot restart problems would show up after installing an MS when I never had this trouble with the OEM ECU. I recall there's a little valve on the fuel rail that's invoked by the OEM ECU but is removed with a Megasquirt because it's considered no longer necessary. To be clear, I didn't completely investigate this path so I'm not sure if it's correct.
My 97 equipped with FlowForce 640's and MS3 Pro also has hot restart issues. It's annoying, but not unbearable. My understanding is the PRC valve on the fuel rail references the fuel regulator to atmosphere, rather than manifold, for the first minute or so after a hot restart. I've played around with trying to mimic this concept with ASE, but wasn't successful. Part of my failure I attribute to not setting the taper time long enough while hot, but I'll save that for another day.. I can't imagine the heat soaked injector would be that big of an issue, especially when there isn't any real evidence (that I have seen) to support it. It's a nice theory, I just don't know if it's truly the cause.
Has anyone tried to utilize the PRC valve on a hot start, actually powering it through an aftermarket ECU? I believe this would take some custom wiring. Might be worth just pulling the line on the fuel regulator and referencing atmosphere with the manifold capped off, just to see if it actually helps with the issue. It should raise the fuel pressure at idle which would in theory be helpful. Another idea as a test would be running the fuel pump in test mode for a couple of minutes, hopefully bringing the rail temp down.
08-25-2019, 09:18 AM
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