3.0L Megasquirt w/ EDIS: Headers running at different temps?

[jangell]

Sorry for the late replies:

To do an LS4 swap, simply open wallet and let money fall out.

I might as well just go electric then. I was hoping to wait another 10 years for enough junked Teslas, Volts, etc to be able to get the parts cheaper and have a better source of conversion guides to draw from (for any car, not just the DMC), though.

-- Joe

[jangell]

How do your timing chain guides look?

The chain guides themselves look fine. The timing tensioner (the large flat surface that the spring-loaded tensioner pushes towards the chain, not the spring-loaded assembly itself) did have some light grooves in it, but they seemed usable, so I just put them back in (that, and RockAuto didn't have any replacements).

-- Joe

[jangell]

This weekend I got everything re-timed and put everything back together, and had just enough time left over to start the car up. I forgot how long it takes to clean up the mating surface to install the new gaskets.

First, the car runs notably smoother. The AFR is still high at 18-19, but that's down from where we before (I think anything over 20 is "out of range"). So way too lean, but at least it's moving in the right direction. It was idling around 900 RPM; taking a way fuel brought it down a little, but of course brought the AFR up as well. I didn't try tinkering with the advance table, which was sitting at about 14.4.

Another unscientific test was just putting my hand behind the exhaust and feeling the pulse from each tailpipe. There was a pretty steady series of pulses from each side (so, all the cylinders were probably firing), and they felt about the same temperature (as much as you can tell temperature from your hands).

The IR thermometer reported more similar readings on both sides, although the passenger side was still a bit cooler than the driver's side (200s vs 300s). It wasn't nearly as cool as it was before, though.

I've attached the Tunerstudio log. This uses the same tune as last time. The movement of the TPS is interesting, since that suggests the throttle is opening as a side effect of engine vacuum, I think... I wonder what would happen if I held that closed.

I had the vacuum gauge hooked up, but I forgot to actually look at it, which is annoying. Next weekend I'll see what that reads, and I'll hunt for vacuum leaks.

One thing that occurred to me: if the idle air motor isn't working, would that account for the very high AFR? I can hear a strong suction sound from part of the throttle where the idle air motor intake is (it's a slot just above the throttle plate), but I don't actually know if that's normal or not. I spent way too much time figuring out the idle air motor wiring, but that doesn't mean I did it correctly.

Thanks!

-- Joe

TunerStudio log: 2018-07-29_14.02.11.msl

[FABombjoy]

I still feel like a Megasquirt noob but here's what I see:

-Very lean. More fuel. Now.

-MAP seems high for idle on stock cams (I'm around 40kpa). Add fuel.

-May not be an issue: Compared to the 2.8 you have a practically 2 dimensional spark table. The DMC 2.8 distributor runs a lot more advance at low load/high RPM. I know nothing of the 3.0 spark requirements though.

-There isn't an idle landing zone in the spark table so your advance number dance up and down while in an idle state which contributes to unstable idle.

-Same with VE. For example, in the 65KPA row it goes 63-60-65-58-60 which isn't realistic. VE generally goes from low to high then back down unless you have a big turbo, variable intake runners, VTEC, etc.

-Your TPS signal increases from 0 to 9% even when the engine isn't running which is bizarre. Seems like a grounding/electrical issue rather than vacuum related. According to the logs your TPS increases 15 percent while running which you should be able to physically see at the cable pulley.
With the cockamamie throttle linkage on the 2.8, if you don't have the stops set correctly your TPS will drift as the assembly heats up, but what would cause such an increase with your setup while not even running?

-You have noise in your sensors. CLT and MAT should be very linear but have some little spikes in them. Batt V shows as low as 6.3 during cranking. By contrast I go from 12 -> 10.9 during cranking.

I can get the clunky 2.8 to idle +/- 20RPM so you should be able to do just as well with with 3.0 once the numbers are good and wiring checks out!

[dn010]

Seems like a grounding/electrical issue rather than vacuum related.

+1

[jangell]

I still feel like a Megasquirt noob but here's what I see:

-Very lean. More fuel. Now.

-MAP seems high for idle on stock cams (I'm around 40kpa). Add fuel.

I'll do that on Saturday. A question, though: Won't that cause the RPMs to shoot up? How would I get it down to 790 RPM once I get the AFR to 14.7? Adjust the timing advance table?

-May not be an issue: Compared to the 2.8 you have a practically 2 dimensional spark table. The DMC 2.8 distributor runs a lot more advance at low load/high RPM. I know nothing of the 3.0 spark requirements though.

I'm not entirely sure what I'd look for in the manual to figure out the spark requirements. I couldn't even find what the idle timing was supposed to be, and ~14 is just what the generated table happened to be. The manual mostly just says that it was "set at the factory" and that it's not adjustable, which isn't very helpful.

-There isn't an idle landing zone in the spark table so your advance number dance up and down while in an idle state which contributes to unstable idle.

I don't think I've actually looked at the spark table before, and am just using the initial generated table. I really should add a 790 RPM column both there and in the VE table for the actual idle speed, which I think is what you mean by an idle landing zone, right?

-Same with VE. For example, in the 65KPA row it goes 63-60-65-58-60 which isn't realistic. VE generally goes from low to high then back down unless you have a big turbo, variable intake runners, VTEC, etc.!

This is mostly an auto-generated table. I might have boosted the first column to try to recover from stalls at idle (read about that somewhere once). I should probably re-generate the table to remove any other odd changes I may have made when I was trying to get it work a few months back when there were more non-software-related issues.

-Your TPS signal increases from 0 to 9% even when the engine isn't running which is bizarre. Seems like a grounding/electrical issue rather than vacuum related. According to the logs your TPS increases 15 percent while running which you should be able to physically see at the cable pulley.
With the cockamamie throttle linkage on the 2.8, if you don't have the stops set correctly your TPS will drift as the assembly heats up, but what would cause such an increase with your setup while not even running?

I'll actually look at the throttles on Saturday -- I didn't notice the TPS readings until I looked at the logs when I got home. To be clear, the TPS is just another line on the graph at this point -- I'm not using it to control fuel, and am just relying on the MAP at the moment.

I'll check the grounding on Saturday as well.

-You have noise in your sensors. CLT and MAT should be very linear but have some little spikes in them. Batt V shows as low as 6.3 during cranking. By contrast I go from 12 -> 10.9 during cranking.

Now that's interesting. I have the dedicated return wire that is common to all the sensors (wiring diagram here, if you're interested: http://www.tmproductions.com/s/DeLorean-EFI-Wiring.pdf ). I also added a ground bus that runs from the headlights to the engine block; the grounds for MS is connected to the end of this bus at the engine block (mostly because this is Josh's harness, and that's how it was set up; I made my own diagram because I had to put on the DB37 connector, and I wanted to make sure I did everything correctly).

I haven't had to look into noise issues before, so I'm not entirely sure how to proceed. I'm guessing culprits could be wires that run too close to the coils, maybe? The VR sensor is a shielded cable, but everything else is just simple wires. It's interesting (well, to me) that that MAT and CLT spikes don't seem to be at the same time. Also that TPS is smooth; I'd have expected noise in all of the sensors. Of course, TPS appears to be wildly off anyway.

I can get the clunky 2.8 to idle +/- 20RPM so you should be able to do just as well with with 3.0 once the numbers are good and wiring checks out!

That's encouraging -- hopefully there's just a stupid grounding issue and I can get it cleaned up fairly quickly this weekend.

Thanks!

-- Joe

[FABombjoy]

I'll do that on Saturday. A question, though: Won't that cause the RPMs to shoot up? How would I get it down to 790 RPM once I get the AFR to 14.7? Adjust the timing advance table?

Good idle is tricky - I would review all of the techniques posted in the MS manuals and forum. You can use timing to control idle but you'll want the IAC to do most of that work.
You do have the ability to set some options under Idle Advance which can allow you to force specific ignition timing at idle, but you'll have to fix TPS to make that reliable.

I'm not entirely sure what I'd look for in the manual to figure out the spark requirements. I couldn't even find what the idle timing was supposed to be, and ~14 is just what the generated table happened to be. The manual mostly just says that it was "set at the factory" and that it's not adjustable, which isn't very helpful.

I generated a table by calculating the curves listed in the DMC factory manual and Volvo greenbooks. Maybe something comparable exists for the even-fire Volvo PRVs? At least as a basis for comparison? Optimal spark tables are built on the dyno, unfortunately.

I don't think I've actually looked at the spark table before, and am just using the initial generated table. I really should add a 790 RPM column both there and in the VE table for the actual idle speed, which I think is what you mean by an idle landing zone, right?

You need a plateau in the table where small changes in RPM don't produce changes in timing, or to configure idle advance settings to do so.

I'll actually look at the throttles on Saturday -- I didn't notice the TPS readings until I looked at the logs when I got home. To be clear, the TPS is just another line on the graph at this point -- I'm not using it to control fuel, and am just relying on the MAP at the moment.

You do have TPS-based accel enrichment. Once you drive the car you'll want TPS to work properly so you can dial in accel enrichment.

Now that's interesting. I have the dedicated return wire that is common to all the sensors (wiring diagram here, if you're interested: http://www.tmproductions.com/s/DeLorean-EFI-Wiring.pdf ). I also added a ground bus that runs from the headlights to the engine block; the grounds for MS is connected to the end of this bus at the engine block (mostly because this is Josh's harness, and that's how it was set up; I made my own diagram because I had to put on the DB37 connector, and I wanted to make sure I did everything correctly).

I haven't had to look into noise issues before, so I'm not entirely sure how to proceed. I'm guessing culprits could be wires that run too close to the coils, maybe? The VR sensor is a shielded cable, but everything else is just simple wires. It's interesting (well, to me) that that MAT and CLT spikes don't seem to be at the same time. Also that TPS is smooth; I'd have expected noise in all of the sensors. Of course, TPS appears to be wildly off anyway.

I like the diagram! I started in on one and gave up, turning it into an excel spreadsheet instead But I was changing it constantly and I have twice the number of things connected -vs- a typical MS setup.

According to the diagram your LC2 is grounded via the sensor return. That should not be connected there and is almost certainly the cause of the drifting value and voltage dips. The wideband heaters are also driven by a PWM which can be ultra noisy (it was in the LC1 and I had to relocate wires just to get it out of my stereo). Move the LC2 ground to a big fatty ground wire and I'll bet a lot of this clears up.

LC2 specs a 5A fuse. That poor, single tiny pin on the DB37 connector has to pass all of that current and handle the sensors too.

The DB37 provided with most MS kits is kind garbage too so that's just too much for it to handle. I tossed mine and installed one of these:
https://b2b.harting.com/ebusiness/en...U2/09672374715
I put these shells on too:
https://www.digikey.com/product-deta...132-ND/1851327
But I'm picky

[jangell]

Good idle is tricky - I would review all of the techniques posted in the MS manuals and forum. You can use timing to control idle but you'll want the IAC to do most of that work.

You do have the ability to set some options under Idle Advance which can allow you to force specific ignition timing at idle, but you'll have to fix TPS to make that reliable.

I'll settle for a halfway passable idle.

But I shouldn't be idling at 2000 RPM, which is what I feel like I'll be at once I increase the fuel to get to an AFR of 14.7:1. Barring a massive vacuum leak, is adjusting the advance timing how I would bring that down again? Or is this not worth discussing until I've fixed the sensor noise and get the AFR down?

I generated a table by calculating the curves listed in the DMC factory manual and Volvo greenbooks. Maybe something comparable exists for the even-fire Volvo PRVs? At least as a basis for comparison? Optimal spark tables are built on the dyno, unfortunately.

I have the Monaco Service Manual and the Engine Student Reference Book, since at the time I was more interested in how to rebuild the engine. I don't have the green book for the 3.0L, but I do for some 2.8L components. You don't happen to know what the pages are in the DMC/Volvo manuals for the 2.8L engine are, would you? Just looking at those will help me figure out what I'm looking for in the 3.0L manuals (and which manual to get in the first place).

You need a plateau in the table where small changes in RPM don't produce changes in timing, or to configure idle advance settings to do so.

Ah, I see now. So like two columns at, say, 780 and 800, with the same values in their rows, so that timing is consistent around 790 RPM? I'll look into setting that up once I get the AFR down to something reasonable.

You do have TPS-based accel enrichment. Once you drive the car you'll want TPS to work properly so you can dial in accel enrichment.

Huh; I thought I had that off (or had the settings configured so that it was effectively off). I mean, I know I can use it, but I thought I was just using MAP for now.

I wasn't clear on if MAP or TPS was preferred. I remember reading something suggesting that MAP was fine unless you really want to tweak things, in which case TPS is more useful, but I can't remember where I saw that now. Initially I just want to remove variables by disabling TPS.

I like the diagram! I started in on one and gave up, turning it into an excel spreadsheet instead But I was changing it constantly and I have twice the number of things connected -vs- a typical MS setup.

I decided to go representative instead of abstract for readability. I spent way too much time on that. It's based on Josh's original diagram, but done over with vector graphics and notes so I understand why things are where they are. Using vector graphics make it fairly easy to change as needed. I also have a label printer and label basically every wire I touch.

According to the diagram your LC2 is grounded via the sensor return. That should not be connected there and is almost certainly the cause of the drifting value and voltage dips. The wideband heaters are also driven by a PWM which can be ultra noisy (it was in the LC1 and I had to relocate wires just to get it out of my stereo). Move the LC2 ground to a big fatty ground wire and I'll bet a lot of this clears up.

LC2 specs a 5A fuse. That poor, single tiny pin on the DB37 connector has to pass all of that current and handle the sensors too.

Ah -- I didn't realize that, but it makes sense now that you mention it. I think I just lumped the LC2 in with "sensors" and thought I should hook it up there without realizing just how much current it draws. I'll make that change first thing on Saturday. Thanks!

I had a fun problem early on where the MS would fail to burn settings, but would mostly seem to work. Turns out the main power wire to MS had come off, and it was leaching just enough power through some of the other pins (possibly the RS-232 to the laptop, even), but it wasn't enough power to do anything halfway demanding. It was amazingly obvious once I finally tracked it down.

The DB37 provided with most MS kits is kind garbage too so that's just too much for it to handle. I tossed mine and installed one of these:
https://b2b.harting.com/ebusiness/en...U2/09672374715
I put these shells on too:
https://www.digikey.com/product-deta...132-ND/1851327
But I'm picky

My immediate goal is to just get it running. I have a few other updates I'd like to do, but first things first. I'd like this conversion to last 5-15 years, at which point I'm hoping that there will be enough junked electric cars and enough DIY electric conversions of various vehicles that there will be a kind of MegaSquirt-like community that will make it relatively straight-forward to convert to electric drive. It seems so much simpler in many ways, once you get around how to actually mount the electric motor in the car and where to put all the batteries... But I'm quite happy to run a gas engine for a while longer yet, until such a conversion becomes more affordable and somewhat more straight-forward, and something fatal happens to this engine/transmission.

Thanks!

-- Joe

[FABombjoy]

But I shouldn't be idling at 2000 RPM, which is what I feel like I'll be at once I increase the fuel to get to an AFR of 14.7:1. Barring a massive vacuum leak, is adjusting the advance timing how I would bring that down again? Or is this not worth discussing until I've fixed the sensor noise and get the AFR down?

You still have IAC open 40 steps at full warm so you can further close the IAC valve. You could also enable closed loop idle control and just specific the RPM you want and see if it works off the bat.

You don't happen to know what the pages are in the DMC/Volvo manuals for the 2.8L engine are, would you? Just looking at those will help me figure out what I'm looking for in the 3.0L manuals (and which manual to get in the first place).

DMC manual specifies the advance by degrees somewhere near the ignition section (?) The Volvo ignition greenbook TP31397-1 has the curve for the OEM distributor (and a few other B27x and B28x motors) but is too old for your engine. Since the 3.0 was totally ECU controlled there is really no reason to have published the curves like this as a mechanic wasn't going to do anything useful with the data. To obtain the original spark map you would have to reverse engineer it from the OEM ECU or measure it somehow. Maybe you could find that data outside of the DMC world.

I wasn't clear on if MAP or TPS was preferred. I remember reading something suggesting that MAP was fine unless you really want to tweak things, in which case TPS is more useful

Either will work, but from what I've read TPS is preferred. It will be a better gauge of your intention. Otherwise the ECU has to watch for changes in MAP which will lag your actual foot.

I had a fun problem early on where the MS would fail to burn settings, but would mostly seem to work. Turns out the main power wire to MS had come off, and it was leaching just enough power through some of the other pins (possibly the RS-232 to the laptop, even), but it wasn't enough power to do anything halfway demanding. It was amazingly obvious once I finally tracked it down.

I had a fun problem where I accidentally hosed the firmware which caused the injectors to lock open w/ fuel pump running. First time I've ever had to siphon an intake manifold. The response was basically, "meh, first time this has ever been reported. You're more expendable than the time it would take to fix"

My immediate goal is to just get it running. I have a few other updates I'd like to do, but first things first. I'd like this conversion to last 5-15 years, at which point I'm hoping that there will be enough junked electric cars and enough DIY electric conversions of various vehicles that there will be a kind of MegaSquirt-like community that will make it relatively straight-forward to convert to electric drive.

That would be fun, especially fast charge becomes a reality. With a gas engine we can emphasize its "touring sports car" qualities but that's difficult to claim if you have to make long stops to recharge every few hours

[Josh]

If you think there is a issue with your IAC you need to address it. If it is not functioning properly it will be introducing more air than the engine needs and causing it to run lean.