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

[jangell]

Looks like the IAC is wired up correctly. I was able to move it back and forth with the TunerStudio test controls. I think the problem was that I didn’t have the IAC’s initial position correct before I installed it. Once I ran the test such that the motor retracts as far as possible in the Run position, and then out to the point that it correctly seals the intake in the Home position, everything worked much better.

The AFR is now a much more reasonable 15-16 with no adjustments. By adding fuel I was able to get it into the 14.3-14.9. I kept tinkering while it warmed up (so, the VE table is a bit of a mess now). At 185 degrees or so I adjust the throttle set screw, which I finally found under the arm. Annoyingly, you have to open the throttles all the way to get it adjust it, so I had to turn off the car and each test. The idle is seeking a little in the mid-700s to mid-800s for now.

Obviously I attribute all success to hugging the car.

I have a coolant leak I need to fix before I go further; I’m going to do that tomorrow. I think the leak is at one of the pipes near the firewall under the intake manifold (one of those two big pipes), so I’m hoping I can figure out how to replace the hose clamp without needing to drain the coolant system first.

I don’t think I’ve fixed my sensor noise issue, unfortunately. The log still shows the TPS creeping up, and the CLT and MAT are still a bit noisy. While I set the idle at 185 degrees CLT as read from TunerStudio, the DMC temp gauge is only showing about 160, although I don’t know if the DMC gauge is just not very accurate or what. CLT when cold is about right at 79 degrees, roughly the same as theambient air temp.

On another note, oil pressure is good. Not sure why the RPM meter isn’t working, but I can worry about that later.

Also, the engine appears to be backfiring — at least I think that sound is backfiring. It’s an occasional pop from the exhaust. Happens every few minutes, sometimes a few seconds apart. I’m not sure what to do about that. I’ll post a video of one of the pops when I’m at a computer again.

Thanks!

— Joe

[jangell]

As promised, here's a video of the popping from the exhaust (pop is at ~10 seconds). The ducting I'm using to try to vent the fumes out of the garage are masking any possible flame, so I don't know if there's a flame or not. This took quite a few tries to record; I'd start recording, and nothing would happen for a minute or two. I'd turn the camera off, and then it would pop again.

This happened at a range of RPMS from 650 to 1000 (which is only range I ran in today). I didn't try revving the engine.

https://youtu.be/4YtrZ0L1YBA

Also, the engine is idling a bit rough, in that you can see it visibly shaking around. It's been so long since I had a working Delorean that I don't remember how smooth it should idle. Of course, the idle is still seeking and it's not even remotely tuned, so hopefully that will go away as I tune it?

I've also attached logs from today. I forgot to start logging before the first start, unfortunately.

Thanks!

-- Joe

Warm up and a few stops and starts while adjusting the throttle screw: 2018-08-04_14.19.22.msl
First log, still cold, but after ignition: 2018-08-04_14.27.40.msl

[opethmike]

Shouldn't shake that much. I'd do that unplug & re-plug one coil pack/plug wire at a time test to see if a cylinder is misfiring. That's what it seems like to me.

[jangell]

I’ll do that after I fix the coolant leak and put back together some of the back of the car. Thanks!

— Joe

[FABombjoy]

Megasquirt grounding is enigmatic. Much of the top row is actually grounds - they have the sensor return separate to put some physical space in there. Pins 1, 2, 7-19 are all ground.

I agree with mike on the shaking. Misfire = fuel in exhaust = random pops.

AFRs are better at the end of the log but the RPM instability suggests a physical problem not a software one. Vac leak, ignition problem, etc. Idle is mid 600s and stepper is at 19 which suggests you want more base idle. It's probably struggling at 600 RPM which exacerbates whatever issue is present. My stepper IAC is at max flow around 140 steps so I shoot for as close to 0 at hot idle as possible, which gives me lots of headroom for cold high idle. I have my cold idle target as high as 1400 RPM tapering to 950 at 175 CLT. The 2.8 is clearly a different beast but I found this give a very smooth, modern-style warmup and avoids a particular RPM resonance that gives ya the tummy jigglies during warms up. Prob not an issue on the 3.0. I just wanted to type "tummy jigglies"

Also check your TPS to be sure that it actually works. I pulled out my hair chasing down a TPS issue that I was positive was caused by my wiring. After ruling everything difficult out I tested the TPS. It was bad.

[jangell]

Megasquirt grounding is enigmatic. Much of the top row is actually grounds - they have the sensor return separate to put some physical space in there. Pins 1, 2, 7-19 are all ground.

I think I figured that ground is ground, so it didn't match which pins I used. I'm not sure how true that is here without looking the board, but it's wired up per spec now. But there's still that noise for some reason.

I agree with mike on the shaking. Misfire = fuel in exhaust = random pops.

Yeah... so it turns out I swapped the cylinder 4 and 5 coils when I re-isntalled them after I did the valve re-timing. It was very obvious, since I have labels on everything (I mean, you'd think I would have noticed when I put them in) -- I just didn't know enough to check it again until you guys pointed out that it had to be a spark problem. I haven't actually tested it yet since I spent the deal dealing with that coolant leak, but I'm betting that fixes the shaking and popping.

As for the coolant leak, it's coming from the connection at the "T" to the hot water valve, on the hose where the "T" goes to the engine. After ruining some hose clamps trying to get it tight enough (and partially covering myself in coolant), I finally removed the hose and measured everything. It seems the engine is 3/4", but the "T" is 5/8". I'm guessing the clamps can't compress the slightly-too-large hose enough to keep it from leaking. It seems that Dayco 87613 will do the trick -- a 1' long 3/4" to 5/8" hose meant for a Mitsubishi. I have no idea why my "T" is smaller than it seems it should be, but whatever. I'll install the new hose next weekend and see if it works.

I did get the back end of the car on while I waited for some of the coolant to drain, so I'm closer to being ready to drive it once it idles properly. I still have a few other small things to do first (refill the A/C, which I hope to do once the idle is good, then re-install the passenger seat, button up the parcel shelf, put the shifter back on, mount the engine cover and louvers, stuff like that), and then I can take it out on the road and immediately stall in the middle of a busy intersection.

AFRs are better at the end of the log but the RPM instability suggests a physical problem not a software one. Vac leak, ignition problem, etc. Idle is mid 600s and stepper is at 19 which suggests you want more base idle. It's probably struggling at 600 RPM which exacerbates whatever issue is present. My stepper IAC is at max flow around 140 steps so I shoot for as close to 0 at hot idle as possible, which gives me lots of headroom for cold high idle. I have my cold idle target as high as 1400 RPM tapering to 950 at 175 CLT. The 2.8 is clearly a different beast but I found this give a very smooth, modern-style warmup and avoids a particular RPM resonance that gives ya the tummy jigglies during warms up. Prob not an issue on the 3.0. I just wanted to type "tummy jigglies"

Speaking of vacuum, I still have the gauge hooked up, and I still keep forgetting to check it. I'll look next week, but at this point I'm guessing that it's probably good.

For the IAC curve, at the moment I just stole the one from Josh's tune, which is set to 180 at max flow and 0 when fully warmed up. The engine was running at 600 RPM mostly because I was more interested in not glowing the cats than I was getting to 790 RPM (which I know Mike said to go for anyway). I would have adjusted the throttle screw earlier, but it's under the throttle arm, so I have to turn off the car to adjust it (that, or rev the engine really high). Hopefully with the coils in the correct holes everything will actually work properly next weekend.

The car is loud enough that I"m not sure I want to go to 1400 RPM at cold idle, but I might turn on the thing that boosts the RPM when the A/C is on, since that does seem useful. I know modern cars do run the idle higher on cold start, but I"m not actually sure why they do that. Once it's running I may re-install those silencers and see what that does to the noise levels. I didn't notice much of a change when I removed them, but there was a week between when I heard the exhaust with vs. without.

Also check your TPS to be sure that it actually works. I pulled out my hair chasing down a TPS issue that I was positive was caused by my wiring. After ruling everything difficult out I tested the TPS. It was bad.

I calibrated it when I set up TunerStudio, but I haven't looked at it since them. I can take another look next weekend. Thanks!

-- Joe

[FABombjoy]

Yeah... so it turns out I swapped the cylinder 4 and 5 coils when I re-isntalled them after I did the valve re-timing.

Bam.

As for the coolant leak, it's coming from the connection at the "T" to the hot water valve, on the hose where the "T" goes to the engine. After ruining some hose clamps trying to get it tight enough (and partially covering myself in coolant), I finally removed the hose and measured everything. It seems the engine is 3/4", but the "T" is 5/8".

Oh man, trying to make the mishmash of hose sizes work was frustrating. If the 3.0 has a 3/4 that further complicates it. Nice that you could find a reducing hose!

I still had the aluminum T on my car and wanted to replace it before it broke. The combo of sizes to bleeder don't exist in anything reasonably priced. I found a manual heater shut off valve at Autozone, removed the valve portion, and soldered a barbed fitting to the top.

Cheapass Bleeder.jpg

[opethmike]

It's not that you MUST go to 800 RPM for your idle; 600-700 is still fine. I just prefer around 800 since I tend to run bigger cams in the engines that I build.

[FABombjoy]

I'd shoot for at least the Chrysler spec for idle speed. If you want to go lower you'll want to consider:
Oil pressure
Coolant circulation / temp
Idle quality with AC and/or full electrical load

If you can get closed loop idle control up and going (should be pretty easy) it'll be much more pleasant under transient idle loading.

[opethmike]

Yeah, gotta watch out for those full loads.