VVT Swap into 92-Start Issues
 

1992 Miata
VVT form NB2
MS3 Pro PNP 9093
700cc Deatchwerk injectors 0.9ms Deadtime
LS2 Truck Coils in wasted spark -3.5ms dwell 2.0ms durration
Using NB Cam and crank sensors
HellaFab Manifold
BW EFR 6258 Turbo
Stock Intake manifold.

Hello all, I finished building my VVT motor and getting it in the car, went through with first startup today. Getting a really rough idle, seem like its misfiring, missing a cylinder(s). I'm not sure at all what is going on.
I can get her started but the whole car shakes. I've began to adjust fuel but i feel like there is more to it than that. I tested coils and injectors and I can activate each one individually. Im looking for advice for my Spark, AFR, and Relative timing tables. Also does anyone have recomended settings for the DW700cc injectors? Doesnt seem like my settings are accurate

PS: any fellow boosted members in the Portland area Recommend a Tuner?

Below is My tables:

Disclaimer: I suck at tuning. Also, I didn't look at your log or tune.

Here are some basics I've run into doing the swap:

If you haven't yet, check out the work savington did for ls2 coils: https://www.miataturbo.net/diy-turbo...8/#post1380088

Are you wired for sequential fuel? If so, are your tunerstudio settings set up to support? When you used the diagnostic tools, did you get the desired sequence?
Sequential should be

Kris at KO Racing is very knowledgeable, and I've tuned a number of cars through my work, AR Auto Service. We don't have a dyno, so we rent Kris's. We generally come out a little cheaper than KO, but he's able to spend some more time on the tunes.

considering we only have 4.5 seconds of log to look at that's not cranking RPM, it's difficult to give much help. VVT shouldn't be doing anything at idle, feel free to set the four 3* cells to 0, although I don't think that's your issue. With ASE/WUE you're at 160-155% fuel during that log and 11.5afr, so I don't believe it's a fueling issue. However if it is completely dead on one cylinder, the wideband will display really weird numbers. Spark table looks ordinary enough.

How much messing around with starting did you do before this log? I would try putting in a new set of plugs and see if that helps, they may be fouled.

I see you have some more attempts later in the log, catching only 1-2 cylinders. Try cracking the throttle a little more, and as a quick test, setting your injector size to 1000cc.

Also, is your vvt plugged in? It might be causing trouble if you haven't calibrated it yet. You have to determine the cam locations where your car is hitting min & max duty. Also, set up gauges in TS to see if vvt target & duty align.

*Sees Curly on it*

:inout:

Thanks for the reply!

I will look into you guys at AR, I think the motor I bought was your old race motor.

I tried a few cranks to see if i could get the afrs in line but the idle was always rough and misfiring, so it makes sense that the plugs are fouled.
When I tried using the throttle to keep it idling it would run but seem off. Lots of pops. I see hard dips in the AFRs in particular locations

Yep, Dip in ARF and RPM at the same time, spark, so how would I fix that?
It could be my plug wires.

Injectors are all flowing i repined inj3 & inj4 to the Harness for Sequential.

If the Blue motor was replaced by an Ecotec then yes?

Yes the issues I've seen or heard of are usually plug wire connections or bad solders/crimps on the wiring.

Even if they're firing in test mode, doesn't mean that's getting all the way to the spark plug. Or that it's firing well under compression. Check your plug gap too. IIRC, the LS coils are more powerful, however still like a smaller gap, less than the .040" they come with at least. Try .022-.028"ish with some new plugs then start looking at plug wires and wiring connections to the coils.

So i pulled the plugs, 2 of them looked clean and brand new, cyl 1&4. check their plug conections, swapped in new manufactured plug wires and the dead cylinder seems to have gone away. im still getting misfires.
Changes:
-new plug
-new wires
-pulled a degree from ignition map
-set VVT map to 0.0

I can get a rough idle but it hovers at 1700rpm. the biggest thing i notice is that i cannot get my map reading into vacume, they stay at ~100kpa, vacume leak?
with the high idle and the one really loud backfired im leaning toward a leak. i have new intake gaskets on the way in case.

how could i check for fueling issues?

New logs:

could my injector settings be off?

Also, what should changing injectors to 1000cc acomplish? or atleast what am i looking for when i try that?

Changing required fuel to 1000cc just quickly removes ~30% fuel, just in case it's fouling plugs. Its simply 1-2 key strokes quicker than selecting the entire table and multiplying by .7.

With the high idle and funky map readings, I'd definitely look for a very large vacuum leak.

I'm really curious about your motor now. Do you have a blue powder coated VICS manifold and valve cover? Last we heard, that motor was in Colorado. At least that's where we shipped it.

Bump/Update
Maybe I got the spare engine?

Changed plugs and wires. fixed any leaks. I can get some vaccume when the engine is running. Can confirm I am getting combustion in all cylinders. I am still misfiring at lower RPMS.

I have my injector deadtime set at 0.7ms now and than seams to have helped with the fueling a bit but I still need to crack the throttle a bit to get the engine to start.

when she does start I have to keep my foot on the throttle to keep it going. once my foot snaps off the revs drop immediately and it dies.

can anyone help with a spark table to use? i feel like my spark table is too inaccurate at the lower RPMS for the idle to work.

Oh ok, you picked up the disassembled engine from my house? I know the one you're talking about now, yeah it was our back up.

Have you tried more fuel? By changing dead time from .9 to .7, you just took .2ms off the injection time. You're able to keep it running by cracking the throttle most likely because by changing the RPM/MAP, you're changing the fueling and getting more fuel. Try a dead time of 1.1 or 1.2 and see what happens.

Your TPS is also all over the place. Is that you going on/off the throttle constantly trying to keep it running, or do you have a really dirty signal? Almost looks like you have your TPS wired incorrectly. That'll really mess with fueling, especially at idle.

Yeah the TPS is wired correctly I'm just going on he throttle that much. I stay on it too long and It leans out so I haven't to release then catch it before it dies.
ill play with 1.1 or 1.2 her in a bit

Played around with deadtime and she seems to like 0.7 to 0.8 and its been doing better at 0.8. I'm able to get her started without touching the throttle but its still really shaky and unreliable.

im still trying to figue out why i vant get below 70 kpa on my map readings

Ok, remember that's only adding fuel, and a significant amount. But you probably can't get a decent AFR reading while it's misfiring. It's certainly nothing definitive looking at your logs.

What's your MAP reading with the engine off? Should be near 100kpa.

When your RPM is jumping all over the fucking place in your logs, your idle duty % is rock steady. Your AFR is also all over the place, but you've tried more fuel by increasing the dead time and say that doesn't work, which only leaves either timing, compression, or spark. Timing is easy to check, make sure your marks are mechanically set correctly. A leak down and compression test is also fairly easy, just do your research. That just leaves spark, I've seen (quoting 18psi here) literally a billion GM coil swaps have misfire due to bad wires, bad gap, bad plugs, bad wiring crimps, bad pigtails, bad coils, or a combo of all of the above. I'd really look long and hard at all your connections. Even if you think they're good, give them a good tug, if they fall apart, you're doing something wrong. Double check you've got a great connection to ground, great battery power with the key on, and there is little to no resistance when probing from the trigger wire to the correct pin at the ECU.

So plan:
1. I'm gonna recheck my timing I know how easy it is to do it wrong so I'm gonna check that. It's the most likely thing to casue my lack of vaccume.

I think it is this over another vaccume leak b/c she can hold a vaccume according to the logs. I'm just starting to think timing is off.

2. Leak tests. I've don't this alread but after I redo the timing ill try again.

3. Compression test after I reset timing.

P.s. I did check my map sensor when I changed vaccume lines (reading 93-100kpa) and it went right to atmospheric 103.xx kpa. When I do remove a vaccume line when its "idling" I can heap a little suction pop. So that tells me that the intake plenum is pretty well sealed so it must be timing/valve train