kickerfox

When it starts warming up around here.

ABdragonVX

Still waiting to find out how you get around the variable intake manifold with your custom manifold.

kickerfox

It will be eliminated. Another thing to consider is the exhaust manifolds/headers. If custom, they will also mess with the VE curve but not as much as the intake will.

It looks like the Isuzu uses Delco/GM electronics so there -may- be a way to reprogram the maps. Since the intake runners essentially just shift the VE to another RPM, I'll consider the tune on my Miata that didn't have a variable intake system. My fuel maps were fairly flat but when viewed as a 3D map I could clearly see the hump where the engine's VE was at it's peak. I don't have the maps anymore but I would guess about 10% more fuel was required. That said, the Isuzu maps should theoretically show two humps since the actuator only has open/closed states. The factory trims should be able to manage a 10% fuel trim (where there is no longer a peak in VE) and also add fuel at the peak in VE, which will be a much higher RPM then is factory programed.

If the programed curves become an issue, and I can't reprogram them, I'll resort to a piggy back ECU like the AEM FIC. I have some experience with it. I used a 1.6L NA ECU to run a 1.8L turbo engine in an MX3 and was able to "piggy-tune" that without any issues. Completely different cam profiles, different intake system, larger injectors, and boosted, yet was easily tuned.

CRO8TIA

lol @ post 469, so you dont check your oil in the 8 on a regular basis ?

kickerfox

Doesn't the engine let you know when it's empty?

kickerfox

Good news! I just got back from a friends house who offered to let me use the 2 car side of his 3 car garage to do my project. Looks like I can get the tear down started soon.

ABdragonVX

You're either an epic troll, or can't read lol.

As for the vim being deactivated...duh lol your making a custom manifold my question was more along the lines of getting the cel to shut off, since it will clearly think the system is working incorrectly. Or am I missing something here?

kickerfox

The ECU might throw a CEL for the solenoid missing. A resistor should fix that. There isn't any positional feedback on the system. The ECU will also see a slightly rich condition but I don't think it's enough to trip a CEL.

ABdragonVX

The Variable Intake Manifold (VIM) solenoid has +12 VDC supplied to one side of the coil, the ECM grounds the other side of the coil to energize the solenoid (ON). The VIM controls the induction control valves that change the length of the intake runners. When the engine RPM is less than 3600 , the VIM solenoid is “ON” and when the engine RPM is more than 3600, the VIM solenoid is “”OFF”. The induction control valves are closed when the VIM solenoid is “ON”, and opened at the VIM solenoid is “OFF”. (info from buster28, planetisuzu)

Guess I just dont see where your resistor is going?

ABdragonVX

I guess if alpine had a supercharger kit back in the day there has to be a way around it.

kickerfox

Your quote is correct.

The solenoid is electronically "low-side switched" by either an npn transistor or a n-channel mosfet. Anything controlled (switched) by the ECU is typically low side switched. If the switch is off, there will be 12v present (if the solenoid is connected). That's one way an ECU can detect if a device is in circuit. If the device is to be removed, a small resistor can be placed in it's place so the ECU still see's the 12v and thinks the device is still there. The other way an ECU can detect a device is by placing a current shunt before the switch. When the switch is on, the ECU can detect a small voltage across the shunt. The only time I've seen an ECU use shunts is with pre-heated O2 sensors. It can measure the current this way and probably detect a failing O2 heater before it goes open-circuit -or- detect the current through the heater as part of a feedback loop to control warm-up time.

I think the impact of vics (variable intake control system) removal is minimal.

The Mazda v6 (KLDE) I used in the sand rail also had vics that had two stages. Both solenoids were failed open-circuit but I didn't have a CEL but it was OBD1. After repairing them, I didn't feel any difference in performance. It sure sounded nice when they opened though. Something along the lines of mmmmmmmmmMAWWWWWWW. Almost deafening considering the cone filter was right behind my head.

ABdragonVX

Well I'm over turning you off the idea. And willing to help, hopefully the Isuzu guys can take something away from it. You seem set haha. Not sure about the current shunt but a dozen beer can do that haha.

WingleBeast

Help? Go take something off his car, it has been 6 months and not a single wrench has been turned.

ABdragonVX

Its winter? Get over it? Lol. Real builds can take years, just can't get over the pick of an Isuzu engine lol

kickerfox

A current shunt is a fractional value resistor like .01ohm. When a current flows through it you can measure a voltage across it. 10mv per amp in that example. If your kid ever wants more torque from those el-cheapo electric scooters, just pop the controller open and look for a ~1/2in loop of #12 wire on the pcb. Run a bead of solder over it to thicken it up.

kickerfox

Hey I started this thread in the end of December. It's been 3. :P Builds take years? I'm not doing a full restoration here. It's just a motor swap.

I would normally agree. I've never owned an Isuzu and it's definitely not one of the brands in my bucket list. It's when I started looking at the engine design that I said "hmm that's not bad" and "omg transmission options".

ABdragonVX

It's just a motor swap....

Sounds like a drivetrain swap to me lol. But I've had a couple lol.

ABdragonVX

My drivetrain swap if it ever comes to fruition will take years lol.

kickerfox

Are you swapping something in your VX?

ABdragonVX

If I keep it for another 2 years ill be picking up a northstar, 4l60e and running the Holley dominator.

kickerfox

I got the garage cleaned over the weekend and will be starting the teardown tonight.

Anyone need any parts? I'll be parting out the complete engine and also selling the 6-speed transmission and ECU. The car runs and drives but, as mentioned, I believe the engine to be failing. It has 74k miles on it. It looks like the trans has been apart. Shifts great.

lastphaseofthis

eh, i'm gonna hate on the izuzu engine as well. a 6g72 or 6g74-75 would be a better choice. and you know all the tuning options out there to make a 3000gt vr-4 500 hp. hell, i'm putting a 6g72 in a 1st gen rx7.

kickerfox

Any supporting reason(s)?

The bits from the front of the engine bay are out. I'll start tackling the engine tomorrow.

Look at all that room! That airfilter/battery support is probably going to go. The battery is most likely going to be relocated to the trunk or placed at the right rear of the engine bay (like a Civic) where the washer fluid bottle is currently located. I have a 1 quart washer bottle I can hide somewhere else. The ABS motor will be replaced with the Isuzu unit.

X7rotor

iTrader: (2)

I spot mountain dew getting it in huh :D

kickerfox

Something has to keep the mechanic awake. :

The engine bay is all prepped and ready for the pull. I still need to unhook the driveline and exhaust but things are moving right along. It might be out tomorrow night.

So now that I have a lot more room to view things... I'm going off *rough* measurements of the Isuzu engine. It was 5 degrees out and a nice yard-walk to the warehouse when I measured it. I may have hurried. The engine looks like it will fit behind the battery support ok but the crank pully and accessories might interfere with it. Hopefully I overmeasured the engine. Width looks good. Exhaust routing looks good. It'll clear the steering shaft anyways.

Some of the Rodeo/Trooper/Axiom/whatevers have the ECU in the engine bay also so it'll be really easy to get it up and running, but, I think it's on the other corner. The instrument cluster will be the biggest headache.

As far as boost goes. I'd love to twin turbo this engine because I have that nice pair of T-25s from a 300zx. A 3.5L should spool the **** out of them. I'm not looking for big boost numbers. 6~8psi would wake it up and the turbos can manage that. Maybe if I have the room I can criss-cross the intake like the zx and keep the low end torque. Maybe I'll wake up one morning and have a billet crank and H-beams in it as well. I'll keep on dreaming of it.

One thing I saw under there, while disconnecting the starter, was how easy it would be to make an X frame to serve as the trans cross-member. Sort of a butterfly-brace. That's only if it becomes hard to connect the PPF to the trans.