1995 Jeep 4.6 Stroker

[mpgmike]

I have a '95 Jeep Grand Cherokee Laredo that came with the 4.0 liter inline 6 cylinder.

Day1_2.png (299.45 KiB) Viewed 3818 times

A popular engine package is to use the 4.0 block and the older AMC 4.2 liter (258 CID) crankshaft for 4.6 liters, with a 0.030" overbore. I built mine a bit different than most. The build requires custom pistons. Fortunately, they are available in mild forgings with different dish volumes. I used a 1996 block for the main girdle support, 2004 TUPY head for the smaller exhaust ports, and it measures out to a 10.5:1 static compression. Furthermore, I'm using Comp Cams Rock Crawler camshaft with more lift and less duration and overlap than stock. Stock dynamic CR is around 7.5:1 and mine is around 9.0:1.

cEng.png (296.02 KiB) Viewed 3818 times

StrokeIn1.png (273.79 KiB) Viewed 3818 times

I heavily modified the cylinder head to promote a faster burn. Sharp edges were seriously radiused in the combustion chamber. I added Somender Singh Grooves. There is mild port biasing to promote better in-cylinder swirl. Finally, I added what I call Powre Lynz to the intake ports. It's like 16 pitch screw threads to excite the boundary layer.

CC1Txt.png (420.36 KiB) Viewed 3818 times

My objective is low-end torque for towing, and fuel economy. Ultimately I want to take it to Roush Labs in Livonia, MI and have the FTP-75 Emissions and Fuel Economy test done on it.

Going from 8.8:1 to 10.5:1 CR, I loaded the fuel tank with 91 octane before the swap. In the heat of late summer, it detonates on a flat doing 45 MPH. Stock timing goes up to 46 degrees BTDC. My best guess is that this engine doesn't need any more than 34. I need serious ignition timing control, which is why I bought into the rusEFI program. In the past I've worked with a MOTEC, Link PC, and MegaSquirt. My UAEFI arrived yesterday, so I'm just getting started.

[AndreyB]

Welcome to the forum! Please make some cool progress and move this project forward!

uaEFI gives your one knock channel, one EGT and one WBO. Do you think you need two/three/six of either of these advanced sensors?

[AndreyB]

Do you have a photo of your trigger wheel? Do you see it on https://github.com/rusefi/rusefi/wiki/All-Supported-Triggers#jeep?

[mpgmike]

I will need the WB O2, but not EGT or knock. Your link went to the Jeep 18-2-2-2, which is what I have. Here is a scope shot I took this morning. Blue trace is CPS, red is CMS, and yellow is cylinder #1 firing. I captured one of these images for each of the 6 cylinders.

Cyl1.png (149.21 KiB) Viewed 3739 times

The stock '95 ECU has 1 ignition coil output, because it uses a distributor. I want to use GM LS Coil-Near-Plug. I cut & welded the coil bracket using 2 factory LS coil brackets. Still have to put legs on it (then sand blast and powder coat it, of course).

cpLS1.png (104.33 KiB) Viewed 3739 times

"scfrontier" loaded his tune for his '98 Jeep 4.0 (installed in an older CJ). I've been looking over the choices he made to jump start my journey.

[mpgmike]

Just shelled out $70 to upgrade TunerStudio MS. I'm going to need the data logging feature at a minimum.

[mpgmike]

I got the ignition trigger Offset dialed in. Used the scope to determine CMS polarity to get coil #1 firing when the distributor was firing #1. Swapped from the distributor ignition wire to the LS coil, one at a time, and the engine ran the same. Waiting for a shipment of ignition parts -- including the secondary wires -- to start driving & tuning.

Wiring2.png (266.74 KiB) Viewed 2936 times

cpReadyToInstall1.png (241.85 KiB) Viewed 2936 times

MountedLoaded1.png (219.21 KiB) Viewed 2936 times

[mpgmike]

I'm waiting on an AquaPulser ignition delivery. Meanwhile, I configured the UAEFI as single coil, output on Coil1. To drive my "dummy" coil, and so I didn't have to modify the PCB, I rigged up an IGBT.

IGBT1.png (264.57 KiB) Viewed 2908 times

IGBT2.png (223.05 KiB) Viewed 2908 times

I could't get the engine to start, with a range of Dwell and timing settings. Frustrated, I cleaned the plugs (wet from fuel), disconnected Connector B (the one with the coil outputs), and jumpered from the stock ignition coil- wire to the coil terminal. Still wouldn't start. OK, I'll remove the IGBT from the coil terminal and make a solid connection with the stock wire. SNAP went the coil terminal stud! Now I have to get the rusEFI working (or replace the coil I won't be using anyways). Jumpered in an LS coil, and with a little fiddling in TunerStudio got it to start and idle smoother than it did stock! Great! Then...CRAP!! The laptop battery hit critically low, disconnected from the rusEFI before I could Burn the latest tune, and shut down. Ran great until I shut it down, then wouldn't start.

While the laptop charges, I made the LS coil more permanent. Also decided to update this thread. Hang on, just checked, the laptop is charged. Back to work.

SingleCoil1.png (269.53 KiB) Viewed 2908 times

[mpgmike]

If anyone is working on something similar and trying to follow all of the bouncing balls I'm volleying, here are 2 other threads I started with questions:

https://rusefi.com/forum/viewtopic.php?f=17&t=2806

https://rusefi.com/forum/viewtopic.php?f=17&t=2811

That said, I know I had the engine running in Single Coil mode on an LS coil yesterday, using B15 Coil #1 output. The battery in my laptop hit the critically low shut down and I hadn't burned the latest settings. The engine ran until I shut it off... then wouldn't restart for anything. After the laptop charged, I went back out and loaded the last tune. Still wouldn't start. Slept, then today checked my connections in my custom LS coil harness. I had Signal Return on cylinders 4-6 but not 1-3. Pulled the harness apart and sure enough, I never spliced that wire! Now I'm wondering how the bleep it ran yesterday with no Signal Return!?! Anyways, now I get to do fun stuff like tuning.

[mpgmike]

After about 10-15 minutes of fiddling with idle settings, the engine quit -- like I turned the key off. Verified no output on B15 - Ignition Coil #1 Output. I changed the setting from Single Coil to Individual Coils and checked for output on all 6 coils. I got output on 2-6, but nothing on #1. Took it into my electronics lab, found #1 output was 30 ohms to ground and about 1k ohms to Signal Return. Traced it back to U103, SN74LVC4245APWR logic level translator.

BadPart1.png (414.2 KiB) Viewed 2759 times

Maybe I weakened it when I fiddled with that MOSFET. When powered down, all of the I/Os should be in a tri-state -- or open condition. Circuit A8 (IGN_OUT1), pin 10 was in a grounded state. All other I/Os were indeed in tri-state. Ordered 5 since they're only $1.26 each on Mouser.

BadPart2.png (317.39 KiB) Viewed 2759 times

[mpgmike]

I think I'm done with rusEFI. I had an ignition output failure. Diagnosed it, ordered replacement part, soldered it in, and got running again. I made a few rookie mistakes and blamed it on myself. Now everything seems to be in order. With the new logic level translator installed, I DIDN'T MAKE IT OUT THE DRIVEWAY BEFORE ANOTHER IGNITION #1 OUT FAILURE!! This time instead of failing to constant ground, it failed with a constant 5 volt output! I'm surprised I didn't blow the fuse.

[AndreyB]

Sorry to hear that you are having a bad experience.

All hellen-family ECUs are using more or less same ignition control circuitry, I would assume that LS coils were used successfully.

Both other designs - proteus and microRusEFI - use tc4427. Please consider adding tc4427 between the board and smart coils.

[mpgmike]

After sleeping on it, I ordered the Ignition IGBTs for dumb coils. The Jeep came stock with a single dumb coil and distributor. For now, I'll replace the logic level translator (again), remove the 0 ohm resistor, and add the driver.

[AndreyB]

Do you still have the exact URL of where you've purchased your LS coils? I would love to reproduce your issue here in NJ.

[mpgmike]

My friend does a lot of major engine work. He swapped a JY LS in a truck. The JY engine came with coils. He gave me the rails off the bad engine. Coils were good when removed. In other words, they are OEM used.

[AndreyB]

He gave me the rails off the bad engine. Coils were good when removed. In other words, they are OEM used.

Does it mean that you had qty 8 at some point? Any chance you could ship me qty 1 or 2? Happy to DM my address.

[mpgmike]

There are 6 physically good coils and 2 that got damaged around the HV wire terminal. I can send you one with a chunk of connector for testing. PM me an address.

[mpgmike]

I boxed Qty 1 GM LS Ignition Coil with damaged tower (but tested and functional), and Qty 1 coil connector with about 4" of wire. It's labeled (AndreyB sent me a PM) and ready to ship. Post Offices around here close at noon on Saturdays, so if I don't make it tomorrow, it will be in Monday's mail (pending some cataclysm like another instant ice age). I must say, I couldn't get this level of support from Jegs, MSD, or even Chrysler Corporation. I feel comfortable sticking with rusEFI and doing what I can to make it work; aside from my frustrated venting.