ktm

How did you calibrate the gauge? You need an empty gas tank to calibrate "empty". My gauge reads "correctly", though it does swing back and forth over time. I am chalking it up to a sender/stock wiring issue for the time being. I used the yellow wire from the stock harness and connected that to the yellow wire for the gauge. The red wire on the gauge connects to +12 v ignition hot and the black wire is ground.

It's not that they are unreliable but rather in your configuration it is the nexus of all of your power supply. If that relay fails you lose power to everything. Additionally, 75 amp relays are specialty items that you most likely have to order on-line. You cannot run down to Radio Shack, Autozone, Kragen, etc. and pick one up if it fails. You can buy 30 amp automotive relays with ease at most electrical and autoparts stores. Under my scheme, the ignition switch would energize Wolf, J&S, LC-1, injectors, and ancillary components. The ignition switch would also provide ignition hot power to the fuel pump and coils with Wolf controlling the relay grounds. The MBC and IAC use two wires (power and ground) and are PWM controlled by Wolf. J&S can share the same circuit. You can have a 30 amp relay provide power to Wolf, LC-1 and J&S with each having their own fuse/circuit breaker.

A few comments: Make to use manually resetting circuit breakers. If a circuit breaker trips, you need to figure out why. If it automatically resets itself then you could damage the down current components. Ground blocks are nice if everything is in close proximity. That may be difficult when you finally wire-up the system. Eliminate the 75 amp main relay. That is a very heavy duty relay and will be the weak point of the entire system. You do not need a relay to feed another relay (in this case the 30 amp for the coils and injectors). I would use a series of relays. One for Wolf, J&S and the LC-1. This relay will provide power to these systems. Use another relay for your fuel pump as explained below. Use a separate relay for your LS-1 coils as explained below. Finally, use another relay for your ancillary components like the IAC, boost controller, etc., and anything else you may add on at a later date. You need a relay for the fuel pump. Wolf uses the white wire to activate and deactivate the relay. It will energize the pump for a preset amount of time you configure at ignition hot key. I would wire up the coils on their own separate relay. I ran into an issue where I would get a random ignition event in the cylinders upon ignition hot key due to the coils being engerized and having the right residual air/fuel mix in the cylinders. You use Wolf to activate the relay once the RPMs are over 300 (cranking). I have not had an issue since. Wolf and the LC-1 can share the same circuit. I would not add anything else to that circuit though. Good luck with the install.

Minor update. I took the car for a quick spin since today was the first dry day we've seen in a week. It seems to be ok though I was nervous the entire drive. I live at the top of a hill on a dead end street. If the car stalls out 500 feet from home it means a tow. I am happy to report that it drove fine for the 2 mile jaunt. Not a single hiccup along the way. I'll take it out for a longer cruise next week. I would like to thank everyone who responded to this thread. Your insight and comments were very appreciated. Happy holidays.

A few of us are running Speedhut gauges. Much nicer than Autometer and substantially cheaper than their full electric gauges.

Standard electrical problems are not too hard to debug. It's electrical problems that manifest themselves are mechanical problems. It's akin to MS Windows problem matrix. All of the solutions are: shut down, count to 5, then reboot.

Again, check out Isky. He has a 290 duration cam, 242 at 0.05 duration, with a lift of 490. I did not see the LSA, but if you supply him with a stock core that has a LSA within 2 degrees they should be able to get a 110 LSA cam.

Congratulations Ron! I know that first fire-ups never get old. It sounds great.

Not quite though it is a relief. If the problem does not rear its head again in the next week then I'll allow myself to be happy. Thanks to everyone for the input.

Major update. I think the problem is solved. Turns out that I had either a loose connection on a relay or a loose ground for one of the relays. The ground was loose enough that the ring terminals could easily move but still be in contact with bare metal though not tight. I also unplugged and replugged the coil and fuel injection relay plugs (two different relays) while testing out the relays with a spare. I started up the car and waited for the customary shut down. The car ran fine for 1 minute, then 2, 5 and finally up to operating temperature. I shut the car down, restarted it with no problem, and allowed it to idle for 5 more minutes. So far so good.

Isky does regrinds. I had them regrind a P90 cam to their L490/L480 assymetric turbo grind - $125 (IIRC) picked-up. However, he does N/A grinds as well.

Minor update. I replaced the CAS today and the car fired right up. I crossed my fingers and was letting it run to operating temperature, but it never got there. Within 1 minute the car shut off again. I could get the car to fire up each time, have it run for 10 to 20 seconds, and then die. I pulled the cover over the ECU and watched the LED to see if there was power interruption to the ECU. The LED did not falter when the car shut off. When the car dies the fuel pump gets energized again and runs for 5 seconds. I thought that maybe the fuel pump relay when bad so I replaced it with a new one I had in a drawer. The car fired up and ran for 20 seconds and died again. I managed to watch the fuel pressure gauge this time and the gauge did not move at all when the car died (no sudden loss in pressure). I fired the car up again and it ran for 20 seconds. This time, however, it sputtered to a stop. I watched my AFR gauge start reading leaner and leaner. It moved to 15, then jumped to 17, 19, back to 17 and then the car died. I need to take a look at my relay controlling the fuel injectors. The injectors are fired sequentially so unless all 6 control wires from the ECU or the ECU went bad, it has to be a power issue if it is related to the injectors. Tony, I did manage to get the timing light on the car when it was running for 20 seconds one of the times. I locked my timing to 20 degrees in the ECU and measured the timing. It was reading 20 degrees. When the car is running I can increase the RPM smoothly. There is no sputter, no missing, etc. and the AFRs are reading what they should. However, the car will just shut off whether I am idling or around 2000 rpm.

The starter will engage the flywheel, it is just not consistently firing off. Sometimes it will fire off and then die 10 seconds later, other times it will not fire off at all. The problem is that the car will not run for more than 10 seconds so attempting to verify timing is a bit hard.

There is a great thread over at Zcar.com (they do have them on occasion) where someone had the exact same problems as I. He did own an o-scope (Tony you were advising in that thread as well) and his CAS checked out "fine". However, upon replacing the CAS his problems went away. It could be an issue with the CAS and RPM. The electronics in the CAS are 28 years old. It is located in a "harsh" environment subject to vibration and heat cycles. However, a replacement CAS is $63 from NAPA and I have 30 days to return it (the shop is right next to my office). I do not want to just throw parts at it and hope something works, but it's worth a shot. The car will start up occasionally. It will always engage the starter, the fuel pump kicks on and the injectors click. The fuel pressure is 43 psi and does not waver (I tested it by rotating the distributor to keep the pump running). It could still be a loose wire/connection some place and I intend to check.

Small update. I managed to work on the car for 20 minutes tonight while I felt somewhat better. I do not own an O-scope, but I have put my DMM to great use. The CAS sees a full 12 volts and when rotated the fuel pump kicks on and the injectors click. I turned it slow enough not to fire the coils (they are set on a relay to trigger when the RPM is greater than 300). The voltage pulse from the CAS was around 6.8 volts. I also tested the ignition switch and have continuity between the battery terminal and all of the other terminals when keyed to their respective positions. That does not rule out either the CAS or switch since they were not under load. Time to start looking for grounds. If no luck, then I will circle back around to the CAS.

Thank you to all that have responded. I was looking for confirmation of my diagnosis. It seems I am on the right track. I researched this issue for 2 days and the overriding them was that a bad fuel pump can have the exact same symptoms. Runs fine, overheats and siezes. Cools down and you can fire it up again. Repeated running builds up latent heat and it runs for a shorter and shorter period. When I pulled the old pump I ran a bench test to see if it would seize up or if I could hear a change in pitch, grinding, etc. While the pump did exhibit a grinding noise, it ran for a solid 10 minutes without issue. After replacing the pump and seeing the exact same symptoms, I figured that it had to be on the ignition circuit somewhere. I've been sick as a dog the last two days and haven't touched the car. The failure point has to be somewhere that shuts down the entire circuit. One bad coil would cause that cylinder to miss given the sequential setup. The COP setup would have to have a bad common ground or bad power. There are two common grounds, one common power and 6 individual control wires. It could be the grounds, the power, the relay, or the fuse box. Fueling could be an issue as well as they are controlled via a relay and all have a common power. Actually, it could be any number of things along the circuits. Thanks again. Looks like my multi-meter and I have a date.

1972 240z with a L28ET Wolf V500 EMS LS-1 COPs and triggered sequentially (not batch fired) 1983 turbo distributor with a reference hole to #1 cylinder drilled next to the optical slot for #1. No MAF. Fuel and spark table setup using RPM and MAP. TPS is only used for over-run fuel cut. IAT and CTS only used for air temp and coolant temp compensation. Walbro GSL392 pump Aeromotive -10 micron filter post pump Aeromotive -100 micron filter pre-pump Aeromotive A1000 FPR Siemens 757 cc/min injectors triggered sequentially (not batch fired) Engine harness is all "new" wiring as of 4 years ago when I first wired up the EMS. New wires to the fuel pump were run at that time as well. The car has never exhibited these symptoms before.

I am running a Wolf V500 EMS with LS-1 coil-on-plugs. I use the 1983 turbo distributor with a reference hole to #1 cylinder drilled next to the optical slot for #1. The ignition is setup for full sequential ignition and injection. I am not seeing errors on the EMS software screen (synch or noise). It could be a loose ground for the coils, loose power for the coils, loose ignition circuit ground, bad ignition switch, etc. One odd thing I recalled last night was when the car shut off I heard the fuel pump key-on again. I could have imagined it, but if so then that could only occur if there was power interruption to the EMS since the fuel pump is set to run for 5 seconds after powering. The symptoms also mirror a bad fuel pump which is why I replaced the pump and filters.

The problem showed up two weeks ago when driving back from the SoCalROC Show-n-Shine Toy Drive. The show was 45 miles from my house. I've never experienced this issue before this time. About 8 miles from my house the car misfired/sputtered/whatever once. It did it again about 6 miles from the house and again at around 4 miles. When I exited the freeway and came to a stop at the light at the bottom of the ramp, the car had shut off during decel. I managed to get it restarted only for it to die about 600 feet down the road. I coasted into a parking lot and attempted to restart the car. It would not run for more than 5 to 10 seconds at a time for a period of 5 minutes. I thought I may have run out of gas (gas sender unit has been acting up) and once I managed to get the car running one more time I managed to drive it 300 feet to a gas station connected to the parking lot. I filled it up with gas and prayed that I could make it the 1 mile to my house. It ran without a problem at the stop light and all the way to the last major intersection before my house at which point it died again. I only had a 1/2-mile to go to my house and it died 3 times on the way to the house. Once in my driveway it would only run for 10 seconds or less and then die. Not a sputtering shutdown but as though the car was turned off. I managed to keep it running for around 30 seconds by reving to around 2000 rpms, but even then it shut off in a similar manner. I replaced the fuel pump with a brand new unit and installed two new filters (pre and post pump). It is still doing the same thing. I suspect it could be a lose connection at the ignition switch, a lose connection on the ignition circuit, or my fuel pressure regulator. However, when energizing the pump the fuel pressure reads 43 psi. There are times when I cannot get the car to turn over at all. I am asking for other possible causes and to confirm if a faulty FPR could cause these symptoms.

It is part of the ignition circuit.

Sounds like a ground offset issue and not necessarily a gauge issue. If it were truly a gauge issue and a pervasive problem, the 'net would be awash in whining about blown motors.

Only if you really, REALLY want a stroker. There are other choices out there with significantly better power return for your dollar. Power is in the head. With NO headwork, only expect around a 7% increase in power over a stock L28 everything else the same. Given that the compression ratio will most likely increase, you will probably see more than 7%. However, you really need to have the head ported, a matching cam, and the right induction and fueling to make power.

Thanks for the images. I've been contemplating ZGs and wondered how they would look with an IMSA rear spoiler.

Dustin, my temp gauge, actually all of my gauges (6 besides the tach and speedo) function fine and as expected. The temp gauge is rock steady and only fluctuates with engine temperature. I have no idea how your would fluctuate with electrical load since the gauge is a resistance style gauge similar to the stock temperature gauge. If your gauge is truly reading higher values with electrical load, is it instantaneous? These gauges use high-speed stepper motors and I would think that an electrical load influence would manifest itself immediately and the needle would jump.

Right here: http://www.thezstore.com/page/TZS/PROD/50-1451