CIS to ITB EFI conversion

[dannichols1474]

Part 15

Enough about brakes and weight reduction, back to ITB EFI conversion.

During close inspection after dyno tuning, I discovered that the electrical cable from the wide band O2 sensor interface unit (14Point7 Sparten2 Lambda Controller) had swung down and was resting against the left header and the cable insulation had melted through on one side (Ouch!). The ECU was still getting a valid air fuel ratio (AFR) signal so I wrapped the wound with electrical tape and added more cable ties to keep the cable away from the exhaust header. Then I proceeded with test driving and auto tuning as I described earlier, but I knew I would need to come back and address the burned cable issue with a more permanent repair.

It's almost Christmas, the 911 is parked and covered in the garage to wait out the winter so it's a perfect time to make improvements to the EFI wiring. I had three items in mind: Correct the O2 sensor interface unit cable and add a connector between the O2 sensor interface unit and the ECU connector block, add a connector between the throttle position sensor and the ECU connector block, and replace the EFI switched power connector (power is sourced from the relay that originally ran the blower motor).

First, I bought a Weather Pack moisture resistant connector set and crimping tool for 12-20awg wire, 1/2/3/4/5/6 pin connectors. When the connector set came I read the directions and then practiced making several mock up connectors to get down the technique for properly crimping the wire and moisture barrier to the pins and then assembling the pins into the connector bodies (male and female). Only when I was able to make proper, reliable connections with the practice pieces did I start working on the EFI wiring (it took me three tries to get the technique down, plus one more sample on a multi pin connector before I was ready).

I decided to start with the single pin connector for the EFI switched 12V.


Next, I cut the three wires from the throttle position sensor to the ECU connector block and installed a three pin connector.


Finally, I went to work on the O2 sensor interface cable. First I removed all the existing cable ties and removed the electrical tape "bandage" from the melted portion of the cable. Then I cut the cable on both sides of the melted portion of the cable.

Before I proceeded, I re-read the documentation for the 14Point7 Spartan2 Lambda Controller to review the function of each of the six wires in cable. When I originally installed the O2 sensor controller the wiring schematic from Al at x-faktory showed four wires connected (power, sensor ground, sensor heater ground, and linear sensor output signal) and two wires no connect (simulated narrow band output, and sensor temperature LED output). After this review, I decided to install a LED so I could monitor the O2 sensor temperature. One failure mode of an O2 sensor is the sensor heater failing and this LED output will let me know if that happens - the LED blinks slowly if the temperature is low, blinks quickly if the temperature is high, and stays on if the temperature in okay. So on the ECU side of the O2 sensor interface connector, I stripped back the cable sheath about 12 inches and I installed a six pin female connector and clipped the blue sensor temperature LED output wire. Next, I made up a ground wire and connected it the frame of the electrical panel at the left rear of the engine bay. Then I installed a two pin female connector for the clipped blue sensor temperature LED out wire and the LED ground wire I had just installed. I then re-wrapped the O2 sensor interface cable with electrical tape allowing for the two LED wires to branch off the main cable.

I installed a six pin male connector to the O2 sensor interface side of the interface cable. I soldered a blue LED to two wires and installed a two pin male connector (the positive LED output is attached to the longer LED lead and the ground is attached to the shorter LED lead). I used adhesive backed cable tie mounts and cable ties to re-install the O2 sensor interface unit and route the O2 sensor interface cable up into the engine bay through the hole in the rear engine mount that was originally used for the secondary air injection air pump plumbing. I slit a piece of vinyl tubing lengthwise and installed it as a grommet for the hole in the rear engine mount. I used adhesive backed cable tie mounts and cable ties to secure the O2 sensor interface cable and the sensor temperature LED to the rear engine mount.





I checked and rechecked all of my wiring connections. I checked to make sure the fuel line connections to the fuel rails were tight. I installed the velocity stack / air filter / rain hats. I lowered the car off the jack stands. I connected the ground cable to the battery. I connected my notebook PC to the ECU with the TunerStudio application running. I turned the ignition switch on - checked for fuel pressure and no fuel leaks. The blue sensor temperature LED was blinking slowly (low temp - engine isn't running). I opened the hand throttle a bit and checked for neutral, then cranked and started the engine. After about 5 seconds running the blue sensor temperature LED was on steady (okay temp) and the TunerStudio gauge cluster showed the system was operating properly. I cracked the throttle a couple of times to verify the throttle position sensor was operating properly. I ran the engine for about 15 minutes then shut it down.

[dannichols1474]

Part 15 continued

With moisture resistant connectors added to the throttle position sensor cable, the O2 sensor interface cable and the switched 12V supply I gain two benefits. I can now remove the engine / transmission without disturbing the EFI electrical wiring at the power distribution panel and the EFI electrical connector blocks located at the front of the engine bay and the EFI system is less likely to suffer moisture induced problems when driving in wet conditions.

[al lkosmal]

Dan,
Keep up the good work and Happy Holidaze.
regards,
al

[NickW21]

This is a great thread Dan and one I'm using to help plan my work on the same project over the winter. I had some questions for you as I begin to plan out the work:

1. In the beginning you mentioned that you drained all of the gas from the tank. What was the rationale for this? I don't know when/if my tank was replaced, but would rather not get into that mess unless I need to I assume I do not NEED to drain all fuel from the car, but will do it if I have to!

2. Do you have any pictures of the mounts you made (or purchased) for the new fuse block/bus and vacuum & fuel linkages? Trying to find something online that I could use as I really have no tools/skill to be fabricating anything like that lol

I'm sure I'll have a million more as I get deeper into it. Wish me luck! I'm gonna need it!!

[PeteKz]

NickW21: Do you have a reason to think that your gas tank has crud in it? If ain't broke, don't fix it.

[rwest]

I’ll add that the rear fuel filter is much higher than the fuel tank, so undoing the fuel lines to the engine will only spill fuel in the lines, not drain the tank.

[NickW21]

That's for the feedback gents! No reason to think the fuel tank has crud in it other than it's a 45 year old vehicle and I've no record of if it was replaced

That said, I can't really afford to replace that now. So, I'll assume it's fine since I've no issues since I've owned the car.

I will say that "If it ain't broke, don't fix it" clearly isn't my MO, since I'm replacing a perfectly functioning CIS system with EFI

[TheBrokePilot]

Do you know if the RHD/ X-Faktory ITB's would have the correct spacing to fit a Carb or MFI airbox on top? Would have to custom make a mounting plate but maybe it could work.

[NickW21]

Originally Posted by TheBrokePilot

Do you know if the RHD/ X-Faktory ITB's would have the correct spacing to fit a Carb or MFI airbox on top? Would have to custom make a mounting plate but maybe it could work.

I think you'd have to go direct to RHD if you just wanted the ITBs. I'd probably look into PMOs or Webers if you're going to run carbs or other MFI. I saw a video recently, where this guy used a 3.2 intake on an EFI setup and he had to get spacers for it to work. I forget where he got them from, but if I find the youtube link, I'll post it here.

Not sure there would be any need for any custom mounting, though, since the engines work naturally with carb/MFI. Perhaps I'm misunderstanding the question?

[TheBrokePilot]

Originally Posted by NickW21

Not sure there would be any need for any custom mounting, though, since the engines work naturally with carb/MFI. Perhaps I'm misunderstanding the question?

I'm just talking about using the OEM Airbox from either early carbs or an MFI engine on top of the RHD ITB's instead of the weber style carbon rain hats. I like the look of the Carbon rain hats but just think it would be cool if you could make it work. In the quote below the OP used a OEM Plastic airbox, modified Zenith airbox mount with PMO ITB's which I believe mirror weber carbs sizing.

Originally Posted by rswannabe

[al lkosmal]

Originally Posted by TheBrokePilot

Do you know if the RHD/ X-Faktory ITB's would have the correct spacing to fit a Carb or MFI airbox on top? Would have to custom make a mounting plate but maybe it could work.

The RHD units are straight, direct to head style vs the Weber/PMO manifold that reduces the spacing down to fit the throttle body spacing......MFI does this to some extent, as well.......so the RHDs would definitely require some custom work. However, PMO EFI/ITBs will work as shown in this thread.... and i have sold and installed EFI kits with PMO/EFI and early carb filter housings...just needed to make the baseplate holes larger if I remember right.

regards,
al

[Showdown]

The airbox will not fit plug and play but as Al pointed out, the RHD parts are kind of modular and there’s a large baseplate that bolts on to the main ITBs that could be modified to accept the airbox. It’s totally possible and I’ve considered it but I don’t really want to spend $500 on an airbox just to find out.

[dannichols1474]

Hi NickW21,

I started off with the fuel tank just to make sure I had a clean fuel source for my new ITB EFI set up. As it turned out, the tank was clean but I gave it a detergent wash anyway. I did a sympathetic restoration on my late uncle's 356C in 2021 and that car had sat unused for 30+ years so a tank clean, etch and reseal was absolutely necessary.

Regarding the mount brackets for the EFI power fuse block, the fuel pressure regulator and the intake vacuum plenum, I used some flat 2 inch wide 1/8 inch thick aluminum stock I had left over from another household project. I bought the aluminum flat stock at Home Depot and I used aluminum because it is light and doesn't rust. The fabrication was really simple: drill holes at the top end of the bracket to mount item to the bracket, then drill holes at the bottom end of the bracket and in the rear shock absorber mount cross brace and attach the mounting bracket to the cross brace with sheet metal screws.

Good luck with your project!
Dan

[dannichols1474]

Hi NickW21,

Here are a couple of photos I just took of the mounting brackets:




Dan

[NickW21]

Awesome. Thanks Dan! Did you replace your engine harness? I've got some sketchy wiring that's rock hard and since I'm doing an alternator replacement also, I already am in need of changing up some of the wiring. So, I might bite the bullet and get a new one made (or try making one myself)... I've finally got the "easy" part done. Getting the monstrous CIS out of the car!

Next step is to do some MUCH needed cleaning of the engine bay!!

[dannichols1474]

Hi Nick,
I did not replace the engine wiring harness on my car, but I did unwrap the harness and CAREFULLY modified / removed wiring that was no longer needed or repurposed (example: I used the blower motor power wire for switched 12V to the new EFI fuse panel) - I really spent a lot of time studying the wiring diagrams I bought before I started working on my car. You might try sending Al Kosmal a message as he knows of sources that can supply custom replacement wiring harnesses. All of the wiring necessary to connect the ECU to the engine (MSD box, Pertronix in the dizzy, O2 sensor interface box, ECT sensor, TPS, fuel injectors) was either supplied in the kit from Al or I made myself.

Dan

[al lkosmal]

Nick,
If you are thinking of having an engine harness made, contact Dennis Powell....(timmy2 on Pelican)
He builds all of the harnesses I provide with my kits...excellent work.

regards,
al

[chrismorse]

Originally Posted by al lkosmal

Nick,
If you are thinking of having an engine harness made, contact Dennis Powell....(timmy2 on Pelican)
He builds all of the harnesses I provide with my kits...excellent work.

regards,
al

Dennis did a nice replacement harness for my CIS - to X-Factory efi change.
Do it again in a heartbeat.
:-)
chris

[PeteKz]

+1 on Dennis.

[NickW21]

Originally Posted by chrismorse

Dennis did a nice replacement harness for my CIS - to X-Factory efi change.
Do it again in a heartbeat.
:-)
chris

Have any pics of the engine bay with harness you could share? Always like to admire a clean engine bay

I am going to try on my own first. I really enjoy a good challenge. When that likely fails, I'll reach out to Dennis