Here is a tale of caution for those of you considering a CIS to ITB EFI conversion.
Earlier this year I met Andy at a local PCA cars & coffee in Soquel. Andy has a 74 911 and he added a wide body kit, rebuilt and swapped in a 3.0L SC motor which he had converted the CIS to ITB EFI. So, given that I also have similar motor work on my 75 Carrera, we hit it off and became friends.
Andy has a friend, Todd, that owns a 79 911 SC 3.0L and Todd saw my ITB EFI set up and decided he wanted that too. Well, Todd paints cars and Andy has a 64 356C that he wanted to get painted (Todd had painted Andy's 74 911 previously and was happy with the result), so Todd and Andy worked out a deal: Todd paints Andy's 356 and Andy converts Todd's SC to ITB EFI.
Andy knows Al Kosmal at X-Faktory.com and decides to buy Al's Option 3 conversion kit (MegaSquirt3 + MS3X expansion board, etc...) because Andy and Todd decide they want to run a coil on plug (COP) set up instead of using the distributor. Andy also decides not to install the Clewett Engineering cam position sensor so this will be a semi-sequential FI with COP waste ignition system.
Since Andy's 74 911 is running an old AEM Infinity ECU, he is not familiar with MegaSquirt and asks me to help with the MegaSquirt tune file set up and VE table tuning duties. Little did I know what I was signing myself up for.
On the first page of Al's installation document is a clear statement about how the target vehicle must be in good running condition or else the ITB EFI installation will become an "advanced" installation requiring more work.
Well, I had never seen Todd's car until I made my first trip down to Andy's house in Salinas. This 79 911 SC looks nice on the outside with a fresh coat of GP White paint and Turbo whale tail spoiler, but beneath that exterior is a car that had obviously been run hard and not well cared for. The exhaust was pretty rusted, the CV prop shafts had inner rubber boots that weren't secured so all the inner CV joint grease was gone, the brakes are completely used up and the shifter bushings and coupler are completely worn out such that the gear shift lever just flops around. Andy corrected the exhaust and CV shaft issues by installing SSI's + a new muffler and new CV prop shafts.
Andy's installation of the ITB's and the EFI + COP hardware and wiring is first rate. He mounted the ECU + a relay board to an aluminum plate and mounted that to the floor pan under the passenger seat. All of the wiring connections are located in the rear shock upper mount cross member area and he used the ground lug on the left rear inner fender (behind where the old fuel accumulator and fuel filter were located) for the EFI ground terminations. Switched 12V is coming from the ignition switch and main relay power (connected to terminal #30 on the relays) is via a 4 gauge cable connected to the battery + terminal at the starter.
The existing wiring is messy as a car alarm system and who knows what else had been added then removed in the past. There are stray wires in multiple places under the front hood near the main fuse panel and under the dash. There is also a ground shut off switch on the battery ground cable with about 30% of the cable strands cut away to allow installation of the shut off switch.
There is also a problem with the alternator which is a replacement unit with an integrated voltage regulator as the original voltage regulator had been removed. The problem is that the generator charge warning light in the dash gauge stays lit even when the starter key switch is in the off position. This turns out to be the reason the battery ground shut off switch was installed.
You probably know where this story is headed....
So before hand, I had set up a tune file using the MS3 sample project in TunerStudio and used the my VE table, AFR table and ignition table values to create those tables for Todd's set up - I rescaled the rpm to 6500 rpm max and I converted the ignition table from 12 x 12 (MS2 standard) to 16 x 16 (MS3 standard). Load sense is Alpha-n using the TPS. The FI is using the MS3X board outputs and is set for semi-sequential. The ignition is using a 36-1 trigger wheel/crankshaft pulley with a Hall effect sensor and a plug to fill the distributor shaft opening in the crankcase (from Clewett Engineering) and Denso style COP units. The ignition outputs are set to COP waste.
I loaded my tune program into the ECU and entered calibration data for the CLT (coolant temp), IAT (manifold air temp) and wideband O2 sensors. We counted the trigger wheel spaces from the case parting line to the crank position sensor, multiplied by 10 and entered the result in the "Tooth #1 Angle(deg BTDC)" field.
Then we opened up the ITB's a bit. Powered up the fuel pump and performed a leak check and regulator pressure adjustment (I set the fuel pressure to 50 psi) without problems.
Then we tried starting the engine - nothing. We spent the next 3 hours checking and retrying. Got a few back fires; otherwise, nothing. By now the battery was low, so we stopped, hooked up the battery charger and called it a day.
I decided to reload / update the ECU firmware so I downloaded the current firmware revision from DIYAutoTune.com to my laptop. I also spent an hour practicing how to perform the Inj/Spark tests in TunerStudio using my car as a test mule.
Several days later, I made the trip back down to Andy's house. I was able to successfully update the MS3 firmware from rev 1.5.2 to rev 1.6.1 and verified the tune file was correct. I was able to successfully test all 6 injectors and all 6 COP units so I knew the injector and COP units were wired in the firing order correctly.
Then we tried starting the engine. This time it started but ran horribly and the TunerStudio dashboard was showing the rpm read out jumping all around and the sync error status light was blinking - it was a mess.
We took a break and headed out to get some lunch. As we went over what we were seeing, we kept coming back to that generator charging light problem. Was the alternator output noisy? I didn't have my oscilloscope with me, but could we isolate the EFI electrical system from the charging system? Then Andy said, why don't we remove the fan belt so the alternator doesn't turn and try starting the engine?
So we went back to Andy's and did that, and the engine started and ran more or less normally, given we still need to verify the timing, sync the ITB's and tune the VE table.
Now a new alternator, new battery ground cable, and a new engine/transaxle ground strap are on order and once received and installed, we can try again to get this CIS to ITB EFI conversion up and running so we can then get Todd's car on the road and use the auto tune function in TunerStudio to dial in the VE table.
Stay tuned....