95PCTBK

i need to find witch wire activates the fuel pump so the holley box can control it. its a 1995, i would like to use the factory fuel pump relay.

tombrammer

I am really interested in your holley efi install. Are you going with coil on plug or somehow using the opti? Are you doing sequential fuel injection or batch fire? Are you installing a crank trigger or simply using the holley to do the fuel only? How will you keep the stock gauges and ECM happy for sensor connections like the engine temp, TP sensor, MAP sensor etc.?
I have a 93 and don't know if a 95 is the same fuel pump wiring but per 93 FSM it is ckt #465 Dark green/white wire from the ECM connection D7.
Why are you going with the Holley ECM, did you ECM fail, or is it for control of Nitro or another reason, thanks for the answers in advance and good luck on your project.

esham

95PCTBK

24x relutor and vortec dizzy for 1x cam signal. i did the single plane intake swap. i hope all the gauges work except the fuel mileage. the holley unit takes the place of the map,tps, iac, cts, and the coil on plug set up. also need to address the fans also. can the cts be spliced inn to get a reading back to the stock computer for the digital reading

tombrammer

Are you going with the holley coils? What intake did you use, is it the GM LT1 carb intake or something else, there are not many options for the LT1. I can't remember what the cts is, remind me?

95PCTBK

coolant temp sensor, ls coils and the super hurricane intake. nitrous outlet elbow

tombrammer

Did you ever find your FP circuit?

tombrammer

Keep posting your progress here is you would because I for one in really interested in how it goes probably others are too. I am having issues with my 93 right now which make me think it might be the ECM, one bank of my engine is running very lean, the other normal. 02 sensors are heated and new, new injectors and when I data log I get the same (very close anyway) BLM's for both banks, I can't think what else would cause that except the ECM. The ECM's for the 92-93 are impossible to find and I am suspicious of repair.

umrpunter

how did this setup turn out? I for one would love to remove all the LT1 related engine controls for a simple self learning setup like the holley. Be so much easier to troubleshoot and control!

tombrammer

Since I last posted here I have converted to the holley hp efi with a holley 60-2 crank trigger with LS coils. It does away completely with the opti. It is a steep learning curve but an amazing system once you get it set up. Plus the fuel is self learning. The hardest part for me was figuring out that there is a delay in the reading for the 02 sensor sense it is mounted in the collector on my LT headers. Once I figured that out I was able to use the data logging which is incredible.

TorchTarga94

Can you make a thread on this and document everything with pics and possibly prices? This is great news for all of us LT1 People. I already have the LS coils so I am curious how much more work is required to fully ditch the opti.

umrpunter

oh this is awesome! would you mind sharing a bit of detail on the project? I have a 92 with 160k on the clock and the opti is factory original (and timing chain is slack). I will be taking apart the whole front end and doing quite a bit. Seems like a good time to put in a similar setup if it works nicely.

C5rider

Just installed an HP in my '85. It's not a NORMAL 85 though. We put a 92 LT1 in it a while back and used an 89 ECM to run it from a crank trigger. It also has a Vortech V3 T-trim supercharger kit on it as well.

Had to go into the Opti, so we figured it was time to do it right. Installed the HP and wired it into the rest of the car. I got the unterminated system and we used the Holley wiring for the engine and sensors. The only modification we made to the harness was for the power supply. We swapped the relay and fuse so that it was closer to the battery, instead of closer to the ECM.

We control the HP from a modified Opti wheel. I got the Opti from Petris Enterprises and Lane Culver was the man doing the math to make the opti wheel work with the Holley unit. I've driven the car around a bit and can say that the Holley HP is an amazing improvement. Being able to tune it on the fly and even allowing it to tune itself is MUCH better, especially if you've modified your car. We're using the HP to control lockup in the trans as well. I've got a 700r4, so it's TV cable driven, the HP only controls TCC. If I had an electronic trans, the Dominator would have been the unquestionable choice. Took a little bit of tweaking, but I really like where it's set right now.

We had a crank trigger on the front of the engine, but it was SO close to the steering rack that I needed to slide the belts sideways to get it between the rack and the trigger wheel. Using the Opti to drive the HP gave us so much more room to work up there and cleaned up the install greatly. We also used a single MSD coil with the HP directing the spark via the factory GM ignition module. It works fine.

Only hangup was we were getting an issue trying to run it in full sequential mode, as the cam sensor was giving us fits. We went to "untimed sequential" and it works fine. Still trying to find out what the issue is there.

We dyno'd the car at Culver Automotive Specialties and it wrangled out 434hp at the wheels. Not too bad for my little 85.

odxr

There have been many efi systems out for years.The ecm box is basically just a processor chip and some memory chips .Going from Pectel and Motec to build it yourself circuit boards in a Megasquirt.The difference is the software that comes with it.Can the end user actually figure out how to program his car without being an engineer on a F1 team?If you combine better software+ wide band o2 sensors+ modern fuel injectors you get a better running car-this is what the newer systems like the Holley are about.Its the quality of the installation that will have the most effect on the reliability of the system.Alot of people try to cheese out and refuse to build a new wiring harness+new connectors+new sensors for the system.There are many places to get new pigtail connctors and sensors cheap-try Rock Auto.Most aftermarket efi systems use GM sensors.Having some kind of forced induction engine makes switching over to a modern efi system pretty much part of the game.Some the aftermarket efi systems can use the opti waveform output for a crank-cam shaft position sensor.More than likely if you quit using it for a distrubutor and just get timing signals from it it will work fine.The other problem with Vettes is that the ecm was used to drive the instrument cluster.I have seen some installs on early c4's where the owner just ripped out all the old gm stuff and replaced the dash and efi system with all aftermarket parts.There are efi systems that can drive an aftermarket lcd instrument display with just 2 data wires from the engine ecm,I am installing a 5.3 ls into my beater c4 and I will have NO gauge wiring.Just a code scan chip plugged into the obd2 data connnector bluetoothed to an ipad.Less wiring=cleaner install.I have been working on cars for 40 years + I some college course work in electronics.The import guys are a little more into tech than the V8 american muscle guys.To you members that did your own install please post if you built a complete new harness for the efi-how are you driving your gauges-what are you doing for crank-cam position sensors,

C5rider

odxr,

We're using the opti sensors for timing and for firing. We installed the Petris Enterprises opti that is modified to use the later style ventilation. I think this helps greatly in keeping the distributor cooler and for longevity. We'll see.

I know the Holley HP system can use a DIS system or various other means of firing each cylinder, and they have their benefits as well. We chose to use the factory-style ignition, including a single coil and the ignition module. It works fine.

As for the wiring, we used an all-new harness supplied by Holley. Since my application has some quirky placements of parts like the throttle body, I chose to go with the unterminated harness and then trim to fit. The nice part was that it came with all the necessary terminals and connectors, you just need to put them on. Wires are clearly laid out in the schematic, and I spent a few minutes putting the various sensor wires together before installing the harness and trimming to length. Only thing was pairing up the 5v reference wire and ground(s) necessary for the sensors. Not a big deal.

When it came to wiring the new ecm to the rest of the car, we accomplished that right at the connectors under the dash. We used the connectors that were already there (right by the factory ecu) and tapped into the particular wires that were still to be utilized. It was a bit intimidating at first. But with a service manual and Chris pulling me back from the edge a few times, it really is pretty straightforward. Overthinking it was my biggest enemy. I went through and made a diagram of each connector and what each wire did. Then, we matched up the wires from the HP that needed to control something in one of those wires.

One thing that Chris suggested that varied from the original Holley harness is that we pulled the injector power from the heavy power cable for the ecu and instead used the original power wires in the original connector for the injector power. This is a fused circuit already and there are two different wires, so we just used one wire for each bank. This way, the fuel pump is on the original Holley fuse and relay, while the injectors are on separate fuses up in the fuse panel.

Here's a photo of the HP wired into the original harness connectors. You can see how many wires were not used from the original harness compared to how many come from the HP. We used the factory dash and all systems work fine, save for the average fuel mileage and range. Oil, tach, water, etc. all work fine. Well, except that my gauge panel needs some help from Batee! LOL! Will work on that next. We did have to run wires for the speedo, since they disappeared with the old harness.

95PCTBK

C5rider

Here is the story of our install into our '85. Remember, NOT a typical 85.

Just thought maybe someone might come across this thread looking for info and wanted to make their search a little easier.

http://www.corvetteonline.com/tech-s...h-a-holley-hp/