Hows it going. Currently swapping an an L31-R with an Edelbrock Proflo XT and Holley HP EFI. At first glance I though I should retain the factory ECM with the swap, but its looking like it will be unnecessary. I thought I needed the ECM to get the ABS and AC to work with the digital climate control but they seem to have separate modules that don't need the stock ECM. Do you guys think it will be better to delete the factory ECM or wire the Holley into it? It's a 1991, it has ABS, and a ZF6. Got a photo of the current status.

 

Not nowing anything about possible replacement ECM I would just be leary of anything that claims self tuning.

 

I have completely eliminated my EOM factory ECM and replaced with the the Holley HP. But I have an 85 and the factory ECM did not do much with dash functions, there is no VATS, etc. on the 85. I also run the Vette Aid dash cluster with the Autometer gauges so I lost nothing there. The Holley HP system is a full stand alone system, I am thinking you eliminate the EOM ECM altogether . It is a MAP based system vs. MAF, so I no longer have a one off MAF sensor specific to the 85 and the worries surrounding that along with burn off relays, etc.

The self learning along with the data logging brings you into 21st century technology ...laptop tuning, etc...I would call Holley and give them your specific application and get the facts which is what I did. Let me know how things go, you have a great set up and it will work great!

 

I also have the Holley HP ecm on my 93 light years ahead of the old factory ecm. The new fuel injector end angle is a great new feature. I kept the old ecm to run the gauges, I think that is the best way. You won't need to wire the holley into the old ecm it will be completely separate, at least it is on my car.
Does the new intake fit under the stock hood? Let us know how this works out for you.

 

I'm running an Accel DFI with my miniram on my 84. The stock ecm is in a cabinet. I have all dash functions except mpg.

 

Not looking into it as much as I should have I decided to delete the stock ECM. I thought all the other computers ran by themselves but I was wrong Now I'm running into the issue of not have a serial output for the CCM? Is there a way to fix this without the stock computer, tricking it somehow? I haven't finished wiring everything, I could be missing a ground for all I know. Only the defrost seems to be working on it, I have two blank lines on the temp readout. I should be done wiring in the Holley tomorrow I'll post an update.This diagram shows where I'm concerned, "800 tan".

 

I am also running the Holley HP EFI System on my 89 with a Lingenfelter SBC 427 with a TPIS Miniram. The self tuning part really does work but, you do need to set the initial parameters so the car will start and idle properly.

If you don't know how to do that find a Holley Advanced Trained Tuner. The tuner I used was able to make a bunch of adjustments for me remotely over the internet. I didn't have to take the car to him.

 

You are misunderstanding the serial data. It is just a communication bus between several components.

The ABS does not care what the radio and AC system are doing. The ECM doesn't care what the radio is doing.

All the 800 wires are outputs to go into a single splice and from there to the port on the ALDL line.

You can run the ABS as a separate entity, and the only thing you need the serial data line for, is to use a Tech1 or Tech2 to communicate with the system.

 

I have a '91 Z07 with an HP EFI in it. I have experimented by unplugging the computer. Here is what I have found. The ABS still works with no computer. The adjustable shocks still work with no computer. The only bad effect I have found is the speedometer and the cruise control do not work. Of course the fuel mileage stuff, etc on the trip computer doesn't work either, even if you leave the old computer in, as it has no injector duty cycle input. That being said, you can make a device if you wish to take the sine wave in from the sensor in the transmission and turn it into a square wave. That will definitely make the speedo work and from what I can tell in the FSM most likely the cruise as well. I have left my computer in place to run the speedo and cruise control. BTW, I can't comment on the HVAC with no computer as I removed my system and mounted the computer on the firewall where the for the AC stuff used to be. Mostly a track car in Colorado so I just don't care about the AC. The cruise is just handy for the long drives to the track. BTW, awesome improvement over the stock unit. I had a Mini-Ram, LT4 Hot Cam, and AFR heads so the stock computer with a mail order tune was hurting Hooked this up and within 10 minutes was running better than the stock computer with the mail order tune.

 

I've been debating for a while now throwing in the Holley HP or Dominator EFI into my '87. You guys are giving me some comfort that doing it isn't so bad. My quirk would be the 4+3 runs off of the stock ECM. I would probably change the shifter **** switch it from a momentary switch to a on/off switch like 85 had and just run it to the relay to bypass the computer functions.

 

So where does the data from the reluctor rings go to? Does the ABS know how to work without knowing speed of vehicle? What about FX3? Doesn't it need to know what speed it is for dampning?

 

The ABS computer takes the info from the reluctor rings and does its calculations of the wheel speed. The ABS is only looking at a few parameters: A) do I have a speed differentail at one or more wheels. B) do I have any yaw input from the lateral accelerometer. C) Do I have any brake input.

The serial data line for the abs just allows you to be able to use a tech 1 or similar to diagnose the ABS.


FX3 gets the speed input directly off of the VSS wiring.

 

Interesting. I was told that for the ABS to work you have to change the reluctor rings.

 

ChumpVette is correct. I can vouch 100% for the ABS working without the computer as I tested that out - plus the FSM says it should given no speed input to the ABS except the reluctor rings.

scorp508: There are programmable outputs on the HP ECU. You can do a lot of stuff with it and there is a lot of aftermarket support on Holley forums and the like. I was just reading something the other day on using them to do boost control for an ECU controlled turbo engine as I own a Rossion Q1 as well and I am trying to help out some of the Noble folks (predecessor to the Rossion) to get rid of the ECU they run that nobody except for two people in the US can tune.

 

When I last looked at the available logic for the programmable outputs there weren't enough conditions to mimic (entirely) the stock 4+3 program. I needed a combination of TPS, RPM, MPH, and current gear selection to really do it up right. I could probably cobble something together.

 

Sorry to Hi-Jack

What are you using for ignition? Does this run batch or sequentiial injection?

Thank you!
Steve

 

Sorry to have taken so long to reply. I use a small cap HEI and it runs batch. Easily could run sequential, just requires a cam trigger or something of the sort for the input signal.

--Calvin

 

I am using a large cap MSD Distributor with the CAM Sync however, my tuner set the Holley HP EFI up as a Batch because it performed a tad better than Sequential.

 

Thank you!

 

..... I run the Holley Dominator in my heap ... I had a 4L60E in it when I replaced the HP with the Dominator ... TH400 now so the trans control is moot ... mine is sequential fuel injection with LS coils ... I use a FAST dual synch distributor for cam , crank signals and to drive the oil pump ... it freaks everyone out when they think they're looking at an LS swap then see a dizzy with no spark plug wires ... I eliminated the A/C and put a 2nd alternator on the brkt to power the Holley ECM ... I primarily drag race the car but it still goes to car events ..... the OEM ECM is still in the car ... the Holley runs all engine controls ... I have a custom dash with analog gauges so I could probably toss the ECM but out of sight , etc. ... Self tuning works really well , it gets tricky when you run a cam with more than 245* duration , overlap puts a lot of extra Oxygen into the exhaust ... I'm still tuning , but the car is getting very consistent at the track ... if I leave the tune alone , I'm within .03 on consecutive passes ... That's actually a lot in terms of bracket racing ...