Well, here is the car I bought

https://www.thirdgen.org/forums/cama...maro-iroc.html

READ THAT AND YOU CAN GET A FULL BREAKDOWN OF THE CAR!

It is a supercharged 87 Iroc 5-speed. It makes 18 lbs of boost now that we have dialed it down until we get the tune spot on... We have the capability to make 24 lbs or so EASILY. Here is the problem... The way the engine is controlled.

Current computer setup

-stock 87 ECM for the main control
-Vortech Super FMU, that raises fuel pressure as boost rises
-MSD digital retard that takes timing under boost
-2 150 lb injecters in the intake tract that is on a seperate computer. They also supply more fuel during boosted applications(the input for this is also branched from the FMU) with a 2-bar map. After reading the instructions on this I think it may be a BEAST to tune)

https://www.thirdgen.org/forums/powe...el-enough.html

Thats the link to the current "extra fuel" for the boost and extra power...

While I'm trying to learn this sytem I think there HAS to be an easier way to tune this thing, than all of these variables...

I was reading about the megasquirt board that would remove the MAF, but he stated I would still need a FMU to increase fuel pressure at a 1/1 ratio. Why can't the MAP sensor read boost and up fuel when under boost?

I have tuned proms with slight succes on simple on/offs and simple setups, although I currently have NO prom burning stuff. I thopught those days were behind me. So that in the fact that no matter what I do I will be starting from scratch.

Any other ideas?

Thanks!

 

Hopefully RBob will respond here, but seemingly the EBL's BPC vs boost would avail such fueling. Albeit FMU used for extra pressure, replace with vrfpr?

Two EBL's hmmmm? As easy to use as they are, that would give a big Megasquirt or AEM a run in value.

The PO/builder posted many, quite lofty, claims most folks question. Not to say impossible, just a tad hinky here & there.

Did the heads get fixed? I would love to see that animal in action as there isn't much left but LSR after being raised on nitro. Yes, that was one of our cars in the avatar. I'll work on getting a shot of the Camaro bodied car in there.

I hope the boss has a clearer answer cuz that puts me in deep water w/my EFI tuning experience.

 

There is one FMU and it boosts FP to both the stock fuel injecters and the 2 ones in the intake tract.

Yes, they are relitively easy to use, but there are just so many variables in this setup I am wondering if there was an easier way to do it.


The car is coming apart this week to fix the issues. Been busy on other things...

I do agree some of his goals are lofty, but the car pulls NICELY. Think it needs a few things to be finished up lie I want it though.

 

Why cant you discard the xtra injectors and buy a set of larger and use EBL? I am not sure how EBL would handle the fact of another system reacting concurrently. FMU is a bit ahh antiquated?

I run N20 system with EBL and it offers some nice features. see dynamicefi.com

 

What is EBL?

Yes, FMU's are very outdated IMHO. Even with megasquirt they recomended I use it still? Why is that? I figured the MAP sensor could enrich fueling at that point

 

EBL= dynamicefi.com

 

edited post #2 that made no sense, even to me.

 

Yes, if i use something like EBL then the other two would be gone. Thats part of my reasoning of wanting to update it is to get only 1 computer controlling everything.

Would EBL still use an FMU?

 

Also...why would megasquirt need an FMU and not EBL?

 

No, at most a vacuum referenced fuel pressure regulator,
I would think.

The EBL is equipped with boost v BPC & timing tables for 2bar MAP's.
The latest version (software) is even more capable.

 

I wish I knew more about boost. But here goes a 2 bar MAP sensor can detect positive pressure. A standard sensor and stock MAP is )-100 MAP whereby 100 MAP is atmosphereic pressure(WOT) and no VAC. Once you get past 100 you are positive pressure or boost. EBL has tables to accomodate yhat 100-200 positive pressure. A FMU is basically a crutch as stock ECU cannot handle boost. So with FMU you are not getting the best it can be. Same on SA tables stock ends at 100 MAP. Not sure on the BPC vs boost but a stock VAFPR timing table again goes 0 VAC to 100 VAC. 0 VAC is atmispheric pressure. so the expanded table can address positive pressure and adjust BPC accurately. It all about accuracy.

Also EBL I believe has more agressive spark retard knock tables when it sees boost.

 

Find a garbage can and throw the Vortec FMU in it. The Super FMU is erratic and will not hold pressure. Get a standard Aeromotive regulator that is boost referenced. Get rid of the 2 "extra" injectors and replace all the injectors with 48lb ones. You can usually find a Holley Commander 950 ecm with wiring, very cheap as it has been replaced by a more modern unit. This will work with a 3 bar MAP is is pretty easy to tune real time with a laptop. That and a wide band O2 hooked up will almost tune itself.

 

You're saying pretty much exactly what I wanna do. It has an aftermarket regulator in the stock place already. Is that not sufficient? I will look into the Holley setup as well...

As far as MAP sensors, I understand how they work, etc. Just didn't understand why the guy from megasquirt was saying that I would need a FMU still. I think that he was just misunderstanding and was meaning I would need CONSTANT fuel pressure, so some type of consistant fuel pressure regulator is what was meant... Anyone confirm?

I do have an AEM wideband that i am installing ASAP. All he had was a narrow band, so I'm truly surprised it is/was as close as it is.

 

Hi There '87 Iroc - with my MAF and a tune and some new injectors (60 to 80's) we can use your GM ECM and tune better than most aftermarket ECM's. Nothing like a MAF sensor to make tuning easy. We can support all the RWHP you are capable of making with that V7 - YSi. No supplemental injectors. Check out my website or better yet just call me: greg 201-891-4690. My email: greg@blowerworks.net

 

email sent...

 

Where is this build at? Any chance on some updates?

 

I also have a 1987 IROC-Z with a Vortech S/C at 23lb's of boost using a TPIS Miniram.

Even though the MAF only handles so much air, The 1221765 ECM isn't capable of handling boost???? You would be better off repinning your wiring harness and using a 1227749 ECM with a 3 Bar Map sensor with a $59 mask to get rid of the FMU and the Timeing Boost Controller. I have never found anyone ((ANYONE)) that can get a tune close enough buy ordering over the phone Proms.. Every engine is different and to achieve maximum efficiency, You need to see what the engine is doing to make appropriate adjustments. Not just guessing over the phone. You can get more info at http://www.code59.org/ about doing this.

 

Well, I do have some updates!

Both head gaskets blown, one piston almost had a hole in it, so the motor is nowq on the ground beside the car.

FMU, FIC are both gone. Harness is out of the car as well and is being converted to a megasquirt system. I chose this for easier tuning and local support.

 

Another option might be going with Holley HP EFI, though more expensive does have a cool learn function plus all the tables seem easy to understand. TraviZ is going to give it a try, hopefully it works out good for him and maybe I'll swap over to it later down the road.

To bad about your car, Zdaddy put lot of money into it, guessing the fix wont be cheap

 

You can also see etching in the wall of the cylinder from coolant sitting in there for so long.

No, the fix won't be cheap, but fortunately I had a fully built 355 ready to go in. Slide in the cam and put the intake on and I should be back together by the beginning of next year. Dropping the car off for some paint work next week.

 

I have sent you an email regarding the engine.