FalconZ28

I am getting back into tuning TPIs again after a 2 year lull.

My 383 Vortec HSR is still sitting unused in my '85 Z28. I've been discouraged on that car for a long time due to the complications associated with burning a chip for an '85 ECM.

My new project is a 1986 Corvette, which has a similar setup, only I kept the factory tpi setup with Vortec heads (wanted to keep it visually close to original for resale purposes). I'm getting ready to burn my first chip, and have some general questions:

I intend to purchase some 29C256 chips to burn and install. What accommodations do I need to make in burning the chip so it's compatible with my 1986 ECM? I intend to start with some minor tweaking to an ARAP bin and improving from there once I get an old blown out laptop for datalogging.

Currently, I am facing the following immediate issues that I'm hoping a good chip will alleviate:

1.) Car feels MONSTROUS when engine is cold. Once it comes up to operating temperature, my butt dyno probably pegs it at only 50-60% of the power of the engine cold. Not sure what this is related to, perhaps the engine really loves the cold start injector?

2.) Idle Air Control problems (IAC) - The IAC will kill the engine, especially when hot, at idle. It enters a cycle where the rpms surge to 1000-1100ish, then drop to 500 and lower. Repeat ad nauseam until the IAC causes the RPMs to dip into the 300s and kills the engine. I am certain that the IAC is causing this, because if I plug the IAC pigtail into a "dummy" and lie it in the engine bay this behavior disappears. This was my temporary solution for a long time.

Those are the two main issues. Considering this thing has the stock EPROM, and the following mods, it doesn't surprise me that it's behaving strangely:

355 4 bolt main
Comp Cams Xtreme Energy 270 Hydraulic Roller (w 1.5 rockers)
http://www.compcams.com/v002/Pages/395/XR270HR-10.aspx
062 Vortec heads
Scoggin Dickey Performance Parts TPI intake
Stock runners
Stock plenum
BBK throttle body (58mm?)
Bosch 24lb injectors

Thanks all!

- FalconZ28

Tuned Performance

iTrader: (92)

The prom is comparable just watch your offsets.

FalconZ28

Yeah I thought I might have to deal with offsets.

I'd like to start with one or two simple changes to start. Do you have any recommendations based on my description of problems above?

Tuned Performance

iTrader: (92)

Start with injector constant. Then You might want to look at knock counts and customize your sa.
Watch int and blm then tune your maf tables. Wot and pe with a wb reading.
Just my two cents. The fan switch may need to be changed too. If the fan runs koeo or in run.

Tuned Performance

iTrader: (92)

Here's a good read to get you started.
https://www.thirdgen.org/forums/atta...air-flow-tuned

FalconZ28

Thanks for the link Tuned Performance. I've been scouring that page all morning soaking it all in.

One thing that I noticed regarding the 29C256 chips - they have 28 pins. There are only 24 pins on the EPROM in my stock ECM - so I wanted to verify that I will have to get an adapter to couple the 28 pin EEPROM to the 24 pin socket in my ECM.

I have attached an image of a 29C256 chip I found on eBay for anyone seeing this thread in the future. It always bothers me when I'm finding lots of good information in a thread but someone's photobucket account is expired so relevant photos are missing, hense the attachment via TGO.

Tuned Performance

iTrader: (92)

You should have a 28 pin 27c128 or 27c256 in the memcal. You can solder in a moates.net d2 or use a g1 adapter

RBob

iTrader: (1)

The '85 ECM will have a 24-pin PROM. But your OP states you want to tune the '86 ECM. Which as Tuned has posted uses the 28-pin PROM.

RBob.

FalconZ28

I had my chips and ECMs mixed up.

The chips I have on hand are 2732s, which I originally bought to program for my 85 Z28. I pulled all my tuning stuff of the shelf where they were sitting, and neglected to realize that the chips I bought two years ago won't work in my 86 vette. (24 pin on the 1985 ECM, and 28 pin on the 1986 ECM Memcal, as you guys corrected me on).

So I purchased three 27c256 chips from Moates (along with a datalogging cable) and they should be shipping out some time in the next few days. Excited to get this thing where it feels like it does when it's cold, and not have to drive with two feet because of the IAC doing funky things.

I'll start with ARAP and killing the cold start injector (and appropriate changes that go along with that) and update this thread iteratively from there. I'm very interested in keeping a comprehensive chip burning log for future tuners to reference, much like contents in the link given by TunedPerformance above.

Thanks so far everybody!

FalconZ28

First Chip Update - 9-29-2017

Hello all, I received some 27FS512 and my ALDL cable from Moates.net yesterday, and had the opportunity to burn and swap in my first chip into the vette (thanks to moates.net for the parts and chip offset guide)

Here is the first custom burn, and ECM specs (or what they should be)

Stock ARAP bin
6E mask
1227165_120 XDF file

- Changed Coolant temp highway mode to 160°F

- Disable EGR if MAT <300°F (This was my method to disable EGR, as I assume manifold air temps will NEVER reach 300 unless something is catastrophically wrong

- VATS disabled (When I loaded the stock ARAP file, VATS was already unchecked, not sure if this is by design or I somehow downloaded a file that was already modified)

- Cold Start Injector Disable - I looked up what to do to disable my cold start injector, but since I am using a 6E mask I believe there are not any provisions at all in order to enable or disable it, because it didn't exist on '89 cars. I think that those modifications are only necessary if you are running a 32 or 32b mask

INITIAL RESULTS:

Cold start was QUICK compared to anytime before. I typically crank for 3-5 seconds before the engine finally fires. This was <1 second. After taking a few more drives and testing under different conditions, I will update to see if this behavior is consistent among different starting conditions.

IAC hysteresis: Still present - although I have not been able to get it to kill the car yet, which is a HUGE step forward in my ability to drive the car casually. The idle seems stronger/ healther, although it does still vary between 500 RPM and about 800 RPM. More testing is needed.

Power: Good but the car was cold. Seemed like the engine was happier to rev higher into the RPM range before shifting to the next gear.

Smells: Perhaps all of my senses were hyper tuned since I was nervous about driving around with my first novice chip, but there was a smell I wasn't used to after I parked the car and shut down the engine, I think it smelled a little rich (smell was kinda "sweet" for lack of a better term). Not really concerned about this at the moment but thought I'd mention it in case anyone has insight.

Now I need to buy a POS laptop so I can datalog in this thing. I'm restricted to desktop tuning for the moment. I guess I could always put a gas generator to get 120VAC so I can setup my tower in the passenger seat

Questions for Chip #2: Any other easy flags should I enable or disable in ARAP and 6E that people have found to improve performance, driveability, etc? I'll be ongoing with simple mods as I try to get those BLMs to 128!

- Don

Tuned Performance

iTrader: (92)

To get the cranking time down add .50 to 1-7 crankpw multiplier. You don't need to do anything to eiliminate the ninth injector in $6e. You will need to recurve you maf tables or take baby steps and lower if rich them globally.