Ok, the winter mods on the '86L are done. Looks good. Goes good. Heats up too much for my tastes.

Last fall, with a Hypertech and a 160 therm, my temperatures went from 175 (fan on) to 160 (fan off) and back and forth. Now they have trouble coming down and sometimes shoot up to near 200. Fans never go off. I don't want a car that runs that hot. It's an SBC. My '72 Camaro (muuuch hairier) runs at a flat 160 (fans always on). There's gotta be a way.

Over the winter I changed to an Edelbrock manifold, SLP runners and a Prof. Prod. 52cc TB. MAF already gutted, many more free-breathing mods intake and exhaust. So I'm getting more air. I installed a normal gasket for the intake, meaning rear crossovers open a la F-body. I also deleted the EGR (didn't fit under the plenum with the new intake). I haven't attached a LED to the EGR control wires to monitor when it comes on, but I've got a feeling at least part of the issue is the EGR coming on, advancing timing (and leaning mixture?) and producing heat in the absence of exhaust recirculation.

No vacuum leaks I can find with a smoker.

So I guess it's time for a TP or TC with the attendant hardware. I'd like to mount a ZIF socket in an accessible location for chip flipping and emulator connection.

I have the original MEMCAL. Right now a Hypertech is installed in its own memcal, whose packs I haven't checked. I think I can axe the EGR on $32 or on $6E, but $6E looks tempting. It seems I could richen the mixture more easily with $6E by maybe lying about injector size or altering the stochiometric AFR. Question: does the $6E produce a mismatch with '86L hardware? E.g., I don't really want to remove the cold-start injector if I don't have to, but will it just stay off with $6E? Any other potential brick walls I could hit? And are the resistor packs in the MEMCAL for a $32 bin compatible with a $6E bin from 1989?

Or do I even have to richen? Is it all about turning off EGR function?

Anything jump out at anyone? Suggestions welcome.

 

Why so cold ? you will never burn off the condensation for the pan

If you think you are going to be playing around some and don't want to be programming and swapping eproms all the time then get the Ostrich emulator
http://www.moates.net/ostrich-20-the....html?cPath=95

which holds the tune in place of the eprom and connects to the USB port on your laptop.
It can be permanently fixed under the dash somewhere .
You then do tuning adjustments direct off your laptop ; even while driving

Not that I am aware
I have run plenty of 6E tunes on various '165 TPI ECM's without problems


Cold start is purely a mechanically switched device not connected or controlled by the ECM.
When the CS switch sees below a certain engine temp when cranking over it, powers the CSI for a specified time
Easily disabled by disconnecting the switch at front of intake

 

Would that be the injector-style connector on the front?

Also, regarding the Ostrich... does it have battery backup, or would disconnecting the car battery blank out the tune?

 

Is not powered from the car or laptop.Has it's own battery supposedly good for 10 years.

Correct
Brass hex head unit on left of intake

 

The MEMCAL resistors are only used in limp mode which you should never get into in any normal scenario. Limp mode is only entered if there is a catastrophic failure of input signals to the ECM, specifically the FMD IC. One of the uncompleted projects on my to do list is to determine exactly what it takes to get the ECM into limp mode. It's not at all obvious... I've never seen anywhere an explanation of whether the LIMP signal comes out of the microcontroller (not likely, as there doesn't seem to be any code to do this) or the FMD chip. It appears that the FMD chip disables the microcontroller during limp mode and takes over the fuel and spark control.

I contributed to a project that Craig Moates was doing about a year ago to create a replacement for the resistor networks in the MEMCAL. I never heard whether or not that project was completed. His plan was to offer a PC board with spaces for surface mount resistors that could be customized for any application. Check his web site.

 

Thanks guys. Good info. Back to the garage. Looks like I've got the project that never ends, but I guess that's what I got it for. I'll post what I find out (or beg for more help) !

Oz, the 160/175 thing is how the Hypertech chip comes programmed to go with their 160 thermo. Perhaps they have some of the other parameters altered to fit. I like it personally; it's how my other (carb'd) rods have worked, and they've run for years without issue. I'll try to read the chip, though I'm not sure what format it's in.

 

The car from the factory goes into closed loop at 122 degrees, it will run fine at 160 degrees.

 

The average Corvette radiator can't get the coolant down to 160°. You need an upgraded radiator for that. That's why the fans run all the time.

 

That had crossed my mind too, but it ran that way last fall before I made the current set of mods. I also recalled trying to cure the overheating in my other car. I got a new radiator and a pair of monster shrouded Summit fans to fit. The new rad wouldn't fit well (shroud hit the steering box), so I put back the old one with the new fans. Runs now at 160 all day. Still, I have a DeWitt fan in the Vette now with the old aux fan in front running together (what a racket). I'll try the programming before I dig into that. I kind of dread replacing the radiator; looks harder than what I've been used to. Also, my little scanner gives an EGR 'duty cycle' of 100 almost all the off-idle time. I don't know if that means "on" exactly, but if it's tampering with the timing maybe it's a factor.

It'd be nice if a '72 Camaro big-block radiator would fit in the Vette since I have one sitting around now. Bet that would do the trick with the same set of Summit fans. But that's too good to be true.

 

BTW, while scoping out Tunercat, I ran across this page
http://www.tunercat.com/Docs/OBDI_Tune_Quick_Start.pdf

It shows a picture of a memcal that has something or other (looks like surface-mount circuitry) overlaid on the resistor packs. It has a patent number visible, but when I search it I get all hits from Australia. Is this the 'later added knock circuitry' I've read of elsewhere or something? My memcal doesn't have it. Just wondering, since I'm considering mixing non-'86 masks with what I've got for resistors.

 

That is a 1990 and later SD memcal, your 1986 memcal will look slightly different.

 

Thank you! More great info.

A Tunercat is on the way, we'll see what happens. Found out with some searching I wasn't the only one fishing around for a 66-pin ribbon cable to mount the whole memcal remotely, but it seems not to be necessary. Guess my r-pak will work ok with either a $32 or $6e, and I wouldn't want to go newer than that it seems.

 

Prob one of the easier radiators to swap out
Disconnect radiator hoses and trans cooler lines ( unplug coolant level sensor)
Unbolt and remove the top shroud , lift rad straight up and out

 

Yeah, and MAM has a supposed direct-swap (for 5 bills). While I'm at it I might as well replace the water pump. While that and the radiator are out, might as well do a cam swap. I'm going to dig myself another hole