BurnoutC4

Hey guys, I have a 1986 C4 vette, I am about to build a new engine for it. Heres the build
377CI Stroker
Dart SHP block
AFR Aluminum heads 2.08/1.60 valve 210cc intake runner 75cc chamber
Scat 4340 forged crank 3.75" stroke
Scat H beam rods
Forged aluminum flat top 4.00" pistons (9.1 : 1 CR)
Hydraulic roller cam 230/244 duration @ .050 lift, 112 LSA .510/.540 lift
Roller tip and roller pedastal rockers
Vortech V2 supercharger (Wont make any more than 5 psi, probably wouldn't have bothered with it if I didn't already have it from a different vette i used to have)
Aluminum flywheel
Doug Nash 4+3 (yes I know, I don't expect it to last, hopefully it will last long enough for me to get a 6 speed)

I am looking for a good knowledgeable TPI tuner, I am located in Connecticut, but I would be willing to travel a reasonable distance, and one thing i want in the tune is to have any automatic function of the OD unit disabled, i only want it to be engaged or disenaged by me with the button.

Thanks in advance
Marc

tequilaboy

Big topic. First things first, 1986 presents some unique challenges due to datalogging issues and 4+3 differences compared to 87-88 cars.

1st question: Are you able to log 8192 baud data with TunerPro and/or DataMaster in the car now with the current configuration?

If the answer is no, do you have access to Diacom and an old pc with a floppy drive? An old Compac portable would be cool if available.

Assume the answers to the above questions are no. If yes, post a log and explain how success was achieved.

If no to all of the above, there are a few possible paths to follow to get to a tune-able configuration before the fun begins.

I would suggest moving to an 87-88 $32B based bin and repinning the shifter switch from pin C8 to C7. This will solve the logging concerns and give you normal control of the O/D via switch. Note: with this approach, there is no way for the ecm to detect 1st gear, so O/D will also be available in 1st gear. This is not a big concern if you intend to control (mostly) manually via switch. The O/D can easily be configured off by default in the bin.

86 ecm pins:
M/T O/D Shifter switch: C8
O/D TCC Control: A7
A/T O/D switch: C7 (open in OD,N,R or P)

87-88 ecm pins:
M/T O/D Shifter switch: C7
O/D TCC Control: A7
M/T 1st gear switch: C8
A/T O/D switch: C7 (open in OD,N,R or P)

4+3 specific tuning is a matter of preference. Retaining some 4+3 automatic control (when activated) along with sensitive kick down settings is a good thing to protect the O/D from excessive torque.

I do have a method for disabling O/D once it has been deactivated automatically, which I would recommend due to the lack of 1st gear detection capability and resulting lack of 1st gear look ahead ok flag setting.

Tuning considerations for supercharging is also a deep subject (hardware and software). More to follow on this topic.

I realize this does not answer your question directly, but you can probably see where I'm going with all of this...

BurnoutC4

I appreciate the fast response. To answer your first question, I don't have any access to datalogging equipment, other than an old PC with a floppy drive.


The info in the 4+3 is very helpful, I will repin the shifter switch, I don't mind that it won't detect first gear because I don't intend to use it at all unless im in 4th. However what do you mean by $32B based bin? The car already has a 1988 (automatic car) ECU in it from a vette I no longer have (with the chips switched) because my 1986 ECU has a problem with the MAF burnoff circuit. That being said they did have identical part numbers


I was looking to find a recommendation for a tuner in my area (CT) or reasonably close to, because I don't have the equipment to tune with. If you know where I can find it, though I don't have any tuning experience I'd be willing (though hesitant) to give it a shot. My electrical expertise is really more based in diag/repair and wiring more than custom tune. The last car I built beyond standard bolt ons was a 1985 monte SS, and I ditched all the electronic carburetor ******** for a holley, so all the tuning was mechanical.


One thing I was wondering about was is there a limitation on the tuning capability of TPI ECU chips? And if yes will my built exceed that? someone locally was telling me I should get a standalone unit (Fast 2.0) but he also doesn't have the capability to tune TPI chips, so he may just want me to buy a system he can tune. He didn't specifically say that the current ECU couldn't be tuned, he just said that HE couldn't.


Like I said even if the tuner is outside of ct, I have access to truck and trailer and am always down for a little road trip

BurnoutC4

I may have answered one of my own questions, when you said an 87-88 $32b bin, you meant an 87-88 chip I assume. because I looked at the 1986 and 1988 wiring diagrams, both pins C7 and C8 detect open/closed switches so I would figure (and correct me if I'm wrong) its in the chip where it knows whether C8 is detecting 1st gear (88) or OD select (86). and I don't see C7 being used on then 86 manual car. So really I more need the 88 chip not so much the ecu? because I believe the ecu itself is the same


The reasons I want to disable the OD auto function are:
1. It drives me nuts when I go to grab 2nd just after the car hits 122 degrees and it up shifts on me when I don't expect it and lugs the engine.


2. I see no reason for it other than for an additional gear after 4th, I've always kept it off in the first 3 gears.


3. SK speed (who built my OD unit) told me that it wasn't really designed to take the load it puts on it on an auto upshift and that I should use the clutch and treat it like 5th gear, especially when used on a modified car.


So if its all controlled by me (and defaults to off until I hit the button) maybe I can get more life out of it before it blows apart and I go 6 speed

tequilaboy

The 86-89 Ecms are the same, however the software mask (or layout of the data and control code) along with the programming differs somewhat between 86, 87-88 and 89 bins.

With supporting hardware, software and fuel delivery, the 165 ecm can support up to approx. 1000 hp without major compromises.

The auto upshift can be hard on the OD clutch, however this can be mitigated with tuning.

For example, my own forced upshift is set for ~130 mph. At this speed in 4th gear direct, the torque has already fallen off considerably, and it is also in the vicinity of my fuel cut rev-limiter setting, so by coordinating the upshift and the rev-limit, the upshift can be torque protected like a modern automatic transmisson.

Granted, its is not an often occurrance to be at WOT at 130+ mph, but it is plausible. I'd rather have it upshift as opposed to bouncing off the limiter until I remember to push the button.

BurnoutC4

ok great, that makes me feel much better to know that I can work with the ecm I have. Can I use the chip from the 88 car and have that one reprogrammed? (my old 88 was automatic).


I agree about the forced upshift at 130mph, it would be beneficial to my own longevity to not have to focus on the button at that speed.


Hopefully someone can point me to a good TPI tuner. I am waiting on an e-mail back from a place an hour from me. They won't do business over the phone only e-mail, hopefully i'll hear back Monday.