OK. 91 Caprice wagon, 305/TBI. Got a 350 and Edelbrock MPFI, and am doing the 7730 ECM swap. I was under the impression I had a 7746 stock, and the re-pin would be 'easy' (HA!).
Now I'm getting info stating that I have a 6965 ECM and associated wiring. I need to know what I've got to start with before I start to re-pin. I will perform a search on 6965-7730 and see what comes up.

Please help.

 

Get a wiring diagram for your car.
Write down each wire/color/pin #/funct.
Get existing diagram for fbody w/730 from net.
Make same list up or use the list that's on Ludis for 727/730.
Match up pins between ecms and make new list.
Post new list on DIY-Prom.

Making the first list will help out a lot with your familiarity.

 

OK, first off, the 6965 is the same as the 747 for pin-outs.

I have re-pinned, and have a couple questions:

Do I need to change my knock sensor? What year/model should I use?

Where do I find my ESC on a 91 Caprice? Its not behind the brake booster. Is it the 2.5 by 2.5 inch flat box on the passenger fender well? I guess I could trace wire colors.

I see I need to add 2 SYS GND INJ at B6 and B7 on the 730 diagram. Where do I connect the other ends of the wires? Connect them to any ground?

What do I do with the power steering pressure switch wire that is not used? Cap it?

Once I get these issues sorted, I can put fire to it and see what happens.

Thanks guys!

 

Which I have mentioned many times. My stock roller L03 was run with a caprice ecm for a while.

 

The KS and memcal should be for the same size V8.
The PS is not used in the 8D. So just tape them up etc.

 

And the injector grounds? Hook them up to.....?

Thanks for the other info.

 

7747 is the same as 6965 for wiring? That's news to me.

 

Dug through the manual, and found the ESC.

I compared the diagrams from the site, and yes, 7747/6965 diagram puts the pins in the same place.


Still unsure about grounds on B6 and B7 for the injectors. I'll search it......

 

Did the search- looked a little deeper and found my answer. Oh, and its not B6 & 7, but D6 & 7.

Will be working it this weekend.

 

Whats even better, is that I used the 8746 definition file to change the fuel, timing, etc on my old engine. The only change going from the 7747 to the 6965 was to add an IAT sensor. The 1992 harness originally used a 299 which is also pinned the same.

 

So that means 91-93 Caprice folks can convert to EBL without repinning, except for the new uses for some ins and outs, right?

The 6965's stock use for the IAT is pretty lame, though. The only thing that I've found remotely useful is launch mode spark multiplier vs IAT.

 

I don't have an answer for you......yet. It would appear to be the case, though.

What do you mean about the 6965 IAT? I checked mine per the manual, and it is dead, but with the rest of the car not up to snuff, I can't say how it is affecting anything. I never did get a code for it when I pulled them. Not sure if I would.

 

My experience with the IAT is that if I forget to plug it in, I can drive the car quite a few miles before the SES lights. It will eventually set a DTC 23 for low IAT, -40°, but not immediately. As long as the low or high temp threshold hasn't been pegged, I don't think the ECM has a way to know the sensor is not working right.

As far as the ECM's usage for it - look at the latest $62 mask for TC. The ECM doesn't do much with that input. There's a very pathetic and rough table of BPC multiplier vs IAT, but it's only like 5 values and starts at a high IAT (48°C or 118°F). Useless. And it doesn't even make sense. It shows the highest BPC multiplier around 80°C, tapering off on either side. I understand the ramp up to 80°C but why would it lean out the BPC at IATs hotter than that?

The only other thing I've seen in $62 is for launch mode SA multiplier. The stock cal pulls launch spark on high IAT, figuring that the higher intake air temp, combined with up to 5° of tip-in advance, would encourage detonation. So they back off on the launch SA as temps climb.

There is also a max KR multiplier vs IAT. The max KR is specified in a table for PE and non-PE (RPM or MAP, respectively) but upon high IATs, it actually will allow MORE KR, which also makes sense.

 

I hooked up a ground to D6 and 7, and connected them to a post under the dash, verified they are connected to the body, did the ESC splice of C and E, put power to it and tried to light it up. NO DICE. I verified spark, and found that I have no fuel. I heard the fuel pump build pressure and stop. I poured some gas down the TB, and tried again, and it sputtered to life for a second, so I'm thinking I've got something amiss with the injector signal. I will be verifying my re-pin/wire color chart. Is there anything else I'm missing? Something my limited knowledge is not seeing?

Thanks!

 

Searching though the board and found that RBob said:

"All ECM grounds are to the engine"

This may be my problem, having grounded the 2 pins to a body pin that the dash support mounts to(about 18 inches inboard of the ECM on the firewall) I will fix/try that today, and report my findings.....

 

with the key on & engine off, do you have power to the injectors?

 

Had to stay late at work and fix the airplane(747), so I didn't get a chance to do anything last night. I'll have to check a schematic to see which wire/where to check, but I can do that, I think. Any shortcuts from those in the know would be great, though....

 

Does the Caprice have a VATs setup? If not, did you burn a new PROM with it unchecked?

RBob.

 

Checked for power at the injectors and have it. No pulse when my son cranked it over with a meter in the injector plug.

RBob- I do not know. I have the 7730 with a F body Memecal, I think per your instructions. I don't have any burning ability, so to answer your question, no I have not, nor do I even know how to do it. Is this my next step? If so, I am screwed for awhile until I can ge that equipment gathered and get schooled about how to do it. Crap.

 

Once again, a little time in the search mode answered my own questions. I do not have VAT's on this car (did not know what it was, till now!), so is there someone out there who can do this for me so I don't have to hunt down all the chip burning hardware? Or is that prom-begging? If the car originally came without a VAT's lockset, can I get a set from the dealer and install it and have it work, or am I better off going with the VAT's disabled? I see that the dealer keys have 15 different resistance values, and I'd need to go through them until I came up with the one that matches the ECM, and get a key that way. Sounds like either way I'm far from being done. Crap again.....

 

The ECM isn't keyed to the ignition key. There is another box involved. Basically you have two choices: burn a PROM with the VATs unchecked, or get a VATs eliminator box. This box may be found at EFI stores (stores so-to-speak). Try jags-that-run and Howell, they may carry them.

RBob.

 

I didn't see/was unable to locate any kind of eliminator box (I Googled), so I guess I'm looking for hardware to become a chip burner, since I'm pretty sure this won't be the last issue for this project. I figure the VSS will be an issue, due to the fact I'm still running the stock rearend with 2.73's, and the memcal for the Z will not have the setting correct for that ratio. This is just what comes immediatley to mind. There will be more, I'm sure, just from reading all the other nightmares involved in this 'improvement'. Get ready for me to ask alot more 'dumb' questions. This is all very new to me and I'm no computer guru.

Darryl

 

painless wiring sells them too, VAT1, VAT2 are the numbers for 2 of the modules they sell to do anyway with VATS. they will need to know the year, motor, & car the ECM came from.

http://www.painlessperformance.com/viewnews.asp