7169 ecm ?

[jim_in_dorris]

The ECM is out of an 86 Monte Carlo 305 auto with CCC. My buddies son is dropping in a 350 with a very mild cam and needs a new prom. Where do I locate a BCC for that? Will TunerPro work to log? He is keeping it as close to stock as possible because it must pass CA smog. I looked through the listing here and didn't find a 7169 even mentioned. Am I going to have to pull the prom on his car and change the displacement? I hope not, but we will probably need to have an adaptor stuffed into it if I can't find a prom. The chip in the ecm is a rom chip, no window.

[EagleMark]

I've never seen anything for them? May be able to find a prom for a 350? But then I don't think the ECM is that smart, it just adjusts fuel via O2 sensor, still controls spark. I'm starting to have a panic attack just thinking about those CCC... Car industry forced into goverment regs before technoigy was ready so they built a patch... those were horrible years? Looked at my sons 1985 Toyota manual and that year has a carb with 17 miles of vacuum lines and 3000 thermal switches, the EFI model is stripped bare...

You can add TBI and go through ref as a 1987? motor transplant. Done that before... been years since I've dealt with CA smog Nazis though so check todays law.

[jim_in_dorris]

After some reading on thirdgen, it looks like the best bet is to find the 87 monte carlo l69 ecm and just swap, although it appears that the computer is so primitive that swapping in a 350 and using the stock ecm won't phase it.

[EagleMark]

Was there any mention of fueling tables? I know it does spark, it like half an EFI system, but thought the fuel end was just on/off and handled by that thingy on carb.

Your a brave man! I like a challange, but they were a challenge when new... all I remember was when it passed emmissions it ran like crap, when it ran good it would not pass emmisions...

I'm just curious as to what you find, let us know.

[1project2many]

Carby ECM! I agree with Mark. Time to get the 12 hr pain pills out.

The carby system controlled spark, but fuel was mainly an adaptive reaction to O2 readings. The carburetor mixture control solenoid was adjusted so a commanded 50% duty cycle would provide proper fuel under most conditions. If O2 looked lean or rich the ecm would alter the delivered duty cycle in an attempt to change fuel. Fuel delivery was a function of the carb setup, not VE tables as we expect today. Understanding and setting up the carb was a bit tricky for some but for this question the answer is that from the ecm's perspective fueling is not altered by a change in displacement.

I would attempt to locate a 350 based ecm / calibration, maybe from a Caprice or Impala or even a truck. The 305 is very much spark limited in stock form and the stock cal is likely to deliver less timing than a 350 cal and it may be more likely to remove more spark if knock is detected. I've replaced 305's and even V6's with 350s and never changed the chip but it was many years ago. Knowing what I do now I'd probably look for a 350 cal.

Modified BCCFind returns a cal for 7169 and 5.7. FFK is from an 86 Caprice with LM1 engine. Changing the search to +LM1 results in a long list of calibrations for Federal and California emissions vehicles:

http://www.gearhead-efi.com/BCCFind/...ml?BCC=lm1+5.7

Data update rate on this ecm makes 7747 look like speed demon. Did you get the commercials with the Slowskis out there? They'd appreciate this ecm. Plus data available is very limited. Very little diagnosis was done with scantool but old fashioned OTC2000 would display data. Cannot drive and record as ecm is in diagnostic mode when delivering data. Spark advance and fuel delivery are fixed in this mode. Unsure about collecting, reading, or burning cals for these as this was before my time in tuning. There's some stuff in the old DIY archives that Ludis posted if you can find 'em but otherwise I'd have to learn an old technology new to figure out what to do.