Okay, the alternator is fixed, the 3.1 harness is in, and the knock sensor (which was giving me a code 43) has been replaced. Now, when I set the timing, it's right on 10 BTDC with the EST disconnected. However, when I connect the bypass, the engine runs like garbage, worse than with the EST disconnected. I checked the timing, and instead of being off of the good side of the scale (BTDC side, generally around 20+ degrees), I'm WAY off of the ATDC side of the scale. Does anyone think it's time for a new ignition module again (the alternator blowing a diode may have fried it, I'm thinking)? I'm not throwing any codes, BTW, other than 12, which we all know what that is. Does anyone have a flowchart for the EST system on a 91?

It may be the module is bad. But whenever I've seen this issue it is the pickup coil wires to the module are reversed. The manufacturers don't always get the right wire colors on the correct side of the coil winding.

Easy enough to test, just swap the wires in the pickup coil connector and try it.

RBob.

Had to replace the module back on Sunday when the engine died right in the middle of a major road and I got pushed into a parking lot (and I already knew the PU wires were right because I've had them reversed before and the engine didn't run with them reversed AT ALL). The ESC system STILL fully retards the timing (20*) and I'm running right now with the bypass open and base timing set around 18* BTDC. I would REALLY love the ESC and code 43 flowcharts from a 90-92 FSM so I can extinguish my SES light.

Code 43 (ESC) charts & tips from the '92 FSM:

RBob.

Any luck?

RBob.

Looks like I have to go junkyard hunting for a MEMCAL. Seems as though the ECM is receiving the KS signal and my MEMCAL isn't processing it (last step at the bottom of the flowchart, lower left corner, IIRC).

Maybe my chip is from a 2.8 car? All I know is that it supposedly came from a 3.1-equipped W-body with a 3-speed transaxle, most likely a 3T40 (didn't engage fourth gear on my 4L60).

It's either that or I get some info and a couple more parts and build myself a VATS delete module so I can run the MEMCAL that was in the Firebird's ECM when I got it.

Edit: putting this edit here to point to the next post. The w-body MEMCAL won't work. That is why the timing is way off. /edit


Take a look at the MEMCAL. There should be a small white board covered in clear goop next to the PROM. That is the ESC module. The original Firebird MEMCAL will have it. Check that the GrandPrix MEMCAL also has it.

Another step in testing the ESC circuit is to put a jumper between the knock sensor center connection and the connector that goes to it. With key-on, engine-off measure the voltage on the jumper. It should be around 2.5 volts.

It is this 2.5 volts that the ECM looks for to prevent code 43. The actual range is greater (.625 through 4.5 volts is OK with AZTY cal).

RBob.

Wait, a FWD 3.1 W-body? Aren't they a DIS system, not distributor?

Can't use that MEMCAL with that PROM. The spark timing will be WAY off. Won't work, no can do. All has to do with the calibration of the SA for the DIS system. Note that this is in the PROM portion of the MEMCAL.

One way is to get a VATs delete module (they are inexpensive already built). And use the Firebird MEMCAL.

The other way to go, which may be better in the long run, is to head over to moates.net and pick up a G1 adapter, Burn2, and a few chips. Then copy the PROM (or get it from the 'net) in the Firebird MEMCAL, turn off the VATs option, and burn a new PROM.

Install the G1, insert Firebird MEMCAL on to side of G1. Put newly burned PROM into G1 socket, turn the key and start driving the car. The reason this may be better is that you can now do some other tuning of the calibration.

RBob.

Yes, a W-body 3.1 is DIS. Didn't know that made much of a difference in the spark advance calibration, however. Guess I do now .

I'd love to do PROM tuning, except the stuff to do it is a little pricey for me right now (my hours just got halved because everyone got out of school for the year ). Yes, the GP MEMCAL has the EST board in the one half. The Bird MEMCAL is an AUJW, BTW... I finally found it this morning. So, basically, there is no hope of my finding a compatible MEMCAL without VATS at the junkyard or on eBay?

:edit: GP MEMCAL's broadcast code is ATSR, FYI. from the 1227727 ECM, IIRC. Been 2 years since I've seen the car and I know the ECM in the garage doesn't have a label on it (got wet or something and wore off and is unreadable).

The DIS setups use 70* BTDC as the base timing. It is offset by 60* (one half of one cylinder rotation) plus 10* additional for the initial SA. This is why when you connect the BYPASS connector the timing goes way foobar.

Since you have a 5-spd, BAWX is the best BCC to use. It supersedes the previous stick calibrations. AZTY is the latest 700R4 calibration. AUJW wil run OK, but won't be the best choice (it is also an auto cal).

I do not recall of any 3.1's using a distributor with the exception of f-bodys.

RBob.

I'll have to see what I can dig up at the junkyards around here and on eBay, then. My fav yard got rid of the only remaining 5-speed it had left (a RS with a 305 so that wouldn't help me), and I know that the PROM from the 84 trans donor (a carbed 2.8) won't help me any, along with the 4-speed 4-banger Camaro I got my PS door from. There are some things there that might be worth looking at, but he's pretty much halved his inventory since I did my trans swap a couple years ago, and I don't know what's left as of right now. I was hoping a DIS chip would work because he DOES have a slew of 3.1 W- and J-bodies that still have their computers in them (even if they don't have their engines or powertrains). Oh, well.

Does that BAWX chip still contain VATS? Probably a dumb ??? but I need to know if I need to look for other parts as well.

:edit: I MAY be able to pull the VATS stuff from the donor car and do something with it. The original ignition key is still in the car (last I checked it was, anyways) and I can bring my DMM along so I can find the resistor value for the bypass. I have to get the wiper motor from that car anyways.

Yes, BAWX has VATs. If you grab the PassKey box also grab the ignition key. Or at least measure the resistance. You can use the PassKey box with a resistor soldered in in place of the key. Then wire the correct output to the ECM.

Note that the MEMCAL needs to be from a V6 engine with a '7730 or '7727 ECM for it to be correct for your set up. This is the CALPAK & knock filter areas. The PROM needs to be f-body V6. Which also will all have VATs.

Note that you can set the PassKey system up to be usable as anti-theft. Solder the resistor into a plug and place a jack hidden in the ashtray, console or such. Then without plugging in the resistor plug the car won't start.

RBob.

I won't be able to grab the key altogether, which is why I would be measuring and recording the resistance of the pellet in the key. I'm praying the car won't be too wet so I can do some work on the dash (t-top car without the tops, anyone? ) to get the VATS module out.

I know the MEMCAL has to be from a V6 3.1. I just don't know how many are left in the yard. Seems like the guy has been collecting an awful lot of 3800 Series I and 3100 cars lately for what little he does have, compared to what he used to have.

I was also planning on having the bypass resistor wired in with a switch for VATS use and connecting the VATS module to my existing starter kill relay, but your idea of using the resistor in a connector is even better. Plug and play... I like that idea.