Stock 86 305 TPI running 89 $6E PROM. Only mods is 24lb Bosch D3's.

I'm getting a couple knock counts (2-3 counts each time) when I stab it - no bog or surge. It looks like the O2 goes lean. I made sure it's not false knock - I pulled 10 degrees out of the last 5 columns of my timing map and it went away. Base timing is set at 6. Timing map is stock 89. WOT afr's are 12:1 after some tweaks to MAF table 5 and 6 scalars (was very rich).

Where should I start with the AE tables.

GD

 

I'd try ae enrichment vs delta Lv8 or change in LV8 table possibly as a start. Wot stomp is a large delta lv8 change

 

Ok - how does this table work? I assume I'm looking at the multiplication factor used when the delta in the LV8 (over a specified time interval) changes by 0,64,128,192, or 256.... interpolated of course for whatever the actual delta is seen by the ECM.... So I should increase these numbers on the lower end of the scale? (I figure my delta is usually somewhere between 64 and 128) or should I increase across the board? Here's what I have now:

0: 12.5
64: 12.5
128: 15.63
192: 20.31
256: 20.31

Sorry I know I'm being a noob about this stuff....

Thanks!
Rick

 

Yeah find the delta where you are experiencing this issue and increase the values there

See if you get a change.

 

Ok I increased the AE delta factor table by 40% across the board. Also wired in my wideband to the Autoprom directly.

When I go to WOT the AFR drops into the 12's no problem now.

Still getting two to three knock counts on a WOT pull. It stops once the knock retard has pulled out about 4 degrees.

Would the timing map be that different from my 86 LB9 to the 89 LB9? Or is there some reason my 155k, 30 hear old engine can't take 30 degrees at 3k rpm? It has 190 compression across the board and seems to be in pretty reasonable running order. I'll screenshot the timing map and post it here if that would help?

I'm trying to remember if I advanced the cam when I did the chain using a Cloyes double roller kit..... I might have. I might have done the 2 degree advance but I can't remember. That would cause my symptom wouldn't it? Doh.....

GD

 

Looking at my logs - I'm still not getting enough enrichment and that's what appears to be causing the knock. My LV8 jumps from 63 to 181. RPM's at 181 are 2400. As the RPM's climb to 2800 I get a few knocks as the wideband (and narrowband) go into the 16 range.

I've already given it like 40-50% more AE factor vs delta LV8. What can I do to get it to come in quicker?

GD

 

I'm a 7730 ($8D) guy, so I'm not familiar with the $6E code.

But on the 7730, there's value in the fuel constants table called "AE delta TPS scale factor" (not to be confused with the "AE delta TPS PW Scale factor"). I'm not exactly sure what it is intended to do, but I do know that when I increase the value, it seems to bring the AE in faster. When I was attempting do dial in how the engine responds to a quick blip of the throtttle in neutral gear, it wasn't until I found this constant and started increasing it that I got what I wanted. Before that, I threw all kinds of additional AE fueling at it, but it didn't get me there.

Also, if there's a AE vs delta TPS, you could try that first. The AE vs delta LV8 on a MAF car seems analogous to the AE vs delta MAP on a MAP car. My suspicion is that by the time the engine load response is picked up by the MAF sensor via the change in air flow (which may be a few milliseconds), it may be too late for the ECM to react.

The delta TPS is picked up much more quickly since it's 100% an electrical response back to the ECM.

Lastly, if it only does this when it's at hot temperature, you could also start by increasing the values that are dependent on coolant temperature. In 7730, I have AE delta TPS vs coolant temp as well as AE delta MAP vs coolant.

 

Hhhmmm I have two scalars called AE Delta % TPS Min (set at 3.91), and AE Delta Min TPS Volts (set at .20).

These seem like minimum changes in the TPS at which it kicks on the AE? Should I lower them?

Rick

 

Can't hurt to try it.

 

Ok I'll lower them down and see what happens.

Rick

 

Well - after doing that I'm not really seeing the lean spike. The narrow band shoots up to 888mv right before the knocking starts. My wideband is lagging a bit behind as it's in the tailpipe not the header so it doesn't really look like I'm going lean anymore.

How can I definitively tell if this is false knock or real?

If it's false, what are my options? Try changing the sensor? It may be original. Definitely has been sitting for as long as the car sat - 11 years or so.

Rick

 

Hey GeneralDisorder I sent you a PM (don't want to get thread off topic).

 

reduce the spark advance and see if it goes away. If it does, chances are it was real.

 

So I think I found my n00b mistake.

I had a very, very rich WOT to begin with. Partially due to a MAF with the upstream screen removed (with no frame of reference this seemed most probably normal construction to me). I had changed the MAF table 5 and 6 scalars to enlean the upper flow areas which did bring me into the 12's.

But I neglected to smooth the transition from table 4 to table 5. So table 4 ended at 129 grams/sec and table 5 started at 117. So when it broke into table 5 the ECM was pulling fuel for a drop in airflow while the RPM's were climbing.

I changed the bottom half of table 5 to smooth this transition without a drop in airflow from 4 to 5. Hopefully that solves my lean knock. Obviously just messing with the scalars isn't enough on its own.

These 8 bit kludged up 1980's tech computers are somewhat new to me. I learned assembly code in the 8086 era of 16 bit PC computing so I have to get into the 2^8 mindset....

Rick

 

Hah... 80's tech... I was making a run yesterday afternoon doing some tuning with my Ostrich II emulator. Made a few minor changes during the run and was thinking, how in the heck did we get by before with erasing/burning/erasing/burning chips??!

With eraseable EPROMS, I had at least gotten to the point where I could pull over to the side, shut the car down, remove the chip, erase it, burn a new one, reinstall it, then start the car and keep going. But it was still a pain... (and I don't even want to recall the UV eraser days!).

Now with the emulator, I can be stopped a light, make a quick adjustment, press download, and after 2 seconds with the engine still running, it's ready to keep driving.

 

Oh I know - we still do some "open source" tuning on WRX's and EVO's where we have to use the flash interface - no chip removal but still have to plug and unplug two sets of connectors and then wait for it to upload, etc.

On my issue I have so far is the connection between the chip adaptor and the ECM is kinda dodgy with the ribbon cable pulling on it. More than once I've had it just die on me due to poor connection.

GD