91 Z28, Lb9 5 spd, headers, cat delet, air delete, stock prom

car is pulling out timing

Knock counts are ranging like O2 cross counts or O2 voltage, not staying on a fixed number or steadily increasing.

Car is showing 108 blms in closed loop

Integrator is at 130

Cell block 4 at idle

If you blip the throttle, it pulls 20* of timing out, then is fine

Any ideas?

btw, fresh wires, plugs cap + rotor and no CEL

 

Did you put in bigger injectors or leave the vacuum line off the fuel pressure regulator? Your BLM shows that you are running very rich.

 

Only change was adding the headers, deleted the smog pump and cat, added a 3 wire O2 sensor

Everything is stock

sad part is I didn't have the mindset to scan the car before doing this

 

I'll SWAG it as the headers/exhaust are hitting someplace or the serpentine belt is slapping. Either will cause knock counts.

RBob.

 

the headers hitting something was my first instinct, but they have plenty of clearance.

The serp belt is new, but the smog pump is still in place, with nothing attached to it for the time being.

What bugs me is the fact that the knock counts do not climb to 255 and start over. They just jump around erratically.

I did a few different searches and came up with RF interference from the ignition. Not sure what to look for from a stock setup that would cause such a problem

back to the search engine

 

While doing the work on the car is it possible that the sensor wasn't hooked back up, or maybe the wire or sensor is damaged.

Other possibility is that the passenger head coolant switch and the knock sensor wires are reversed.

Try grounding the knock sensor wire through a 3.9k ohm resistor to ground. No knock at all should now be displayed.

I think that the jumping around of counts is because it is continuous knock being reported and is rolling over between ALDL frames.

RBob.

 

My first thought is that it fell off during the install too. Checked it is connected securley to the proper sensor. Not sure the secondary fan lead would reach that far down the block honestly. The wiring is away from the headers and Y-pipe. I can't see any visible damage to the wire loom or connector, but that doesn't mean a whole lot.

Car is on its way back to VA, so I'll be doing long distance diagnostics from here on out.

I've never seen a knock sensor count like that, especially when it isn't pulling any timing out. it only pulls timing out when you tap the throttle.

My old 305 did this, but nowhere to this exteme. It would count up to 255 and start over. Wound up having a balancer that was off by 60* or so and I was guessing at the timing........

I'll try the ground and resistor this weekend

thanks

 

Knock retard typically won't happen while at idle. Counts may happen, but the ECM will not pull timing unless either the RPM or the MPH is above a threshold (for each).

RBob.

 

Well I finally got my hands back on the car to see if I could figure out what was going on.

First I grounded the KS through the resistor as suggested. No change.

Next I swapped out ECMs, no change

Then, for the hell of it, I swapped out the stock memcal and it worked.

Apparently the stock chip isn't any good. Go figure. Why that matters when using the moates adapter is beyond me, but that is the source of my headaches.

Thanks for the suggestions, now I just need to find a good V8 memcal and then I can start tuning this. Car runs a lot better now though. Go figure

Thanks again

 

The SD setups ('730) have the knock filter module located within the MEMCAL. It is the white board opposite the EPROM.

RBob.

 

well that would explain the problem. The white board on the stock memcal is cracked...... grrrrrr

thanks for the feedback, maybe this will help someone with a similar problem

 

Rbob:- What does SWAG mean/stand for in this context? Where do the 165 MAF set-ups have their knock filter module located? Is it also within the MEMCAL?

Jaysz28:- Glad to hear you've now found the cause. What a bizarre problem to have!

 

Hope you don't mind me taking a SWAG at the answer

SWAG = Scientific Wild-*** Guess

165 ECMs, like the earlier C3 ECMs, have the knock circuitry in a separate ESC module, which on thirdgens is normally located on the driver's side firewall near the MAF & fuel pump relays. In other words, no, it's not within the MEMCAL.

HTH,