So I'm running ZZ4 113 heads and a LT4 Hotcam (24502586). I'm running with 10* timing in the ECU and on the dizzy. Getting popping AFR with NB is 14.0, WB I can't get a good reading on I think the sensor is bad. When the popping finally goes away it runs like a raped ape, trying to get this cleared up. Posting diag files tomorrow.

 

Likely need more AE. Or the fuel pressure is dropping off.

RBob.

 

You have 10 degrees initial (on the distributor) and 10 degrees of advance programmed-into the computer? Total of 20 degrees? That doesn't make any sense.

What is a "popping AFR"?

 

What he likely means is that the distributor base timing is set to 10* BTDC, and the initial SA in the calibration is also set to 10*. This is required so that the ECM knows what the physical distributor timing is. This way the base is taken into account to get the proper SA at the crank.

RBob.

 

I meant to say that the car is popping and the NB is reading 14.0, so I'm not sure why as it is not that lean.

^^^ Correct assumption

Here is the .csv for the dump file.
Whats killing me is that AFR reads 13.5, but my WB is jumping between 7.4ish directly to 22.4ish and back. Is the WB shot? Which do I listen to? WB is just past the y connection and NB is in the stock location.

 

The NB isn't reporting an AFR, it is in milli-volts. On the diagnostic display graph the mV scale is for the NB, while the AFR scale is for the WB. Uncheck the preferred WB button and the AFR scale goes away. Note the color of the traces and the color of the scales.

To a degree the WB is following the NB. When the NB is lower then 450 mV (lean) the WB shows about 22 AFR.

Then when the NB is reporting rich the WB goes to about 7 AFR.

Either the WB is bad or incorrectly set up, or the WUD device setup for the WB is incorrect.

RBob.

 

It turns out I was watching the ARF column in the dump and the cAFR on the screen thinking that was my current ratio. I have a better understanding now. I also read another of your posts about the LM1 WB so I changed my settings. Update and findings on Friday...

 

In preparation for tomorrow I have been going through your old posts. I have a LC-1, now the manual states "Note: The LC-1’s heater ground and system ground wires should share the same grounding location as the device to which you are feeding the analog outputs to."
But you say that the analog ground should go to the EBL right? Just trying to figure out the crazy readings. That and I'm now learning this WB I bought 10 years ago is a POS...

 

It is best to tie the heater and analog grounds to the engine block. You do not want to tie the heater ground to the ECM. That's why they both need to go to the engine block.

RBob.

 

RBob, I was reading https://www.thirdgen.org/forums/tbi/...ning-help.html and you state in post #11 that the injector flow rate should be 80.5. I'm guessing this is a mistake on my part ans I am putting in the modified flow rate that is calculated from the new pressure rating. Am I correct that I'm doing this incorrectly? I finally got my car to idle with an even AFR 12.5 still rich but better than the bounce I had before. posting updated dump tomorrow. Thanks in advance.

 

There is a lot of misinformation about the TBI injector flow rates out there. It started back in the '90s when folks were first getting into the GM ECMs and EFI.

AFAIK there are three different injectors for the domestic BBC units: 75 #/hr, 80.5 #/hr and 46 #/hr. The 75 & 80 units are at 13 psi. With the 46 #/hr units run at 30 psi for 74#/hr actual flow ('94 & 95 MY).

There is a gentleman selling "90s", but he lists this at 14.7 psi fuel pressure.

RBob.

 

Here is the current .bin and .csv dump file. My fan system isn't running right I had a massive 44" shop fan blowing on the car, when I realized the car had gotten hot I shut it off.

Hoping that some light can be shed on this. My WB is no longer connected as it died, and I'm not sure if it's the controller or the WB itself. FP is at 23#, which would give me 106# using 80lb injectors. Motor specs are listed below. Comp is believed to be around 10.5:1.

 

I have a LS1 pump on the car, I don't think the pressure is an issue. I have monitored the VAFPR and there was no movement.

 

Put the fan relay under ECM control. Pin C2 at the ECM is fan control, run that to the head temperature switch wire that is supposed to be located in the passenger head between cylinders 6 & 8.

In stock form the fan is controlled by the A/C system pressure switch and the head temperature switch. With the EBL can now have it too control the fan.

Once that is done get a log of accelerating where the engine pops out the intake.

RBob.

 

Calling this weekend a success, as the new thermal switch was the key to getting the fan working. I'm thinking that I might run the other one off the ECU pin C2. After the fan was fixed I found the culprit to the popping issue. My headers decided to take out 2 of my spark plug wires. So after a new set and some fiberglass thermal boots we were back up and running with a decent idle. Laptop battery was not of sufficient charge for logging this weekend.

Question though. Now that the idle is not being impeded by the misfires I want to re do the TPS and Idle set screw. The question is during this process is the EST bypass supposed to be connected or not?

 

For the IAC, easier then that. On a warm engine with no other loads (in P/N, no A/C, no lights or fan...), adjust the idle stop screw to achieve an IAC step range of 5 - 10. Can use the WUD to see the step count. Also note the WUD's idle indicator, if it goes off need to turn off the engine for 10 seconds and restart & continue.

RBob.

 

Well it appears that I made a novice mistake and didn't re-torque my head bolts, and the result was I ate a head gasket. So we will see if I warped the head as well...

 

What head-gasket did you use? Most head gaskets don't require re-torque, if the assembly and torquing was done properly. It's not like GM retorques head gaskets when they build an engine.

I'm not saying retorquing is bad. I retorque most of the time, although not always. It shouldn't be the difference between a running engine and a popped head gasket, though.

 

Well you are correct, the over-temp issue I had because the fan wasn't kicking on I'm sure played a large part in it as well.

 

Ok, well the head gaskets were fine. So, I'm assuming that the heads were improperly torqued. Thankfully I didn't do them, so I can't be blamed... but I was the idiot that didn't check it

Well I have new thinner gaskets and an ARP bolt kit tore it apart today and got one head back on today, the other one tomorrow. Restart and see what happens.