NJFBOA - Home of New Jersey's Camaros and Firebirds - View Single Post - Getting my new 406 SBC installed, running, and driving

IROCZman15 · 06-12-2023, 08:30 PM

This is a long overdue update post, but I did get to teh track back on may 28. I did some stuff prior and thought I had all the gremlins worked out. Unknown to me, is that the misfire likes to come around after the car has been driven and warmed up...so that caused havoc at the track. I no longer have any of the dashcam videos, but three of the 5 runs i got were garbage due to the misfire coming about. And I spent a good amount of time in teh pits checking over wiring, plugs, swapping to known good tunes etc, but in the end, I only had two full passes (#1 and #3). Pass 3 got me a great mph in the 8th mile at 95.49 mph and the 1/4 mile was 118.69 mph which is a p.b., and I didnt feel the misfire that time, but in actuality, it was partially there.

( this video below is the only track video and it was pass 5)

https://www.youtube.com/watch?v=CJh_3mlNC_M

timeslips:

but:
here is the wild stuff the tachometer on BOTH the oem dashboard gauge and the digital holley gauge was going. The engine was not changing rpm that quick, but the computer was seeing the values and compensating afterwards with big swings in the timing, IAC, and whatnot. However, the other gauges and values on both dashboards were clear and steady (free from the spike) so I kept ruling out RMI and electrical interference.

videos:

https://www.youtube.com/shorts/CnW9JtzeRs0

https://www.youtube.com/shorts/czgIdSJL2uU

Drove the car home gently and took a few days to dig into it. Started at the battery in the back and dug deep into the wiring all the way up through the body, under the console, into the engine bay, etc. Checked timing with a timing light, static timing tests, installed ferrite beads on some wires, moved plug wires, even unclipped connectors and checked a bunch of the tiny pins. Ran a vacuum test on the engine and almost pulled some valve covers off too, but I had been chatting with Scott over at EFI systemsPro and he mentioned that it seems the ecu is getting a bad signal from the distributor, and that lead me to start checking the wiring there. Thats when i saw it: at some point in time (probably when I had the intake manifold off last year) I must have removed some of the plastic loom that usually covers all of my wiring, from teh 3-wires that go into the underside of the hyperspark distributor. The unprotected wires were then left to sit alongside the sharp edge of the distributor hold-down clamp, and that caused them to get sliced open over time. Whew! I got the wires sealed, shrink wrapped, secured and with plastic loom back on it. Car fired right up and ran smoooooooooooth. Test drive went well also. whew.

Datalog screenshots from Pass 2:
(see the bright red, thats rpm, and it looks noisy, but spikes and dips) not in a cycle or rhythym either, just intermittent, this is what baffled my brain) this log is idling in the stagin area, burnout, and then the 1/4 mile pass which let off after a bit)

Closeup of the spikes during idle:

closeup of the rpm spikes during pass 2:

Pass 3 was much cleaner, but I was ready to get off the throttle if I detected big misfires. According to the log, there were a very slight few which i only felt at the top end:

The sliced wires (not sure how I overlooked it, but i did)

.

Also:
I did a complete holley efi software download, I loaded up the newest firmware onto the handheld, and loaded the newest holley sniper ecu firmware, and bought a new 8gb SD card for the sniper too. This was a crazy thing for me to do because I am a very low-tech person.
I did this because of the wild looking datalogs I was getting where there was tons of missing data. And, success. the firmware, sd card, software now has me up-to date and free from missing data in the logs.

I wanted to do new pads and rotors for the front this winter, but just didn't get to it. My rotors had turned ugly over years of autocross and dragracing with them, and I only had a little bit of pad life left anyway. A clean set of front rotors will be good for Carlisle, and great for UMI in July. Bolted on the powerstop Z23 font kit for 1LE brakes/C4 HD, and painted the calipers afterwards. Also removed the front lakewood 90/10 drag struts and rear lakewood 50/50 drag shocks, and put on the adjustable koni yellows. Bolted the front sway bar back on with all new bushings on the endlinks. Installed new "roof-rail" (upper window) weatherstripping just this weekend also, and painted the rear decklid's metal trim black as it was nasty.

This was the flat-black metal primer. I went with a satin finish and it turned out good, but no photos of it at the moment.

Still hopefully going to find time to get a full detail job on the paint and under the hood in hops of getting to Carlisle next weekend. car is running gooooood though!

06-12-2023, 08:30 PM	#565
IROCZman15 10 Second Club / Meet Coordinator Join Date: Dec 2004 Location: Roxbury, NJ Posts: 2,101 iTrader: (8)	This is a long overdue update post, but I did get to teh track back on may 28. I did some stuff prior and thought I had all the gremlins worked out. Unknown to me, is that the misfire likes to come around after the car has been driven and warmed up...so that caused havoc at the track. I no longer have any of the dashcam videos, but three of the 5 runs i got were garbage due to the misfire coming about. And I spent a good amount of time in teh pits checking over wiring, plugs, swapping to known good tunes etc, but in the end, I only had two full passes (#1 and #3). Pass 3 got me a great mph in the 8th mile at 95.49 mph and the 1/4 mile was 118.69 mph which is a p.b., and I didnt feel the misfire that time, but in actuality, it was partially there. ( this video below is the only track video and it was pass 5) https://www.youtube.com/watch?v=CJh_3mlNC_M timeslips: but: here is the wild stuff the tachometer on BOTH the oem dashboard gauge and the digital holley gauge was going. The engine was not changing rpm that quick, but the computer was seeing the values and compensating afterwards with big swings in the timing, IAC, and whatnot. However, the other gauges and values on both dashboards were clear and steady (free from the spike) so I kept ruling out RMI and electrical interference. videos: https://www.youtube.com/shorts/CnW9JtzeRs0 https://www.youtube.com/shorts/czgIdSJL2uU Drove the car home gently and took a few days to dig into it. Started at the battery in the back and dug deep into the wiring all the way up through the body, under the console, into the engine bay, etc. Checked timing with a timing light, static timing tests, installed ferrite beads on some wires, moved plug wires, even unclipped connectors and checked a bunch of the tiny pins. Ran a vacuum test on the engine and almost pulled some valve covers off too, but I had been chatting with Scott over at EFI systemsPro and he mentioned that it seems the ecu is getting a bad signal from the distributor, and that lead me to start checking the wiring there. Thats when i saw it: at some point in time (probably when I had the intake manifold off last year) I must have removed some of the plastic loom that usually covers all of my wiring, from teh 3-wires that go into the underside of the hyperspark distributor. The unprotected wires were then left to sit alongside the sharp edge of the distributor hold-down clamp, and that caused them to get sliced open over time. Whew! I got the wires sealed, shrink wrapped, secured and with plastic loom back on it. Car fired right up and ran smoooooooooooth. Test drive went well also. whew. Datalog screenshots from Pass 2: (see the bright red, thats rpm, and it looks noisy, but spikes and dips) not in a cycle or rhythym either, just intermittent, this is what baffled my brain) this log is idling in the stagin area, burnout, and then the 1/4 mile pass which let off after a bit) Closeup of the spikes during idle: closeup of the rpm spikes during pass 2: Pass 3 was much cleaner, but I was ready to get off the throttle if I detected big misfires. According to the log, there were a very slight few which i only felt at the top end: The sliced wires (not sure how I overlooked it, but i did) . Also: I did a complete holley efi software download, I loaded up the newest firmware onto the handheld, and loaded the newest holley sniper ecu firmware, and bought a new 8gb SD card for the sniper too. This was a crazy thing for me to do because I am a very low-tech person. I did this because of the wild looking datalogs I was getting where there was tons of missing data. And, success. the firmware, sd card, software now has me up-to date and free from missing data in the logs. I wanted to do new pads and rotors for the front this winter, but just didn't get to it. My rotors had turned ugly over years of autocross and dragracing with them, and I only had a little bit of pad life left anyway. A clean set of front rotors will be good for Carlisle, and great for UMI in July. Bolted on the powerstop Z23 font kit for 1LE brakes/C4 HD, and painted the calipers afterwards. Also removed the front lakewood 90/10 drag struts and rear lakewood 50/50 drag shocks, and put on the adjustable koni yellows. Bolted the front sway bar back on with all new bushings on the endlinks. Installed new "roof-rail" (upper window) weatherstripping just this weekend also, and painted the rear decklid's metal trim black as it was nasty. This was the flat-black metal primer. I went with a satin finish and it turned out good, but no photos of it at the moment. Still hopefully going to find time to get a full detail job on the paint and under the hood in hops of getting to Carlisle next weekend. car is running gooooood though! __________________ 1987 IROC-Z - modified Last edited by IROCZman15; 06-13-2023 at 08:46 PM.