El Camino Central Forum banner

1 - 11 of 11 Posts

·
Registered
Joined
·
98 Posts
Discussion Starter #1
I just got my 383 SBC up and running again. I'm using Holley's EFI system with computer controlled timing. I think I may have my timing off a bit. I'm getting a loud pinging/popping sound from the engine whenever I try to give it gas when the RPM's are real low or when I gas it in a higher gear. I don't see anything out of the norm with my timing. I feel like I've had this problem before but I can't remember how I fixed it. Any advice?

SPARK


AFR
 

·
Banned
Joined
·
5,787 Posts
looks a little lean to me but :dontknow: i would fatten it up a lil and pull out a lil base timing
keep us updated plz with results:beer:
 

·
Registered
Joined
·
12,538 Posts
on a normal carbed motor
id say pinging/rattling is too much timing..

and by popping?? if you mean a light backfire back thru the intake??
that sounds like a lean condition..

i noticed in the base spark table 24* is the lowest?? that seems like a lot,,
but maybe not at idle,, depending on the motor,,
cant remember but were you talking about going with a cam with less overlap??
if so you may need to back that off a little..

also in the idle tuning box it shows 12.4* at idle??
so i guess you have more going on there than just the base timing table..

IIRC your runnin a blower also and tunin thats over my head,,so you may want to disreguard anything i said..:dontknow:

dont forget to retorq the intake after a few heat cycles..:texas:
 

·
Registered
Joined
·
98 Posts
Discussion Starter #4
I'm breaking in the motor without the blower and I'm running 91 octane instead of E85. It did sorta sound like a backfire from the intake but I'm not 100% sure. I'll see if I can try and duplicate it again with a video and post it on here. Then I'll back the timing off a bit.
 

·
Banned
Joined
·
5,787 Posts
if your breaking it in without the blower then wont you have to go and remap it when swap in the blower?? what kind of blower btw?? boost level ?? just trying to help:beer:
 

·
Registered
Joined
·
98 Posts
Discussion Starter #6
if your breaking it in without the blower then wont you have to go and remap it when swap in the blower?? what kind of blower btw?? boost level ?? just trying to help:beer:
Nah, I'm using the same map that would be there with the blower. Holley EFI has a self-tuning feature where you set your AFR and depending on what the O2 reads, it'll adjust the fuel map to try and match the AFR that was set. When I put the blower back on, the part of the map where boost is applied wont be tuned, but the rest will be. I'll just have to ease into the boost slowly so it'll "learn".

The blower is a Procharger D-1SC
 

·
Banned
Joined
·
5,787 Posts
oh ok i see now. did you back off the base timing?
add some fuel to it and pull out about 3 degrees and see if it likes it hope it helps
 

·
Registered
Joined
·
98 Posts
Discussion Starter #8
oh ok i see now. did you back off the base timing?
add some fuel to it and pull out about 3 degrees and see if it likes it hope it helps
OK, I'll try that out. I gotta put a couple of the spark plugs back in from checking them last night. They look fine. I'll let you know how it goes.
 

·
Registered
Joined
·
555 Posts
OK, I'll try that out. I gotta put a couple of the spark plugs back in from checking them last night. They look fine. I'll let you know how it goes.
Air/Fuel:
Good, you're reading the plugs. That is the ONLY way to tune the A/F ratios (Not with the O2 sensor reading). Also, in order to tune by reading the plugs you need to make sure you're getting accurate readings. You need to shut the engine off under full load and at wide open throttle (6500rpm), just like they do on dynos. This is the only way to accurately get a good plug read. If you let the engine idle for only a moment, carbon will build up on the plug and give you a false read (too rich).

Timing:
If you have a digitial ignition system that allows you to set and change the timing with a laptop, you still need to check the timing with a timing light to make sure its where you want it to be...:beer:
 

·
Registered
Joined
·
98 Posts
Discussion Starter #10
**UPDATE**
So I kept messing with the timing and fuel and I couldn't get the pinging to go away. Also the throttle was still really twitchy. So I called Holley' Tech line and they had me email them my tune and datalog. I got a call back within an hour saying my idle was all jacked up. Basically I had my ECU idle set to 900RPM but my throttle bladed were open too much and I was idling around 1100-1200. So my idle air controller (IAC) was constantly closed because it was trying to compensate for the extra air coming in. After a while, the ECU was trying to pull timing to bring the idle down. He had me close my throttle blades until the IAC read about 30% at idle on the Holley software. After that, the pinging went away and the throttle is super smooth coming off idle.
 
1 - 11 of 11 Posts
Top