Slightly related to
previous issues with my rebuilt engine running too cool, on cold days if I try and accelerate hard the engine has no beans and stalls. Sometimes it will even backfire. Once the engine has completely warmed up however it isn't a problem. I've been running tests since last week and I can conclude it's the computer keeping it too retarded, but it's not the computer at fault. Here's my theory:
The CeC will not enter closed-loop until the TAC switch opens (and the coolant switch closes) and signals the intake air temperature (and the engine) is sufficiently warm for the carburetor. I've verified the switch is good and the warm air duct and the vacuum switch for it are working, just with a colder than normal engine the manifold's not getting hot enough fast enough for what I'm used to and it's taking longer to satisfy the TAC switch. While the computer is being told the air cleaner is too cold still it retards the spark as much as it can get away with to generate waste heat and warm up the block and the exhaust. As soon as the TAC opens it adds spark timing again and you will hear the RPM drop. You can see this on a hot engine by unplugging the TAC and jumping the pins. Without activating the sol-vac or idle control solenoid the RPM will increase and it will exit closed-loop until you pull the jumper.
When idling and under light loads this isn't a problem but if you try to accelerate hard (EG: you turn a corner and give it the beans to enter onto the highway) you still have a very retarded spark when it doesn't need it. Because the Eagle doesn't have a Throttle Position Sensor it relies on the two vacuum switches to detect a heavy load condition, at which point it takes a second but it adds as much timing electronically as the engine wants (on top of whatever the vacuum advance can deliver), BUT if the base timing is too retarded you'll feel that brief lag before it can advance the spark and that's the issue I'm getting.
I've been getting around it the last few weeks by creeping into the pedal before it completely stalls and eventually the computer bumps the timing and you're good to accelerate normally.
So when the engine was rebuilt I had the shop verify my Dorman harmonic balancer had the timing mark in the correct location because I've seen a lot of people say it isn't. They found it was two degrees off and marked the actual TDC with silver pen. Well I'm dumb and didn't make a more permanent mark and the marker has faded away and I also can't remember if the drifted mark was two degrees too advanced or too retarded.
Topic: Timing too Retarded? (Read 263 times)