Making progress, but still have issues with the Paxton (Wideband graphs included

[toddwallace]

Ok..I pulled the Demon and went with a Holley 650 with .25 carb spacer.. Car starts and runs about the same, but the problems personality has changed. Before, the car would die and not start (with strong smell of fuel) after 30 minutes or so... NOW, it runs fine and starts shutting off after 30 minutes, but it jump starts itself when you are driving and starts back up. When at a stop, the car will fire and immediately shut off. It does seem to get unusually hot in the engine compartment, but the temp gauge seems like it runs in a normal range. I truly believe, I have some electrical/fuel problem that gets aggravated by the hot engine compartment. I have hooked up a wide band and it is running real rich. below are my numbers..

Car at startup with 2 raps on the throttle

Car after 30 minutes of idling

Thoughts?

 

[gotstang]

On the first graph, what is going on when it first spikes upward? It's going very lean then which makes me wonder, since it's not lean any other time. Or, is that during starting?

 

[toddwallace]

The first graph has 2 quick raps on the throttle...

 

[daveSanborn]

I truly believe, I have some electrical/fuel problem that gets aggravated by the hot engine compartment.

An ignition coil that is overheating will cause some of the symptoms you've described.

 

[Lemondrop]

An ignition coil that is overheating will cause some of the symptoms you've described.

Yeah, he had a similar post at vmf and I suggested using a blow dryer to heat up ignition parts to figure out which one was sticking him.

 

[toddwallace]

That makes sense.. I am going to relocate the coil so that it is away from the engine to see if that helps..

 

[gotstang]

That makes sense.. I am going to relocate the coil so that it is away from the engine to see if that helps..

If it's breaking up when it gets hot, that's not gonna do much. Following lemondrop's suggestion or waiting until it craps out and dousing it with icewater would be much more effective, but in the end, if this is what's happening, you're gonna have to replace the culprit.

Could also be the hall effect sensor in the distributor crapping out, if you're running an electronic unit. I've been bit by that bugger at least 6 times in the last few years.

The more I think about it, the more I think lemondrop is right...either that or you have a fuel problem (vapor lock?).