Cascade Crew

Twilightoptics · Posted: Mon Jul 30, 2012 5:00 pm Post subject: BBC TBI dance

L19 engine. GMC 3500 7.4L TBI 1989

Was running fine. Then fire up one day and it runs like someone stuck a Thumpr cam in and dies after some off throttle idle lopes.

-CTS is reading correctly.
-TPS is good.
-Fuel is fresh
-Engine will rev up and half ass smooth out, but will stay running, though you can still tell something is off.
-Disconnected one plug wire at a time and had no change in the engine.
-CAP/Rotor are newer and still look good with no obvious arcing marks.
-Gets 200 knock counts in just a few seconds and continues raising the counts.

Now I wasn't in crappy enough clothes to go looking for the knock sensor on the ground, but alldata says the sensor is infront of the starter, and the knock module is on the intake at the right rear above the valve cover. Well the knock module isn't there and I don't see a connector for it either.
I couldn't see the knock sensor with my light from sticking my head under. I'll check again when I go back next week.

Thinking dizzy/ICM or Knock sensor circuit?

aaron_sK · Posted: Mon Jul 30, 2012 7:10 pm Post subject:

I kept looking around after we talked on the phone (because I have no other pressing projects to work on Razz

) and found these. Looks like ESC module is on the other side of the firewall.

91RSVert · Posted: Tue Jul 31, 2012 9:19 am Post subject:

Both injectors are spraying fine?

Twilightoptics · Posted: Tue Jul 31, 2012 10:03 am Post subject:

Love it when they change things for no reason! I'll look above the steering column I guess!

Injector patterns are fine and consistent.

chevymad · Posted: Tue Jul 31, 2012 1:40 pm Post subject:

Egr stuck open?

Twilightoptics · Posted: Tue Jul 31, 2012 2:53 pm Post subject:

No vacuum on the line and pulled the line off it didn't change anything. I haven't pulled the EGR off at this point, but was thinking that as well. When I go back I was going to bring my vacuum hand pump and see if I could get EGR action.