I swapped a BBK 58mm TB onto my '88 LB9. Within 15 miles, the car stumbled, then threw an engine light. Pulled the code and it's a 33 and 42. There's no vacuum leak. Does a higher flow TB usually throw a light? If so, I'm selling it. As for the 42, I haven't messed with the timing in months, and the EST wire is plugged in. What would the TB have to do with the timing advance? The TPS is adjusted correctly after the swap. Before I get flamed, I have done a search and got partial answers. Thx.

 

Why not swap back and see if it throws the codes again? That's one of those things... many agree you don't need the big TB and it will cause problems, many agree you don't need the big TB and it won't cause problems. Then there are the 'others'...

 

Your code 33 can be set by the larger amount of air being drawn through the MAF due to the larger throttle body that you now have installed on the car. The code 42 could just be an intermittent affair, clear the codes and drive it for awhile to see if they both come back.

 

Well it kept coming back within 15 miles of driving, until I adjusted the TV cable again. Then it went away and hasn't been back. For kicks I took the cable out of adjustment and the light came back on. I don't know how, but for some reason the TV adjustment is tied into the ECM. Must have something to do with load vs. rpm and the ECM thought something was up with the timing. O well, it's fixed. Don't know if the TB was worth putting on, but I had it laying around.