[volleykinginnc]

My 2002 ST4S has developed a nasty cough. Best way to describe it is once I start off it coughs or burps and sounds like it's trying to die and is coming from the intake (not the exhaust). Does this whether hot or cold.

This started after my ECU died and I took it to the incompetent stealer who put in a DP performance ECU. They said that they did not adjust the TPS or Throttle bodies so my question is...should they have done this when changing out the ECU?

 

[RedST]

should they have done this when changing out the ECU?

Oh, most definitely. The ECU stores the values for max and min readings from the TPS (or what it *thinks* those reading are). From the factory you have about a 1:100 chance that the TPS values will be correct on a new ECU.

Best to get it reset.

 

[tonered]

It is most likely needs a TPS set and throttle body sync.

The ECU controls the TPS. An ECU change would require a sync, IMHO.

I had the same issue by short-cutting a previous sync.

Have a good one.

(holy lack of proof reading, Batman)

 

[christian]

The just off-idle cough is most likely due to a lean idle mixture.
Ask your dealer to set the trimmer to a richer value with the Mathesis, say by +20, +30 or even +40 points.

Let me know!
Chris

 

[twerth]

The just off-idle cough is most likely due to a lean idle mixture.
Ask your dealer to set the trimmer to a richer value with the Mathesis, say by +20, +30 or even +40 points.

Let me know!
Chris

I've had the "just off-idle cough" as long as I've owned my ST4s. I just completed a valve adjustment, TPS adjust and throttle body sync, and the cough is still there. The bike runs great otherwise.

My experience with other bikes and cars makes me think the lean idle is a likely cause. Is there a way to adjust the trimmer without the Mathesis (i.e. at home)?

 

[tonered]

twerth,

Just curious, did you disconnect the vert TB when adjusting the TPS? I didn't on my first one and developed a cough. Afterward, I disconnected it and life has been a lot better.

Have a good one.

 

[twerth]

twerth,

Just curious, did you disconnect the vert TB when adjusting the TPS? I didn't on my first one and developed a cough. Afterward, I disconnected it and life has been a lot better.

Have a good one.

No, I didn't disconnect anything when I adjusted the TPS. I didn't see that in LT's manual. Are you talking about disconnecting the wiring harness or linkage?

volleykinginnc, sorry if I hijacked your post. I'll get out now.

 

[tonered]

I think were still on target here.

To set the TPS, the throttle cable should be release from the cam, the idle lever fully loosened, and the link rod removed from the vertical TB (there is an e-clip on there). I didn't do the last part on my first go. I don't have LT's manual with me, but I think that is in there. This was causing my sneeze stalls. Just to note that I nailed both voltages both times. Also, I do get a random backfire through the intake after engine braking down to above idle. I think it may be from my low-end rich condition (no gastester yet).

Have a good one.

 

[JasperST4]

I think were still on target here.

To set the TPS, the throttle cable should be release from the cam, the idle lever fully loosened, and the link rod removed from the vertical TB (there is an e-clip on there). I didn't do the last part on my first go. I don't have LT's manual with me, but I think that is in there. This was causing my sneeze stalls. Just to note that I nailed both voltages both times. Also, I do get a random backfire through the intake after engine braking down to above idle. I think it may be from my low-end rich condition (no gastester yet).

Have a good one.

That wasn't in my LT manual. I don't see the gain. There's only one TPS and the other body is synched to it. All I did, as per "The Good Book", was to back off the idle screw so the bodies are fully closed.

 

[tonered]

I forgot to look last night. I am seriously surprised that step isn't in there. It is definitely in a write up somewhere. Found it:

http://www.bikeboy.org/ducati4vthrottleb.html

Tons of good reading here.

The problem is that the linkage can prevent the horiz TB from fully seating. It definitely happened to me. You can try this, with the Duc running, give a gently push forward on the vertical TB arm. It will sneeze just like a sneeze stall.

Have a good one.

 

[JasperST4]

I forgot to look last night. I am seriously surprised that step isn't in there. It is definitely in a write up somewhere.

I believe it comes after manually setting up the throttle bodies so that part should be done. He does say to push down on the butterfly valves to see if the reading changes.

 

[tonered]

Okay, I'll buy that. So how about I state it this way. If experiencing sneeze stalls that can't eliminated otherwise, try setting the TPS and balancing the TBs with the additional step of disconnecting the vert TB linkage. It takes just seconds. The only problem is that we are dealing with a mostly blind e-clip location. At least there aren't many places it can go until it bounces on the floor.

Have a good one.

 

[twerth]

I forgot to look last night. I am seriously surprised that step isn't in there. It is definitely in a write up somewhere. Found it:

http://www.bikeboy.org/ducati4vthrottleb.html

Tons of good reading here.

The problem is that the linkage can prevent the horiz TB from fully seating. It definitely happened to me. You can try this, with the Duc running, give a gently push forward on the vertical TB arm. It will sneeze just like a sneeze stall.

Have a good one.

I followed the procedure by bikeboy and it completely cleared up the sneeze. Thanks a million tonered!!

When I disconnected the linkage, I checked my base setting and it was off a little, so that might have been it. Also had to readjust TB sync after the TPS was correct.

The other thing that I didn't get from LT's manual is using the air bleeds to adjust idle. They're both a little farther in now (1/4 - 1/2 turn) which should richen the idle mixture. Since the coughing feels like a lean mixture problem, this might have been the ticket.