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stumble with light throttle
Hi all, I am about to head out on a long 3 hour drive back to college for 4 days, and was wondering if you could help me with something real quick?
I have my car barely tuned. It runs quite well when cruising, but has nothing tuned for boost so I am staying out of it. I also don't even have the secondary injectors mapped out yet. The major problem right now is that when I tap the gas, the car will turn off. So when I try to go from a stop to a moving state (as if taking off from a stop sign of a stop light) I have to press the gas further than I need to, either spinning the clutch, or making me look like an idiot, just so that the car won't turn on instantly. What maps would this mean I need to mess with? I just installed my wideband, and have it working quite well. I idle right at 12 afr right now. I haven't really got much of a reading while driving as I have been paying mainly attention to my coolant temps. I have been messing with the map at 1000 rpm (because that is where I idle) but I haven't been noticeing any changes. Where would I go to add or move fuel from the sport RIGHT after you get off the 0 throttle map? Thanks ~Tweak |
does this stumble happen when cold or warm or both??
are you using the zero throttle map? also you may need to adjust your throttle pumps |
both warm and cold.
Yes I am using the 0 throttle map. Adjust throttle pumps, check. I will try to figure out how to do that. Thank you for the quick reply. Would it help to get a wideband reading from when it happends? I looked at help at the throttle pump maps and that sounds exactly what I need. I will head out and see if I can fix it. Thanks! |
opps forget this post. :) Found the throttle pump maps. Tricky.
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Update : I played with the throttle pump maps, and little seemed to change if any. But I disabled the zero throttle map all together and it runs smooth now. After this week when I get more time to play with it, I will figure out why the ztm is causing it to turn off at 1% throttle. :/
Thanks for all the help! ~Tweak |
I was going to say ditch the zero throttle map. Unless you're running a very radical port or ITBs there is no advantage to the zero throttle IMO. And as you have found tuning how it comes on and off that map can be tricky.
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+1 on ditching the zero throttle maps... The zero throttle map works from 0 RPM to 2000RPM.. so any adjustments to the fuel maps below 2000 rpm will not affect the idle making the transition sometime difficult to map
Zero Throttle One problem that often occurs with performance engines is rough idling. The manifold design, cam motors that vary the airflow at zero throttle will not allow the Zero Throttle Map to operate correctly.characteristics, etc. can cause instability in the airflow. This makes fuel metering difficult. In particular, the Map sensor often cannot correctly read the manifold pressure, as it is non-existent, weak, or pulsing too much. In many cases though, once the engine has some speed, the manifold pressure signal is useable. The best method of mapping the engine is using the manifold pressure as the load. If in this configuration idling is causing a problem, the Zero Throttle Map should be tried. This Map maps the fuel delivery at zero throttle below 2000 rpm. There are a few requirements that need to be met before you can use this Map. Firstly, your throttle position sensor must be calibrated properly. Secondly, the Map relies on there being a consistent airflow at zero throttle for a given engine speed. That means that devices such as idle speed |
Awesome! Yeah, it is driving VERY smoothly right now. It really had me thinking that I did not know how to drive a stick, every light it would fall on its face haha. I feel as though my trip is going to be quite easy now.
Thanks. ~Tweak |
Make sure your throttle dead band is set correctly, if its too high or too low it will either not engage the throttle pumps at the appropriate time or not at all.
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Well, right now I just wanted to get it running smoothly my trip. I don't think I am going to touch it now since it's working quite well. Just did a 200 mile trip with NO problems except the car getting a little warm. I am just going to drive it like this till I can have BDC give me a full tune. :D
I am sure I'm at the point where I know (or think I know) juuuusstt enough to get me into trouble, and not able to fix it. haha Thanks ~Tweak |
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