Just a quick question. When I rev the engine in park and while in closed loop, if I move the throttle smoothly It revs nice and smooth. But if I hit it hard it has a slight hesitation just of idle. Now It seems to do this when driving as well but very slightly. Its not a pop or anything like that and my current tune is very good +-3 blm's. Now just wondering if I should increase the tps%AE or the Map%Ae??? I would think that I should up the TPS%Ae do to the quick change in throttle but Im not sure. Any help would be greatly appreciated!!

 

If it's practically an instant hesitation or pop, dTPS. If it's lean for like 1.5 seconds, dMAP. A fast responding wideband is SOOOOO helpful during this stage of tuning.

 

It is just an istant or so it does not last for more that .5sec's. Now with tpsae it goes from .5 to .25 should I increase that entire range or just the larger tps movemant area?? THanks again and I know I need a wideband but the wife is on me for my recent order of new heads and cam LOL. Cant wait.

 

What ECM are you using? IIRC, some of the truck ECMs are set up to have the TPS deliver most of the AE. On my PCM when it was stock, almost all the AE was delivered through the dTPS. May not always be the best method, but in some apps., it can respond faster.

 

something tells me this is always going to be an issue with TBI. I dont have tunerpro at hand but there are also "duration" factors that can be applied. That is the lenght of time the quantity of AE is applied. adding duration takes away from the quantity so balance those changes. I played with it ever which way on both TPS as well as MAP. Seems best drivability is having most of the AE in my TPS tables for me. You might take notes as far as the TPS movement in data log and the affect of change in SOP and do same on the MAP changes seeing if a change in one table favors over the other. ALso there is a AE table for RPM. I found that out this year. I was lean at 2400 rpms(bog) at load only and i dumped in a lot of AE 2000-2400-2800(more at 2400) and it smoothened it out. I have a 454TB so that add to AE misery. Also seems OL(enrichment) operation provides better AE for me.

 

Im currently using the 7747 ecm. I appreciate the help and advice guys I will attempt to adjust it a little better now knowing what to look at. I kinda figured that I should use the dtps for this problem, but your thoughts just confirmed this for me. THanks again and Ill let you know how it goes this weekend.

 

90c350, be careful with the TPS AE as it also provides the AE that should normally be provided by the dMAP. It sounds like the AE you need is short term for covering for manifold filling and transient response of the ECM and sensors. This is short, and only needs to last for a couple hundred milliseconds. IIRC, the TPS AE on the truck setups is used to cover for the fuel dynamics, which means that it provides AE over several seconds. Adjusting it may fix the momentary stumble, but could also cause a massive bog with black smoke afterward. The options are to move your long term AE over to the MAP AE and adjust the filter coefficients and such as needed for the MAP and AE TPS (MAP AE long duration, TPS short duration), just live with it, or compromise somewhere in the middle with the long and short term AE requirements.

Yeah, the AE required varies quite a bit with manifold temperature. Its tolerable with an auto, but its a nightmare with a stick if its not tuned properly. The only way I could get nearly seamless AE operation was to rewrite all the code and use the manifold temperature instead for the MAP AE filter coefficients, %DC, and multipliers. Not surprisingly, when the manifold is cold I need about 20x the AE that I need when its near engine operating temperature.

 

Thanks again Dimented your expertise is alway's helpfull!!! I seem to have it coverd with just a slight increase in the dtps. THanks again guys.

 

If this is at low(er) engine speeds it is common to cover some AE with the VE table. The reason being that the engine won't stay in the low speed area if you are hitting the go-pedal, and it is an easily repeatable amount of added fuel.

For port injected engines it is even more common to cover tip-in with AE in either the MAF or VE table(s).

Good to hear that you have it fixed. The '7747 has a decent range of adjustability for AE.

RBob.