TPS vs MAP

[dean]

Hi

I am running TPS with MAP correction. I am having trouble getting rid of a off idle flat spot. A friend is trying to get me to run MAP only.

So what are you running with your EFI turbos? TPS, TPS with MAP correction or MAP only? And how is your throttle response?

Also if you can give me good reasons to convert to MAP that would be great. I can think of one. Mapping might be easier with MAP only.

Thank you

[GJF]

Dean this is a funny topic for me. For some reason DTA leans torwards TPS. This method is like tuning a mechanical injection car. And it also makes for more map jumping to fine tune. It will generally be good for a nice clear day but have issues in drastic weather change as it is very hard to compensate for the drastic change. Typically club cars or N/A engines with low speed velocity work well with this setup.
With MAP it immediatly handles these changes because it is always adjusting to the current conditions. It does still use the TPS to provide the ECU the instant on/off response fuel needed during free reving and transition. But to go this route you will need to redo all your maps, but once it is done you never need to touch it again unless you do major engine changes. PM me and and I'll give you my number, I can further explain my two cents if you are interested.

[WERK I]

I often wonder about the granularity of some ECU's/software. That is, the sampling rate of the ECU in relation to either the TPS or MAP. If the granularity isn't there, it would be extremely difficult to compensate off idle characteristics, since granularity isn't there since you're dealing with a very small area of the VE table.

[David]

I'm running TPS with MAP correction. Mine's fine off idle, but I do have a bad flat spot around 2500 rpm at part throttle which my tuner atributes to the Carrera manifold. I think it's a tuning problem.

[hobieboy]

I am with GJF and I also only used MAP based tuning for mine. I find that unlike NA motors, depending on whether you are on/almost-on boost, relying on TPS to affect fueling can be very inconsistent & difficult. Particularly when I was tuning for accel enrichment - relying on TPS delta means that I'll need different enrichment depending on where my starting MAP was.

[GJF]

Usually a flat spot that doesn't show a lean AFR at a particular point,means too much fuel in your MAP vs TAU map. This is your asyncronous fuel map, it is like a accelerator pump on a carb. Some ECU manufactures call this map different names but it is the same thing. Some display the map numerically while others have a bar graph. Once your base map AFR's are at the desired setting then this map is used to fine tune the transition of idle to rev's, and part throttle acceleration. Another important part is the throttleplate at fully closed position. Typically you want it closed so the IAC is open 6-7%. This will insure you to have good control over your idle. I really can't stress this setting be correct enough. It will make your life so much more easier. If you use a larger TB you might need to drill a hole in the throttleblade in order to reach this setting. On every 80mm TB I have put on a Carrera 3.2 intake I have had to drill a 3/16 hole to acheive the 6-7% with a GM IAC. I know alot of people have used the Bosch IAC and have had good results without drilling the TB. But then again every motor is different.

[DonE]

I use MAP.

The TPS is used for acceleration enrichment as a percentage over time. The faster I press the throttle, the more fuel is introduced (then quickly decays).

Some software overlays TP (to create a 4D table) to control individual throttle bodies using EFI.

[dean]

Sent you a PM GJF.

I do want to change to MAP. I am curious to see the difference. I think I should be able to get rid of the off idle hesitation but I haven't been able to so far.

Thanks

[WERK I]

Originally Posted by dean

Sent you a PM GJF.

I do want to change to MAP. I am curious to see the difference. I think I should be able to get rid of the off idle hesitation but I haven't been able to so far.

Thanks

Have you tried playing with your ignition timing in a case like this?

[dean]

Yes I have played with the timing some. The motor goes instantly lean or so the a/f gauge says when I stab the throttle from idle.

Thanks