Rogue_Ant

Good question. I've never heard anything other then hearsay.


Rogue

eniac

With a Link you still have temperature correction. I had a wire break on mine causing the car to run extremely rich. This is a common problem since the sensors are very cheap. I have not had any issues with temperature changes on my Link driving going from 55' to 105'F outside air temp. The Huntley MAF I use to have did not have a temp sensor and that was terrible, I had to constantly adjust it.

Quick edit: I just rembered how the temp sensor connects. No the Link does not do anything with temperature correction, that is correct. The temp sensor included connects to the DME so the Motronic does the temp corrections as it would stock. There is no need for the Link or any PB to do a temp correction when it's already there in the DME.

The only problem I do have is a slow repsonse time from the Motronic not being able to keep up, or possibly the combination on the pb and DME. The Motronic is a very old computer. For comparison, how well would you think a PC from 1988 would work with anything made today? Same with the Motronic although not as bad as the PC comparison it still has lag.

Jake951

This seems to be consistent with what I observed with the Link MAP. I think it also explains the famous (or infamous?) "off-idle stumble" that users reported with MAP. When you hit the throttle, the A/F ratio momentarily would go very lean (therefore the stumble), as though it was taking a fraction of a section for the DME to respond to the change. The MAP signal would respond immediately to the throttle change, but the fuel always seemed to lag behind slightly.

Interestingly these problems don't seem to exist with MAF and Motronic. Perhaps the reason is that the MAF sensor is located upstream from the intake manifold, whereas the MAP sensor is downstream in the intake manifold. This means the MAF senses the air flow change slightly sooner than MAP, which gives the DME a bit more time to respond and therefore compensates for the delay in the Motronic response. Does that make sense?

sawood12

I thought that the DME doesn't correct real time for temp in the stock set up. As far as I understand it takes a single temp measurement at start up and makes the corrections then, so it doesn't constantly correct for temp. A MAF does as it needs the temp input to be able to calucalte the mass air flow.

Rogue_Ant

This is what I've heard before, but I completely dissagree with the reasoning. A sensor at the very beginning of the intake track will be slower to respond then a MAP sensor connected directly to the intake manifold, IMO. That said, however usually MAP based enrichments are too slow. Which is why 90% of my enrichments are TPS based. TPS based enrichments are very fast, and using them I've eliminated any lean-stumbles.


Rogue

badcoupe

If you realize as I did that link box is off by about 500 rpm and start changing values way down low in the range(it's been a few years don't remember which cells) the idle stumble is gone. I noticed that where I made changes, the actual change was 500-700 rpm different on the dyno. Tim at speedforce also noticed this. you basically had to move your whole map a few cells. I never could figure why noone else picked up on this. You make a change to a cell but the change would happen in a different area. Maybe it was because of the interpolation. Either way I would love to try the translator one one of these cars. I made over 800 hp on a dsm with one before the owner went standalone.

Jake951

I had quite a bit of experience with the Link PB but never observed that effect. I always found the PB acted correctly on the intended cells, at the least the way I interpreted the labeling of the cells. IIRC the rpm label of a cell actually marked the rpm at the center of a cell (or maybe that's what you are describing). I do know that the Link unit did interpolate the fuel settings into adjacent cells to make smooth transitions between cells but the designated one was always the cell that was affected the most.

GPF

Hi Stephen,

which version of his chip do you use? I would love to try his chips but I didn't think he had one for a MAP setup.

Regards

Graham

Rogue_Ant

My buddy (Dean) in his 3000gt VR-4 (twin-turbo), who is running the same Piggy-Back as me. He is the second race - against a supercharged mustang. BTW, this is the cars very first shake-down pass (and at 5200').



*Not my video*

Rogue

Pauerman

Cool vid!

Thanks for sharing your MAP experience with us Rogue - I think TPS based enrichment is the way to go. Badcoupe's suggestion of tuning 500 RPM off the target load cell only reinforces that using MAP based enrichment is too slow - at least with the Link MAP setup.

eniac

I had contacted Russel prior to ordering because I had a few other special requests on my chip. For the MAP he told me to select AFM as the option along with the injectors and turbo I was using. Before ordering I would call or email him.

eniac

I have trouble trying to tune in TPS mode, I get inconsistant stuttering and lean conditions. In MAP mode the car runs great and doesn't stall out if I mash the gas.