NicD

iTrader: (7)

Well, you will never get rid of the sloppiness down low but you will make it more manageable with lower fuel pressure. Also depending on your 3 bar map sensor it may not be reading your vacuum very accurately which is also going to make idle and decel fueling "fun". That's why I like the DPE corvettes 2.5 bar map sensor as it's accurate all over and most people don't need more than 2.5 bar of measurement.

1320

iTrader: (6)

seems like evry time asks what injectors, the vendors are real quick to try and sell. But when people are just solving problems, the herd thins out a lot.

Now where is that video I posted, that a vendor had removed? It was a you tube video showing spray patterns on a high speed camera. It seems the moderator that removed it and said I was pushing some injector might have a bias? Cause just seeing it, in this case, definately could have avoided this thread entirely.

Good luck with the idle......I went another way but Im not allowed to tell you.

HydroStream6

iTrader: (16)

The injectors are 846. The map is a 3 bar "GM1222xxxx" but I'm not positive on who makes it. I'd like to get a new map but I find so much differing information on them that I can't figure out if I'd be better or worse off.

FYI, I'm planning on maxing out this turbo on my setup, which should be around 20psi I'm thinking on this setup.

HydroStream6

iTrader: (16)

Oh and my email is bigadam@rochester.rr.com

When going from 4 bar to 3 bar, are you just adjusting the injector tables?

NicD

iTrader: (7)

OK, that is the old 3 bar map sensor that looks like a rectangular block correct? Yeah, that's the one that only goes down to about 40 kpa on the floor and is only around 8% accurate at that. I would highly recommend the 2.5 bar map sensor from DPE corvettes. It's accurate from about 20 kpa up to 250 kpa +- 1.5%. That old 3 bar map sensor is not going to make things any easier at all. What kpa does your car idle at?

Those injectors are the old Ford 160s with the light grey (white) top correct? Those are pretty nasty down low with some funky characteristics but still tuneable.

For the most part yes, but with big injectors like that it's usually got some minimum pulse width errors baked into the VE table, etc that need adjusting. Note that it will happen even if you had 100% accurate injector data when you end up riding the minimum pulsewidth...

HydroStream6

iTrader: (16)

Yes, it is the rectangular block looking type. If I switch to the 2.5 bar map, will that affect the OS that I'm running at all? Or just plug in new map and off I go?

The injectors are indeed the whiteish top "Bosch" or "Ford" type.

From looking at logs, looks like she idles in the 40kpa range.

NicD

iTrader: (7)

It won't affect the OS since you already have the 3 bar loaded. You will need to change the scalars for the map sensor and that's it.

OK on the injectors, I have data for those for aftermarket computers but it's fairly straight forward to convert to LS1 PCM format. I'll work on that shortly...

Idling around 40 kpa is what I was afraid of, you are at the mercy of that old MAP sensor at this point and if you want more driveability and accuracy you will need that newer sensor.

HydroStream6

iTrader: (16)

I looked up that map. Looks to be very linear from 20-250kpa. Is this an off the shelf GM sensor or does DPE do something special to it? It's a little pricey but if it's all you say it is, it's probably worth it.

I appreciate the help. I just got a base tune on our RX7 project as well, so I can use what I learn here with that. It's a 5.3 with a GT2-3, good springs, LS9 gaskets, ARP hardware and a 7875 as well. It's scary already on 8lbs. Also on E85, the 60lb injectors on that are already done though. Will probably tune that one in on the dyno now at the current boost and leave it until my buddy learns how to drive it, haha.

NicD

iTrader: (7)

It's a different sensor that is transplanted into the factory housing so it's a direct bolt on type of deal. It's definitely worth it when dealing with the wide range that you have.

HydroStream6

iTrader: (16)

Do you happen to know what the different sensor is? Also I received your email, I'll look at it more closely when I'm home from work. Thanks again

NicD

iTrader: (7)

It's the Motorola MPX4250AP I believe but it's the part number without the "body" so it fits better inside the OEM map sensor case. The sensors themselves are cheap, it's the labor to integrate it into the factory casing that makes it expensive.

HydroStream6

iTrader: (16)

I might just order the $13 sensor and give it a shot. Nothing a soldering gun can't take care of. Looks like I would just need the ground, VCC and vout. My stock MAP is still in the stock location and it's hard for me to swap with the intake on. I keep it installed because I plug it and the MAF in and flash a different tune for inspection.

HydroStream6

iTrader: (16)

So we ordered 3 of these sensors a while back. I finally wired one into the RX7 today. Man does it run better! Just swapping the sensor itself and reflashing for the different offset and slope made a HUGE difference. Did some fine tuning after that, so much better now. Definitely will be doing the GTO in the spring.

Ryan K

iTrader: (11)

I run my base pressure at 40#, idles great, and running a 9.114 @ 152 mph I am at 60% Duty cycle.... Drop the Fuel pressure.

HydroStream6

iTrader: (16)

I dropped the GTO to three bar a couple months ago and retuned due to nics advice, helped a lot.