$0d Code with turbo, boost

**dave w** · 12-26-2014

Originally Posted by Six_Shooter

This is what most people find when they use a 2 BAR MAP on a 1 BAR code and only try to modify the VE and spark tables based on scaling for the different MAP sensor.

The BARO updates don't update correctly, and a few other parameters that rely on a 1 BAR MAP sensor being attached and knowing that 5V = (approx) 100 kPa. Many people have got it to work, but it always seems to be a compromise.

Interesting information. I'm thinking the Baro updates at startup? I'm wondering if two MAP sensors could be used, 1 bar MAP at startup for Baro then the 2 bar after startup? Maybe use a DPDT relay to switch between MAP Sensors for the Baro reading?

dave w

**Six_Shooter** · 12-27-2014

Baro updates more than just at start up. It'll somehow do it while the engine is running and at WOT.

**delcowizzid** · 12-27-2014

we used to use 1 bar code with 2 bar sensor pretty much set default map at key on at 50kpa.it may not be defined in your xdf or may not exist. halve all the table kpa values and fudge the injector rate to double fueling so the ve table didnt max out LOL

**scottyd** · 12-27-2014

I had worries that it wasn't as easy as that seemed. I read a thread not long ago where a fellows solution was to use a 1 bar map and just up the fuel in the 100 setting only, basicly I suppose any time the engine was in boost it got more fuel and the higher the rpms the more fuel based off a single column for tuning... seems simple but also seems crude and not very linear.

**96lt4c4** · 12-27-2014

Originally Posted by delcowizzid

we used to use 1 bar code with 2 bar sensor pretty much set default map at key on at 50kpa.it may not be defined in your xdf or may not exist. halve all the table kpa values and fudge the injector rate to double fueling so the ve table didnt max out LOL

I have been researching, looks like a lot of people just keep right on using the 1 bar map sensor. I guess I will just have to see at what RPM this thing starts to build boost and use the PE parameters to subtract timing and add fuel. If it starts building boost at say 2500 RPM then just make sure I am entering PE early enough to use the PE AFR and PE timing tables to do what I need to do. I may revisit the 2 BAR map after I get it up and running. I will look around in the hack and through the .XDF file to see if I can find anything.

Trying to figure out why I would need to fudge the injector rate? I had thought about lowering mine to richen the whole thing up. No mater what I did to the VE tables I was still way lean. So i could see where lowering the injector value would richen everything up but don't understand why.

**Roadknee** · 12-27-2014

Originally Posted by 96lt4c4

Trying to figure out why I would need to fudge the injector rate? I had thought about lowering mine to richen the whole thing up. No mater what I did to the VE tables I was still way lean. So i could see where lowering the injector value would richen everything up but don't understand why.

An engine with decent induction, heads, cam, exhaust, etc., will need more fuel than you can provide by setting VE cells to 100. Since the code won't accept VE over 100 you need to reduce the injector value.

**96lt4c4** · 12-27-2014

Originally Posted by Roadknee

An engine with decent induction, heads, cam, exhaust, etc., will need more fuel than you can provide by setting VE cells to 100. Since the code won't accept VE over 100 you need to reduce the injector value.

I was trying to drive the truck with no boost. Just the 2 bar map installed thinking that by re-scaling my tables that it should still run to 100 KPA just like normal. But it ran horrible. I am going through the MAP and Baro update tables right now, comparing them to a GMC Syclone bin but I am not real sure what I am looking out or how these tables work.

**scottyd** · 12-27-2014

Have you ever considered a FMU? raises fuel pressure at a determined ratio based off boost to push more past the injectors. For example 1:6 one pound boost raises 6lb fuel.. Iirc thats what Paxton and other supercharger companys were doing with TBI and early mpfi applications.

**96lt4c4** · 01-02-2015

Well drove the truck last night, boost comes in quick, around 2000 RPM. I had to set my PE enable TPS to about 25 % to get it to richen up, which it does. But, it starts to lean out as the RPM picks up, so I have to let off pretty quick. Only about 5 pounds of boost right now. I retarded my timing table about 7 degrees in high load area, not getting any spark knock. I am thinking about putting main spark table back where it was and pulling timing with the PE spark table.

Today I am going to try hooking my AFPR back up to vaccum/boost source and raising the fuel pressure back up to about 60 psi, about 43 psi right now. 5 psi boost should raise raise fuel pressure 5 psi. I may have to fudge the PE AFR table to get it to richen up as RPM climbs. Open to any ideas here.

But man! turbo is freaken awsome! until lit goes lean...lol

**Six_Shooter** · 01-02-2015

Wait, you're running an MPFI setup without vacuum(/boost) referencing the FPR? If that's the case, connecting a vacuum source will help lean out idle and richen up high load/in boost areas.

**96lt4c4** · 01-02-2015

Originally Posted by Six_Shooter

Wait, you're running an MPFI setup without vacuum(/boost) referencing the FPR? If that's the case, connecting a vacuum source will help lean out idle and richen up high load/in boost areas.

Yes I am, I had it connected to vacuum but had disconnected to troubleshoot other issues. I am hooking it back up today.

**delcowizzid** · 01-04-2015

start with a standard base fuel pressure 38psi or so idling withe the vacuam diss connected .running 60 psi base will just drop the flow rate of the pump so much right off the bat even before boost adds more pressure

**Roadknee** · 01-04-2015

I am impressed with how quickly you got that put together. Are you still running the 2-bar MAP?

I'm pretty sure the PE spark table won't accept negative values.

The fuel regulator that scottyd mentioned in post53 might be worth a look.

**96lt4c4** · 01-05-2015

We did get it done really quick, worked on it over the holidays, had vacation days. You are right PE timing won't take negative numbers. Right now I have about 50 psi fuel pressure with the vacuum hooked up. I have the same style injectors and pump thats in my Camaro and it runs 62 pounds all the time. It has really only taken me a few days to get the major bugs worked out, the thing runs like a raped ape...lol. Still on 1 bar, 2 bar is going to take some effort.