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| tjpreul | tuning and MAP questions | ||
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Elite Guru
 
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I left my stock MAP sensor in when I installed my supercharger. Is the stock sensor a 1 or 2 bar? Next what engine control managment systems are you running if you have added a supercharger. My car is a '92, so I am currently tuning with a piggyback system from Split Second.
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Posted on: 2012/7/4 4:10
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| djxib | Re: tuning and MAP questions | ||
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Senior Guru
 
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Stock sensor is a 1-Bar - tops out at atmospheric. I'm running a Vortech V7-YSi supercharger on my 92 with the stock GM computer. Tuning with a supercharger and the stock computer is pretty involved and I've already spent a lot of time on mine - but the car drives really well and makes good power.
I'm very interested to hear how you progress with the piggyback system. From what I have read, piggyback systems are good for fueling in most situations )cruise, idle, WOT), but can struggle with automatically dealing with transient situations (e.g. from cruise to WOT) unless they are configured. Not sure if the Split Second system tunes spark - is it configurable with a laptop (e.g. at the Dyno?) What model of system did you get? Let us know what features is has. Good luck with your tuning, keep us posted! |
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Posted on: 2012/7/4 11:32
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Andy 1996 Greenwood Collectors Edition LT4 Previously 1992 Convertible Polo Green. 383 LT1/LT4 forged/balanced. V7-YSi, Alky. 608RWHP... Now sitting at a dismantler with a salvage title. Still runs... |
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| tjpreul | Re: tuning and MAP questions | ||
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Elite Guru
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djxib, are you running a FMU (Fuel Management Unit)? The issue right now is it seems that the car runs different everytime. Which I have heard is a downfall of a piggyback. I think I need to switch to a 2 bar MAP, so the changes in the stock computer will not be as drastic.
I took it to a tuner and they had asked for the plugs to be at .28, I had them at .34. After I did this I basically had to start over just to get the car to run. Since the engine is new they just did a drivable tune so I can put on some miles. |
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Posted on: 2012/7/4 17:48
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Vegas wasn't built on winners. '92 auto, MSD, Banski, Taylor wires, SS lines, C5 rims, 3.07 gears, white gauges, seats from a '96. Motor: Forged rotating assy, Probe pistons, CC valvetrain, AFR heads, Procharger P1SC |
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| tjpreul | Re: tuning and MAP questions | ||
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Elite Guru
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I called Split Second, and hopefully found the issue. The piggyback computer has a 2 bar in it, and you keep the stock 1 bar on the engine. Then make the output voltage reading match with key on engine off. Take these numbers and put them into a formula. This is the number I am to enter into the 500rpm row. By doing this it will make the piggyback MAP read correct to the size that is needed (ie 1.5). Currently I have the same numbers filled into this row as what are needed for the fuel (which are lower).
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Posted on: 2012/7/5 19:35
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Vegas wasn't built on winners. '92 auto, MSD, Banski, Taylor wires, SS lines, C5 rims, 3.07 gears, white gauges, seats from a '96. Motor: Forged rotating assy, Probe pistons, CC valvetrain, AFR heads, Procharger P1SC |
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| tjpreul | Re: tuning and MAP questions | ||
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Elite Guru
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Everything is adjusted now. The piggyback computer is what sends the MAP signal to the ECU. The MAP sensor had an output of 4.72v with key on, engine off. The voltage from the piggyback at this same point was sending 2.4v to the factory ECU. I adjusted the cell value in my chart, reloaded the piggyback computer and now have 4.72v output.
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Posted on: 2012/7/6 4:05
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Vegas wasn't built on winners. '92 auto, MSD, Banski, Taylor wires, SS lines, C5 rims, 3.07 gears, white gauges, seats from a '96. Motor: Forged rotating assy, Probe pistons, CC valvetrain, AFR heads, Procharger P1SC |
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| djxib | Re: tuning and MAP questions | ||
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Senior Guru
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Interesting. Do you have any specifications of the unit? I may be looking for a way to run a 2 Bar MAP at some point..
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Posted on: 2012/7/6 15:07
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Andy 1996 Greenwood Collectors Edition LT4 Previously 1992 Convertible Polo Green. 383 LT1/LT4 forged/balanced. V7-YSi, Alky. 608RWHP... Now sitting at a dismantler with a salvage title. Still runs... |
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| tjpreul | Re: tuning and MAP questions | ||
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Elite Guru
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Quote:
This one has a built in 2 bar that you can adjust the voltage output. I am still trying to work out the tune. It was much better with the MAP sensor corrected. I was running lean today, and kept adding fuel but there was no change. It kept showing about 15 on the AFR and I would add fuel, but it would run worse every time. I am thinking it was not staying in closed loop, with how it wasn't responding to my increases. |
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Posted on: 2012/7/9 3:53
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| tjpreul | Re: tuning and MAP questions | ||
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I am even more confused now. Without the car responding to the increases, then eventually running worse while showing lean I figured it was stuck in open loop. I called Split Second with a few follow up questions. They say to disconnect the O2 sensors when tuning, so the car stays in open loop. Then when it is tuned to hook them back up. As said in the previous post it will be running fine then either really rich or lean.
Tonight I opened the gap back to .35, hopefully this will smooth it out even more. I have ordered the heated O2 sensors. Mine are old and the single wire. They might not be reading accurate. |
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Posted on: 2012/7/10 3:00
Edited by tjpreul on 2012/7/10 3:19:29 |
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Vegas wasn't built on winners. '92 auto, MSD, Banski, Taylor wires, SS lines, C5 rims, 3.07 gears, white gauges, seats from a '96. Motor: Forged rotating assy, Probe pistons, CC valvetrain, AFR heads, Procharger P1SC |
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| djxib | Re: tuning and MAP questions | ||
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Senior Guru
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I'm trying to get my head around how this is supposed to work. So what you're saying is the piggy back unit has a 2-Bar MAP sensor so you can tune for boost (up to 14.7 psi).
However - I assume it's intercepting the MAP signal to your ECM, and therefore the ECM sees the 2-BAR voltage? Are there other features of the piggy back that are relevant? (BTW - please post model number / specs of the piggy back so we can get an idea what it's supposed to be doing and hence what you may need to do in the tune) It may be that this is a 'classic' 2-Bar MAP tune which requires you to effectively re-scale the VE tables.. since the ECM will now be looking up a different part of the table for each MAP value.. e.g. 100Kpa (WOT) will not be at roughly 50KPa in the table. (Some good write-ups / sticky on this topic in the tuning section of thirdgen.org). What instructions did you get with the unit? |
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Posted on: 2012/7/10 22:23
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Andy 1996 Greenwood Collectors Edition LT4 Previously 1992 Convertible Polo Green. 383 LT1/LT4 forged/balanced. V7-YSi, Alky. 608RWHP... Now sitting at a dismantler with a salvage title. Still runs... |
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| djxib | Re: tuning and MAP questions | ||
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Quote:
Scrub that - I meant CamaroZ28.com. Apologies |
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Posted on: 2012/7/11 0:29
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Andy 1996 Greenwood Collectors Edition LT4 Previously 1992 Convertible Polo Green. 383 LT1/LT4 forged/balanced. V7-YSi, Alky. 608RWHP... Now sitting at a dismantler with a salvage title. Still runs... |
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| tjpreul | Re: tuning and MAP questions | ||
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Elite Guru
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I bought the Procharger and unit off of ebay, it had the piggyback and software with it. This was a never installed unit that had been purchased in '06. However the Split Second p/n is FTC1-075. Which I don't think is available anymore due to the lack of sales. It is a fuel and spark management system. It has a vacuum hose that runs to the box, then sends the voltage to the factory ECU for the MAP reading. You set the output voltage by changing the value in the table to match the factory MAP at atmospheric pressure. By doing this it will compensate for having a forced induction engine. After that you have a table that you adjust the fuel levels with. According to them it is to trick the factory ECU to thinking it is at a different part of the set table. Then you are to readjust the fuel at that certain MAP point to even it out. Here is a link.
http://www.splitsec.com/technotes/Fue ... sing_2-bar_Map_Sensor.pdf It is to add or remove fuel when and where it is needed. Then this table is an "overlay" of the factory table. My confusion is when I called Split Second they say to tune without the O2's. When I first start my car the AFR is reading high 13's to 14's. Then it drops to 10, which I think is when it goes to closed loop. Yes, the signal wire from the MAP sensor is cut. The new signal is sent to the factory ECU from the piggyback. At 0 psi, I have them matched at 4.7v. When at idle (although not connected) the factory MAP has an output of 1.9v, and the piggyback has a 1.2v. This makes the factory ECU think it is running at a lower rpm, so then you can use the fuel table to adjust to the correct level. |
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Posted on: 2012/7/11 4:18
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Vegas wasn't built on winners. '92 auto, MSD, Banski, Taylor wires, SS lines, C5 rims, 3.07 gears, white gauges, seats from a '96. Motor: Forged rotating assy, Probe pistons, CC valvetrain, AFR heads, Procharger P1SC |
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| djxib | Re: tuning and MAP questions | ||
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Senior Guru
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Quote:
OK - I read through the tech notes and I think I understand what it's trying to do. Basically without going into the stock ECU it tricks the ECU into a different part of the VE tables based on a modified MAP signal, and you can modify that signal using the Split Second tables. From memory the 1-Bar and 2-Bar MAP sensors have some funky overlap at low voltage which can make idle and low speed tuning very hard. However, you have the overlay table that should help out. I guess the piggyback expects that somewhere in your stock ECU table is an entry that will deliver the correct fueling for any given 2-Bar MAP signal and bigger injector combination. You are going very rich (10:1) when in closed loop - are you seeing rich on both O2's (i.e. pegged above 900mv) in a scan? Or are you just watching a wideband sensor? Do you have an aggressive cam? I ask because I have a fairly aggressive cam and I get horrible split BLM's on my 92 that messes with the readings at idle, and you could chase your tail on a 'false rich' reading. I havent tried disconnecting the O2's to force open loop (I do it in the ECM) but in general you want to run in closed loop for a while during datalogging because it can give you some very good initial idea how the engine is running (BTW - low MAP voltage means the ECU is looking up a lower KPa reading, not lower RPM). I'm not sure if I am helping much because this approach is new to me too - however I do recommend that you capture some scans so you can see where the ECU thinks it's running rich or lean (you'll need it to be in closed loop for this). If you have some datamaster scans I'd be happy to take a look. Cheers |
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Posted on: 2012/7/11 16:39
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Andy 1996 Greenwood Collectors Edition LT4 Previously 1992 Convertible Polo Green. 383 LT1/LT4 forged/balanced. V7-YSi, Alky. 608RWHP... Now sitting at a dismantler with a salvage title. Still runs... |
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| tjpreul | Re: tuning and MAP questions | ||
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Elite Guru
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I don't have datamaster. I have a wideband that I am watching, and pulling random plugs. It was showing lean, and when I pulled the plugs they were white. I adjusted the numbers up by .5 then it was showing rich. I moved them back down to where I had them and it was still rich. This is why I am going to try new O2's.
My cam is the Comp 266, which is basically a stock replacement. I will have the get the harness to do a scan. That is next on my list. If this ends up not working. My back up plan is to install the FMU that came in the kit with the Procharger. |
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Posted on: 2012/7/11 17:27
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Vegas wasn't built on winners. '92 auto, MSD, Banski, Taylor wires, SS lines, C5 rims, 3.07 gears, white gauges, seats from a '96. Motor: Forged rotating assy, Probe pistons, CC valvetrain, AFR heads, Procharger P1SC |
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| djxib | Re: tuning and MAP questions | ||
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Senior Guru
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Quote:
Comp XFR 266? That's a long way from stock and even more aggressive than my cam, you'll definitely be gettng cam reversion (causes splits). In my opinion you'll be chasing your tail at idle with only the wideband. Suggest getting the ALDL cable (Moates does an excellent cable that converts to USB) and datamaster for 20 free scans. Drive the car around a bit, find out what it's doing above idle. I'm not sure the FMU will help (unless it allows you to adjust base fuel pressure with an adjustment screw) - usually used only to help boost FP when the engine is in boost. |
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Posted on: 2012/7/11 18:43
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Andy 1996 Greenwood Collectors Edition LT4 Previously 1992 Convertible Polo Green. 383 LT1/LT4 forged/balanced. V7-YSi, Alky. 608RWHP... Now sitting at a dismantler with a salvage title. Still runs... |
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| tjpreul | Re: tuning and MAP questions | ||
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Elite Guru
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Its the xtreme energy 266HR-14, rated for 1-5k. I am not ready to go to the FMU. It is the one with the adjustment screw and will raise the fuel pressure while in boost.
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Posted on: 2012/7/11 20:10
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Vegas wasn't built on winners. '92 auto, MSD, Banski, Taylor wires, SS lines, C5 rims, 3.07 gears, white gauges, seats from a '96. Motor: Forged rotating assy, Probe pistons, CC valvetrain, AFR heads, Procharger P1SC |
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| djxib | Re: tuning and MAP questions | ||
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Senior Guru
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Quote:
My mistake - I was looking at the overall duration rather than duration @ 0.050". |
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Posted on: 2012/7/12 13:20
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Andy 1996 Greenwood Collectors Edition LT4 Previously 1992 Convertible Polo Green. 383 LT1/LT4 forged/balanced. V7-YSi, Alky. 608RWHP... Now sitting at a dismantler with a salvage title. Still runs... |
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| tjpreul | Re: tuning and MAP questions | ||
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Elite Guru
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I think I am on the right track. I have unplugged the O2 sensors and the tune is not jumping. Split Second says to tune then plug the O2 sensors back in. I need to smooth out and adjust the table a bit more. The only thing is now is when I first start the car it shows lean for a few minutes.
My next two thoughts are: Was it switching in and out of closed loop too fast without having heated sensors? With the factory computer still with stock injector settings. Will it compensate too much since I have larger injectors (when it is in closed loop)? |
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Posted on: 2012/7/15 19:39
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_________________
Vegas wasn't built on winners. '92 auto, MSD, Banski, Taylor wires, SS lines, C5 rims, 3.07 gears, white gauges, seats from a '96. Motor: Forged rotating assy, Probe pistons, CC valvetrain, AFR heads, Procharger P1SC |
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| tjpreul | Re: tuning and MAP questions | ||
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Elite Guru
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I have the tune really close to 14.2-14.6 when idling. I have hooked up the O2 sensors and it is staying around 15.2-15.5. So now I am back to the question of how much does the factory computer compensate when reading rich or lean. The reason is I have a facory chip, but larger injectors.
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Posted on: 2012/8/12 22:51
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Vegas wasn't built on winners. '92 auto, MSD, Banski, Taylor wires, SS lines, C5 rims, 3.07 gears, white gauges, seats from a '96. Motor: Forged rotating assy, Probe pistons, CC valvetrain, AFR heads, Procharger P1SC |
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| Matatk | Re: tuning and MAP questions | ||
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Webmaster
 
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I can't give you an actual number, but O2 sensors are what are responsible for changing the fuel...rich or lean. So it can swing the fuel a lot.
Are you sure your wideband is showing the same numbers as the stock O2s? I think that piggyback system sounds like more trouble than it's worth vs just getting an actual tune. |
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Posted on: 2012/8/13 12:34
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2002 EBM convertible, Magnusson supercharger, cam, headers, etc. 1989 Corvette...RIP |
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| tjpreul | Re: tuning and MAP questions | ||
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Elite Guru
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Quote:
I will admit the issues I was having were caused by user error. Once the MAP settings were corrected things are going much better. The AFR is leveling out in how much it fluctuates. Your second comment is what I am not sure about. The AFR is showing lean, but the plugs have been reading good (tan). I just don't want to blow the motor from being too lean. I can tell the factory computer is what is pulling it to the lean side now the O2 are connected. |
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Posted on: 2012/8/13 19:45
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| Matatk | Re: tuning and MAP questions | ||
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I think reading plugs can get you in the ballpark, but people put too much emphasis on it. This isn't the 60's where we don't have computer technology any more. If your wideband is accurate, that would be good for me.
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Posted on: 2012/8/13 20:08
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2002 EBM convertible, Magnusson supercharger, cam, headers, etc. 1989 Corvette...RIP |
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| tjpreul | Re: tuning and MAP questions | ||
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I put about 200 miles on the car yesterday. Basically cruising 60mph back and forth between two towns just north of me. There were a few 1/2 throttle pulls, and throttle variation. I did get an EGR code in the last 20 miles, but I have a spare I will put on/check.
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Posted on: 2012/8/20 17:44
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Vegas wasn't built on winners. '92 auto, MSD, Banski, Taylor wires, SS lines, C5 rims, 3.07 gears, white gauges, seats from a '96. Motor: Forged rotating assy, Probe pistons, CC valvetrain, AFR heads, Procharger P1SC |
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