High boost troubleshooting

[DrewC]

Stock FPR for a 3B with rs2 injectors - (11.something AFR with RS2 tune under full load, 12.something FR with Swann tune under full load)
No clue what the voltage to the pump is under load, but for what it's worth, it's relayed.
Gap is .025

[themagellan]

Well, I think I texted both of you. I'm hoping I found most/all of my issue, but it's too early to tell. I was driving up Guanella Pass (which is awesome by the way) and at the summit (11,700 feet) my car decided to die on me and not start again. Poking around wiring, I was able to narrow it down to the wires leading to the coil (before the splice necessitated by the 034 High Output Coil upgrade). If I wiggled them around I could get it started again, and further, if I had it running I could poke at those wires and kill the car.

It seems possible to me that we disturbed that area enough to make already bad wiring go worse a couple days ago with the Coil upgrade. I have yet to fully strip back the insulation on the wiring harness and narrow it down even more but that's tomorrow mornings job.

Was slightly terrifying being 12k feet up a mountain with no cell signal and the car not running but we got back safely with only a couple more hiccups along the way.

Wish me luck this wiring is causing my high boost hiccups too

Drew,

Poking around wiring, I was able to narrow it down to the wires leading to the coil (before the splice necessitated by the 034 High Output Coil upgrade). If I wiggled them around I could get it started again, and further, if I had it running I could poke at those wires and kill the car.

This was a familiar issue I was trying to track down with my car last summer, and at one point I experienced the exact same issues as described above. After a while my car eventually died while driving along, but I luckily made it home. I discovered the G28/G4 sensors in the engine bay were arcing to the spark plug wires or the lead was arcing - Not too damn sure why. My resolution was to route the ignition coil wire and spark plug wires, and G28/G4 sensors through insulated sleeves and route everything seperated. It immediately started working, although I needed to buy another G28 as mine had been fried in the friendly interaction, the G4 seems to work fine still.

It's a free option to check out, but maybe you've already done this - But give that firewall a good look.

[DrewC]

Where did you find the insulated sleeving? Would be happy to try it out

[themagellan]

Where did you find the insulated sleeving? Would be happy to try it out

Haha, well I first used rubber tubing cut in half, and then ordered some cheap plastic sleeving to put over it. I ended up taking the rubber part off and leaving just the plastic loop, but that was after I really spent some time positioning it in the engine bay.

Rubber Tube


Wire Loom - (You can buy in the stores too)


http://www.ebay.com/itm/SPLIT-WIRE-LOOM ... 34&vxp=mtr

On a less advised note: Enough tinfoil would even work for diagnosing, although it could be a little bit weird and difficult to wrap those wires in that type of material. Use your imagination!

[DrewC]

I routed the ignition wires away from the sensor wires and didn't see any change. Spritzed them with water to see if I saw any change in RPM and nothing there either. Can try insulating them further down the road.

Eli came over and cracked open the ECU to find a custom 2.5bar MAP sensor. I believe stock is 2bar?

[chaloux]

Not sure what stock is for the 200 but stock is 2.5 for the s cars.

[bradyzq]

2 bar is stock for a 3B.

[DrewC]

Interesting development. My MAP sensor seems to have failed. I'm getting overboost codes at idle as of a few days ago, and the dash readout is 2.0 bar (+/- .1 ) all the time. (aftermarket boost gauge shows anywhere from normal vacuum to 12psi and fueling still remains consistent and good)

So. question. if I had a failing MAP sensor on this ECU would that cause ignition and/or fuel cutout or just limit my boost?

I don't have a problem buying/trying a new MAP sensor but seeing as the RS2 ECU didn't seem to help much I'm not super hopeful a new MAP will solve everything (surely should get me back above 12psi though)

[scubadave]

Not sure why you want to debate whether or not to replace a junk part unless you plan to replace the ecu with vems. Replace the map with a 3 bar and see what happens. What else can you do really? Its a known failed part, if there is something else wrong, how do you expect to find it without everything else working properly...

[loxxrider]

What effect would replacing the MAP with a 3 bar have? Would the maps need to be re-scaled?

[DrewC]

Yeah that was the part of the post I forgot to articulate, is it as easy as swapping the 2.5bar for a good 3bar or does the tune need to be further modified or injectors changed at the minimum?

[scubadave]

Im not sure about that. That is a question for Marc.

[Marc]

installing a 3 bar map in place of where a 2.5 is expected will cause overboost on a big turbo. (5v on a 2.5 bar sensor is 1.5 bar boost, 5v on a 3 bar sensor is 2 bar boost. the ecu is targeting a voltage not a boost pressure).

[scubadave]

I had a 3 bar in my AAN ECU running MTM 1+ and it boosted up to around 24 psi, assuming they tuned it for that map sensor. However it did dett as the stock injectors were not up to snuff and were maxed out and is the main reason I upgraded to the vems and better injectors. Whats his best option at this point, and would he benefit form installing a 3 bar and adjusting the tune? Or are we looking at a possible yard sale on the side of the road if he takes the billet K26 up into the low 20's on pump gas with his stocker? I guess the question remains, what do you want out of the car and what are you willing to do to get it there?

[themagellan]

Interesting development. My MAP sensor seems to have failed. I'm getting overboost codes at idle as of a few days ago, and the dash readout is 2.0 bar (+/- .1 ) all the time. (aftermarket boost gauge shows anywhere from normal vacuum to 12psi and fueling still remains consistent and good)

So. question. if I had a failing MAP sensor on this ECU would that cause ignition and/or fuel cutout or just limit my boost?

I don't have a problem buying/trying a new MAP sensor but seeing as the RS2 ECU didn't seem to help much I'm not super hopeful a new MAP will solve everything (surely should get me back above 12psi though)

Drew!

Can you please please please use the mity-vac on the ECU reference line? Please also check every single little vacuum reference line from the ECU into the firewall area.

The first time I hit fuel cut, it terrified me and I spent weeks hunting down tons of things until I realized everything looked good but a massive leak would show up past 11PSI on the line.

I would test is to 25 psi at a minimum and completely redo that area if you haven't already.