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Background: at a WSIR track day before last thanksgiving going up the hill in turn 3 my car started feeling like it was out of gas, loss of power etc. Limped back to pit and put some 91 VR gas in. Problem seemed to go away, but same thing next session. Thought it was bad gas maybe, limped to chevron and filled up. Didn't make it home, could get power sometimes, and other times would fall flat and miss. Didn't think I could make it over the mtns that way, so had some drinks at the Palmdale outback waiting for the tow truck.
Going on the bad gas idea I changed everything in the fuel system, eventually flushing tank, all filters, lines, new pump already, FPR and Damper. I had recently replaced every hose and vacuum line, and installed ported K27/6. Replaced S and R sensors (that was fun), tried known good DME, nothing cured the problem, checked all sensors for resistance and function.
Took it to a dyno to see if we could replicate problem on dyno, watched fuel pressure during pulls, it was good, first run 340whp, second run went lean and backed out, 3rd run 353whp. This confused me more, but also assured me it wasn't mechanical.
Also checked compression and TDC cam alignment. At wits end.
A I met some fellow rennlisters to try out the DME, and VEMS came up. Heard good things. We decided to do a group buy.
I figured the DME wasn't telling what was going on, and I was tired of new chips every time I added something. Knowing VEMS had trigger logs, regular logs and a way to view everything that's going on it was a good restart on the problem.
I had been talking with Raceboy about it for a while and set it up, and waited for my box.
I merrily tore out my AFM and distributor, and fabricated a turbo intake tube with AOS, vapor purge and BOV ports, and welded in a bung for temp sensor right uphill of the throttle body, and had them powder coated.
My box came, but the 80# Injectors were accidentally included in another kit so I installed everything else while I waited for them.
My disto is back on to cover the hole until I machine out some clearance on the prototype block off plate from 3D printed Porsche parts.
So when the injectors arrived I was ready to go. Put them in, turned it over without DME relay to build oil pressure since it'd been months, and got ready for the glorious first start.
And then ran my battery down cranking. Never figured it out with Raceboys help that weekend, could get it to catch but never run. Next weekend tried it again, and with some config tweaks got it to fire up. I idled ok and I drove it around, but it felt like it was missing power. Also, it took starting spray to help it to life. Still not right.
With various checks, tweaks and changes suggested by Peep, today is got it running right. Starts up quick, pulls strong, auto tune works a charm for getting it right. It took checking my s and r sensors many times, reversing polarity on the ref sensor and changing it back, tracing pins back to vems to double and triple check. Eventually we tried changing something in the trigger ref table, and that started it up, but it ran like a tractor and wouldn't rev. Used timing strobe and ignition lock to get to TDC with reversed ref polarity (could be cheap facet sensors, Bosch ones are in mail), and then it ran but still had trigger errors. Switched polarity back to normal, reset TDC after trigger with light, and no more trigger errors, clean triggers and an engine that fires right up.
Drove around South Bay auto tuning, and with my MBC in place still (haven't implemented EBC yet), I get 17psi by 3200, and it pulls well to my 6599 redline, although the boost does start to drop off by then.
I still have more tweaking and tuning and learning to do, and setting up EBC with Peep, but even though in my case there were some weird things to figure out, it has solved my initial problem, and looks to be the start of having my car be function fast and fun again. Thanks Raceboy, who is very gracious with how many questions I ask him via FB messenger a day.
Any questions don't hesitate to ask, with the age of DMEs and AFMs I think this is a great option to keep the character but step up management into a more modern realm.
Hell yeah. Standalone is the answer for our cars, for both performance as well as reliability and diagnostics. My NA has been nothing but flawless since installing MicroSquirt and my 951 is getting something even better.
*totally unrelated to VEMS*
I also had trouble with the cheaper speed and reference sensors that I ordered from Pelican Parts. I ONLY replaced the sensors in the first place because I had to smash the original ones when I did a clutch install. Car presented with no start a couple days after the clutch install. I assumed it was the S/R wiring harness, so i replaced it with lindsey racing. no change. Eventually I got it running by switching the speed and reference sensor position on the bell housing.... just the physical sensor location, the wiring had been correct. This made no sense so I ordered the Bosch sensors. Continued using the FAE ones while I waited, and even though it would run for the most part, there were some random stalling issues. Recently put the Bosch ones in, and no trouble since.
I run a single sensor on the front of the crank with an aftermarket trigger wheel. The sensor is $30 new and provides a digital signal... no intermediate analog/digital conversion required, which causes the most common issues with aftermarket ECU setup. Obviously the VEMS unit works fine with the stock ones out of the box. But I'll take a single, cheap, and easy to access sensor any day.
Very interested to see how much power is made going to VEMS. What was your engine management previously?Mods? Have similar mods myself. Also, is it possible to use aftermarket crank and trigger wheel setup on VEMS?
Vems is in the short list of addons for my 951. It appears that the install is much more complicated than I thought. Is there an installer in the Northeast who I can contact?
The install is not hard, if I can do it - anyone can do it. Mine fired up first try and the sensor calibration is simple.
Ill ask a general question as I know Peep prob gets too many emails - I drove mine around and "auto-tuned" and then couldn't figure out how to burn config to ECU haha, how do you do that? Mine actually seemed to drive pretty damn well out of the box so there must be some kind of 951 based tune installed. I also need to setup the round gauge - gotta do some more reading on that.
I blew an intercooler hose off during my first drive while logging/auto-tuning so no big deal I couldn't save it - Ill just do it again, going to throw new plugs in it before I do that as mine seems to have a small miss at idle / kind of a tiny backfire or pop...once rolling seems to clear out and pulls well.
What's the current delivery time for the Vems? I could ask directly from Peep, but i'm sure he is busy enough making them and and answering more important questions.
I just started my car for the first time with VEMS after the winter storage. It was a nice surprise that then car fired up on the first crank after sitting for 5 months. The pre-crank prime cycle for the fuel pump makes a big difference in starting the car. Previous years would involve cranking and cranking and cranking.
The install is not difficult, best purchase I've made for my car. I bought the solenoid from Peep to integrate boost control into VEMS but I also have a Turbosmart EBC sitting on the shelf, I'm not sure which would be easier to make work.
Sam, you can easily email me if you have any questions! I always find time to answer.
But you burn the config by just going to any menu or dialog where BURN button is present (it turns red with autotune active and making changes).
04-05-2017, 11:07 PM
87 951 VEMS Install
I always find time to answer.