Droops83

Have you datalogged both scenarios to see if any of the relevant sensor readings are drastically different when running well and not? Looking at Shortyboy's video, it is clearly running lean when it acts up; does yours do the same? In both cases, it could be a sensor ground or other wiring issue that the VEMS is more sensitive to than the factory DME. Make sure your bellhousing grounds are clean and tight; if not this can cause all sorts of strange issues, whether VEMS or bone stock.

Same thing for the power side; check for voltage drops at all of the junction points from the battery (starter, bellhousing, alternator, etc). Make sure the sensors are getting a full 5V reference.

Well, it does if you have it set up for an idle control valve like I do, but it can be set up to run without like these two guys have done.

I supposed it could be something interfering with the speed/ref mark signals, but the odd part is that your engine runs so lean when it acts up (and it sounds/acts lean in your video). The original Bosch Motronic DME has a pretty robust, specialized chipset to process these speed signals, which are quite noisy. The VEMS is one of the few aftermarket ECUs that seems to play nice with this type of inductive/ring gear setup, but it seems like it is perhaps not as tolerant of noise/wiring issues as is the factory DME. How is your speed/reference mark wiring harness on the car? Any crappy aftermarket ignition wires or anything else that could be causing electromagnetic interference (EMI)?

blade7

I thought the map Peep supplies uses the ISV but not the TPS idle circuit ?

Droops83

The only way the factory DME or VEMS ECU knows to activate the ISV is via the idle contact in the TPS.

You might be confusing the fact that jumpering the connector in the engine compartment is no longer used to set base idle---you have to use the VEMS software to deactivate the ISV to do that.

Raceboy

It's not using idle contact in factory TPS, only uses variable resistance part of the TPS (3 pins).

Regarding starting or not, you should observe/log the injector pw when idling and then adjust cranking enrichment and/or starting VE so that it is close to what engine likes when idling. Obviously something is off when it does not want to start, you should check the injector pw then also.

Droops83

Well I stand corrected, then! Thanks for the clarification. Any particular reason for that?

Tom M'Guinn

I have no idea about the VEMS but always wondered if the separate switch was simply a function of limited processing power in the old 8051-driven DME's. With ample processing power, how hard would it be to set a flag in software when the pot reaches the idle area?

NCLA951

gpr8er

I was able to get my low speed and cruize semi dialed in with autotune. As of now I'm not able to decipher how to set up the ebc config in VEMS. If someone could provide a screenshot of their settings I would greatly appreciate it. I plan on running about 16psi. So for now I plan on using a MBC. Also wondering how you guys are using autotune to set fueling under boost? Autotune requires that the cell being tuned remain constant for about ~2 sec. Thanks for the help.

NCLA951

NCLA951

Droops83

For EBC, you will need to install an aftermarket boost control solenoid like this (factory cycling valve won't work):


My VEMS wasn't configured correctly for EBC when I first got it. Peep changed it for me after I sent a config file to him. Use the factory cycling valve wires, and in the "output channels" menu of VEMStune, set the boost control channel to "Injector output 4 (7A) Grounding, InjGroup." Then set your boost curve how you want it. The PID boost control works great.

Let me know if you need advice about plumbing the boost control solenoid (I assume you have a dual-port wastegate).

gpr8er

Yes, I have the solenoid valve and Tial 38. Had it all installed and plumbed. My problem is that the setting menu in VEMS are beyond my comprehension. So for now I'm using a MBC.

Droops83

Here ya go. Make sure you change the boost control output setting to injector output 4 as I posted above.

Then set your boost control target vs RPM table and have fun! The PID boost control quickly learns the optimum boost curve.

gpr8er

Thanks!!
Had to put off messing around with the car today, found a screw in the work truck tire. Heading out to see the Thunderbirds off the coast of Huntington Beach

shortyboy

Hi Peep,

My car runs great, when it gets a good start But it takes a few cranks to get that good start. If I run the car on a bad start, it seems like it's running lean. Please see video I posted will try and get better videos of problem. Another person is also experiencing the same exact problem as me.