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The 60-1 clewett setup did solve the scalloped flywheel problem.
One side effect I am experiencing is that if the vehicle is turned off, the cooling fans turn on, and then the key is turned back on, vems will read the cooling fan as the trigger wheel and believe the motor is running at around 600rpm and start firing the injectors. The only workaround I have found is to wait for the fans to turn off before turn the key back on. The risk with this workaround is that when my wife was driving, she stalled the car in stop and go traffic, didn't hear the fans running, and tried to restart it. This flooded the motor and took about 5 minutes to get started again. I was just thankful it didn't happen in the middle of the freeway.
That's not good! Is there any way you could move the sensor bracket away from the fan motor(s)? You might even want to consider thinner, modern cooling cooling fans (SPAL, etc), to keep the motors and their magnetic fields further away from the crank sensor. This would have the side benefit of saving weight and creating a bit more space for working on the front of the engine.
In hindsight it seems like the TTV 60-1 flywheel is the ultimate solution for those having trigger issues with the VEMS, but since you already invested in the SPEC setup and installed it, you'll have to make it work!
EDIT: You should contact Clewett and see if there is a Hall sensor available for this setup to replace the standard inductive sensor. If so, a simple wiring change and VEMS setting changes and you should be good to go.
That's not good! Is there any way you could move the sensor bracket away from the fan motor(s)? You might even want to consider thinner, modern cooling cooling fans (SPAL, etc), to keep the motors and their magnetic fields further away from the crank sensor. This would have the side benefit of saving weight and creating a bit more space for working on the front of the engine.
In hindsight it seems like the TTV 60-1 flywheel is the ultimate solution for those having trigger issues with the VEMS, but since you already invested in the SPEC setup and installed it, you'll have to make it work!
EDIT: You should contact Clewett and see if there is a Hall sensor available for this setup to replace the standard inductive sensor. If so, a simple wiring change and VEMS setting changes and you should be good to go.
The sensor bracket can't be moved with the Clewett setup. A different fan setup is probably the best option to prevent the interference. I couldn't find much information on the forums about a plug and play aftermarket fan and shroud option. I will contact Wizard Cooling to see if they have any fan+shroud setups available for the 944.
The TTV 60-1 flywheel setup would be the best solution but unfortunately, I am already committed with the push clutch.
Clewett does make a hall sensor and he said that it would solve my issue. I contacted Peep for details on switching from a magnetic sensor to a hall sensor and he stated that it would require VEMS internal modifications as well as wiring modifications to work.
Maybe try a shielding of some sort? In between the sensor and fans.
As for my attempt. I've clean grounds, replaced. Battery ( mine was dead after a few weeks sitting and it's 6 years old.) swapped injectors and replaced fuel pump with bosch 044, fuel filter, inlet and outlet lines and sock filter. I also noticed some clicking in the ecu when I'm having the rough start/running issue. Next, check gap of s/r sensors on flywheel , replace sensors and updated bracket. I've also replaced wasted spark coil and plugs in the past, trying to fix issue.
Swapped out hi Torque starter for stock unit and still same issue. Ohm out speed reference sensors and both around 924 ohms, will grab an oscilloscope to check output but I also did a trigger log of both conditions. Please see attached pictures of both trigger log png, marked good and bad. Also uploaded two videos of engine running and video on vems screen. Good condition, lambda is good, afr is good and idles a bit below 1k. Bad condition lambda is not spot on, afr is lean and idles below 900. You can clearly hear the difference in exhaust ton, even though it's straight pipe, you can hear popping in the bad video. I've got 72# delphi hi impedance injectors, saving up for deka 80s. New fuel pump filter, tank outlet filter, bosch 044 fuel pump, CEP fuel rail with automotion adj. Fuel pressure regulator ( this is probably the next step in troubleshooting, this or the fuel damper?) anyways check out the pics and videos and share your thoughts. I'm inclined to send my ecu in for repair also after burning the ignition transistors, but this issue I'm having was before I blew them. Or if someone is willing to test my ecu, I'll send it and see if issues follow. Thanks in advance.
GOOD
https://youtu.be/xE4pX3-Ld6w
BAD
https://youtu.be/C0zPIP8QQQ8
Forgot to post these pictures. It's the VEMS ecu main board. As you can see I burned a trace when u blew the ignition transistor. I placed a jumper wire to fix it. I also notice a resistor out of place, wondering if anyone else's is like this also.
More testing today. And although I have a set of new Facet brand speed reference sensors coming in, I think the ones I have in right now are good. They ohm out good at 924ohms, when using a volt meter, I get 2.9v at pins 8/27 when I crank. It over. Took off sensors and found a bit of metal on the speed sensor, cleaned it off, installed still same issue. Used an oscilloscope to measure waveform of speed sensor and I'm getting more than 4v, almost 10v peak to peak. ( see attached picture ) . So now I'm back to thinking what else to test. I tested my aeromotive adjustable fpr and according to the gauge, on start up, fuel prime, I get about 30psi, about 38psi when running, 43.5psi with vac line off. But when I shut off engine, the pressure bleeds off very quickly. No more than a minute or two and pressure goes to zero. Not sure what else to test. Any thoughts?
That is a definite fail for a solder joint. Any idea what the circuit is part of?
should be the WBO2 heater. Apart from that, In my case the connection to the WBO2 sensor was not wired correctly. I noticed that as I could not calibrate the sensor.
... So now I'm back to thinking what else to test. I tested my aeromotive adjustable fpr and according to the gauge, on start up, fuel prime, I get about 30psi, about 38psi when running, 43.5psi with vac line off. But when I shut off engine, the pressure bleeds off very quickly. No more than a minute or two and pressure goes to zero. Not sure what else to test. Any thoughts?..
30psi when running at idle on a stock fuel system is ok. Leak test minimum pressure after 20 min --> 14.5 psi.
30psi when running at idle on a stock fuel system is ok. Leak test minimum pressure after 20 min --> 14.5 psi.
So it might be my Aeromotive AFPR.It goes to zero in a few minutes. Had it a few years as part of my CEP billet fuel rail. Will swap it out and report back. Thanks
Swapped out speed reference sensors with new facet brand and swapped out aeromotive adjustable fuel pressure regulator....same issue. Have not regapped sensors due to good output on oscilloscope. Running out of ideas. My next guess is ignition switch. Since there's contacts for starter and dme/ecu there if they're dirty or corroded, a few clicks on and off would clean the contacts thus making a good start condition. Off to spend more money and wait another week or two for it to come in. Anyone interested in a good used set of reference sensors and adjustable fpr?
Shortboy, I haven't been following along and not sure your symptoms, but those pictures of the circuit board are pretty ugly. In addition to toasted traces, it looks like it overheated to the point of melting solder and dislodging components, and looks like that one TO-220 component overheated pretty badly -- (MOFSET?) second from the right on the lower side (did you test it?). Also, as you work to patch the visible damage, do you know if this is a 2 layer board and/or if there are also internal trace layers? If this is a 4+ layer board, then without a schematic and lots of multimeter time on your hands, it would be virtually impossible to know if the board is still ok.
Separately, it seems like Aeromotive FPR and replacement rails have caused issues on these cars in the past, despite good pressure etc. I've never investigated why and/or if there's true cause and effect, but people have reported flat spots and hiccups, etc.
01-19-2019, 12:23 PM
