CSX3170 first time out with new engine

[Buzz]

Thanks for sharing your adventures in CSX3170, Bruce! Its always a fantastic read with your great insights into the nuances of tuning, sorting and racing an original 427 Cobra. A first hand account of thrashing the car that inspired many of our automotive dreams is a rare and special thing 50 years after the Cobras ruled the earth.

[Ron61]

Bad things: I am going to have to provide separate ground circuits for 5 separate pins on the ECU back to the battery 3 are 10 gauge to try and prevent noise contamination.

I am not much of a mechanic but could you wrap your wire with a filter type wrap to prevent it picking up noise and other electrician interference? We used that type of wrap on out main frame computers and also in some of the missile guidance systems. I hope that you get it sorted out and am looking forward to your next posts as I try to keep up with what you and Morris do.

Ron

[Cobra #3170]

Originally Posted by Ron61

Bad things: I am going to have to provide separate ground circuits for 5 separate pins on the ECU back to the battery 3 are 10 gauge to try and prevent noise contamination.

I am not much of a mechanic but could you wrap your wire with a filter type wrap to prevent it picking up noise and other electrician interference? We used that type of wrap on out main frame computers and also in some of the missile guidance systems. I hope that you get it sorted out and am looking forward to your next posts as I try to keep up with what you and Morris do.

Ron

Thanks Ron,

Yes shielded wire is very effective at blocking inductive or capacitive coupled signals. I have it on all the low signal level input lines. This problem is related to voltage drop over ground circuits which effectively lowers input voltage because the computer just sees the difference between ground and input lines. The theory is that the ECU is going into Flash mode which automatically cuts off the fuel injectors and the pulse that fires the MSD.

They think a low voltage condition could cause the jump to flash mode. Since I have 1/0 welding cable for a positive feed to the starter solenoid I am going to upgrade my ground to the same thing and go from the battery to the block. I will also put the ground wires they recommend on the ECU as well just to eliminate that as an issue. The alternator current going up and down as I come off idle might cause a big drop across ground loops so hopefully that solves the issue. I just now moved the car into the garage and it ran perfectly of course, I am not at an event where it would surely quit again.

[ScratchBuilder]

Bad things: I am going to have to provide separate ground circuits for 5 separate pins on the ECU back to the battery 3 are 10 gauge to try and prevent noise contamination.

Hello,

I'm an Electrical Engineer and I would suspect that the larger gauge wire will help with voltage drop, but not during cranking or noise issues.

Can you get some EE support from FAST? I would think the noise source would be from the ignition system and maybe different routing of it's power connection may help or adding some capacitance to the input power pins to the FAST ECU which can help with noise and brownouts.

I find it curious that the system jumps into flash mode.
I can see a low voltage causing a brownout and the controller to reset but not go into upgrade mode. Can you try another FAST controller, maybe this one has an issue with it?

Best,

SB

[Cobra #3170]

Originally Posted by ScratchBuilder

Bad things: I am going to have to provide separate ground circuits for 5 separate pins on the ECU back to the battery 3 are 10 gauge to try and prevent noise contamination.

Hello,

I'm an Electrical Engineer and I would suspect that the larger gauge wire will help with voltage drop, but not during cranking or noise issues.

Can you get some EE support from FAST? I would think the noise source would be from the ignition system and maybe different routing of it's power connection may help or adding some capacitance to the input power pins to the FAST ECU which can help with noise and brownouts.

I find it curious that the system jumps into flash mode.
I can see a low voltage causing a brownout and the controller to reset but not go into upgrade mode. Can you try another FAST controller, maybe this one has an issue with it?

Best,

SB

I too am an electrical engineer although trained many years ago I still build many micro processor based projects and write my own code in low level language. I am familiar with filtering and isolating inputs with my own projects
so it seems odd to me that they would put a product on the market that is susceptible to low voltage spikes or electrical noise within a vehicle environment. They did not bother answering my email at all regarding these questions. I am getting help from a gentleman that is familiar with all these after market systems and helped with the tuning effort on the dyno. He is not sure why it goes in to flash mode but says it can happen with a low voltage condition. You would think they would make it more difficult for that to occur say require multiple pin inputs of 12v or more but who knows what the designer was thinking. If you look at comments on the product there are lots of complaints about low voltage stability so the basic design has issues. Changing ECU's is not an option right now because FAST does not care what I think. I suppose if this isn't resolved I will switch to Holley and try to use some of my FAST tables as a starting point. The car runs in alpha n mode so it just uses look up tables based on MAP, TPS temp, and RPM. I saw some fluctuation in alternator output so there may be an issue with the Nippondenzo alternator regulator. The MSD ignition is grounded to the block and it's source voltage is significantly isolated from the FAST input voltage.
The problem with most aftermarket electronics is poor engineering, that is why I run a Bosch fuel pump for the injection. I am trying to make this work so I don't have to drop another $2200 on a new ecu and then reprogram it.
I think the ECU pins have lots of room for improvement like gold plating them for corrosion resistance, my battery terminals are gold plated why not dry circuit ecu connectors? It doesn't cost that much, again poor engineering.
Now that I am home I can run the engine with a computer connected to the system to monitor error codes and put a scope on to look for noise and voltage spikes. Since I have that ability now, it will probably run fine while being watched and then fail at the next event July 1 when I can't do anything about it. (joke) I will get off my soap box now and get back to work on it.

[Barry_R]

I have wrestled with a few of these installations as well. A friend who is pretty darn good with electrical and electronic stuff (has hands on some projects in orbit...) says that the FAST guys always blame the ground no matter what's wrong. It's their favorite "whipping boy" and probably often accurate given the installations they see in the garage builder & street market.

As an old street racer and sales guy with a car habit I do not have the true knowledge to diagnose these things - I just repeat what I am told, and keep trying stuff until it works - or breaks. Take my comments as such.

I suspect that some of the aftermarket sales volumes on these kits are as low - or lower than the prototype volumes on an OE project. Means that there are limited development opportunities or resources, and consumer products are fairly immature from an OE perspective. Every customer gets to be a development engineer.

My buddy demands that I install a couple of those big "firecracker" capacitors in line with the power supply. He also concurs with the idea of keeping all the sensor side leads isolated from any high voltage stuff, and wants the ignition box wires completely isolated from the EFI system wires. Almost seems like the two companies never speak with each other (with Holley acquiring MSD those two may have an eventual advantage). I really dislike the wiring terminals and attachment to the box - seems like some sort of mounted pigtail and strain relief to a robust connector would be more effective in a race car oriented product.

And when nothing seems to work you send back the box and they send you another one that fixes the problem. You never learn what that fix entailed, nor whether your wiring was "cause or effect" but you do learn that the mysterious problem really existed in the box and not in your installation.

[hinoonaz]

Enjoying this post. It seems a lot of people from different sites and car shows claim FAST is really good. Is it because most of us are in the norm as far as sophistication on engines or what. MSD and Holley 650 work well for me and I can work on it. I can change the oil on my wife's Pilot and don't want to go any further. You on the other hand are in a knowledge zone way beyond me for sure. Curious though on what do NASCAR and even Pro Stock drag cars use. One constant RPM and the other for 6 second bursts. They are all EFI now. Thanks for sharing with us shade tree mechanics. Gary

[Dominik]

In the 90s I had the most troublesome ECU controlled cars in our shop. 90% of failures are gound related.

The crank sensor is very sensitive when it comes to gapping and a pick up behind the balancer might help (axial instead of radial, if my english doesn't fail me).

ECUs typically have a compensation for voltage drop when starting with a weak battery or in winter to "convince" the management system to start irrespective. Dending on the range you could just be too low.

A welding cable for negative from the battery direct to starter cannot be a mistake (35 or 50 mm2).

Good luck!

[Cobra #3170]

Originally Posted by Barry_R

I have wrestled with a few of these installations as well. A friend who is pretty darn good with electrical and electronic stuff (has hands on some projects in orbit...) says that the FAST guys always blame the ground no matter what's wrong. It's their favorite "whipping boy" and probably often accurate given the installations they see in the garage builder & street market.

As an old street racer and sales guy with a car habit I do not have the true knowledge to diagnose these things - I just repeat what I am told, and keep trying stuff until it works - or breaks. Take my comments as such.

I suspect that some of the aftermarket sales volumes on these kits are as low - or lower than the prototype volumes on an OE project. Means that there are limited development opportunities or resources, and consumer products are fairly immature from an OE perspective. Every customer gets to be a development engineer.

My buddy demands that I install a couple of those big "firecracker" capacitors in line with the power supply. He also concurs with the idea of keeping all the sensor side leads isolated from any high voltage stuff, and wants the ignition box wires completely isolated from the EFI system wires. Almost seems like the two companies never speak with each other (with Holley acquiring MSD those two may have an eventual advantage). I really dislike the wiring terminals and attachment to the box - seems like some sort of mounted pigtail and strain relief to a robust connector would be more effective in a race car oriented product.

And when nothing seems to work you send back the box and they send you another one that fixes the problem. You never learn what that fix entailed, nor whether your wiring was "cause or effect" but you do learn that the mysterious problem really existed in the box and not in your installation.

Thanks Barry,
I am afraid you are right on all counts, there are some very good filter capacitors out there now that were only dreamed of several years ago in terms of capacity. Kinetics does not have much pull with FAST so I may be on my own in terms of getting a replacement box. I couldn't agree more with all your comments especially on customer development of their product.
I did find an area where one of the main grounds could have some unwanted resistance so maybe that will help. Going to pull the alternator too and have it checked for output. We have a test scheduled for July 1 and 2 hopefully I can resolve it before then. Thanks to everyone for your ideas and comments.
I almost went with BIG Stuff but was told support not good, cam't believe it is worse than FAST though. I have the crank sensor at .015" so that should be a non issue, the dry sump belt limits what I can do with the crank sensor in terms of package. Kinetic's had big problems with hot start and had to have a battery charger on the dyno battery to make it run so yes the "box" might be the root of all this evil.