Synapsis

So I pull my MSD 6A box off my VW and bolt it into the Iroc along with an MSD Pro Billet distributor and coil... Everything works fine, the A/F ratio gauge reads rich a little more than before, but I don't notice much of a performance hit. The radio has the typical clicking noise I remember from the VW. But when I go to plug my laptop into the ECM to take some data, it's giving me checksum errors and it shows my timing to be 11300 degrees advanced (that's not an exaggeration) and my RPM is in the 27000 range.

Has anyone else had this happen? I'm trying to figure out if the ECM is being effected, or the laptop. I have the box mounted to the firewall where the A/C blower used to be. I've ordered their noise supressor (looks like a basic capacitor to me), just wondering if this is common.

Danno

Actually that is very possible. My profession has been in RF communications and what you are getting is most likely RFI interference. Depending on grounds you may be picking up RF interference through the interconnect cable from the ALDL connector and the laptop. This is why I hate these aftermarket ignition parts, they do nothing and generate a lot of broadband noise. The way to try to filter would be to wrap the connecting cable to the lap around a ferrite core. This will decouple some of the noise. The next step requires an oscilloscope which most people don't have access to but it sometimes the only way to pinpoint noise. Scoping the supply line to the ign unit will show if there is any excessive noise on the 12 volt line. If your lap is getting that confused and the car runs well then most likely it is pickup through the cable. Also sometimes moving voltage supply lines closer to the battery will help reduce radiated noise. The battery is a GREAT capacitor. Modern ECM units are very well decoupled at the input and outputs and will not be confused unless there is something radically wrong. Sometimes an inline filter will help but only if is power line related. A quick trick, open and close the hood when observing the lap. See if it changes as the hood is moved. This is a great way to determine point of entry. You can always try another ground braid from the chassis to the hood. LOL

88IROC_CVTFAN

This is good info. I have recently acquired an MSD digital 6 in preparation for nitrous. I am concerned as to the physical location. I am considering under the dash but on the drivers side to avoid proximity to the ECM. There's no room under the hood because of A/C.

Has anyone done this under the dash?

Thanks

Gta-Paladin

Make a bracket and put it ontop of your battery

88IROC_CVTFAN

Thanks, this isn't the first time I've made things more complicated than they have to be. I'll check the battery location and let you know how it turns out.

racereddy20

I have a 6al box, coil and wires from msd. I never had a problem with the modules. I started having this problem about three months down the road. The car was idling and running like it was just going to die. I took the 6al box off and the problem wasnt as bad. So i thought the box was bad. I took it to a local speed shop and they tested it for me. They told me it was fine. We started talking and they said that it sounded like it was a fuel problem. They also said that the box would just exaggerate the problem. I went home that day and started my car. I took off the air cleaner and one of my tbi injectors literally looked like it was dripping fuel. I bought new injectors thinking that this would fix the problem. I installed them and one didnt work. The other one just didnt spray anywhere as near as the old ones did. In frustration I put the old ones back on (but I had replaced the pod gasket) and fired it up. The hesitation, stumbling, and rough idling just disappeared. I did the dance of joy (perfect strangers). Well anyways, the next day I threw the 6al box on again (i wrapped up my car at close to 3 am the night before). I noticed the radio noise right away. I thought about what I did, and I realized that I used a different grounding spot. I switched it back to the original spot and the noise went away. I am running my box like this, I have the positive running on the alternator (red wire hooking up to the alt) and I sanded a square inch area on the frame above the driver side headlight. I grounded out there). People always talk smack about hooking up to the alternator. All I have to say is that My buddy works for msd. He's been doing it for as long as I've know him (going on 4 years now) and he told me that everyone does that. I have no problems with it so I'm not going to change it. Also on a side note, MSD, Federal Mogal, and Fel-pro are out here. I'm not talking about distribution points, but actual production warehouses (and in the case of msd their headquarters). And whats really funny is that MSD isnt listed as msd they're actually autotronics corp.