Garmin 188C/Sounder affecting Ignition Timing

[faulkemup99]

I posted in the Johnson Motors section originally but was told since the problem sounds electrical, to try this forum, so here goes:<br /><br />I have a brand new Garmin 188C Charplotter/Sounder combo unit. I had it professionally installed. Ever since getting the boat back, it has run horribly(steady miss) above 4,000 RPMs. Never ran like that prior to this, motor has been great(93 Johnson 140 V4 2-stroke). I decided to try running it without the GPS connected, motor runs GREAT. Plug it back in, turn it on, motor misses. Any thoughts? <br /><br />1. The GPS power and neg are connected to a fuse panel under my dash. The red is connected to the "MAIN" connection, where the hot from the battery is connected( I guess this is where the fuse panel gets its power. There was an empty fuse bank but the mechanic opted not to use it, instead, connecting it to "Main"). The unit does have an in-line fuse. The neg is connected to the fuse panel as well, at a 4-bank connection plate.<br /><br />2. The transducer is hooked up as well, they ran the wire back through the hull with all the other wires.<br /><br />Which one is more likely to be the problem? My feeling is its the transducer line. If that is the case, whats the best way to isolate that line, as I dont know where else to run the wire to the back of the boat?<br /><br />Any help is greatly appreciated.<br /><br />Would love to be able to use the motor AND the GPS/Sounder at the SAME time, lol!

 

[dingbat]

Re: Garmin 188C/Sounder affecting Ignition Timing

I find it hard to believe that the transducer cable is doing it but I'd also find it hard believing that the unit itself is causing the problem if you had not already proven the issue.<br /><br />I'd unhook the sonar cable from the unit to see if that changes anything. Then if it didn’t I’d move the power wire over to a separate circuit and see what happens. <br /><br />You don’t by chance have a second battery you hook the sounder up to? That would isolate the ignition system from the sonar unit power supply

 

[Ralph 123]

Re: Garmin 188C/Sounder affecting Ignition Timing

You should call garmin and be sure to tell us what they have to say:<br /><br /> http://www.garmin.com/contactUs/

 

[faulkemup99]

Re: Garmin 188C/Sounder affecting Ignition Timing

I did call Garmin, they never heard of such a thing, they say. I have always heard good things about their customer support, but I have to say I felt a little brushed off by them. Nope, we never heard of such a thing, all we can offer you is to let you send us the unit to check it out. I am reasonably sure nothing is wrong with the unit, but the installation.

 

[faulkemup99]

Re: Garmin 188C/Sounder affecting Ignition Timing

I left this out of the prior post, but I have called some of the service centers in my area, and a couple of them have heard of it happening, and they seem to think it would have to be something related to the sonar. They explanation I get is this: A GPS is only a receiver, so it cannot interfere with electronic ignition, but that the sonar is emitting signals that can interfere. The problem is where is the interference? Is it where the transducer wire runs right by the engine on its way to the transucer, or is somewhere along the wiring harness going from the dash, through the hull, to the rear of the boat? Then again, maybe its the way the power wire to the unit is hooked up(see original post).<br /><br />At a loss.

 

[Ralph 123]

Re: Garmin 188C/Sounder affecting Ignition Timing

It would most likely be the transducer wire. It could have a poor or defective shield, causing it to act like an antenna and that is being picked up by the ignition system. Try moving the wire away from the engine and/or is it possible to shutoff and/or disconnect just the sonar and try it? In that way, you could rule out the head end from putting interference onto the electrical supply.

 

[Seasport]

Re: Garmin 188C/Sounder affecting Ignition Timing

Hi faulk, I agree with the others. Disconnect the transducer wire and see if that fixes the problem. If it does, maybe the shield on the transducer wire has a bad connection. I guess only a new cable will verify this as you can only get to one end. Otherwise, you could try moving the cable a little away from the other wires in the wiring loom (if you can).<br /><br />If this doesn't fix the problem, try running the unit from a separate battery as dingbat suggests. Hard to believe though that it can be generating enough interference on the power supply to affect the ignition.

 

[swist]

Re: Garmin 188C/Sounder affecting Ignition Timing

Something is really weird here. That's a plain old carbed 2-stroke with a very simple electrical system (been there, done that). No computers or fancy solid state ignition control modules. To misfire it via an external force you would have to direct a VERY strong electromagnetic field somewhere in the ignition primary cicuitry.

 

[JB]

Re: Garmin 188C/Sounder affecting Ignition Timing

Hmmm. Two possibilities: <br /><br />1. The pulsing nature of the power use by the sonar could be feeding through the power system and upsetting the powerpack. That needs isolation.<br /><br />Run the ground wire for the 188 directly to a seperate terminal and then to the battery ground post. Run the 188 power lead directly to a seperate terminal near the one for the ground lead and from there directly to the battery + post. Connect a polarized, 10 microfarad capacitor (at least 25volt, better 50volt) between those two terminals. That should filter out any loading noise and keep it away from the powerpacks.<br /><br />2. The lead going to the transducer should be coaxial cable, which is normally self shielding. If there is a break in the shield connection it could become an antenna, broadcasting high power spikes to terrify the powerpacks into wetting their pants. <br /><br />Disconnect the transducer cable from the unit. If the trouble goes away, replace the transducer (including the cable).<br /><br />Good luck.

 

[amirm]

Re: Garmin 188C/Sounder affecting Ignition Timing

JB is on the right track if noise is a problem. However, without isolating the power for the 188 from the engine, the cap would need to filter out the noise form the ignition and the 188 which is unlikely to work. You would need a diode in line to do this right. But it is worth a try. I would also put a .1 microfarad cermaic capacitor in parallel with the electorlytic one that JB mentions. This cap would filter out the high frequencies which could also be a problem (these caps are not polarized so you can hook them up either way). Finally, for either one of these to work well, they should be placed next to the instrument, not far away from it.<br /><br />This is a long shot. But if nothing else works, check out the alternator in your engine. I have little idea how a two-stroke engine alternator works but if it is belt driven like many in 4-stroke, and the belt is loose, you could be getting nasty intermitten charging pulses that are triggered by the additional power consumption of the sounder. These can cause all kinds of malfunction. And I am speaking of personal experience here....<br /><br />Amir

 

[Seasport]

Re: Garmin 188C/Sounder affecting Ignition Timing

May be worth trying a completely separate battery to power the GPS before you start adding filters etc. - just to verify that it is power supply related. This shouldn't be necessary however.<br /><br />Let us know what you find. Did you make contact with the guy who had interference problems between his Garmin & VHF?

 

[gss036]

Re: Garmin 188C/Sounder affecting Ignition Timing

I have heard so many wierd stories about transducers over the years that I always run a<br />3/4" plastic pipe of some (sorts), then run the cable through the plastic. This shields the cables in case of problems. I think I would be talking to the Proffesional Installer since they created the problem.

 

[qapd]

Re: Garmin 188C/Sounder affecting Ignition Timing

Faulkemup99,<br /><br />I run the exact same GPS/FF Garmin-C. Installed it myself in a '97 Mako 191. I ran the sonar wire in the same tube all the other electrical is run through. Wire is even tie wrapped to engine harness. I have never had any of the symptoms you are describing. Engine is '98 Johnson 150 Ocean Pro.<br />I agree with others disconnect the 188 and run the boat. If you dont have the same symptoms your professional installer has messed up something. I would ask to have their mechanic go along for the ride. If everything is ok they should repair their mistake.<br /><br />Good Luck,