4.3L HO OMC Cobra problems

[Boatin Bob]

Re: 4.3L HO OMC Cobra problems

Have you tried this site for the switches? <br /> OMC Parts

 

[pra51]

Re: 4.3L HO OMC Cobra problems

A update to my problem with my omc cobra ho 4.3.<br />I replaced the ignition sensor which is mounted on the back of engine as ex-omc mech.had suggested,no luck.I replaced the coil pack on top of ignition module,no luck.I then notice that the gm 3.8 module has a big heat sink on the bottom and omc module does not.I went to a electronics supply house and got a can of cool spray.When I ran mine and got it good and warm,then let it set for 45 mins or so it had to spark.I sprayed it down with cool spray and it started.I have not figured out how to unbolt that module from the plate it is mounted on behind carb.Still think the best thing is to put a distr.in it.Anybody figured out how to unbolt the module?<br />Phil

 

[Juancho]

Re: 4.3L HO OMC Cobra problems

IT IS FIXED!!!!!!!!!!! You guys are not going to believe what the problem really was. To back up a little bit, I went to my favorite OMC/Evinrude/Johnson part dealers. The place is called Sea-Way Marine, and they are in West Seattle. As far as OMC is concerned, these guys are it. We are talking about a pats supply warehouse that still has OMC brand touch up paint, which is probably 10 years old, judging by the look of the can. Anyhow, long story short, they had both switches in stock, and only $30 each. I installed the switches and took her out for a test run. The engine still went into limp mode.<br /><br /> I fiddles with some things, tinkered with others. One thing I did notice, anytime I ran at over 2800 RPM the oil pressure seemed a bit high. I finally figure it out, it was the oil pressure that was making the eingine go into limp mode. In other words, the switches and computer module were working correctly this whole time. Now by too high, I mean almost normal. This engine system is very sensitive to oil pressure, and I think that if you use the wrong oil, or overfill with oil, it will set off the limp mode. Now, the oil pressure gauge has two sets of measurement, PSI and KG per CM. If your oil pressure is at the 5.6 KG per CM mark or above, it will trip the limp mode.<br /><br /> So, in the end, the thing that fixed my problem was an oil change.<br /><br />Phil,<br /><br /> Are you saying that you are using a computer controll module for a GM 3.8?

 

[Boatin Bob]

Re: 4.3L HO OMC Cobra problems

great news Juancho...thanks for the feedback!

 

[pra51]

Re: 4.3L HO OMC Cobra problems

Juancho<br />No I am not using a module for 3.8.But I looked at one and it looks just like the cobra ho,even the plug on it.But the gm 3.8 has a aluminum heat sink under it and the omc does not.I wish I could figure out how to make the 3.8 module work though.I did email back and forth a guy who was having problems with his omc cobra module and was trying to make the 3.8 work but never got it to.It seems there are very few if any people who really know anything about the cobra ho module.<br />I did get information from a guy who converted his to a distributor system using a aftermarket hei none computer controled distributor.

 

[Juancho]

Re: 4.3L HO OMC Cobra problems

Phil,<br /><br />Unfortunately, replacing the control module with a distributor, seems to be the best solution. I just think it would be a pain, because you still need to install a new wiring harness, and ESA shift module.<br /><br />However, before replacing the control module, I would make darn sure, it is really the cause of your problems. I would be inclined to replace all the sensors, including the knock sensor and timing sensor, before replacing the system with a distributor. I was convinced my control module was shot, because of the erratic behavior associated with the S.L.O.W. <br /><br />Now I have pin pointed the problem, to a high oil pressure issue. Even after changing my oil to Mobile1 synthetic it still runs a little on the high side. I think the PO may have installed the wrong oil filter, and the funky remote oil filter setup, probably doesn’t help. <br /><br />One thing I know for sure. After running for about 30 minutes the oil has a chance to heat up and the pressure drops significantly, and then no more S.L.O.W. issues.<br /><br />As for the control module from a 3.8, you could probably get the engine to run with one, given a lot of modifications, but you would still have an ESA shifting issue. The HO control module also has shift assist built in, and that is something the 3.8 module would not have.

 

[jcoxon3]

Re: 4.3L HO OMC Cobra problems

OK...diagram on it's way, let me know if it's not clear enough, not the best scanner in the world.

I know its been along time but would you happen to have the wiring diagram for the hei conversion from the spitfire ignition on the 4.3 HO 1990