I had an interesting experience troubleshooting a problem with my motor and I wanted to let others know about it and see if anyone else has ever seen this.

I searched and couldn't find anyone with a similar problem or solution.

I have a 1993 LT1 with LT4, heads, lt4 intake and a hot cam installed in a 1988 Mazda RX-7.

I was having very weird problems with the motor not running at all, or running very rich. The spark plugs were soaked with fuel, smoke pouring out of the exhaust. I checked and rechecked everything. I even put on another new vented optispark (I had converted to the vented opti when I changed the cam).

Sometimes the car would run fine for a few minutes and then it waould act up. Everything looked perfect and the computer showed no codes at all so I was completely stumped


Then I noticed that one of the female pins of the optispark wiring harness (the one that plugs into the opti) was very loose. I pushed it back into shape, plugged the harness back in and everything worked perfectly It was only 1 of the 4 wires.


I have since noticed that after a while the pin loosens up again.

Anyone have any ideas how to make a permanent fix?

Anyone ever experienced the same thing?

I suspect that a lot of Optisparks may have been replaced when this loose wire was the only problem.

Thanks for any ideas.


Rob

1988 Mazda RX-7 w/ 1993 LT1/T-56

 

Weird....any of those pins should have tripped a TC. Especially if it was the High or Low Res signal....

 

It was the pin at the "bottom" of the plug.

 

rao. I had a very similar problem with my `95 camaro a year or two ago. I have an accel DFI harness for the LT1 and had to modify it because the plug on the opti pigtail wasn't deep enough for the `95+ opti. I used the opti pigtail plug from a stock wiring harness and wired it in. Everything worked perfect on my LT1 until the upper radiator hose started leaking DIRECTLY into the optispark through the ecm to opti plug. I didn't have a good rubber weatherstrip on the plug. within a week the car went from running great to not running at all. The antifreeze fouled all the connections into the optispark. I rebuilt the pigtail using new crimped female plugs and a new weatherstrip on the plug. You can get donor female plug ends from your local parts store from other GM pigtails for things like AC. I now use the anti-corrosion gel they sell for battery terminals that's still conductive just incase water still gets in there.

I went to the local dealership, none of which locally are willing to make a deal, in search of the optispark pigtail. They quoted me $150. heh. for a plastic plug that fits into the optispark. I laughed. I didn't laugh when I was forced to by a "new" optispark.

 

I also had similar problem. it was throwing a crank pos code. tunred out that one of those pins was bad. i got the new harness pigtail from gm. 40 bucks i think

 

very good to know.. and.. an LT1 in an rx7!!!!! i wanna see!!! ur not too far from me! i wanna meet up some time

 

Thanks for the suggestions

There a couple of cars like mine up in Wisconsin.

I expect to be at Union Grove opening week to get some times.

 

ew, go to byron.. much better then UG... i wouldnt send my worst enemy to UG.. ull be about a tenth or so faster at byron too!