View Full Version : Limp mode 1991 Comp
I recently purchased a 1991 Comp. I am having problems with it going into limp mode for no reason. I check my oil pressure & temperature and all is fine. I have talked to my Supra dealer and he has given me a couple things to check for. Bad spark plug wire connections & bad ground. I have checked the spark plug wires but am leaning more toward a bad ground. Another problem I am having, which might be related is that the fuel, oil and temp lights seems to come on intermitently. Sometimes they stay on full bright and other times they kind of flicker at half intensity. When they are on, all the gauges read fine. I have traced the ground wires from those lights and they lead to a small circuit board attached to the left, back of the dash support. What is this circuit board? Should I just bypass the grounds for those three lights to a ground stud I have installed? Any other ideas would be greatly appreciated.
I hava A 1994 Sunsport and my boat went into limp mode also. The computer engages limp mode when a sensor tells it that the engine is overheating or has low oil pressure. There are two sensors for each on my boat, one for the guages and one for the computer. Replace the ones for the computer and see what happens. The Temp sensor I had to replace was right on top of the waterpump.
I have now spent the big bucks and got my boat running fairly well. The problem with it going into limp mode was the "Protec" computer system. After having the carb rebuilt three times by three different mechanics and checking all the spark plugs wires, that was what ended up being the problem. One hint of advise is don't trust your local car mechanic to answer all your problems about your boat. There are some significant differences and that is where I went wrong. I have found out that this PROTEC system is obviously a problem with all older Supra's and I am posting this as help for future 'searchers'. I had to replace the entire computer/wiring system under the hood. Supra does sell a retro-fit kit which essentially rids you of the computer system. You go back to a cap & rotor type design, although of the highest quality. There was a post here but I just can't seem to find it now. I read that post after I had pretty much determined the problem. That person said he had a back-yard mechanic look at his boat and he determined that when the boat wouldn't start (hot) he just needed to take a very wet cloth and lay it over the coil back at the back of the engine. This would cool it down and do something to the computer to allow spark and the boat would fire up. Upon reading that article, I was happy to know that the $1000CDN retro-fit kit I had already ordered WAS going to solve my problem. As much as I hate putting water on electrical components, I did try that technique while I was waiting for my part to arrive. It worked everytime! Who said water and computers don't mix!? Ha, ha!
As for the gauges flickering, I did talk to Vince at Discount Inboard Marine and he did say that for some reason the circuit board or wiring under the dash panel does give grief. He instructed me to simply giggle the wires and that would normally solve the problem. Although I don't think that's a fix, after spending the $1000 above, the lights are a small problem for the time being and I haven't really experimented with it.
This post is just simply a fore-warning for those of you who are going to buy a Supra (or who already have one). Be prepared to replace that PROTEC computer system. It was a great idea at the time but it just did work out for Supra in the end. The company, PROTEC, also no longer exists so you can't just replace that computer. Coming from me, a guy who loves computers and anything they do, I was sad to see it go but my boat ran great for the rest of the summer after I installed the retro-fit kit.
02-10-2005, 12:04 AM
Yep, had a few of those problems myself. I removed the complete ignition system with an MSD Pro billet distibutor and Crane Hi6 box. Rewired all the temp and oil press sending units.Removed all the knock sensors and misc BS. Wired a ground from my gauges to battery. Soldered all electrical terminals to gauges and have cured all gauge and engine electrical hickups at this piont. Works so much better.
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