Timing Thunderbolt IV systems

[rmoore]

I have had problems getting my boat to plane out. It is a 1993 Crownline with a 4.3 lx engine. I got some good advice from the this forum and now I have more questions.<br />I checked the base timing and it is 8 degrees before top dead center. I took the rpm's to 2500 and it advanced to 4 degrees after top dead center. The book say's it should advance 22 degrees. This is very short of that. What could be the possible cause. I checked the two wires coming from the distributor and they are connected good. Earlier this year i put on a Accel coil, could that have caused the problem. Looking forward to hearing from you guys.<br />God Bless America. <br />

 

[Yepblaze]

Re: Timing Thunderbolt IV systems

Gee that sure doesn't make a lot of sense.<br /><br />Is it fuel injected computer controlled? If so perhaps the knock sensor wire is grounding out or acting up to throw the electronic advance into a serious retard condition.<br /><br />Does it have a mechanical advance weight system in the distributor? <br /><br />Is it perhaps cross firing between two closely routed ign wires at speed giving the screwy readings?

 

[rmoore]

Re: Timing Thunderbolt IV systems

yepblaze<br />It is a barrel carb motor. I was reading a poorly written manuel, and if it is correct, the timing should not have gone to the after top dead center, it should have gone further to before top dead center.

 

[ODDD1]

Re: Timing Thunderbolt IV systems

Ray, these tbolt4 systems are pretty basic...regular automotive type coil, no mechanical or vacuum advance, advance is programmed into the ignition module....if the unit runs at all, you can rule out the coil and distributor sensor...all that is left is that expensive little module...<br />are you sure you have a problem? I have seen many cheap timing light read falsly at rpm<br />'s any higher than idle...you may be getting a 'shadow' signal from an adjacent plug wire, too........how does the boat perform? if what you are saying is accurate, I would doubt the boat would get anywhere near on plane....

 

[rmoore]

Re: Timing Thunderbolt IV systems

ODDD1<br />The boat takes forever to get on plane. I have lost about 1500 rpm's on the the top end. Do you agree the timing is going in the wrong direction? Can an ECM module be bad and the engine still run?<br />Thanks for your quick response.<br />

 

[ODDD1]

Re: Timing Thunderbolt IV systems

Ray, if that timing you see is correct, the boat wont make enough power to get on plane... lots of things can make you lose 1500 rpm on the top....heavier load in the boat, increase in elevation,a hull covered in green hair,a fouled plug,a balled up prop...I can go on an on, but you get the picture.....my concern was, your troubleshooting has some holes in it, an I would hate to see you toss parts at it without makin sure you know what the problem is....and yes I have seen these ecm's run a motor when failed, but not very often...usually when they fail they dont work at all....

 

[rmoore]

Re: Timing Thunderbolt IV systems

ODDD1<br />Sorry to ask so many quetions. I did check about everything you said. Your right, and I have been throwing parts at it. I have replaced the carb, plugs,wires,coil,fuel filter,cleaned the bottom of the boat and even put a different prop on it(smaller pitch). I did try this timing light on my car just now and it did advance/go in the right direction. Any other suggestions you have would be appreciated.<br />Thanks<br />

 

[rmoore]

Re: Timing Thunderbolt IV systems

ODDD1 or others,if you would like to send me direct e-mails, My e-mail address is rmoore010@earthlink.net.<br />Thanks

 

[rmoore]

Re: Timing Thunderbolt IV systems

Update. I talked to a Crownline dealer today and told him the results of my timing checkout. he ask if I put the the system in the timing mode. I had no idea what he was talking about. he said you have to ground a wire to put it in the timing mode on thunderbolt IV systems. Does anybody have this procedure?<br />Thanks<br />

 

[ODDD1]

Re: Timing Thunderbolt IV systems

Thunder bolt IV systems are point and shoot, no special procedure required....thunderbolt V is what he is talking about...

 

[rmoore]

Re: Timing Thunderbolt IV systems

ODDD!<br />Update. I took my boat to a Crownline dealer today. They called me this afternoon to tell me the base timing was at 8 btdc. He said it should be 8 atdc? My book says 8 btdc, I'm confused. He also stated that the new carb i put was not a marine carb. The box it came in says it is a marine carb that is coast guard approved. Because he felt it was not a approved carb, they would not dyno the engine. I got ahold of the carb manuafacturer (Edelbrock)and had them call the dealer?<br />What do think about this? Should I go to a different dealer.<br />

 

[ODDD1]

Re: Timing Thunderbolt IV systems

Dealer is not helpping you here... timing is 8* BTDC...having it any lower will seriously hamper power output..you should get an addl 14* advace from the box over 2500 rpm, for a total of 22*.....perhaps time for a module...

 

[info@illuminationtech.com]

Re: Timing Thunderbolt IV systems

Problem sounds almost identical to the ones I was having. Check "wakemaster" Posts regarding Electronic Ignition Timing Problem, and make sure you use "Genuine GM Parts"!

 

[ODDD1]

Re: Timing Thunderbolt IV systems

Wakemaster!! How did you fare??? back on top an runnin hot???

 

[rmoore]

Re: Timing Thunderbolt IV systems

To All<br />I finally got the thing running correctly. I took it to a dealer close by. He checked the timing and it was set at 8 ATDC not 8 BTDC. What I did not take into consideration was the engine turns counter clockwise and not clockwise. After he changed the timing we checked to my sure it was advancing the required amount and it was. They then dyno the engine and it's spec was at 4600 rpm the engine should produce 3400 to 3650 psi. It produced at 4600 rpm,3600 psi.<br />Thanks everyone for your interest and help during my trying times.<br />

 

[ODDD1]

Re: Timing Thunderbolt IV systems

Timing off 16*....Hmmm....wonder how that happened??