flibuoy Posted January 12, 2005 Share Posted January 12, 2005 My 94 LT-1 is still a no start....second harness/second Optispark, seems to troubleshoot OK as far as my ability takes me anyway. Street and Performance harness with VATS bypass etc. I am looking for a real wizard in area to go through it. Plan B is to ask who would like a bargain on a low miles LT-1 with accessory mounts for Hybrid Z..less computer and harness...... If you are in Houston area and know a for sure, honest to goodness person please let me know here or privately. thanks John Quote Link to comment Share on other sites More sharing options...
Tim240z Posted January 12, 2005 Share Posted January 12, 2005 Let me ask you some basics...forgive me if this sounds dumb, but.... Do you have fuel pressure?(is the pump running, and priming) Are all the harness plugs plugged in? (pull each plug and check that the pins are secure....somtimes they push out the back) Is the PCM getting the right power? (4 ign. pos, and 1 constant pos) Are ALL the grounds wires earthed? (add extra engine to chassis grounds if necessary----is the battery neg. making a good ground to the chassis?) Do you have fuel in the tank? Double check the routing of all the ign. wires from the opti to the plugs. The opti has the numbers printed on each terminal. Are you getting power to and from the coil/module? Are you getting spark at the plugs? Are the injectors firing? If all the above is correct, then it should fire.... :| Quote Link to comment Share on other sites More sharing options...
80LS1T Posted January 12, 2005 Share Posted January 12, 2005 Just to add one to Tims list... *Are you getting oil pressure? If not it will not let the injectors fire because if you have less than minimum oil pressure it will not send power to the fuel pump enable wire. I know my Street & Performance harness was wired this way. Oh and I think there are only like 2 power feed wires on the harness? And like Tim said make sure you ground the engine to the chassi. I had some weird electrcial problems untill I grounded my engine with 2 ground straps. Guy Quote Link to comment Share on other sites More sharing options...
flibuoy Posted January 12, 2005 Author Share Posted January 12, 2005 Tim and Guy I appreciate the quick responses...but those items have ALL been gone over...yes the aftermarket uses an oil pressure switch, which is installed on tree with Datsun sender. I have a Holley 100PSI pump through stainless...no leaks...vexing because even the fellow who built this harness for Street Performance (outside, sideline vendor)was helpful and we, over the phone, retraced a lot of the possible problems in real time. The grounding(s), positive feeds are all good by multimeter. I keep having nagging feeling the two Optisparks ("rebuilt") from AutoZone are bad...one even LOOKED bad. Of course I learn slow, but learn well...did NOT reinstall waterpump when last one went on. Hate to spring for new Delco...particularly when problem has been elusive. A loaner PCM would help I guess...troubleshooting has been narrowed to fault at PCM, harness, connectors, Optispark...or as they call it on Chevy sites...Opticrap, the coil, the coil module etc or underinflated left rear tire. Anyway, back to my pressing desire to express I know not what I do...John Quote Link to comment Share on other sites More sharing options...
80LS1T Posted January 12, 2005 Share Posted January 12, 2005 So do you know if you getting spark or not? Guy Quote Link to comment Share on other sites More sharing options...
Tim240z Posted January 12, 2005 Share Posted January 12, 2005 DO NOT buy the rebuilt autozone junk....they are notorious for not working. Not saying that is the problem, but just from what I've read on Z28.com. Get a new Genuine GM one. Search on Z28.com there is a guy in Florida at a Buick dealership that has great prices!! I will try to find my old invoice if you need..... Do you have spark at the plugs (all of them)? Quote Link to comment Share on other sites More sharing options...
Tim240z Posted January 12, 2005 Share Posted January 12, 2005 Memory caught up with me!! Call Jason Cromer at Sam Taylor Buick in Florida: http://www.samtaylor.com/html/parts.html Tim Quote Link to comment Share on other sites More sharing options...
80LS1T Posted January 12, 2005 Share Posted January 12, 2005 Just out of curiosity did you have the motor apart at all? Like did you have the timing chain off? If so are you sure you set your timing right? Guy Quote Link to comment Share on other sites More sharing options...
flibuoy Posted January 13, 2005 Author Share Posted January 13, 2005 I am reasonably confident I got 2 dead Optisparks in a row...one at least had either high or low...this one is dead...not to mention 2 stripped holes for cap reverse torks....have a known near new one enroute.... No, engine was only opened for inspection and closed, pan and valve covers. A comment on Street and Performance harness....great for automatic or 6 speed with VSS, asked for Park Neutral delete...did not do it...asked for a smog delete...did not get it...asked for VSS delete, did not get it, asked for no fuel pump/oil pressure interface due to using Z wiring...did not do it....called twice for "tech" after using all material on the site...one admitted he did not know anything...the other argued my T5 has electric speedo etc...anyway on 4th-5th call Mark the owner took time to give me # of outside guy that builds them...HE was helpful. Remember they charge an extra hundred $ due to "superior tech support and product quality" So I should have sent it back but feels better to complain. The mounts for A/C and alternator are great and probably still the only ones that work. Mark is a real success story, but very used to BIG $ projects now. I am off on trip til later next week....maybe it will heal itself John Quote Link to comment Share on other sites More sharing options...
jack46 Posted January 17, 2005 Share Posted January 17, 2005 The opti spark is NOT complex. The schematic is here (click below) Opti Schematic (Click me) There are mainly three signals from the opti spark. The output of the coil to each plug. Put a timing light on coil and if it fires then it is ok it is controlled by a pulse on 423 white (from ECM) if no spark AND there is a signal on 423 then module is bad. Of course you can check that the rotor and cap are transferring the spark with timing light also. If there is coil spark in and nothing to plugs then rotor missing or problem with cap and rotor. The other two signals are the high and low resolution signals from the opti spark (B20 and B2). They provide information to the ECM to allow it to know the crank position. The ECM uses the position to fire the injectors, and to determine when the plugs need to be fired. Basically the high resolution allows the ECM to control engine events, since there are 360 pulses on wheel and using rising and falling edges allows the ECM to precisely control events. The low resolution includes information on which cylinder is approaching TDC. For trouble shooting all you need is to know is that they pulse when engine is turning over. You can display the pulse trains on an oscilloscope or simply see that they are varying with a meter. Hope that helps. Doing this should allow you to know if the ignition is firing or not, and if the coil is firing you could check that all plugs are receiving fire (with timing lite). Also determine if injectors are being pulsed. I suspect you are NOT getting fuel to the rail. Another test is to connect a fuel pressure gauge to rail on a 94/95 there is a shrader valve at the rear between the fuel rails. It is slightly off center and closer to the passenger rail. I would start with fuel pressure check then see if coil is firing, and injectors etc. Good luck let us know Quote Link to comment Share on other sites More sharing options...
Guest HectorM52 Posted February 28, 2005 Share Posted February 28, 2005 Did you ever get it running? I know your answer... Quote Link to comment Share on other sites More sharing options...
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