|
|
Post by x383xstroker on Apr 5, 2006 1:24:05 GMT -5
got new 383 lt1 back with big cam. stock heads. now the engine is in and i cant seem to get it started. could it be that my pcm is reading the 383 crank and making it spark differntly? i mean its turning over and somtimes back fireing. if i need a tune ill send it out to pcmforless.com someone told me that it could be the dowel pin behind the opti. but if it wasnt installed right u wouldnt get anyspark at all right. i mean im geting nice spark at the coil but at the plug in my opinion looks a little low. thanks.
|
|
|
|
Post by Fire67 on Apr 5, 2006 9:50:44 GMT -5
Well if your getting spark at all, Id start looking elsewhere first. You need fuel, air, and spark to run and engine. You have spark, and air is easy, so Id look towards your fuel system. Simply check everything over to make sure its all hooked up correctly, then listen to the injectors with a stethoscope or piece of hose to make sure they're firing. Also make sure you have the fuel pressure you need.
If all that checks out, go back to what you know.
Which would be that you have spark, and fuel, so since the air part is kinda hard to screw up all thats left is the timing of the fuel and spark.
If your opti was installed correctly the timing and fuel events will trigger correctly for a 350 (assuming you still have not got your 383 mail order tune). With those events timed for a 350, they will still run a 383, just not optimally.If it was not installed correctly, even one notch off on the crank dowel will cause a no start. Or sometimes a start followed by backfiring and stalling. The opti tells the PCM when to fire the injectors and coil.
By your description, I would check the opti at this point for correct installation.
To answer your question about the cam dowel, if it sticks out even 1/16" past the cam bolts, it will engage fine. I dont think the one on my buddy's motor even stuck out that far, it was probably flush with the cam bolt heads and it engages fine.
The weak spark at the plug could mean several things, but since you do have some spark, I wouldnt worry about that untill after you figure out the no-start situation.
|
|
|
|
Post by x383xstroker on Apr 5, 2006 12:21:08 GMT -5
thank, i think im going to take apart the opti today and check where the cam dowel is. ill let u know later what happend
|
|
|
|
Post by x383xstroker on Apr 5, 2006 19:27:20 GMT -5
well took it apart, its in the right spot. do u think the fuel injectors are big enough.. its 400 at the fly wheel cause we dynoed it with a carb intake and distributer setup before we put the lt1 intake on...the stock injectors are 24 #..i did a fuel pressure test its 40 psi..
|
|
|
|
Post by Fire67 on Apr 6, 2006 9:37:16 GMT -5
Even if the injectors are the wrong size, they should still start and run the motor.
Ae you sure theyre firing? Sometimes these wiring harness get brittle and still work fine untill you mess with them (Like doing a motor swap) and then cause all kinds of trouble.
Make sure you hear some clicking out of each, if not then use a noid light to make sure it is or isnt getting voltage to work.
Check over all your wire harness connections really good. Make sure the opti harness is seated firmly into the opti, and connected to the main harness at the other end. Also if you have a haynes manual, it should have the step by step on how to check the ignition module with a volt-meter to make sure everything is within spec.
I hope you find the problem soon, as Im running out of ideas... If anyone else has some ideas, Im sure Greg would appreciate it!
|
|
|
|
Post by 1bad2k2ta on Apr 6, 2006 11:38:21 GMT -5
I am not as familiar with the LT1s as I am with the LS1s, but are you sure the crank and cam timing gears were aligned properly? Other possibilities would be cam and crank position sensors and their related connections.
|
|
|
|
Post by x383xstroker on Apr 6, 2006 11:42:19 GMT -5
thanks alot guys, i should give it to my mech. ive done everything i could, its geting little spark, got fuel(40 lbs) wires on right, checked the opti dowel pin, its all correct, i never seen anything like this..well im thinking it has somthing to do with vacuum...all my vacuum stuff is not hooked up im having trouble hooking it up but i dont think it could cause a no start.
|
|
|
|
Post by Fire67 on Apr 6, 2006 12:55:13 GMT -5
Actually, all the vacuum stuff very well could cause a no start... If you have EVERYTHING open anyway. Get the vacuum stuff worked out and connected. If that doesnt solve it, get ur hands on a scanner that allows live monitoring of the PCM information. With that info, you can confirm the correct operation of the opti's optical sensor, TPS, and all the rest of the sensors for that matter. I wouldnt be suprised if hooking up all the vacuum stuff would solve your problems though  Dont give up on it yet! You'll figure it out with a little patience and have more pride in it because you didnt pay someone to get her going. 1bad2kta- His crank and cam position sensors are built into the opti. If he has a 96-97 motor, there will be an additional crank position sensor on the timing cover thats used for missfire detection. If the optical sensor goes bad inside the optispark, it will not be able to correctly tell the pcm when to fire the injectors and coil. Wich could cause the no-start situation. If there was a problem with the missfire detection crank sensor, it would still run because the pcm only uses it to get info for emissions. |
|
|
|
Post by fast93z on Apr 6, 2006 13:22:36 GMT -5
If you have a stock tune with a 383....this will be much of your problem. I have not read this whole thread but if no-one has not mentioned a re-tune.......get it done. Makes a huge difference!!! |
|
|
|
Post by 1bad2k2ta on Apr 6, 2006 15:00:01 GMT -5
Thanks, Justin.
I knew hanging around this site would be entertaining and educational. ;D
|
|
|
|
Post by x383xstroker on Apr 6, 2006 15:36:22 GMT -5
u guys are awsome and much patient with me. i know enought but learning, i think these forums are made for learning and geting more exp. more than fixing the prob. i would much rather do it my selfe instead of paying someone....
|
|
|
|
Post by x383xstroker on Apr 9, 2006 0:07:56 GMT -5
well, lol sorry to post this but i found out that a couple of plug wires were on wrong, well now its tryin to kick over, lol i feel so stupid, now i just need to get new plugs cause i dont trust the ones that are in there.
|
|
|
|
Post by Fire67 on Apr 10, 2006 8:42:19 GMT -5
Cool man, glad to hear it was something simple... Even though it does suck to find out it was something so simple after going through it over and over.
At the least, its a learning experience. I bet you wont over-look the wires ever again.
|
|
