Unknown LT-1 Issue
12-03-2008, 10:19 PM
#21
Launching!
Join Date: Jul 2008
Posts: 255
Likes: 0
Received 0 Likes
on
0 Posts
Formula 350-I pulled the plug off the temp. sens. fan is on immediately, set to come on at 160. Plugged it back in same thing. Pulled the knock sensor plug, still a no start when warm. Denso O2s will be in tomorrow, and I already bought a GM IAT and Temp sensor. I was going to put it in last, but you think it may be the problem? I have a brand new shiny MSD opti sitting right next to me
as we speak. I may not even have to put it in? Probably will anyway
I will try the sensors one at a time and let you all know the outcome, maybe I can save someone else the expense that I have gone through.
as we speak. I may not even have to put it in? Probably will anyway I will try the sensors one at a time and let you all know the outcome, maybe I can save someone else the expense that I have gone through. 
12-03-2008, 10:27 PM
#22
TECH Fanatic
iTrader: (10)
Join Date: May 2005
Location: Charlotte, NC
Posts: 1,197
Likes: 0
Received 0 Likes
on
0 Posts
Fans are always on when you have an SES light. Don't think its opti but couldn't hurt to put the MSD one in (full opti or just cap and rotor?) its a nice piece. Make sure everything is clearance and your ticking isn't from something outside the motor. IAC? Couldn't hurt to check that
12-03-2008, 10:29 PM
#23
TECH Fanatic
iTrader: (10)
Join Date: May 2005
Location: Charlotte, NC
Posts: 1,197
Likes: 0
Received 0 Likes
on
0 Posts
Just thought of this, could be your fuel pump going out, i have seen cars that will be fine at start up but once they get warm they loose fuel pressure, put a mechanical gauge on the thing and see what the fuel pressure is doing, if the pump is on its last leg that little bit of temp increase from the circulation could cut it
12-04-2008, 12:04 AM
#24
Considering you said your tach was going crazy and it only idled on cold starts. and you had to wait 10 to 15 minutes for it to restard.. My guess is opti, and or the 'opti box' I had the same issue with my LT1 and a new opti fixed it for a bit.. then the gay opti box went out.
and FYI the opti is still being used by the delteq... Its how the delteq knows which coil set to fire....
-Mark
and FYI the opti is still being used by the delteq... Its how the delteq knows which coil set to fire....
-Mark
12-04-2008, 11:53 AM
#28
Launching!
Join Date: Jul 2008
Posts: 255
Likes: 0
Received 0 Likes
on
0 Posts
deviladvocate-sorry I didn't mean to but in on this thread so much. Your Delteq coil setup still uses the optical sensor of the opti if I am not mistaken. Isn't that one of the parts that gets corroded by moisture making it read incorrectly. Seems like you could have all the exact sames symptoms of an bad opti and actually have a bad one because it is still there(minus the burnt cap and rotor, plastic rivets breaking, and arcing inside). You still have the problematic sensor. I agree on trying everything else cheaper and easier first, because it seems like everyone just points at the opti. I have a new opti ready to go in, but I am bound and determined to try everything else first, just because I want to know the exact problem if I can. Have you had any luck or fixed the problem yet?
12-04-2008, 01:25 PM
#31
Launching!
Join Date: Jul 2008
Posts: 255
Likes: 0
Received 0 Likes
on
0 Posts
Not the temp sensor, IAT, IAC, knock sensor, fuel pressure, injectors, ICM, coil, plug wires, or plugs, O2s are next and I am very doubtful ......then full MSD opti. Only code I have is a ses light code, because I don't have the light bulb hooked up. That will make the fan come on early, that shouldn't make it not start, right? I guess I will have to hook up a light.
12-04-2008, 02:20 PM
#32
It will still start and run like that. I dont see why it wouldnt, it has nothing to do with any of the information sensors.
More than likely its the opti. Either that or you have a really messed up harness like I did.
-Mark
More than likely its the opti. Either that or you have a really messed up harness like I did.
-Mark
12-04-2008, 02:36 PM
#33
TECH Senior Member
iTrader: (3)
Join Date: Oct 2006
Location: Decatur, TN (N-W of Athens)
Posts: 7,564
Likes: 0
Received 4 Likes
on
4 Posts
Not the temp sensor, IAT, IAC, knock sensor, fuel pressure, injectors, ICM, coil, plug wires, or plugs, O2s are next and I am very doubtful ......then full MSD opti. Only code I have is a ses light code, because I don't have the light bulb hooked up. That will make the fan come on early, that shouldn't make it not start, right? I guess I will have to hook up a light.
Crooked, when you do end up (now, or later) doing the Opti, I recommend a few things. First, to use a small bit of silicone around the o-ring on the cap, to totally ensure no leaking can occur. I know MSD's design is really good as it is, but better safe than sorry. If you aren't running a vented cap, and you feel adventurous (this is what I plan to do when the dreaded moment comes) is to make it vented. Now, I'd practice on your old cap first, but I'd drill a very small hole in an area you know would be a safe spot to do it and then insert and glue in a plastic barb fitting. I don't recommend metal just in case it even could arc to it. Then you'll have a vented setup and just run a vacuum line to your CAI (before MAF if you do) or in the intake somewhere. IF funds allow, I'd also snag a new water pump while you've got it all torn apart anyways :\ Unless you've done one recently, it's only a matter of time before you have to do it again right? If you don't feel like doing the previous stuff (silicone and vent mod) then I at LEAST suggest you drill and tap out the water pumps weep hole, thread in a barb fitting, and run a vacuum line down to the bottom of the motor past the Opti. You could also just glue in a small piece of metal tube instead of drilling and taping the pump out, would be less work, and then just clamp the hose onto it and route it to the ground. So when the pump eventually does give up the ghost, it'll **** on the ground and not your Opti
And if anyone has any opinions or suggestions about what I said, by all means say something
If you feel/know something is a bad idea, it won't hurt my feelings heh
12-04-2008, 02:46 PM
#34
My delteq system acted almost exaclty the same way yours did. Replaced the opti. and it was fine. if it doesnt, look into wiring. check EVERYTHING.
using a voltmeter check for 5v across singal and ground pins for every sensor. Check your grounds. most important part.
Im riding on the opti being the problem..
using a voltmeter check for 5v across singal and ground pins for every sensor. Check your grounds. most important part.
Im riding on the opti being the problem..
12-04-2008, 04:09 PM
#35
Launching!
Join Date: Jul 2008
Posts: 255
Likes: 0
Received 0 Likes
on
0 Posts
Thanks again for all the great help guys! Formula 350- the money part does suck, but there are others with this same problem. I have been very diligent about replacing one thing at a time and running tests (ohm meter, boiling water, testing wires, grounds, etc) and even replacing parts I suspected to be good, I have even run the tests on the new parts to compare to the old. I start it and warm it up exactly the same, if possible. My IAC was definitely bad. I figure at least I'll have a spare good one in case of emergency and i won't keep suspecting that part even though it was good.
Unfortunately I just got my o2s ($85 for 2 Densos!) and am going to go put them, I am sure to have the same problem. Next step is the opti, I don't feel like buying a new water pump, because when it goes I want to go electric, but drilling and tapping for a drain line is a great idea and I will try it. A little silicone between the cap and rotor sounds good too. FYI-If you go MSD opti the one that fits 93-96 is vented and comes with the parts to convert Thanks for the idea!
Unfortunately I just got my o2s ($85 for 2 Densos!) and am going to go put them, I am sure to have the same problem. Next step is the opti, I don't feel like buying a new water pump, because when it goes I want to go electric, but drilling and tapping for a drain line is a great idea and I will try it. A little silicone between the cap and rotor sounds good too. FYI-If you go MSD opti the one that fits 93-96 is vented and comes with the parts to convert Thanks for the idea!
OOPPTTII
12-04-2008, 11:24 PM
#38
Launching!
Join Date: Jul 2008
Posts: 255
Likes: 0
Received 0 Likes
on
0 Posts
Pulled the opti. It had some nasty stuff in it. Oily, varnish, junk. Looked like the drain hole vent hole was plugged. The rotor had some stuff in the slots and the sensor had some oil on it. Didn't look like the seals were doing much. Cap was a little worn as well. I hope this is the problem. I'll get the new MSD one in this weekend and post up.
By the way My .02 on the MSD vs. the stocker is it looks well worth the money (we will have to see how it holds up though). One of the two seals is deleted, there are less cheesy pieces inside, the cap is a 10 times as stout and has an extra screw holding it down, brass contacts, the rotor is a hundred times more solid, and it replaces the intermediate plug harness between the opti and manifold plug. I feel a lot more confident in it compared to the stocker.
By the way My .02 on the MSD vs. the stocker is it looks well worth the money (we will have to see how it holds up though). One of the two seals is deleted, there are less cheesy pieces inside, the cap is a 10 times as stout and has an extra screw holding it down, brass contacts, the rotor is a hundred times more solid, and it replaces the intermediate plug harness between the opti and manifold plug. I feel a lot more confident in it compared to the stocker.
