LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

LT1 problems

Thread Tools
 
Search this Thread
 
Old May 20, 2005 | 03:05 PM
  #1  
2001 B4C's Avatar
Thread Starter
Registered User
 
Joined: Jul 2004
Posts: 96
From: Indianapolis
LT1 problems

ok so we have an LT1 in our 83 malibu wagon, it has never ran

full opti is brand new, new coil pack, new painless wiring harness, new plugs and wires. turns over fine, has no spark though, i took out the sparkplug and i can visualy tell it has no spark. any suggestions?
Old May 20, 2005 | 03:18 PM
  #2  
whatsup's Avatar
Registered User
 
Joined: Jun 2003
Posts: 489
From: everywhere
Re: LT1 problems

What do you mean by "new coil pack"? Does it have a single coil that feeds the opti...or has it been changed over to the Deltec coilpac(s) system....mutiple coils?
Old May 20, 2005 | 03:41 PM
  #3  
Pasky's Avatar
Registered User
 
Joined: Jan 2003
Posts: 1,362
Re: LT1 problems

Either the ICM or VATS.
Old May 20, 2005 | 03:46 PM
  #4  
2001 B4C's Avatar
Thread Starter
Registered User
 
Joined: Jul 2004
Posts: 96
From: Indianapolis
Re: LT1 problems

supposedly they disabled the vats.. with a chip..

it has a new single coil pack to feed the opti, stock everything..
Old May 20, 2005 | 04:12 PM
  #5  
Pasky's Avatar
Registered User
 
Joined: Jan 2003
Posts: 1,362
Re: LT1 problems

Is it those $15 chips on ebay? I'd double check the wiring and I had a buddy break 3 of those, they just shorted on him after every two days. I'd have VATs programmed out. Is the fuel pump priming? Injectors firing? If not, its vats.
Old May 20, 2005 | 04:19 PM
  #6  
2001 B4C's Avatar
Thread Starter
Registered User
 
Joined: Jul 2004
Posts: 96
From: Indianapolis
Re: LT1 problems

fuel pump is good, i pressed the thing on the fuel rail and its presurized, and i can hear the pump going. how do i check if the injectors are working? its been quite a while and its possible the injectors are also not squirting, but there is deffinatly a spark issue, ie none
Old May 20, 2005 | 04:28 PM
  #7  
Pasky's Avatar
Registered User
 
Joined: Jan 2003
Posts: 1,362
Re: LT1 problems

Basically if you smell gas while trying to start it his I always know. Also if your plugs aren't sparking, pull one out and it should smell like gas. If its dry their not firing. Is the fuel pump going to the PCM or is it going to power when the key is turned? If its going to 'power when the key is turned' you can't tell if its vats. If its going to the pcm and the pcm is grounding it, vats is not a issue.
Old May 20, 2005 | 05:54 PM
  #8  
2001 B4C's Avatar
Thread Starter
Registered User
 
Joined: Jul 2004
Posts: 96
From: Indianapolis
Re: LT1 problems

not sure exactly what that ment, but the fuel pump is on a toggle switch

someone told me that LT1s dont have chips in the comptuers also

so it is probably the VATS then that is keeping it from sparking?
Old May 20, 2005 | 06:29 PM
  #9  
Pasky's Avatar
Registered User
 
Joined: Jan 2003
Posts: 1,362
Re: LT1 problems

Yes, and you telling me its on a toggle switch tells me the PCM is not controlling your fuel pump. Im pretty sure your issue is with VATS. Thats correct on no programmable PROMs on the ECM's except the 93 lt1's out of f-bodies (maybe the 92 vettes too, dunno). You can still have your pcm programmed and its far better than proms. Check out www.madz28.com
Old May 20, 2005 | 08:44 PM
  #10  
2001 B4C's Avatar
Thread Starter
Registered User
 
Joined: Jul 2004
Posts: 96
From: Indianapolis
Re: LT1 problems

its a computer out of a 93 Z. so it does have the chip, correct?
Old May 21, 2005 | 05:25 PM
  #11  
Pasky's Avatar
Registered User
 
Joined: Jan 2003
Posts: 1,362
Re: LT1 problems

Yes, it has a re-writable prom chip for the ECM.
Old May 22, 2005 | 12:05 AM
  #12  
curtSr's Avatar
Registered User
 
Joined: Jun 2002
Posts: 19
From: Loma Linda, California
Re: LT1 problems

Verify that your battery feed to the pcm is from a circuit that does not shut off during cranking. That was a problem that I had during my lt1 swap.

Good Luck.

Curt Sr
Old May 22, 2005 | 02:41 AM
  #13  
1racerdude's Avatar
Banned
 
Joined: May 2003
Posts: 6,661
From: LA (lower Alabama)
Re: LT1 problems

Do you have 12V to the coil with the key on?If not put a 12V wire direct to where the 12V supply is and see if it will fire.Ya need a wiring diagram to make sure it is the right wire. Disconnect the 12V wire from the harness that's in the plug in so no damage will occur if something is connected wrong.At that point it is only feeding the opti.
Do you have a '93 PCM and a '94 or later engine or wiring harness?
Maybe Inguneer or some one smarter than me on computers can chime in and give advice on the difference in the computer system and what will work with what.
As mentioned above the VAT is a very likely option.
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
dbusch22
Forced Induction
6
Oct 31, 2016 11:09 AM
InfernalVortex
LT1 Based Engine Tech
3
Jan 17, 2015 09:35 AM
1LEThumper
Forced Induction
40
Jul 14, 2003 12:45 PM
JSK333
Car Audio and Electronics
5
Sep 9, 2002 10:33 PM
smacz28
Drag Racing Technique
7
Aug 6, 2002 01:51 PM




All times are GMT -5. The time now is 09:53 AM.