Lt4 wont start
Thread Starter
Race Director
Joined: Apr 2007
Posts: 10,215
Likes: 7
From: Lafayette LA
St. Jude Donor '09
Lt4 wont start
well went out to my car to go somewhere and the damn thing just wants to keep turning over , and wont start.
Its not getting spark, i have changed the coil with no luck.
I have also changed the opti-$*%! in the last 6 months.
is it possible that the wonderful opti-spark has gone out again?
Also its an lt4 create motor in a 95 A4
Its not getting spark, i have changed the coil with no luck.
I have also changed the opti-$*%! in the last 6 months.
is it possible that the wonderful opti-spark has gone out again?
Also its an lt4 create motor in a 95 A4
Instructor
Joined: Jul 2007
Posts: 129
Likes: 0
Fuel pump working? Try taking a sqeeze bottle of gasoline and squirting about 2 tablespoons or a little more directly into the intake manifold. You will need to remove the rubber boot around the throttle body to do this and open the throttle gate.
If the car starts and runs for a little bit and then shuts down burning the 2 tablespoons of gas you squirted in, then your fuel pump is bad. If it does not start at all, you got other issues.
Could be an injector problem as well.
If the car starts and runs for a little bit and then shuts down burning the 2 tablespoons of gas you squirted in, then your fuel pump is bad. If it does not start at all, you got other issues.
Could be an injector problem as well.
Nut Job
Joined: Mar 2008
Posts: 363
Likes: 12
From: Monticello Florida
LT4's are also notoriously susceptible to Optispark problems due to a leaking water pump. Isn't it grand how they put the distributor unit under the water pump? 
Bet they didn't consult Zora about this one.
Bet they didn't consult Zora about this one.
Thread Starter
Race Director
Joined: Apr 2007
Posts: 10,215
Likes: 7
From: Lafayette LA
St. Jude Donor '09
well i can hear the fuelpump priming.. and what i think is fuel going to the injectors..
and i serously doubt it would all of a sudden just quit on me/
so im voting on opti..
at least i hope soo.. all i have left to do is pull the harmonic balancer pully
and i serously doubt it would all of a sudden just quit on me/
so im voting on opti..
at least i hope soo.. all i have left to do is pull the harmonic balancer pully
Thread Starter
Race Director
Joined: Apr 2007
Posts: 10,215
Likes: 7
From: Lafayette LA
St. Jude Donor '09
i changed the coil .. and there was no improve ment..
so i pulled out a spark plug , *it was at night* and layed it on the exaust manifoil and had my friend try to start the car
so i pulled out a spark plug , *it was at night* and layed it on the exaust manifoil and had my friend try to start the car
Le Mans Master
Joined: Dec 2004
Posts: 5,789
Likes: 8
From: Myrtle Beach SC
St. Jude Donor '05-'06
The coil and ICM are 2 different things. You can pull it and take it to get tested. Do you have a FSM? If you don't you could have bought one with the part money you wasted.Your only problem is with the LT4 section but most of that is the same as a LT1
Last edited by Redeasysport; Apr 8, 2008 at 04:31 PM.
Racer
Joined: Sep 2007
Posts: 393
Likes: 0
From: Bartonville Illinois
Replacing the opti is enough work that I would try to make sure it is bad. You have stuff thats easy to get to without crawling under the car. Coil, coil wire, ICM, Opti harness and connectors.My opti crapped out after pressure washing the engine, But it was corroded from moisture. It never really quit, the car just lost some performance.
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Le Mans Master
Joined: Dec 2004
Posts: 5,789
Likes: 8
From: Myrtle Beach SC
St. Jude Donor '05-'06
Replacing the opti is enough work that I would try to make sure it is bad. You have stuff thats easy to get to without crawling under the car. Coil, coil wire, ICM, Opti harness and connectors.My opti crapped out after pressure washing the engine, But it was corroded from moisture. It never really quit, the car just lost some performance.
Thread Starter
Race Director
Joined: Apr 2007
Posts: 10,215
Likes: 7
From: Lafayette LA
St. Jude Donor '09
and i have books they are all at home. i am at school
i mean i doubt that the ICM just went out
thats the thing that the Coil bolts to rigth?
Le Mans Master
Joined: Dec 2004
Posts: 5,789
Likes: 8
From: Myrtle Beach SC
St. Jude Donor '05-'06
ICM is the ignition control module and they "go out" all the time. You can be driving down the road and the car dies. It happened to me and many other forum members so don't "doubt" when we tell you something. Once you trouble shoot it according to the FSM you will nail it down. They have to be installed a certain way or they will just burn out again.
Drifting
Joined: Nov 2004
Posts: 1,484
Likes: 0
From: Nanaimo, BC
I think that might be a bit of an overstatement. The 92-94 LT-1's are definitely "notoriously susceptible", but in 95 they brought in the vented opti-spark which helped to reduce the incidence of 'wet opti-spark' problems significantly. Not to say that the opti isn't the problem here though, it certainly could be, they're just not nearly as problematic as the 92-94's..
Thread Starter
Race Director
Joined: Apr 2007
Posts: 10,215
Likes: 7
From: Lafayette LA
St. Jude Donor '09
ICM is the ignition control module and they "go out" all the time. You can be driving down the road and the car dies. It happened to me and many other forum members so don't "doubt" when we tell you something. Once you trouble shoot it according to the FSM you will nail it down. They have to be installed a certain way or they will just burn out again.
Le Mans Master
Joined: Dec 2004
Posts: 5,789
Likes: 8
From: Myrtle Beach SC
St. Jude Donor '05-'06
It takes about 15 min to take the ICM out and get it tested at Advance or Autozone. Time is money and I hate to see a Vette owner waste either. Geeze we get "taxed" enough. The FSM will tell you how to trouble shoot the ICM But I bet it is your problem if not it takes a lot less time to rule it out than to change an opti.
Le Mans Master
Joined: Dec 2004
Posts: 5,789
Likes: 8
From: Myrtle Beach SC
St. Jude Donor '05-'06
Yep. That controls the coil. Make sure you have heat sink paste behind it. These literally burn up if you don't. When you take it off you will see where the paste goes don't wipe it off.
Nut Job
Joined: Mar 2008
Posts: 363
Likes: 12
From: Monticello Florida
I think that might be a bit of an overstatement. The 92-94 LT-1's are definitely "notoriously susceptible", but in 95 they brought in the vented opti-spark which helped to reduce the incidence of 'wet opti-spark' problems significantly. Not to say that the opti isn't the problem here though, it certainly could be, they're just not nearly as problematic as the 92-94's..
5th Gear
Joined: May 2008
Posts: 5
Likes: 0
Hi guys another brother in trouble...
I am having the same problem but my 93 LT1 restarts and runs (in carport) fine. I checked fuel pressure and its on in spec. no apparent sign of pump leak. I am hoping for a ICM problem but cant find a parts store around here to test it (I live in Cow Hampshire) Most parts guys here look at me like I am nuts. My question is what is this FSM you mention and how can I test the module. Any tips welcome as i dont want to spend 100$ on a module if its the opti. Thanks
I am having the same problem but my 93 LT1 restarts and runs (in carport) fine. I checked fuel pressure and its on in spec. no apparent sign of pump leak. I am hoping for a ICM problem but cant find a parts store around here to test it (I live in Cow Hampshire) Most parts guys here look at me like I am nuts. My question is what is this FSM you mention and how can I test the module. Any tips welcome as i dont want to spend 100$ on a module if its the opti. Thanks
5th Gear
Joined: May 2008
Posts: 5
Likes: 0
Anyone out there has any thoughts no this or ever gone through this problem? Hate to start throwing parts at it. Its easy to find a no start problem but these intermittent issues can be expensive. Give me your best guess from experience please and I will appreciate it as this is my frist (and last) opti spark vehicle.
Last edited by Bill DeSimone; May 13, 2008 at 08:57 AM. Reason: added words
Race Director
Joined: Mar 2006
Posts: 11,628
Likes: 1
From: Sherwood, Arkansas
Hi guys another brother in trouble...
I am having the same problem but my 93 LT1 restarts and runs (in carport) fine. I checked fuel pressure and its on in spec. no apparent sign of pump leak. I am hoping for a ICM problem but cant find a parts store around here to test it (I live in Cow Hampshire) Most parts guys here look at me like I am nuts. My question is what is this FSM you mention and how can I test the module. Any tips welcome as i dont want to spend 100$ on a module if its the opti. Thanks
I am having the same problem but my 93 LT1 restarts and runs (in carport) fine. I checked fuel pressure and its on in spec. no apparent sign of pump leak. I am hoping for a ICM problem but cant find a parts store around here to test it (I live in Cow Hampshire) Most parts guys here look at me like I am nuts. My question is what is this FSM you mention and how can I test the module. Any tips welcome as i dont want to spend 100$ on a module if its the opti. Thanks