Tune-up didn't help much
Thread Starter
Instructor
Joined: Apr 2001
Posts: 232
Likes: 0
From: Hayward, Ca
Tune-up didn't help much
I've changed the plugs, wires and oxygen sensors on my car. It runs better but at highway speeds it still runs rough and when I step on it the valves clatter. I am thinking about changing the coil. Good idea? Can anyone give me a suggestion?
(I'm driving a 92)
[Modified by Breezy, 7:57 AM 12/9/2001]
(I'm driving a 92)
[Modified by Breezy, 7:57 AM 12/9/2001]
Thread Starter
Instructor
Joined: Apr 2001
Posts: 232
Likes: 0
From: Hayward, Ca
Re: Tune-up didn't help much (vader86)
Thanks guys. Boy do I hate that "Opti-spark" word. :mad
Scorp- FYI, No adjustment is possible on the vin P timing. Its set at the factory.
[Modified by Breezy, 9:27 AM 12/9/2001]
Scorp- FYI, No adjustment is possible on the vin P timing. Its set at the factory.
[Modified by Breezy, 9:27 AM 12/9/2001]
Le Mans Master
Joined: Sep 2001
Posts: 7,928
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From: More cowbell...
St. Jude Donor '04
Re: Tune-up didn't help much (Breezy)
Are you having problems starting as well? I was having similar problems- real rough idle, NOISY valves, and also had problems starting, (however she drove like a champ at anything above idle). It turned out to be the fuel pressure regulator. You can check this by running the engine, and removing the vaccum tube that plugs into the back of the fuel pressure regulator. If fuel starts spraying out, your fpr is bad.
-Mark
-Mark
Thread Starter
Instructor
Joined: Apr 2001
Posts: 232
Likes: 0
From: Hayward, Ca
Re: Tune-up didn't help much (MarkLT1)
Are you having problems starting as well? I was having similar problems- real rough idle, NOISY valves, and also had problems starting, (however she drove like a champ at anything above idle). It turned out to be the fuel pressure regulator. You can check this by running the engine, and removing the vaccum tube that plugs into the back of the fuel pressure regulator. If fuel starts spraying out, your fpr is bad.
-Mark
-Mark
Le Mans Master
Joined: Jun 1999
Posts: 6,272
Likes: 2
From: Chino Valley AZ
Cruise-In I Veteran
Cruise-In II Veteran
Currently Corvette-less
Re: Tune-up didn't help much (Breezy)
Breezy,
It cery well could be the Opti, but most likely not the coil. Don't forget that the EGR 's plays a primary role in cylinder combustion performance. It is located on the rear of the intake, and a piece of cake to remove, check, and replace. One way to check it in place is to hook a vacuum pmp to the diaphragm and apply vacuum when the engine is idleing. If it starts to shudder and stumble when you slowly open it, then the EGR is OK. The EGR gas port could be plugged with carbon also.
As I said, the EGR on the LT1 engine is apiace of cake to replace, unlike the beast within the L98. Try that, and if you would like for me to help with your diagnosos, please feel free to write me at PurpleC4@qwest.net ~~ or stick with this thread and I will try to follow it.
At one time I had the most ill performing LT1 in the United States (it seemed that way anyway). It is actually a fairly easy engine to diagnose and repair. ~ Purp
It cery well could be the Opti, but most likely not the coil. Don't forget that the EGR 's plays a primary role in cylinder combustion performance. It is located on the rear of the intake, and a piece of cake to remove, check, and replace. One way to check it in place is to hook a vacuum pmp to the diaphragm and apply vacuum when the engine is idleing. If it starts to shudder and stumble when you slowly open it, then the EGR is OK. The EGR gas port could be plugged with carbon also.
As I said, the EGR on the LT1 engine is apiace of cake to replace, unlike the beast within the L98. Try that, and if you would like for me to help with your diagnosos, please feel free to write me at PurpleC4@qwest.net ~~ or stick with this thread and I will try to follow it.
At one time I had the most ill performing LT1 in the United States (it seemed that way anyway). It is actually a fairly easy engine to diagnose and repair. ~ Purp
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Burning Brakes
Joined: Oct 2001
Posts: 1,135
Likes: 17
Re: Tune-up didn't help much (MarkLT1)
Are you having problems starting as well? I was having similar problems- real rough idle, NOISY valves, and also had problems starting, (however she drove like a champ at anything above idle). It turned out to be the fuel pressure regulator. You can check this by running the engine, and removing the vaccum tube that plugs into the back of the fuel pressure regulator. If fuel starts spraying out, your fpr is bad.
-Mark
-Mark
Le Mans Master
Joined: Sep 2001
Posts: 7,928
Likes: 1
From: More cowbell...
St. Jude Donor '04
Re: Tune-up didn't help much (Breezy)
Breezy-
Sorry bout that, my bad.. I guess I just totaly misread your post.
Daniel-
The FPR can be found on the passenger side, under your fuel rail covers. The picture below shows my new adjustable regulator (pointed at by the blue arrow thats kinda hard to see), so yours will look just a little different (the vaccum tube will be coming strait out at you, rather then down as in this picture). Just start up the car, and pull that vaccum tube out, and if fuel starts to spurt out of the hole, your regulator is shot.
Once I replaced mine, she ran like new! Hope it can fix your problem!
-Mark
Sorry bout that, my bad.. I guess I just totaly misread your post.
Daniel-
The FPR can be found on the passenger side, under your fuel rail covers. The picture below shows my new adjustable regulator (pointed at by the blue arrow thats kinda hard to see), so yours will look just a little different (the vaccum tube will be coming strait out at you, rather then down as in this picture). Just start up the car, and pull that vaccum tube out, and if fuel starts to spurt out of the hole, your regulator is shot.
Once I replaced mine, she ran like new! Hope it can fix your problem!
-Mark
Burning Brakes
Joined: Oct 2001
Posts: 1,135
Likes: 17
Re: Tune-up didn't help much (MarkLT1)
I shure hope it's the FPR and not the opti-crap!!!
Thanks Mark - Without that pic I would have pulled the radiator hose or somethin' :jester
[Modified by Daniel DK, 11:00 AM 12/10/2001]
Thanks Mark - Without that pic I would have pulled the radiator hose or somethin' :jester
[Modified by Daniel DK, 11:00 AM 12/10/2001]
Advanced
Joined: Jun 2001
Posts: 85
Likes: 0
From: Princeton NJ
Re: Tune-up didn't help much (Daniel DK)
Daniel-
Glad the pic helped. The FPR is pretty easy to change too. You just have to pull off the fuel rails, undo a screw, pull the old one off, put the new one in, and hook everything back up. Took me about 20 minutes (although I did this 1 week after changing my head gaskets, so it seemed like cake compared to that job!) Let us know if it works. (BTW: this is my normal account. I was on a different computer this weekend, and couldnt remember my password.. oops).
Glad the pic helped. The FPR is pretty easy to change too. You just have to pull off the fuel rails, undo a screw, pull the old one off, put the new one in, and hook everything back up. Took me about 20 minutes (although I did this 1 week after changing my head gaskets, so it seemed like cake compared to that job!) Let us know if it works. (BTW: this is my normal account. I was on a different computer this weekend, and couldnt remember my password.. oops).