C4 Tune Up
Thread Starter
Racer
Joined: Jan 2001
Posts: 384
Likes: 0
From: South Bend, IN 46628 Indiana
C4 Tune Up
What does a complete tune up on a '91 (L98) engine entail? I have previously owned two Corvettes but they were both pre '81 C3s and as you may know, a tune up on a C3 is a simple process. I am under the assumption that a tune up on a C4 is a much more complicated matter.
Also, what is a good indication that a L98 (C4) is in need of a tune up, would it be based on mileage or performance?
The car has about 4000 miles on an engine that was professionally rebuilt at about 43,000, it runs well most of the time but on occasion, when I get on it, it seems to bog out, as if it is getting to much fuel.
If there is any input that you can provide, it is greatly appreciated.
Also, what is a good indication that a L98 (C4) is in need of a tune up, would it be based on mileage or performance?
The car has about 4000 miles on an engine that was professionally rebuilt at about 43,000, it runs well most of the time but on occasion, when I get on it, it seems to bog out, as if it is getting to much fuel.
If there is any input that you can provide, it is greatly appreciated.
Racer
Joined: May 2001
Posts: 378
Likes: 0
From: Dunmore, Pennsylvania
Re: C4 Tune Up (Mr. Sharky)
Ok, here is my attempt:
Basic - plugs, cap, rotor, fuel filter, air filter.
More involved - wires, clean TB.
I'm sure there other things you can do that I did not mention, but the above should be a good start, if this does not clear up your problem
then you will have to do some involved digging.
Some of the above things are a real pain in the butt to change (plugs, wires, fuel filter).
I had a miss at idle, turned out to be one of my original plug wires was cut behind the engine, could not see it until I pulled them, I also
found that the insulation would easily pull right off. I guess after 11 years in the heat they had it.
Good luck.
[Modified by jeepie91, 12:11 PM 4/5/2002]
Basic - plugs, cap, rotor, fuel filter, air filter.
More involved - wires, clean TB.
I'm sure there other things you can do that I did not mention, but the above should be a good start, if this does not clear up your problem
then you will have to do some involved digging.
Some of the above things are a real pain in the butt to change (plugs, wires, fuel filter).
I had a miss at idle, turned out to be one of my original plug wires was cut behind the engine, could not see it until I pulled them, I also
found that the insulation would easily pull right off. I guess after 11 years in the heat they had it.
Good luck.
[Modified by jeepie91, 12:11 PM 4/5/2002]
Thread Starter
Racer
Joined: Jan 2001
Posts: 384
Likes: 0
From: South Bend, IN 46628 Indiana
Re: C4 Tune Up (jeepie91)
Thanks jeepie91
My problem with bogging seems to be an intermittent one; does anyone view that as an indication of what the cause is?
[Modified by Mr. Sharky, 11:20 AM 4/5/2002]
My problem with bogging seems to be an intermittent one; does anyone view that as an indication of what the cause is?
[Modified by Mr. Sharky, 11:20 AM 4/5/2002]
Thread Starter
Racer
Joined: Jan 2001
Posts: 384
Likes: 0
From: South Bend, IN 46628 Indiana
Re: C4 Tune Up (vader86)
I am assuming that the fuel filter was replaced 4000 mile ago, during the rebuild process. I doubt that the injectors or the fuel pump were replaced at that time.
Pro
Joined: Oct 2001
Posts: 554
Likes: 1
From: CA
Re: C4 Tune Up (Mr. Sharky)
I did my first every tune up last weekend!!! (Mine...not the car's). New plugs and wires made a big difference. I did the cap and rotor and fuel filter too. I bought the oxygen sensor two nights ago and will do that this weekend. That should be an easy part swap. I have the new fuel injectors and egr valve but I have to really psych myself up for that task. Maybe the weekend after next...or how about a little encouragement and motivation from the forum.
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Safety Car
Joined: Mar 2000
Posts: 3,620
Likes: 2
From: Hillsboro OR
Re: C4 Tune Up (Mr. Sharky)
Make sure the fuel filter has really been replaced. Then check the fuel pressure. I suspect the bogging is running out of fuel as opposed to too much. That could be caused by a weak fuel pump, connections to the pump, or clogged vent system on the tank.
