Power Loss
11-16-2018, 12:35 PM
#1
Power Loss
When I push the engine hard, at times it seems to stop making power over about 3k rpm. Other times it’s strong until past 4K. My car has about 155,000 miles and feels stock. I don’t know what has been done to the engine before I picked it up about 5k miles ago. Judging by the rest of the car, previous owner kept it stock. I have a new fuel pump and filter. There was an msd box which I disconnected and can’t feel any difference. Where should I start looking?
11-16-2018, 01:06 PM
#3
Le Mans Master
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L-98 isnt really a high revving engine. Youre really all in at 4500 ish rpm.... so with 155k miles on it, maybe shes a little tired.... hard to know without knowing what the maintenance history was on the car. Have you done a primary ignition tune up on the car? I would start there...
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L.V. Vette (11-16-2018)
11-16-2018, 01:17 PM
#4
Melting Slicks
Something also to consider in a high mileage car this old is the condition of the Cats. Clogged or partially clogged cats will cause the engine to fall flat at higher rpms.
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L.V. Vette (11-16-2018)
11-16-2018, 02:03 PM
#5
Le Mans Master
Is that an HEI distributor? Could be heat related. This year had a similar problem and turned out to be the coil in the cap. The secondary resistance was way off even though it produced spark and resistance would change with temperature.
Coil is not hard to get out. If I remember the resistance tolerance was 3K-30K ohms and I read about 18K ohms which is about normal. There are a couple of good YouTubes to watch if you need additional help step by step.
If you run out of items to check, you might want to look at the coil.
Last edited by pcolt94; 11-16-2018 at 02:06 PM.
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L.V. Vette (11-16-2018)
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L.V. Vette (11-18-2018)
11-18-2018, 10:10 AM
#7
Appreciate all the replies. I will look into cats and ignition. The fuel filter is easy enough to change. It may be heat related. Thinking that the engine typically feels stronger before fully warming up.
11-18-2018, 02:34 PM
#8
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So after a set of plugs, wires, cap & rotor, fuel filter, air filter... make sure you set the timing Follow the FSM or even a Chiltons will tell you how to get that done... There is a brown wire I think that you need to disconnect then after the engine is at normal operating temps, set the timing with a light, tighten down the distributor and plug the wire back in....
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L.V. Vette (11-18-2018)
11-18-2018, 06:26 PM
#9
Race Director
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I agree with 81c3. Always perform a basic tuneup before trying to diagnose an issue.
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L.V. Vette (11-18-2018)