Rep Power: 0

My 94 civic EX seems to still be losing power. It has the d16z6 Vtec. I have recently replaced plugs with NGK Iridiums, new K&N air filter, new fuel filter, and I had coolant issues, so I had to also replace the thermostat, radiator, and coolant temp. sensor. After all this, when it's warm outside I seem to lose power and fuel economy. So bad that it once took me almost quarter of a tank to go 30 miles. It seems like the engine doesn't have enough power to get going quick enough, and it sounds extra loud for some reason. Taking off, about 1-3k seems to be the worst. My exhaust is straight piped with no cat so a plugged cat is not the issue. I'm getting pretty stumped with this

 
Rep Power: 191

Have you checked your timing.
I am having power loss on high end about 40mph up. So I am going to do some valve adjustments because i can hear some slight pining.
Are you losing coolant.

 
Rep Power: 313

Valves shouldn't cause your car to feel like it's losing power. It could be the timing but then it should feel like it's lacking power all the time. Start by cleaning your throttle body.

 
Rep Power: 191

?? O2 sensor, any codes.

 
Rep Power: 0

It could be 02 but no one local has an obd1. Also, throttle body is very clean, I cleaned it recently. Maybe timing then? I am losing coolant.

 
Rep Power: 0

I cleaned my throttle body as well, so I know that's not the issue. It could be 02 I suppose, but no one local has an obd1. I am losing coolant, maybe it is timing? Is there an easy way to tell if timing is off?

 
Rep Power: 313

Possibly a head gasket. Do a coolant system gas check if that comes back negative a pressure test. You have to find out where you are losing the coolant and you will probably get your power loss answer as well.

How much coolant are you losing?

 
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I was losing coolant, but now that I just did some work on the radiator and sensor the problem may be fixed. I highly doubt it's my head gasket. My exhaust is clear, and no coolant in my oil, no oil in my coolant. I'll be getting my dizzy timing done soon, and i'll let y'all know if that fixed it. Thanks for the help guys!

 
Rep Power: 313

Start there, if your no longer losing coolant it's not your head gasket. However, I doubt it's the timing, it would be doing it all the time not only when it's hot out.

 
Rep Power: 0

Well since I got the car it has definitely lost power. It just seems to be worse when hot. Could replacing/upgrading my plugs throw off dizzy timing?

 
Rep Power: 313

Not unless you physically move the distributor, which you don't when replacing spark plugs.

 
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There is a possibility your rings are worn out. When the engine gets warm it expands a little causing less compression. Ive seen it numerous times. You can still have a blown head gasket also even if your not losing coolant and you dont have oil in your coolant or vise versa. It could be blown between the cylinders like they usually do on these cars

 
Rep Power: 313

Actually, most head gasket failures on these cars result in exhaust gases in the coolant.

 
Rep Power: 191

Just a update, I checked my valve and two where a little lose but most importantly my timing was off by four teeth. Now there is no more pining and it feels much more powerful.

So did you check your timing yet?
I know you said its when its hot out but just in case.

 
Rep Power: 0

I work in a Honda dealer as a Honda tech and almost all of the head gaskets ive had to replace has been blown between the cylinders.

 
Rep Power: 313

90% of the head gaskets that blow here are between the cylinder and the cooling jacket... But if your a tech you see a lot more of them than I do.

 
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I want to apologize, i was thinking this was on a 91 model. Your right after 92 a lot blow between the cylinder and water jacket. Sorry