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Discussion Starter #1
Well on the 23rd of Feb., a few days after my birthday, I was looking around magazines for a C4. I ran into one going for around 6k(pretty good) It's a 1992(first year for the Lt-1 motor). It's a beauty, some sort of blueish greenish color, I'd have to post some pictures soon(and it's in fair to good condition) but with the low pricing came the high mileage(nearing 150K). Anyways, I took it to the mechanic for the basics(New oil, oil filter, tranny fluid, fuel filter and differential) As I was driving down the expressway a rattle started(I was doing the speed limit(70)) It appeared to be coming from the exhaust. I also noticed my throttle response wasn't what it was early that day(at least it felt that way), in all rpm ranges, it just wasn't catching like it used to, if anything it's slacking. Could it be exhaust troubles chocking up my engine or what's the deal?? Another thing,maybe it's because the weather over here got warmer today but my oil and coolant temp. were rising to low 200's(214-222) where it would usually be around 184-201. Any answers or suggestions would be appreciated.(I plan on taking it back tomorrow morning to see what's the troubles) Thanks SVC.
 

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Well on the 23rd of Feb., a few days after my birthday, I was looking around magazines for a C4. I ran into one going for around 6k(pretty good) It's a 1992(first year for the Lt-1 motor). It's a beauty, some sort of blueish greenish color, I'd have to post some pictures soon(and it's in fair to good condition) but with the low pricing came the high mileage(nearing 150K). Anyways, I took it to the mechanic for the basics(New oil, oil filter, tranny fluid, fuel filter and differential) As I was driving down the expressway a rattle started(I was doing the speed limit(70)) It appeared to be coming from the exhaust. I also noticed my throttle response wasn't what it was early that day(at least it felt that way), in all rpm ranges, it just wasn't catching like it used to, if anything it's slacking. Could it be exhaust troubles chocking up my engine or what's the deal?? Another thing,maybe it's because the weather over here got warmer today but my oil and coolant temp. were rising to low 200's(214-222) where it would usually be around 184-201. Any answers or suggestions would be appreciated.(I plan on taking it back tomorrow morning to see what's the troubles) Thanks SVC.

A coolant temperature of 220 degrees is perfectly normal for C4's. So don't let that worry you. The rattle you're hearing could be coming from most anywhere, so I'd advise you to jack the car up and start pounding on things with a big rubber hammer until you find something loose or touching something else.
 

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Discussion Starter #4
I was thinking it may be the cats, had a friend with cat problems on his 87, well good to know 220 temp is nothing to worry about, thanks for the replies. I will post my solution to this whenever I find what is causing it! Hopefully help someone out in the future.
 

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I was thinking it may be the cats, had a friend with cat problems on his 87, well good to know 220 temp is nothing to worry about, thanks for the replies. I will post my solution to this whenever I find what is causing it! Hopefully help someone out in the future.
My temp is always right around there, and please do post your results.:thumbsup3:
 

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Bring car up to operating temp and with a laser thermometer test temp before cat and just after cat. The temp should be the same if the cat is working properly. As far as the cooling temp goes it sounds normal as stated. :thumbsup:
 

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Was optispark addressed at around 100k? Plugs, wires etc? If doing city driving you can expect the temp to go over 200 a little. I personally have never seen my oil temp over 200. Generally stays around 180-190 unless I let the car idle for ten minutes until cooling fan kicks on.
 

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Discussion Starter #8
Well here I am with the diagnostics, took it to the mechanic, we went under the floor and had someone rev it from uptop. The rattling was coming from my converter and nothing else around it was loose. Turns out when I got all the fluids changed and engine flushed, the engine was running smoother and more powerful and that took out my converter!! The rattling noise comes on at around 2500-3000 rpms at rev and around the same while cruising around 70+ Mph. So if you feel your C4's exhaust rattling, feeling lack of throttle response and power, or stalling out, this may be one of the problems. If I can't afford a new exhaust system right away I was thinking on having someone take the exhaust out midway(including the converter)(I'd get a nice mean sound :)) So I hear keeping it on will not only rob me of horsepower but hurt my engine, what's everybody's take on my possible solution?
 

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Couldn't you just have the cat. converters changed out ? I had the same problem on my '94 and had them replaced with some generic hi-flows. It wasn't terribly expensive and restored a decent amount of power back to the car even though it wasn't the "prettiest" job.

If you are in a non-emissions county, you could just remove the cat. converters and have some "test pipes" put in.

Removing the cat. converters completely and running open manifolds would be a bad idea and wouldn't do anything good for your car.
 

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Discussion Starter #12
Thanks for all these ideas, I will keep them in mind. I could change out the cats. to high-flos but from what i've seen(pricings) I could just save up a few more and possible go for a full chambered exhaust system from Ecklers or MidAmerica. Borla or Corsa would be nice too though I'm not planning to spend too much.( I want a meaner sound coming from my Vette anyways,stock note is nice enough though louder couldn't hurt, unless we're talking about hearing :)
 

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Thanks for all these ideas, I will keep them in mind. I could change out the cats. to high-flos but from what i've seen(pricings) I could just save up a few more and possible go for a full chambered exhaust system from Ecklers or MidAmerica. Borla or Corsa would be nice too though I'm not planning to spend too much.( I want a meaner sound coming from my Vette anyways,stock note is nice enough though louder couldn't hurt, unless we're talking about hearing :)
That's what I would do if I were you bro.
 

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Couldn't you just have the cat. converters changed out ? I had the same problem on my '94 and had them replaced with some generic hi-flows. It wasn't terribly expensive and restored a decent amount of power back to the car even though it wasn't the "prettiest" job.

If you are in a non-emissions county, you could just remove the cat. converters and have some "test pipes" put in.

Removing the cat. converters completely and running open manifolds would be a bad idea and wouldn't do anything good for your car.
The less restriction on the exhaust system...the better!!!
 

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Discussion Starter #18
Turns out this whole time I was mistaking the freakin resonator for the cat. converter :X. It was my resonator that was screwing with me. Here are the results: I took the Vette over to a muffler shop(one that I could trust and know they do good work) had my resonator eliminated and in place had two straight pipes put on. Less weight and a little hp gain I imagine. I was a bit amazed with the result, just taking out the resonator and you get a bit more aggressive tone :), both at idle and damn sure at acceleration. Soon after my throttle and acceleration felt smooth again, no more holding back. Problem solved(for now I hope!!!) My next step for the exhaust will either be buying muffler eliminaters or just a full straight pipes system. Will have to post a video then :)
 

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Turns out this whole time I was mistaking the freakin resonator for the cat. converter :X. It was my resonator that was screwing with me. Here are the results: I took the Vette over to a muffler shop(one that I could trust and know they do good work) had my resonator eliminated and in place had two straight pipes put on. Less weight and a little hp gain I imagine. I was a bit amazed with the result, just taking out the resonator and you get a bit more aggressive tone :), both at idle and damn sure at acceleration. Soon after my throttle and acceleration felt smooth again, no more holding back. Problem solved(for now I hope!!!) My next step for the exhaust will either be buying muffler eliminaters or just a full straight pipes system. Will have to post a video then :)
When I bought my 92 the previous owner had replaced the resonator with straight pipes. I liked it that way so when I did the longtubes and bullet cats I had the muffler shop connect them to the stock mufflers. I love the sound and its quiet enough I can run the car on the race track durring quiet hours :thumbsup:
 

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Discussion Starter #20
Well I'm back at it again. Didn't want to start another topic instead I'll continue on this one. I took the Vette today out for a little spin, just as I was getting home I start to hear a whistling noise. I got home and left it running, got out to inspect where the noise was coming from. It seems to be around the gas tank area possibly towards the top gas cap. I'm sure it's nothing to worry about, though I'd like to know if anything knows what it could be?
 
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