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breaks up



i have a 81,just did a tune up and a new trans,when i nail it in drive she goes good until she reaches 4 grand and then she tends to break up or wine out till it finally gets t 5 grand and then it shifts,,,,not feeling right at all only had her for 2 months,,,,,any help would be great thanks.
Welcome to CACC.

As you know, there are a variety of things that can cause this problem. When you did the tune up, what did you actually change/adjust?

Any modifications on the car?

Did it do it before the tune up as well?
it was doing this before the tune up,had alot of z28s never had this problem,,now my air pump is frozen,,my heat riser might not be working either,,,,maybe one of those might have something to do with this, Thank you for your help, love your car
Do you have a feel if it is an engine or transmission bogg? If it is breaking up at higher RPM (engine miss firing) the dwel could be floating or you can have a dirty or cracked distr. cap, bad plug wire, spark plugs gap to wide,,,,to the choke not working right. In the old days I'd put the dwell tach on her, but it isn't that easy on you L81.

Welcome to The Corvette Action Center Community and take a look at L81 Vette Registry when you have a chance.

Don't think you need to worry about the air pump causing this problem. That is fairly easy to replace, and is done on an exchange basis at most autoparts stores.

I don't think the heatriser is doing this either. Breaking up can be caused by an interuption in the fuel flow, or a breaking down of the ignition.

You will have to go through the "basics" at each level. A bad fuel pump can cause this problem. The coil could be weak. For some reason the float level in the carb could be low and need to be raised.

My money is on an ignition problem. Like has been mentioned, it could be worn parts in the distributor, a bad cap or rotor, or the ignition coil. You also mentioned you had an 81. Is your computer still up and working? 5K is the red line, if your computer is still active then I would suspect that this is could also contributing. At any rate it would appear that your ignition is breaking down at high rpm.....more trouble shooting ahead. Keep us posted :w
One thing not mentioned is an exhaust restriction. Are any pipes squished? Could the cat be clogged?
Have you made any carb/head/cam modifications recently?
Have you tried disconnecting your EGR and see if this improves the situation? How do your spark plugs look? Any arcing in the cap? Plug wires in good shape? #5&7 wires clearly seperated?
Good luck.
thanks alot for all of your help,ill keep you posted on what was wrong,going to work more on it this weekend,,,,,,thank guys,,,,,this is sooo cool.

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