this is for a friends 91 bird.

just installed some headers, y-pipe, no cat, cutout... he has flowmaster catback, 3" from the headers allllllll the way to the end

it really started to run like **** from the install... got home and checked the engine... burned though 2 wires... replaced all the wires, still crappy, got those plugwire socks, and cap, rotor... checked the firing order everything was fine. but still ran like poo

when u press on the gas... it lags and u can totally feel the lost power! it also surges when push it.... bump bump bump bump feeling... no power....

what could this be? could it be the computer?? or something... we replaced the o2 and all that jazz... hmm

HELP!

 

Did you change plugs too? I would bet money its igntion related.

 

Has the car stored a trouble code? Is everything tight with the exhaust, no leaks? Good luck!

 

I'd check for exhaust leaks. that would be my first guess. Then make sure your installed the O2 sensor and knock sensor.

 

we installed a new o2 and i don't think it would have to do anything with the knock sensor...

i don't think u would get a leak right after install... + it was done pro.

 

Check the wire routing and that the wires are seated properly on the plugs.

 

Sounds like your 02 sensor has a poor/no ground. Run a jumper wire to the body (metal part) of the 02 sensor and the other end to battery ground, see if that straigthens it out.

 

does anyone think it could be computer related??? ill tell him to get it scaned but that cost a pretty sum.

 

This is something that i would definitly check. However correct me if im wrong when you first start the car it doesnt use the o2 sensor at all it only uses it once the car has been running for 10 or so minutes so if the car starts fine and is okay and then all of a sudden goes all weird its probably the o2. Id definitly get him to check the codes but id just use the paper clip method...

 

this isn't my car, im doin this for a friend, so this "paperclip" thingy-ma-bob ya... i dunno what ur talkin about

 

You can blow a chunk of money at autozone/pep boys, etc and get a 'scanner' that will do the paperclip job for ya.

If you prefer to use a paperclip, I think there is a tech post on thirdgen.org...or you can probably do a search here.

It sound like ignition to me too. What type of wires did you guys put on there? Have you checked the coil/cap/rotor for problems?

 

MSD 8mm. we check the rotor and cap and what not... just old... so we replaced them with just the stock replacements

 

Recheck your spark plug wire order. Make sure you have the correct firing order. Also, don't run the #5 and #7 in line with eachother from the cap to the cylinders. They should cross at the cap and run away from eachother to each cyl. Chevy 350 engines are known for this problem. The wires induce a spark into the other cyl. I think #5 is first and can induce a spark into the #7 when #5 sparks. This will misfire #7. It's been a problem ever since this engine has been around. I've also heard a lack of backpressure can cause a low power concern. I've had two vehicles that lost the exhaust after the cat. and they both lost power. I still haven't had a satisfactory answer to this. If all else fails, reinstall the original exhaust and see if the power comes back. If it does then the exhaust he bought is mismatched for his set-up. Or try putting it back in pieces, I would start with the converter and go back. Hope this helps.

 

You sure it isn't a vacuum leak because you broke or disloged a hose?