Ive been reading everyones post for a few weeks now and have finally registered. you guys have taught me so much about the bonneville. im ready to start doing some performance mods to it.

Heres some background:
The car has 2200000 miles on it and is running great. EVERYthing works 100% on it still thanks to good driving and alot of TLC. its always had a rough idle but nothing to be concerned about, i figure it to be old age. So i finally convince my dad that the car needs new struts cuz when ever i pull my trailer and have about 2 tons of load in it my tail bottoms out and the car bounces alot. i also at the same time asked to put a magna flow on it just for some nice sound.

Heres what happened:
I shopped around and got a great deal for four heavy duty lifetime warranty stuts and a magna flow also wiht a lifetime warranty. out the door it was 695. so he changed out the struts, he (the manager) showed me the old ones and you could push them down all the way, and it would take about 15 seconds for them to spring back. so they were definaly shot. that was all said and done, everything was good with the suspension. now came the muffler. a fiunny side note is that the pipe bender broke with my pipe in it so it took them an extra hour just to get it out. anyways they welded the muffler in. next he started the engine and noticed that the engine was running VERY rough, and at times begning to stall. he offered to do a free fuel injection cleaning. this next step i shat a brick. he ran it at WOT with the cleaner going into a vacume hose and the cat got red hot. he said that happened because the cat was clogged, but that doesnt make sense becuase i passed smog the previous afternoon with flying colors and the cat was only two years old. once he was done with that, he released the car back to me abd i drove the car home. right when i put it in drive it almost stalled. i floored it and the car hardly moved at ALL. i was very pissed. i drove it at city speeds and when i wanted to accelerate the car miss fired on what seemed like every cylinder, thje car and engine shaking violently. now i was very very pissed. i took it back there (Midas) and drove right to the office skidding my way in. i walked up to hte manager and siad "i am very angry right now" he opened the shop back up and siad that there was too much back pressure and he for free changed the cat with a high flow one. he did that and i took it for a spin around the parking lot. it felt exactly the same. i left it over night and called him this morninig. he said the compuiter wasnt spitting out any codes so he doesnt know whats wrong. i dont know if he fried my valves or cloged or fried my enjectors or what. he belives now that th knock sensor is bad.

what the hell am i going to do. now all i want is my bonny to be back the same way it was. this whole muffler thing was just so i could have a cool sound, not f@#ck up my engine :(

any word of advice, any comments, any diagnoses you may have will be much appreciated

thanks so much

Patrick

Can't be clogged valves because exhaust mods wont do anything but help out the movement of gases. The one thing I can think of is for you to put some injector cleaner through the engine and get an air filter. Sounds like air or fuel related problems. Also your cpu itself may be bad.

Welcome to the forum, glad you could join us. I agree with Buzz, I doubt that it is related to the exhaust work or muffler that was added. It cold be a fuel delivery problem. There are a lot of fuel lines under there near the back, make sure the integrity of those is OK, injector cleaning might do it.

Sit tight and some of the experts will get to it and maybe give you a clearer idea of what the problem is. Look on the bright side though, when the car is running top notch again, you'll have a high flow cat and Magnaflow muffler....two very good mods

ok i just got off the phone with the manager of midas and asked for a update on whats going on. he told me that he had the exact same thing happen to him with a LeSabre. Hes bringhing in the international brain child VP guy for the midas'* in this area. he claims he knows everything. Mike, the mananger claims that the problem existed before i came in, and the free flowing muffler installed onbly brought this problem out, myself and my fellow car guys think this is a load of crap. i think he messed up my fuel system with that fuel injector cleaner IV dealy he used. do you guys agree that a simple muffler change wouldnt do any of the symtoms i described? im still pissed and am bringing my freionds who know alot about cars to go confront the owner.

well.. humm.. if he said that this has already happened to another car.. it may actually stem from his shop. I believe you mentioned bout him welding.. what did he use to weld? Mig Welding? or oxy cedaline ( sp? ) .. if it'* the electric style MIG.. he may have shorted out your PCM cause he may not have disconnected the ground of the battery. If you had an exisitn problem and didn't degrade till now.. I don't know.. that'* always possible.. to that degree.. ouch. I don't know. If it was one of the sensor.. It should've thrown a code then

Yeah what drifter is saying has a pretty good chance of being the problem. I never thought of that!

Problem Solved! my dad and i searched through the shop manuel (the big three incher) and decided that the C3i (computer controled coil ignition) module was fried. when i picked up the car today, thats exactly what the guy had to change out in order for all six cylinders to fire. The car runs great now. All and all, i got a new ignition system, new high-flow cat, four heavy duty struts and magnaflow mufller. i only payed for the struts and muffler. everything else was at his cost since he failed to disconnect the battery when Mig welding the mufller on and frying the module cuz of the groud loop. Car sounds great now !

Good news!!

Glad to hear the car is running top notch again

You lucky little bastard.

Quick! Go out and buy a lottery ticket!

I like this kind of story. Such a happy ending. Welcome to the Forum!!