Well Just Started Happening. Car When It Fires Up Sounds Like It Is Missing Becuase It Is Rough And Car Shakes Like Hell. But It Is Funny If You Peg It At Idle It Clears Out And Will Idle Okay For Awhile Then It Goes Back To Doing It Again. Also When You Peg It After You Fire It Up The Thing Smokes And You Can Smell Raw Fuel Out The Back Exhaust. Also It On Highway Like Tonight And Peg It It Hesitates A Little Off An On.

Recent Upgrades Are Msd Cap And Rotors, Msd 8.5mm Wires. Gm Acdelco Platinum Plugs, New Stator, New Alternator. New Msd Blaster Coil. New K&n Filters, New Egr Valve, New Egr Vacume Module, Had Top Of Plenum Out And Fully Cleaned It. Throttle Body Bypass, Timing Just Checked It And Is At 8 Degree's Advance, Does Have Hypertech Stage 2 Chip.

I Ve Had 4 Fbody's And This Thing Just Stumps Me, The Hesitation Or Missing Or Rough Idle Just Started Out Of The Blue.

I Can Think Maybe Leaking Intake Or Plug Wire Loose, Or Timing Too Far Advanced I Dont Know Help!!!

 

I've had this caused by the following:
1) distr. cap cracked or had condensation
2) TPS loose or bad connection
3) plug wires arching
4) my computer went into some loop mode and had to replace it.

Good luck. It could be any of the things you recently installed. Tell us more about if you replaced that stuff because it was acting up or did it start after you did the stuff.

 

my car did this to me, turned out to be a misseated computer chip (wasnt cliped down on one side) also check the MAF when they start to go they can make the car run really rich and idle poorly thus the smelly exhaust and poor idle. ANother thing that commonly causes that is a IAC or idle air control, the little thing in the throttle body that adjusts according to the throttle position, if you cleaned the plenum it may have gotten gunked up or clogged, so check that as well. One other thing that can cause this is possibly a bad spark plug wire or crossed wire, i made that mistake once..very frustrating. get back to me if none of those things solve your problem or symptoms become more obvious. problems are very common like this so dont fret just be patient and double check all your equipment!

 

also you can bump your timing to about 10* adv. if you want, with the stage 2 chip it may help a bit as the chips tend to be conservitivley tuned anyway. i run my stock chiped car at 10*, works very well, starts easier, and pulls a bit harder.

 

Yea I Cannot Advnace It Anymore The Is An Automatic Knock Retard On The 91-92 And This Is As Far As I Can Get It Until Computer Starts To Be Retarted And Retard Timing Back By It Self .

It Is Not A Miss Plugged In Wire Becuase It Was Fine When I Did The Massive Tune Up, Also The Tps Sensor Is Brand New, The Iac Is On The Bottom Of The Throttle Body Right? And That Is By-passed, Throttle Body Bypass Coolant.

I Am Going To See What A Gm Scanner Says This Week Just Getting Frustrated

 

possibly a stuck open/leaking injector

 

I think the '91 used a speed density. Is it in the same place as the MAF? My Fiero had a problem at idle and to see if it was the MAF the guy unhooked it with the car running and then it ran better. He said because it ran better dissconnected it was the problem. Not sure if I was scammed or not but it did fix it.

 

Yea It Is Speed Desnitiy, No Maf To Unplug That You Talk Of

 

Something like that was happening to my 91 camaro and it ended up being the fuel pump. The filter on it was ripped to shreds and it wasn't picking up enough fuel when it was just sitting in one place but once it was moving and you punched it then it would run fine for awhile.

 

Have you checked the EGR or the lines going to it?

 

oh sorry bud forgot it was speed density - when i first got my car they problem got progressivley worse, which lead me to believe it was the fuel pump, yet pressure was good at all rpm's with a gauge hooked up to the rail. Turns out the injectors actually started clogging up and failing, half the engine ran excessivley lean and half ran too rich...and flushing them wont work so i went with the LT1 injectors which will run a little rich without tuning but use a pintle style tip if i remember correctly.

 

I Am Thinking Leaking Injectors It Starts Fine After Just Been Running But In Mornings If Fire It Up You Smell That Raw Fuel And Blue Smoke And Rough Idle. Also I Hold It Wot When Starting And That Shuts The Fuel Off So That Means For Some Reason There Is Already Fuel In The Cylinders. I Have Run 3 To 4 Cans Of Injector Cleaner Through It But No Better. Also When I Come To A Stop At A Light After Driving It Has Never Stalled Yet But At 500 Rpm The Car Just Starts To Shake And Hesitate, If Hold Brake And Gas And Rasie The Throttle The Car Stops Shaking! Also The Egr Is New So Are The Lines And The Vacum Module Too.

 

Have you check all of the psark plugs again... new or not you can still have a bad one. I've gotten bad one from the parts store. Also stay with AC plugs.

 

well good and bad news, i almost gurantee it to be the injectors. WHEN mine started going it started really rich and smoked excessivley, when i came to a stop while it was hot it almost seemed to stall, but never would. IT just sat there and shook at about 450rpm, but if i held the brakes and pushed the gas i could get it to idle. Also as far as i know those injectors can not be flushed or cleaned with much success. I tried to flush mine and the car died ( had it done professionaly) then later found out the multec injectors can not be flushed, this was after i ran cleaner through it which most likely busted the rubber gaskets. AFTer replacing the old ones with LT1 injectors the car runs much much stronger and smoother. starts right up revving to 1500rpms and idles down to 1k for warm up, torques the chassis on take off and burns the tires through the first two gears...its amazing how bad the injectors were failing, yet it still ran - some say gm cars run bad longer than most cars run at all.

 

Dude That Is Exactly What The Car Is Doing If It Comes To Idle After Being Hot And Been Driving It Rattles And Shakes Like Crap, Will Clear Out If Hold Gas And Brake At Same Time But I Hate Myself Becusae I Just Sold My Lt1 Injectors On Ebay, Out Of My 96 Ws6 With 30,000 Miles. Honestly A Month Ago. Yea My Plug Wires Were Checked Saturday On A Left At My Buddies Work And Are Fine, And The Plugs Are Ac Delco