BizZzatch350

iTrader: (33)

Noticed its gotten worse, once the car gets warmed up it shakes prety bad at idle, like at a light or drive through, it wont ever die, gauges look fine, when I acelerate the car doesnt do any thing funny, it doesnt look like its idling low and the tach isnt bouncing around or any thing. Its prety much a bolt on LT1, runs fine also, any sugestion? cant seem to figure out why it idles so bad when its warmed up, the car doesnt miss or stumble when driving.

95FbFormula

iTrader: (25)

Mine does the same thing never found the problem begining to think no one knows or its just an LT1 thing.

onebadblackz

iTrader: (1)

my mechanic said it was a LT1 thing

94 Formula

Have you connected to a scanner to see that everything is working properly?
Checked to see your AFR at idle?

nodnarb481

iTrader: (3)

how bad is bad? my car will shake and rumble at idle but its nothing unbearable.. i hooked up a scanner and what not and all is well

krayzie7th

check your egr it might be stuck open.You might want to hook it up to a scan tool.

bmccrary

Its an LT1 thing, but according to the smart *** at AAMCO says I have a cylinder missing.

-bryan

BizZzatch350

iTrader: (33)

It got worse after Long Tubes, my Blazer also has a slight shake at idle as did my 93 when it was all stock, but nothing really noticable, this thing shakes prety good, way worse than it ever did stock.

95 Formula

iTrader: (2)

its that huge cam you got in there..mine shakes too.

FAD2BLK93

The shaking is caused by the computer ajusting the idle mixture when the 02's are in closed loop. The computer is constantly making ajustments from lean to rich to keep the fuel mixture at a constant. I refer to it as the 02's are bouncing in closed loop. In open loop the computer is at a constant fuel trim.

dhdenney

iTrader: (53)

He mentioned having long tubes. Do you think it could possibly alter the O2 readings enough to make it idle a little rough?

BizZzatch350

iTrader: (33)

I'm running the stock non heated O2s also the car has TR6s in it.

Tim,
Ha! I wish it was cam that caused the shaking lol

carzman5678

A shake? Couldnt that be a motor mount? Start simple and then work onto other things.

BizZzatch350

iTrader: (33)

Doesnt seem to do it all the time, checked the mounts when I did LTs, they were fine

Pretyflywiteguy

my car vibrates like crazy at idle when its in gear, but its 3.4L

FAD2BLK93

Do you have heated 02's? Are the headders coated? Is it running smoothly in open loop? if you are not having drivability issues I wouldn't worry about it

BizZzatch350

iTrader: (33)

No single wire non heated, the headers are coated its smooth most of the time.

taner

iTrader: (6)

IAC motor, clean it first if you haven't .

g'luck.

nodnarb481

iTrader: (3)

speaking of closed loop.. i think we should do away with this supposed closed loop.. seems like thats where all the problems are.. i wish i could run in open loop all the time because the car runs GREAT.. im sure theres a reason there is closed and open loop tho i just never looked into it

carzman5678

My car ran fine in closed loop. When the car goes into Open loop it reads from the O2 sensors, which optimizes the air and fuel for emissions and MPG.