mikes98z

iTrader: (9)

Hey all,

I have a low idle issue with my 97 Trans Am and its starting to aggravate me. After about 15 minutes and the car warms up, it starts to misfire and hesitate at idle...if you give it some gas, it goes away and runs smooth. When its cold, it runs smooth.

I changed out the coolant temp. sensor mounted on the pump but that didnt help.

I need to change the plugs and wires in it (125K miles on them!), but if it were ignition, woudnt the hesitation be all the time and not just when it gets warm?

Could it be O2 sensors, they are original on the car as well.

Optispark was replaced about 17K miles ago as well as cap and rotor.

I am lost....................

contraststriker

iTrader: (14)

definitely sounds like O2 sensors, and if you're not sure just have autozone scan it for free--I'm sure you'll see the codes. The whole "warming up" thing indicates problems once she's in open loop.

mikes98z

iTrader: (9)

Thanks, I will head there on the way home and have them scan it. I think the LS1 cars have 4 if I am not mistaken......are there two or four on the LT cars...sorry, I just bought it and I am up in my office at work right now. Thanks again!

contraststriker

iTrader: (14)

you have a 96 so you have four O2's...2 pre- and 2 post-cat. The sensors before the cats are the only ones that would cause idle problems.

blkchevyz

yeah i agree, sounds like o2 sensors. and like he said, its the pre cat ones you should be worried about

mikes98z

iTrader: (9)

I looked it up and found that there is only one part number at the local autozone but have researched and that GM has two part numbers.......what the difference? I assume it has to do with the temperature of the exhaust???

Thanks for the help.

VanbibberLt1

hey if you figure this out let me know!! ive been having the same problems out of my 95 ta. ive done plugs,o2s and changed out the PCV valve and its still there. no ses light at all..

when its cool outside the car runs fine. warm weather the car starts up and idles funky and then goes away after about a minute

mikes98z

iTrader: (9)

I will post up my findings.....advanced auto guy tried to put the OBD II scanner on it and said my ecm was bad..his scanner couldnt pick up the computer....I am like huuhhh? local shop said they didnt know their a$$ from a hole in the wall.

I just met another wrenchhead that lives about 5 minutes from me and he has one...we are going to diagnose it...if its not the O2 the next step would be to check the EGR out. We shall see.

mike

WONCAMARO

iTrader: (6)

I've got the same prob with my car. So far I have replace the opti, cap and rotor, plug wires, plugs, injectors (used but with less miles), cleaned the iac, cleaned the map sensor, cleaned throttle body, and tried some other little tricks. I ran the car last night after the injector swap and coul not get it to start missing out like it usually did, but I will try a longer cruise today cause I am sure I am still going the wrong direction with it, but don't have a scanner for obd 1 (95 model t/a). My car does the same exact thing although. After some warm up time, it starts to miss at idle, sometimes like it wants to die and then it kind of chugs once I hit the gas until the rpms spin up just a bit to cruise speed.

WONCAMARO

iTrader: (6)

Injectors didn't help at all. My egr was deleted from the computer during the tuning process so I pulled the egr and built a block off plate. Figured the egr may be hanging open even though the syptoms I am accustomed to of a malfunctioning egr aren't what I am having. Yep, it didn't help. I am thinking o2 sensors for sure now. Gonna pull em to inspect and clean. For all I know, one of them could be melted. I've seen it before.

phirepower

iTrader: (2)

have you guys check your rockers, i had a similar a similar issue and i readjusted them... bingo

WONCAMARO

iTrader: (6)

I have roller rockers with poly locks. I readjusted them and even replaced two puch rods until I found out that the clicking was a header bolt that fell out. Still not the cause of my miss. Plus I would think that a misadjusted valve would cause a miss at higher rpms also rather than just at idle and low rpm takeoff.

WONCAMARO

iTrader: (6)

Pulled the o2s tonight. Soaked em in solvent and cleaned with carb cleaner. Will see if it helps. Broke from all the damn parts I've replaced so far so new o2s will have to wait.

95TXTA

As of yesterday I noticed the same issue. I haven't driven the car in 3 days and it's been raining like crazy and really humid so I went to start it up and once the rpms dropped and it heated up I got what feels like a miss to me. It comes in surges and the but the tach are not jumping around when it happens. Car never dies and when I gave it a drive around the block it ran smooth giving it gas.

I was begining to fear mositure got into the opti or somthing but I just replaced it a few months ago and I would think it would mess up not just at idle. There is no hesitation at start up either.

My car isn't tuned yet either since my rebuild so i'm sure that isn't helping.

LT1Falcon

iTrader: (3)

well it wouldnt hurt to change the o2's either way. i picked up about 1 mpg in my S10 when i changed them and they had about 117k miles on them

95TXTA

Bump...

Anyone have any luck with a fix yet?
Cleaning of O2's work?