before you say it, YES i have searched.

im not sure if this is the same hesitation other people have experienced.


my problem came on very quickly.


3 days ago i noticed a very very slight random "bucking" or hesitation while cruising between 1600-2000 rpm.

2 days ago the hesitation was slightly more frequent, and noticable in the lower gears also, instead of just cruising.

today im afraid to drive the car it is hesitating so bad..........its now doing it many times, atleast every minute, but still seems very random, and happens more during cruising than acceleration.


i replaced the MAP sensor this morning, but that didnt change anything. the seal around it was fine also.

engine was running perfectly up until 3 days ago. it had a new opti and water pump at 63k, and new plugs at 70k (well 7 new plugs, i couldnt reach the last passenger side plug). it now has 80k.

is this possibly the o2 sensors going bad? would it happen that quickly?

i also purchased a new fuel filter, just in case i should change that also.

 

just an idea.......do you think that 8th plug i didnt change might be fouling things up?

i cant change it without dropping the y-pipe, which is a pita.

 

not to abuse the TTT, but i really need to figure this out tonite, cause i have time to work on it all day tomorrow.

 

Fuel Filter... change it. If it is a fuel problem, check fuel pressure and run a cleaner to lightly clean your injectors.

Check before replacing... Do you have a scanner? Can you read the live data?

Are you getting 13-14.5 volts from the battery during idle?

Is the TPS and IAC operating properly.

 

voltage always reads about 15 when running.


no scanner, and no one close by i could take it to without chargin me an arm and a leg.


ill probably change the fuel filter just for the hell of it...........im wondering if i shoudl go ahead and change the o2's also.



btw.....i found an install guide with pics for the fuel filter, but it was for the LS1......im assuming everything is pretty similar, but is the schrader valve in the same spot? (im at work now, cant look at car)

 

Hey Wild1, why did you ask about the voltage? I am curious cause I am having the same problem he described.......

 

well i bought some new o2's on the way home from work today. unfortunatly all they had was bosch crap.........so ill put those in for a few days until the ac delcos arrive, then swap them. thank god dicount auto is so lax on their return policy.


tomorrow i will change the o2's and fuel filter, then post an update.

hopefully that will fix everything. if not im gonna be pissed!

 

It really sucks to remove and replace components. It can get very expensive. But if it is old, then it probably needs to be done anyways. Too bad you can't scan for current data.

You'll probably get results from the fuel filter. I'd change the O2s after the fuel filter if needed. The filter is located on the rear rail behind the driver under the car. It's pretty easy. Hold it away from you because fuel is going to spill... protect your eyes and have a drip pan to catch the fuel.

A good idea is to de-pressurize the fuel rail. Push the shraeder valve down and fuel will spray out... cover with a rag and protect your eyes... then remove the filter.

 

About voltage levels, if it is low the ECU may not get correct readings from the sensor or interpret them correctly. Low voltage levels can cause driveability problems... particularly engine performance.

 

ill do the fuel filter first, then drive it for a little.




i just found a pic of where the schrader valve is.........there is no friggin way to reach that thing to properly relieve fuel pressure and catch the extra fuel. I HATE GM ENGINEERS!


can i just unscrew the fuel filter and let it spray.

 

i changed my filter w/o releasing the pressure, i did not spray at all, only dripped a puddle of about maybe a cup or less of gas, like nothing at all, honestly its not a problem....btw i also have trex out of tank fuel pump so that might affect pressure in some way...but doubt it

 

Yep, just unscrew it slowly to let the pressure drip. Wear glasses or stand back. It only sprays for a moment.

 

well, just got done changing the fuel filter.........didnt have any effect.



waiting for the engine to cool down so i can change the o2's.........the driver side looks so easy, but the passnger side looks like a nightmare, the y-pipe is in the way.............any easy way to change it?

 

I wish you had access to a scanner. It could help. But you're doing the best you can. If the filter hasn't been changed then it was a good idea anyways.

For O2 sensors, there is a special 13/16 socket with a notch cut into the side so you don't crunch the wires. If you don't have one, you can get an O2 socket for about 4-5 bucks. Best way to get to the passenger side is by under the car... depends on the type of headers. I've got the Edelbrocks, best from under the car.

Good luck.

 

stock manifolds and ypipe............i can touch the o2 with my hand from the bottom, but im possible to get a wrench to it.

bah.........i just found out there is a place about 20 mins away that will scan codes for free. oh well, car is already on ramps and one o2 is changed.

i cant find a decent way to get the second o2