burnrubr88

iTrader: (2)

All of a sudden the other day when I left my car started to stumble, like it wasn't getting any gas or something was off. I would give it and and it would just stumble and drop in rpm's, not moving. It even died completely on me once. I had this problem before and then it just all of a sudden stopped a year ago.

So I replaced the front o2's with bosch 13111's yesterday and it seemed fine everytime I took it out. I thought that might have been the problem so I was relieved that it was running fine. Until tonight I left to go somewhere and low and behold it stumbles again, when giving it gas the rpm's drop and it wants to die, then finally gets gas and takes off. So the o2's weren't the problem after all since it is still doing this and no o2 sensor codes..

any ideas on what it might be? I have cleaned the MAF but that doesn't seem to help. Also I was planning on doing a cam install soon and then getting it tuned so when the tuner I go to does the tune would he be able to tell maybe what it is or not? I don't want to do the install and then my car still runs like sh*t.


sorry for the long post.

any suggestions are greatly appreciated.

Black FormulaLs1

iTrader: (10)

is the car throwing any codes? more than likeley it is a missfire code..check your plugs and wires...and again check your 02's...how many miles are on this car? if it will run at all and there is an autozone or advanced auto near by they have an OBD2 scanner and will check your codes for free...that should be of some help or atleast get you pointed in the right directioni!!

Black FormulaLs1

iTrader: (10)

also dirty injectors? or a clogged up fuel filter?

rd_ls1_z

Try unplugging the MAF. If the MAF is the problem, the car should run better since it will stay in open loop, using the MAP sensor instead of the O2's and MAF. Had this problem with a Grand Prix GTP, and cleaning the MAF didn't work, but unplugging was fine. If you don't notice a difference with the MAF unplugged, it's something else.
Also, it's possible that you might be having fuel injector problems. My Z28 would sputter and then start going, blowing black smoke and unburned fuel, but only if it was a cold start. Happened to be two clogged injectors on the passenger bank, which caused a lean condition on two cylinders and rich condition in the other two. Lastly, just an idea, the fuel filter could be clogged, not allowing enough fuel.

If you have any codes, post them up. Hopefully you'll get some soon, which willl make things easier.

RPM WS6

iTrader: (3)

Moving to General Maintenance section....

burnrubr88

iTrader: (2)

nope no codes after replacing the o2's. that was the only code (can't remember what code it was but it was an o2). and I work at a GM dealership detailing cars and one of the mechanics ran his Tech2 on it and there were no signs of other problems that it could see. the car has 88,000 miles

and as far as the fuel filter goes, that shouldn't be the problem I just replcaced it about 5,000 or so miles ago.

burnrubr88

iTrader: (2)

how hard is it to pull the injectors?

rd_ls1_z

I had to have the dealership pull them since I didn't have the tools to scan the engine properly, nor did I have my service manual, and they just cleaned them out. All I know is that it pissed me off that the mechanics burned over half a tank of fuel and 175 miles on the car to fix the problem....but that was two years ago. Did the mechanic look into any of the history?

burnrubr88

iTrader: (2)

Look into the history of what?

rd_ls1_z

The computer should save any errors until they clear themselves or someone clears them. When I was having misfire issues, the SES light didn't turn on, however, there was a saved pattern of misfires from previous events that where saved, but did not throw and SES light. Hopefully, there is some saved data that can be retreived using the Tech2 since you're at a dealership.

burnrubr88

iTrader: (2)

alright I will see if he can look into that

also is there any possibility this could be a small vacuum leak? would that cause problems like this?

rd_ls1_z

That's a possiblity too, didn't consider that one. Check you EGR system for any issues, like a bad seal or maybe an EGR value problem, but I would think that would throw a code (no EGR for me, so I'm not completely sure). Also, the PCV system may have a leak in it. Maybe check the coils for any problems there, and the spark plugs too, if you haven't already. Hope this helps a bit...

burnrubr88

iTrader: (2)

egr/air is deleted though I'll check the pcv system. could an old pcv valve cause it? I don't think it has ever been changed out.

rd_ls1_z

Possibly, if it's stuck open allowing more "air" into the intake or a loose/cracked hose, which would cause a lean condition in the cylinders, which may result in your misfire. Really, all you can do is go through each system, being fuel (injectors, lines, filter, pump), vacuum, and then ignition (plugs, wires, coils), to make sure all is functioning and not broken. It's hard to say exactly without a code, being there, or without a service manual....

burnrubr88

iTrader: (2)

ok I will check on all that stuff. thanx. but how would I check to see if the coils are bad?

burnrubr88

iTrader: (2)

does anyone have a pic of where the pcv valve is? i seemed to have forgotten

rd_ls1_z

I'm at work, so I don't have the service manual handy to tell you haw to check the coils. I'm not sure where the PCV is on '99's, I think that may have changed the system for the '01's.

burnrubr88

iTrader: (2)

found the pcv valve. but still need to know how to check if the coils are bad if anyone can help.

rd_ls1_z

If no one responds, I'll try to remember to look it up in the service manual tonight when I get home.

burnrubr88

iTrader: (2)

changed the pcv valve today. the damn thing looked like it was probably the original. but still don't notice a difference