if i let my 98 z24 sit parked for a couple hours i have a problem, when i start it, it runs fine, but if you immediately give it gas, then it starts to spudder and almost dies, but if you let it jerk and miss for bout 20 sec. then it clears up and wont do it anymore, until you let it sit parked for a couple more hours. any ideas what this might be, i already replaced the plugs, and the coil pack housing. oh and if i start the car and just let it idle for bout 3-4 min without givin it gas, it wont do it at all. help! this is bothersome!

sounds fuel related possibly? change fuel filter? maybe an injector issue. if your letting it sit for a few minutes that would mean that it works itself back to normal in that time, so it would have to be related to warmth and running of the engine. i dont have a Z but could be an idle control problem. ill let someone smarter chime in, just throwing out a few ideas.

i dont know what it could be, it isnt heat related cause if it sits long enough to do it, sometimes its still not cooled down, so it still does it while its warm.

any ideas?

mine does something similar, but its mainly after a few starts throughout the day, usually when the car is warm.
i let it sit for about 30 seconds and its usually fine,
i was working on replacing my idle control valve but never got that far. lol

its a mystery to me why it smooths out. but im gonna take it to a shop this afternoon and let them fiddle with it. hopefully its nothin major.

well i got it back from the shop, said the car was perfect up and down, no sensors or anything bad but he told me that it might be a faulty TPS startin to go bad. so i went home and replaced it.....nothin, still got the same problems, i think im gonna change the fuel filter, maybe that will help out, any ideas?

o2 sensor, changed mine along with fuel pressure regulator, plugs, wires, fuel filter. smooth sailing now.


This life goes passin you by
It might go fast if you like
You born, you lived, and you die, oh oh ohoh
If life goes passin you by
Don't cry
If you're breaking the rules, making your moves, paying your dues
Chasing the cool
-Lupe Fiasco

i have heard of people changing there o2 sensor and it smoothing out but most were on 2.2.l i got the ld9. but im droping it off at my school and letting the automotive technology teacher work on it, hes really good so maybe he can help me out.

Answer me this: Does your car use coolant? Do you have to occasionally add to the coolant bottle?

If so, you have a head gasket problem. You are precisely describing a slight leak into a cylinder. It sputters/runs rough for a few seconds while the coolant burns off and then smooths out. It is common on these cars.

Mike

My 99 Z24 ran perfect - but decided to make it even better by adding pacesetter header and exhaust. Now it would trip O2 codes. Change the rear o2 sensor and still tipped o2 code. Changed the front sensor and have put on 2500k with no more CEL. BUT now after starting it cold, it runs fine for 30 -40 seconds, then starts sputtering for about the next 10 seconds. After that it runs like a top. (the last thing I changed was the front o2 - thinking of changing it again.)

michael- no it does not use coolant at all, i will go get a compression test done just to be sure, and bob i am havin the same problem but i havent changed any o2 sensors as i am trowing no CEL. im really thinking about selling my z and goin back to my ln2 sunfire, it was slower than anything out there but it was alot more reliable.

Now I'm going to convert my old rear heated o2 sensor into a heated front sensor. I've read this change could solve all my problems. (since the heated sensor that I took out was't the problem - it will cost me nothing to try.) Should get it done this weekend and will post my results.

If it is a coolant leak, you might not see much variation in a regular compression test. It would show up better in a leakdown test. Also, there is a test you can do on the coolant that can tell if combustion gases are contaminating the coolant. That test would be your best bet.

When I had the leak, it used coolant very slowly. It sometimes took months for the "Low Coolant" light to come on. If you have never had to add fluid, then it is probably something else. EGR or maybe O2 sensor.

Mike

would the egr throw a cel code?


98z24, lowered 2", aem intake, cat-back striaght pipes!, cop ligths in the front and rear, 18" liquid metal's, primer black, tint, full audio and video.

There wasn't an egr on my 99 z24. When I took off the cast iron exhaust manifold, the bypass for the egr was not there. When I put on the headers I had to fab a plate to close off the port on the front of the engine. (It was either that or take the headers off again and weld the egr bypass shut, which I should have done, if I had known about it at the time.) EGR's can throw a code in the p04xx range.

thank you



98z24, lowered 2", aem intake, cat-back striaght pipes!, cop ligths in the front and rear, 18" liquid metal's, primer black, tint, full audio and video.

if i had a bad o2 sensor or a bad egr would it not throw a code? and also i hear bosch o2's are horrible, i havent checked but maybe the previous owner put one of those in there.

any info?