any advice with my L03? car was running great and all of the sudden i got a bucking jerking. a few minutes later the RPM was jumping up and down, really bad(1000 RPM or more) car backfired twice and died. i put my hazard on and pulled off to the side of the road. i waited a few seconds and started it back up. ran like crap for a few seconds, i gave it some gas and it smoothed out. it ran great the rest of the 70 mile trip. this car does this infrequently and its interment. i makes it very hard to figure out what it is. im thinking EGR, TPS, or something allong those lines. most of the time this car runs like a dream its only on rare occasions that is does this. i had a problem with my MAP sensor earily this spring. i swapped on out with my s10 blazer and havent had any more trouble with that. but i still have a problem that exists. how do i diagnose something that i dont have any codes and it is infrequent? im taking this car on a 800 mile round trip next weekend and i need to make sure she's good to go.
P.S. i have driven this car 4,500 miles since i bought it in may and its a strong L03 but i need to fix this annoyance.

 

i tested the EGR valve(hand vaccum pump). it holds vaccum when engine off. valve does move like its supposed to. i also put vaccum on it while it was running and i heard a RPM drop. vaccum does not hold when engine is running but it does seem to provide RPM drop. i ran the engine at operating temperature, put my finger over the vaccum line and revved the engine. EGR vaccum selinod does provide vaccum but it doesnt seem that it is all that much. how much vaccum should it pull? how much does it take the open the valve? it does appear to be working however. the hand held vaccum pump is the only type of gauge that i own. does all of this seem normal? so far the EGR system appears to be functioning properly. what should i test next?

 

Id say check your fuel pump, because I had pretty much same thing happen to me except mine decided to die while making a left hand turn with oncoming traffic coming at me mine ran good for a few seconds when I unplugged the map, and then it would die(because it cant run without map) so I thought it was my map well it turned out to be a fuel pump

 

guy that i bought the car from said he replaced the fuel pump. i recently replaced the fuel tank and the strainer looked newer so id say that i would believe him.when i first bought this car it was doing this alot more often. the more i drove it the less run-abilty problems( but the problem still exists, now it is much less frequent) i have had so i dont think it would be the fuel pump. i have driven this car almost 5K miles since i bought it. a fuel pump going south would have failed already. i would also note that your car will run with the MAP disconnected, it just wont run as well as it should. when you unplug the MAP the computer runs from "limp home" values.