ok guys so like i posted before i had a lot of hesitation and a backfire through the intake in low rpms...so i changed the plugs, and no place around here had the ngks so since i needed them bad i just bought the bosch platinum 4 prong plugs. anyway...it ran fine for about a day of not much driving, then it started doing the same thing again, hesitation and backfire through the intake, and it's getting worse. now the idle is pretty rough also. it "coughs" every couple seconds especially w/ the ac on. i ordered new plug wires, but the ones on there really don't seem bad at all. they're not brittle or anything. i guess it could be the coil pack too, but it runs pretty smooth in the upper rpms. the more load it has on it the rougher it runs. also, there's not cel, so i'm kinda confused about what exactly is causing this. it's pretty bad now, i can't even get the car moving fom a stop w/o burning the clutch in order to avoid backfire x( . i guess it could be the o2 sensor too, but i checked the wires from it and they looked fine, everything was connected, and there's no cel for it. i really need to get a datalogger. could it be a timing issue? i don't know how the timing would go off, but i would think that it'd be worse than this and that that would definitely cause a cel. this all happened very suddenly, it's not like it's been gradually getting worse for a while, so i'm stumped. lemme know what u guys think :) tia

bump!

check your map sensor. it should read 4.5v with the car ON but not running.

when i said it was my o2 sensor i was wrong. it ended up being my map sensor.

thanks...i'll check the map. were the same type of probs being caused by your bad map?

I had the same problem and it was my plug wires. I replaced them with NGK wires and all is fine. I too checked my plug wires and they looked fine, but that was definately the problem. What type of wires did you get that you had to order?

well w/o actually hearing the car run i dont know for sure, but you may have gotten bad gas somewhere. water in the gas will slowly but surely fill the fuel filter and force it all the way to the motor. i had the problem with a mustang gt, it started out skipping, poping and backfires when i mashed the throttle and steadily worked to the point that i could barely move the car. just pull the fuel filter (WITH A CATCH CAN UNDER IT) so you can see exactly what comes out of it. water will seperate from the gas and you will see it if its there.

i really hope it is the plug wires, cuz i need my car and it really isn't driveable as it is. i was going to order the magnecor wires online, but now i don't know if i want to get those or the msd's, ngk's, or accel's. which do all of u use? about the bad gas thing, that's exactly what i thought at first, because this started happening while i was away upstate(in the mountains). i had to use this no name gas from the one station in the whole town, and i ended up really having fun w/ m car on the mountain roads. i took some hour long trips, where i drove pretty hard a lot of the time. i noticed this all after that and figured that i fouled the plugs w/ the bad gas and the way i pushed the car. since then i've tried to minimize the backfiring by using 93 octanesince it's backfiring through the intake, i figured using a higher octane might help minimize it a bit. the thing is, if it was the gas, wouldn't the plugs be the only ignition aspect that is affected, and i've changed them. i'm gonna look at the fuel filter and inside the throttle body tomorrow. there might be some gunk in there, but since it wasn't a gradually thing, and was rather sudden, i can't see how it could be something like tb buildup or anything else like it. i have noticed that the throttle response has gotten slow too. it takes a couple moments for the throttle to repond after jabbing it, and you can tell that it's not the cable or anything. it just seems like i have a really heavy flywheel on or something. i dunno. thanks for the input fellas, and any more is appreciated. i need to get my baby back up and runnin'. :( tia

go with the msd plug wires. i believe 992gnt did a comperison between them, another aftermarket brand, and stock and the msd's blew them out of the water

if theres water in the gas, changing plugs wont help it. you need to take off the fuel filter and shake all the fuel out of it to see what comes out. if there is any sign of water then you need to get a new one. depending on the amount of water that was in the gas would determine how fast the motor reacts, and after you do this there will more then likely be more water to come in from the tank.

I had the exact same problem with my car. Shuddering at idle, and at low rpm, and intake backfiring.It almost seems like it's misfiring. I did a fuel purge, changed plugs, wires, and fuel filter. It was good for about 5 weeks, now it's acting up again. If anyone else has any other ideas, I'd be interested too.

I have been having that problem a bit latley too. My car idles fine but if i rev the engine or if i am cruising at a normal speed and downshift or if i have had my foot off the gas for a while and i hit the gas hard it backfires kinda sounds like its from the intake but i am not sure my plug wires and plugs are about a year old and i have no idea what the problem is but my car is too damn sexy to make noises like that! anyone know whats going on?

97 Eclipse GS
Aem CAI, Obx 2.5" Stainless Cat back, Tomm's coilovers, Blown stock struts :-) , Black housing projectors, Blitz Body kit, Dark blue metallic paint, Alpine cva-1005 head unit (6.5" indash monitor), Alpine type-R 6.5" component set, boston acoustics 5X7" in the rear, 2 alpine type-r 12"s Pheonix gold sub amp and eclipse 4 channel.

Hey, I had the same thing happen to me and I changed all of that stuff(plugs, wires,fuel filter, and had the induction cleaning treatment done) and it turned out to be the ignition coil. If you have any friends with the same cars swap the coils and see if that works. The car would idle fine, but anytime you would put a load on it(take off, stomping the gas even while sitting still) it would sound like it was about to die and hesitate real bad. Once it got about 3k rpm it drove fine. Hope this helps some/all of you. I got the coil from NAPA for around $60 bucks I think.