Engine keeps on hesitating

[wzntha]

I just had an sr20det put in my car at a local shop and the first time i got it back the car kept hesitating and would bog sometimes between 2k-3k rpm. so i brought the car back and the shop said that they replaced the O2 sensor and rewired the car. the hesitation went away for about 5 days and now its back again. i went for a drive earlier and it started hesitating between 2k-3k again. there isn't much hesitation in 1st and 2nd, but once i go into 3rd, 4th, or 5th, the hesitation occurs. most of the time, the engine revs up to about 2,300 rpm and i would hear the boost building up(well, i think it is...it sounds like air flowing) as i step on the gas, but the engine seems like its struggling to rev any higher and would stay around the same rpm. also, every now and then, my exhaust would make this popping noise(i think its backfiring?). if anyone can help me on this, it would be greatly appreciated. i just drove to school this week and i don't know if my car is in a drivable condition to get back home(about a 45 mile drive).

[driftingmy240sx]

sounds like the car is flooding or may have a weak spark. make sure you have a good set of plugs in the car and check to see if they are fuel fouled.

[wzntha]

i checked my car this morning and i found out that one of the bolts that holds the coilpacks down was missing. i called up the mechanic that worked on my car and he said that's probably the problem, so he's gonna get me another bolt. since i've been driving like this for a few days, would the the spark plugs be fouled by now?

[OldmanPurdy]

Pull it out and check it, if it fouled change it, won't cost you any more than a few bucks and 5-10 miniutes of your time and you will know for sure that it is good.

[wzntha]

k, i'll go do that. thanks for all the advice guys.

[wzntha]

i went to go check the spark plugs today and as i pulled the coilpack out, i noticed that the mechanic broke the bolt and left it there!! do you guys think it'll be safe to drive about 45 miles back home like this? the car runs ok, but every now and then, it would still bog and backfire from the exhaust. i need to get home to take this screw out because i don't have any tools with me now.

also, my dad was wondering if this bolt acted as a ground for the coilpack, but he isn't sure since he's not familiar with distributorless engines and im not sure because im a noob at this stuff=X. if it is, will this effect how the engine runs? im probably going to replace all the spark plugs and coilpacks if the engine keeps running like this, but i just wanted to make sure that it might be a cause to this problem before i start replacing things (also, the tops of the coilpacks are a very light shade of yellow and i heard that if they turn yellow, it means that they need to be replaced. is this true?)

[wzntha]

Also, when the car is idling, is it normal for it to idle between 700-900 rpm? if i let the car sit there, it would idle at 700 rpm, then after a few seconds it would move up to 900 rpm, then back down to 700, and it would keep alternating like this. is it suppose to do this or is it suppose to stay at a constant rpm? thanks in advance.

[driftingmy240sx]

the coil packs will operate normally with missing bolts. you have have incoorect ignition timing causing that problem while driving. also sounds like you have another problem with the irratic idle.

[wzntha]

actually, i replaced the bolt for the coilpack and the hesitation went away, lol. every now and then it would still do it, but it pretty much runs fine most of the time. the weird idle still happens though...i have no clue what's causing that.