haromaster87

Okay,

My car's been runnin kinda goofy since I bypassed my smog pump. It siezed so I just ran a shorter belt and looped it to bypass the smog pump. Anyway, the first weird thing was when we put the new belt on, and started the car for the first time, then dropped the hood. I have to drop my hood from about 10 in for it to latch and as soon as it landed, the car revved to about 2k, and sat there for a few sec, then came back to idle. It was idling up and down but it's always done that so I didn't think much of it. Me and my friend were puzzled, but I just wanted to get home. So headin home I hit some rail road tracks doin about 35-40 and the initial bounce made the car try to revv again, but instead it just kinda lightly bucked and smoothed out. I didn't think much of it as it only happened when I hit fairly hard bumps. So today drivin to school it was actin so strange. It would kinda hesitated, and buck around and stuff. I'de be goin along around 1700-2500 rpms and it'd start buckin really hard tryin to change rpms. Then sittin in traffic I had the clutch in and all the sudden, sittin still, it revved to 2k for about 6 sec all on it's own. I checked to see if the gas was sticking, but nothing. I searched and found some info on the TPS which I suspected and I read on here that you can unscrew the tps and tighten it back down to do it. I did that and idle seemed to smooth a bit and it seemed to rev okay in the garage. I haven't driven it yet so idk but what else can cause this? Btw, it's an '86 5.0 5spd.

Thanks,
Tony

5.0kid

check your IAC idle air control its on the tb. take that off and then clean it out with some break clean if its all carboned up go to murrays and get a new one. i had a surging problem with my can and getting a new IAC cleaned it up a lot the only making it surge now is my cam

haromaster87

^^^I forgot to add I have a brand new IAC on there. It doesn't seem to work though. I think it not workin is somethin on the motor and not the IAC itself. The IAC never kicks in to keep idle when I try to use a/c or somethin. The car just stalls.

haromaster87

Aight, well, I went out there, took the IAC off, cleaned it anyway, and did some other stuff. Car starts up fairly smooth. Then as it's just sittin there idling I would hear this random quick scraping noise(seemed to come from the front passenger side of the engine bay) and then the engine would revv up to 2k and kinda slowly settle back down. It did this about 4 times all of which involved the scraping noise and then revving. Idk if it'll still buck(I can only assume it prolly will) but I know the motor shouldn't revv itself. I wonder if my TPS is goin bad? That still doesn't explain why the engine made a scraping noise before revving though. I also went to the back and it seemed to be a fair bit rich.

mattdel

hmmm.

as far as the revving goes, it could be the TPS or the IAC. i'm gonna lean towards TPS given the sputter/bucking issues.
my car revs to 3k when i start and bounces from 700-1350 during idle, with a bad IAC.

the scraping you're hearing is probably the air pump clutch getting ready to seize up on you. get yourself a long long screwdriver or 3' extension bar for a ratchet. stick one end on the air pump, as close to the pulley as possible without interrupting the belt, put your ear to the other end of the bar, and have someone snap the throttle.
the quick RPM jump should cause the clutch to make a squeal noise and you'll hear it through the bar.

LT61

Yea, I have pretty much the same problem except mine rarely corrects itself to idle, i either have to shut the car off, or I have to let out the cluth when im going real slow to the point where it almost wants to bog out and then sometimes it corrects itself. From what i've noticed there is no reason for this to happen, at least it when you hit a bump, I can be sitting at a light and all of a sudden im now idleing at 2500 rpm. Any help would be greatly appreciated. Btw, i got an 87 5.0 5 spd

haromaster87

Thanks for the reply. That makes sense, cept my air pump is bypassed. It all together siezed so it's still there, but it has no belt around it. All the other accesorries are there though. Like I said, it never did this before I bypassed the smog pump. I'ma hit up Autozone and have em pull codes and see if anything comes up. Still though if anyone else has an idea of what it could be please do chime in.

P Zero

Dont think its that Matt

-P.

haromaster87

Gotta love helpful post like this... lol jk jk but seriously you have any idea what the scraping noise could be or why it causes the car to rev?

ford82

if i was you i would eliminate all of that smog crap, from the pump to the tubes, unbolt the tubes out of the back of the cylinder heads and get you a, i think its a 1/2 bolt, not sure the thread, and bolt it in place where the hole is from the tube.and theres half your problem gone and plsu you get a little more room under the hood.