My car has been hesitating for awhile, which I fiqured out today is actually from the car backfiring in the header. I noticed that the car was ideling a little high (1100rpm), so with the car running, I unplugged the IAC and revved up the engine. The car ran exactly the same and the idle didn't change when I unplugged it. I plugged it back in, and it still ran the same as when it was unplugged. I'm thinking the valve in the IAC is stuck or siezed, wich would explain the backfire and the fact I'm burning plugs a little. The car at very least should have severe ideling issues when it's unplugged shouldn't it?
I have a 97 2.4, and I'm assuming the plug going to the round thing on the front of the throttlebody (facing the radiator) is the IAC. It's held on by 2 torx bit bolts, and is next to where all the vaccum lines go. I'm pretty sure the car shouldn't run the same with it unplugged, I just wan't to double check with you guys first since some of you know a more about LD9's than me at the moment. Thanx
this what ur talkin about man
if so this is ur tps not iac
If its your Iac that we are actually talking about then, it wont change if it is unplugged. It is not a springy plunger that when is unplugged will release the plunger. It doesnt work like that. Its actually a type of geared stepper motor that when unplugged will assume the last command and stay there. It is possible that it is bad though. if it doesnt change position would be a good sign of being bad. Take it off, push the pintle in firmly until it begins to move, you can push it all the way in but dont pull out on it. choose a desired length and measure it. Reinstall it. start the car let it run for a few min. turn it off, remove the Iac again, remeasure its position to see if it has moved.
01 cav w/01 3400 gam gt 4t45e
Hey joe, thats actually a good idea thanx. I was ondering if it was a stepper motor, or valve or what not. I'll try that.
Hey gary, I know what my tps and map sensor look like, and I figured the sensor/valve in question had to be the iac by ruling out the others, and by just plain looking at it. I actually lauphed qwhen I saw the picrue of the tps. Btw, it's definatly the one in the second picture. I was pretty sure, I just wanted to make damn sure since this is my first obd2 car and I'm used to having a lot less electronics. Thax for the info, I quess I just sounded a little more cleuless than I really am when I typed the post, where did you find those nifty pictures anyway?
After I take care of a few things, I'll go out and thry the mesuring thing, and see what happens, I just hope iac's arn't too expensive if its bad.
Thanx guys.
Well, I did the thing your talking about with the IAC, and it didn't move at all. The plunger was covered in black oily soot, but the throttlebody was clean inside, I don't understand how that works but oh well.
I replaced it and the car just went ape @!#$. The hesitation would get better, than worse, and back again. Plus the car couldn't seem to decide where it wanted to idle. I came home and I have the battery completely disconnected right now. I'm going to let it sit for awhile and see what happens. I sure hope that either the problem goes away or I at least fiqure it out soon because a dang IAC cost me freaking $86, and although it WAS bad, It would sure be nice if it where causing the problem I'm trying to fix. It seems like the easier it is to take off the car, the more expensive it is. If the problem is still there, the next step is a $30 TPS, and if thats not it, I don't have a freaking clue anymore. If I take it to a shop, they'll just blame the mods to the car, and I know they arn't the problem.
I dont know about your year but on most , you have to relearn the idle , some require a specific procedure like to block the front wheels, but in drive run for so long, then turn it off and repeat.and others just to run it under normal driving conditions for 1 or two drive cycles. a drive cycle is usually the time it takes it to get to closed loop fuel. the second cycle sometimes takes longer though.
If I were you I would try driving it around and see if you can get it to reset. That is if you can drive it with the running problems that you have.
describe the hesitation that you have. It it while under a load, just ideling......
01 cav w/01 3400 gam gt 4t45e
I've got a manual, so blocking the tires wont work
The hesitation is under load, it idels a little high but OK. If I snap the throttle over half way to rev it up in nuetral, it hesitates and backfires a few times until it's over 2 grand. Driving the car it does the same thing but throught the powerband getting better the higher the revs are. When I let off the gas and coast to slow down, the car pops and backfires a little, but I have a really open exaust and you can hear everything. (why I'm thinking of replacing the muffler in the other post.)
Thanx, I'm not sure whats causing it yet. The battery has been disconnected for over 20 houres now, I'll just have to see what the car does later. I replaced the plugs a month ago, and the problem almost went away completely, then the car blew an injector seal, ad it's been doing it again ever since, even after I replaced the seals and the injectors arn't leaking anymore..
God this is getting old
I hooked the battery back up after being diconnected for 24 hours, and the Idle has adjusted itself but the problem is still there. I get paid on friday, but am really low on money until then.
A few people have mentioned that TPS could be going bad, do you really think the tps could be causing this? I'm definatly replacing the plugs again next time I do anything to the car.
I'm also hearing a high pitch rattle I never noticed before coming from god knows where unter the hood. I sounds almost like the timing chain, but if I jumped a tooth, you wouldn't think the car would run fine at 1/4 throttle but not at 1/2 throttle or over. The sound seems to be coming from around the same location as the idler pully, god I hope it's not the chain. I don't have the $$ to fix that right now, I'm planning on having it replaced along with the water pump sometime this year when I have my cams put in, but not now.
You guys think I should just replace the TPS and put a new set of plugs in it for now?
Have you ever changed the plastic coil housing? When it goes bad it causes lots of weird stuff like poping, missing and backfires. If you replaced it and bought the cheap one it could be bad also. I have put the cheap ones on , only to last 2 weeks then take a crap. This is a very common problem, If I had one in my cav, I'd have some tools and a spare in the trunk.
01 cav w/01 3400 gam gt 4t45e
The coil housing actually cracked on it a year or 2 ago. It almost complelely droppe cylinder #1. I had to drive an hour home on the freeway with only 3 cylinders. I took it to a shop because I didn't know what was wrong and they put a new one on, so I't probably not the problem. I know for sure the TPS isn't the problem now because I changed it, and put a new set of Ac Delco's in it. The problem just keeps getting worse.
I'm taking it to a shop in the morning thats pretty good at fiquring these things out, plus they know my dad and so far are taking my word that the car has ran fine with the exaust thats been on it for over a year. We're thinking maybee one of the spark plug boots are shorting out, or maybee a coil or the ICM is just getting old. There usually good at this stuff, so hopefully they can fiqure it out right away.
I've already replaced the fuel pressure regulator, all the injector seals (where leaking), the idle air control valve, the throttle posistioning sensor, and spark plugs.
Just so no one post on this thread again
The car is fixed.... it was the dang coil pack AGAIN! I't should have been the first thing I checked, but I fiqured it wouldn't be the problem since it was replaced recently. It will be the first thing I check for now on. Thanx for all your help guys. After replacing all those things that where going out (but not causing the problem), the car runs great now that the problem is actually fixed.
I'm gunna look into a MSD coil swap, I'm tired of the dang coil pack going out all the time.
