Ok i'm sure many of you read i had a high end miss. Well i ended up unplugging my IAT sensor and putting a resistor in there it ran great for like two days and i had no misses. Well my car sat for two days because i was sick and didn't feel like going anywhere and i was just cruising around and my car started missing through the whole rpm range and it was just buckin whenever i gave it gas. Well i decided i'd pull that resistor out and just plug it back in. Sure enough the miss was gone until i hit 5000-6000. I know i can just get a new sensor but i want to make sure that's the problem first. I don't understand why it would work fine for a few days then mess up. I'm going to put a brand new resistor in tonight and try that out.

 

How much is a new sensor? If it is not too much i would just invest in a new one. Im confused as to why the resitor worked for a few days and then quit, maybe it was just a bad resistor or went bad quickly.

 

was there a big difference in the temperature in your area between the days it functioned well and the days it sucked?

 

Ok this is what i seem to have figured out. With the IAT plugged up i only have the miss from 5000-6000 no matter what tempature it is outside or anything. With the resistor (i think it tells the computer it's 57 degree's) well it ran fine at first i think it was because it was around 50. So i think your on to something (mourningyou) about the fluctuating tempature. I know it's above 70 today and it was missing when i was coming home.So it seems that the resistor will work well only if it's around 57 degree's.I think i'm just buy a new sensor because they are only 10 bucks.

 

Ok guys i'm just really confused and want to get this fixed. Today while coming home my car was just hesitating all over the place, in the high and low rpm's whenever i give it a little gas just enough to keep up my speed my car will hesitate for a second or two, it kind of like bucks the whole car and then it's fine again but whenever i give it a little gas it does that. I plugged the IAT plug back into the sensor and the same thing is still happening. I decided to buy a new sensor still no luck. One intresting thing is when i floor it won't hesitate at all except it's not pulling as strong as it should at 5k and up. So what should be my next move? I know it's related with the IAT Sensor or the Pcm because when i first put a resistor in the IAT plug my car ran perfect until about two days later. Any input would be great this is really starting to annoy me i thought i got the problem fixed but i guess not.

 

whens the last time you had a tune up? check the plug wire boots at the opti. i noticed mine had a similar problem (high rpm miss) and i noticed that when i switched optis that some of the wire boots wouldnt sit completely flush on the opti. the boots would slide up just the slightest bit. they looked like they were connected and would even click into place, but then would end up sliding back off just a bit. i'm sure this would be off just enough to cause a problem at higher rpms. i ended up having to trim the end of one boot a bit to get the wire to click on to the opti-plug (whatever it is). one of the wires i had to actually put a zip tie on to keep it from sliding back off. wouldnt hurt checking them out. mine would idle fine most times and would have a bad misfire at 5k+ rpms. just an idea.

btw- i think my trouble was coming from not putting the boot on far enough on the wires with the kit i put together and then using the grease that they recommend. but, its worth checking still at this point in the game.

 

I bought the car with 52k on it and it now has 57k. We bought the car from my dad's friend and he told us it just got a full tune up not to long ago. So i'm pretty sure the plugs/wires are fine. And now my car is hesitating through the whole rpm range so it's not just that high 5k to 6k hesitation. My car whenever i give it a little gas it may hesitate and studder a bit and then it's fine until i give it more gas. At wot my car runs great until it hits around 5k and i can feel it not pulling as strong.

 

might be opti time then...

 

I doubt it has anything to do with the IAT. Sounds like it could be about anything though. MIght hook up a fuel pressure gauge to see if you are getting good fuel pressure throughout the rpm range. If that is fine it will probably be some kind of ignition problem plugs, wires, coil, or the dreaded opti.

 

Ok i decided to try a 3.3 resistor because that would be closer to the outside tempature. And sure enough my car didnt hesitate at all until i reached 5k to 6k. I replaced the IAT sensor today but that didnt fix it so it's got to be something with my pcm i'm thinking. The 3.3 should tell the computer it's somewhere around 65-75 not sure but in that range and i think it's about 67 outside right now. I was running the 57 and my car would hesitate at lower rpm's and all through the rpm range so i know it's IAT or pcm related.

Edit- I forgot to add now since i added that resistor my ASR OFF light comes on when i start up the car? And it stays on for about 30 seconds and as soon as that light goes off my SES light comes on.

 

I dont think your IAT sensor has anything to do with a missfire. You say before you bought it a full tune up was done, well double check it. Look at the wires do they look like they have 57 thousand miles on them? And while you are looking at them check for a burnt wire.

 

Alright guys i think some of you aren't reading what i'm typing because everyone keeps saying it's plugs/wires or something else yet when i had the 5k to 6k stumble and i put a 4.7k resistor in there the STUMBLE WAS GONE for about 2 days. And then i think since the tempature changed my car started missing again, so i tried a 3.3k resistor to put it in a closer range of tempature for yesterday and my stumble almost completly went away i could barely feal it. I know you guys belive there's noway it could be something to do with the IAT but yet i have put a resistor in the plug of the IAT sensor and my hesitation would be gone? I'm not trying to sound harsh but your telling me that my car could be stumbling really bad and then i put a resistor in and the stumble be gone there's just noway if i had a problem with my plugs/wire or coil or something that it would go away at the same time i put a resistor in. I know i may sound a little mad but i'm just trying to get my point across because i know just about everyone on this board knows a whole lot more than me and i know you can help me out.

 

The Change in timing that the PCM is doing because of the IAT change could be revealing a weakness in your ign system.

 

Does the miss happen as soon as you start the car or only after it has been running for a while (open vs. closed loop). Its a good idea to log the car to see if there are any codes, and to see if the sensors (eg. o2 sensors) are giving appropriate outputs.

The high rpm miss and the bucking etc. at lower rpm could be different problems - at times they seemed to have been isolated from one another.

 

Maybe it's just me but I am just trying to figure out why you would start a missfire and stumble diagnosis with the IAT. You may want to give us a little more info about your miss and stumble. What parts other than the IAT have been checked or replaced?