IAC valve??

[93 x]

Hi i have been having a problem with my truck it started when I was in the drive through lane, I was in drive and all of a sudden the truck jumped rpms to about 1500. ever since then the rpms go up then stay there and sometimes come down. But just driving the other day the car just shut off on me going around a corner, so I put it in nutreul and it started. then just this morning it started then died and then would not start for at least a good 3 solid minutes of cranking, and then on my way to work it did it agian in the middle of an intersection. So I suspected the IAC, so I replaced it with a used one i had laying around but it still KINDA has the same symptoms of the idle being higher than is should. There are no codes tripped all though the engine light flashed real quick one time when the rpms jumped. I do work in a shop so I can use an eight thousand dollard diag machine but it wont help with out a light on. If anybody can help it would be great!! thanks all

gordon

 

[Roadrunner777]

IAC is the most obvious cause. 5 minute deal to pull it and see if the valve moves freely.

 

[93 x]

IAC is the most obvious cause. 5 minute deal to pull it and see if the valve moves freely.

My old one valves did move freely I just figured the electrical part pf it was getting bad

 

[93 x]

bump

So the car keeps dieong on me and takes forever to start. Anybody have an idea

 

[Xeek]

mine does sorta the same thing. keep in my my tranny is going out also, if that has anything to do with it.

my idle in park is 800ish, drive is 550, for normal. with a few revs in park or randomly while driving, it jumps to 1k at idle at a light. it downshifts to 2nd, then 1st then jumps to 1k. sometimes itll go back down by itself, not very often tho. if i shift into park it jumps to 1.3-1.5k and if i try to shift to any movement gear if 'clunks' into gear but then theres nothing and it stays at 1.3k.
does that last part happen to you? it may just be my converter for that part, not sure.

im going to buy a new iac here soon, see if that solves it.

i did have it start and die on me once, and only cranked after that. pulled the fuel pump fuse and cranked, replaced, started right up no issues.
do you happen to have any weird cranking issues? cranks for 1 second then 'locks up' on itself and stops cranking?


just looking to see if any of this is related

 

[rustbucketMI]

Even without a CEL there may still be some stored codes that you can read. Since I haven't had a CEL since replacing my O2 sensor, 8 years ago, I'm not 100% sure about how many codes are stored. I work on new cars with OBDII and I know there are multiple codes you can read without setting off a CEL.

 

[93 x]

ok so i got a code it was a temp sensor for the comp i replaced it and my car does not die anymore but it still lurches becuase of rpm jumps. i cleaned my valves did a ohm and voltage check on my iac what else could it be. what determens the iac to change randomly

 

[Xeek]

my new one is on the way right now, but i have other issues so i cant report on it yet.

but supposedly they dont close all the way and allow air to pass and raise the idle, and possibly other issues.

 

[Roadrunner777]

ok so i got a code it was a temp sensor for the comp i replaced it and my car does not die anymore but it still lurches becuase of rpm jumps. i cleaned my valves did a ohm and voltage check on my iac what else could it be. what determens the iac to change randomly

Really, anything before the intake valves could cause issues. IAC and the Mass Airflow sensor are typical. Someone had a similar problem and found a crack in the plastic duct from the MAF to the throttlebody. Throttle position sensor could do this too.

 

[93 x]

bump

so i havent heard anything new but this is what has been hapening.

i unpluged the iac and turned up my idle it ran great for a while about 2 days.

now the rpms drop while im moving and it wants to die like sometihng is making it suck way to much air and not enough fuel.

so i came to think that maybe whatever is making it want to die triped the computer and told it to turn up the idle on the iac.

latley it wants to die and when it does its easy to start again not like before when the iac was pluged in.


any ideas would be great as im getting very angry!!

thanks all!!

 

[something9000]

you might also try the coolent temp sensor it sounds dumb but i had a problem that caused the truck to run a little warm untill i got it fixed it the truck would raise the idol slighty by itself. Just a thought

 

[Roadrunner777]

Did you ever look into your Mass Airflow Sensor?

 

[93 x]

thank you for the replys everybody!!

i fixed it!!!!!!!! so i started wiggling wires like crazy to every sensor and found that the maf would kill it when i wiggled it!! i loked in the plug and saw a peice of rubber??? in the number 4 pin i pulled that sucker out and cleaned all my pins and the maf and voila its great agian!! although the iac seems to still be a little on the high side but its a million times better than before.

thank you everybody on this site you guys are wonderfull!!

 

[Xeek]

i took some qac or whatever its called, electrical cleaner and sprayed my maf harness. it looked a little dirty. so ill see how it goes after getting some miles on it