# maf? iac? runnin weird.



## apmason (Jul 21, 2004)

'95 D21 ka24e standard 2wd. Periodically, but at least once every time I drive it, my trucks idle will drop to like 400rpm. It slowly claws back up to about 1000 as I sit at a light or sit stopped for whatever reason. Reading some of the other threads here I suspect that its the MAF or IAC valve. My manuals don't show the locations of those parts or give any maintenance instructions. I understand that the MAF is very sensitive. Does my problem sound like a MAF/IAC issue? Where are these parts located?


----------



## apmason (Jul 21, 2004)

Also, for diagnostic purposes, I'm getting a CEL that reads EGR and I just replaced my cap, rotor, plugs and pcv. This problem predates the work I have done and hasn't changed since the work was done. I started to replace the EGR but discovered a badly leaking vacuum hose (leading to the vtt) and replaced that. The CEL hasn't gone away but I am not sure i have driven far enough for the ECU to reset. Any help is appreciated.


----------



## SPEEDO (Jun 9, 2003)

might try cleaning the EGR, there is also a hose that goes to the BPT valve that may have collapsed or has a hole in it..


----------



## SPEEDO (Jun 9, 2003)

oh... the maf is a black box, located on the top of the throttle body


----------



## zanegrey (Dec 5, 2005)

read the sticky ..

read the codes...


----------



## apmason (Jul 21, 2004)

Thanks speedo. I have a replacement egr, I was just hoping that the vacuum hose was the problem there. I'll replace it this weekend. Zane, I read the code and all it said was EGR. I don't think that my trucks symptoms indicate an egr issue. Hopefully I am wrong and when I change out the EGR the other problem will go as well. Would the code still read EGR if the problem was the vtt?


----------



## zanegrey (Dec 5, 2005)

i think those are egr symptoms..


----------



## apmason (Jul 21, 2004)

Wellallrightythen. Zane, you seem to be the go to guy on this stuff, good advice I have read so far. So ideally come Sunday my issues will all be solved. As a side note on EGR work, what size nut is it that connects the exhaust tube to the EGR? I am gonna need a new wrench b/c that sucker is big. Not the nut that connects to the exhaust manifold, but the one that connects to the EGR pointing back to the firewall/trans. Thanks in advance!


----------



## zanegrey (Dec 5, 2005)

you do not need to tke off that big nut..

use the 2- 10 or 12 mm nuts tha hold the egr valve on...


----------



## apmason (Jul 21, 2004)

I am not clear on this EGR thing then. I tested some of the EGR/VTT vacuum lines and replaced the ones that seemed to fail. If the problem is with the unit then I need to replace it. Aside from the two nuts you are talking about it has the tube that goes around back of the engine to the exhaust manifold. That tube is affixed by a big nut. If you think I can do some maintenance on it without removing it that would be great, but I am totally prepared to replace the unit. I have a replacement already. I was just wondering about the nut. What makes you think its the egr though? From my understanding a faulty egr doesn't re-rout exhaust gas back to the intake. this wouldnt lead to a low idle, just poorer emissions? Am I wrong about how an EGR works?


----------



## zanegrey (Dec 5, 2005)

i guess i was assuming you were going to remove the exhaust mani as well..

it is not my idea that the egr valve is bad .didn;t you say the codes said it was the egr valve..

if it is leaking it can cause a low idle or no idle.
if it is sticky and can cause a low idle and then as it slowly releases a creeping idle..

if it is bad altogether than what is to stopp the eg from going what ever direction..



simply push the diaphram in the egr ..does iut move evenly ..do you hear a slight sucking sound ??


----------



## apmason78 (Feb 27, 2009)

You are quite right. I did say that the egr coded popped up, I just didn't think it was related. I'd rather not take off the entire exhaust mani. I could see how if it (egr) were stuck open it would cause problems, as it would starve the engine of oxygen, but the diaphragm moves smoothly and vacuum applied to the top hose actuates the egr. I am not detecting any other leaks. I'll try again with the engine running to see if it closes smoothly once open and in use. If I open the throttle to build vacuum and feel the egr open that means its good right? Upon releasing the throttle it ought close. Its this closing that may be causing my problem. ie exhaust gas passing thru at idle. I hadn't considered that b/c the problem doesnt happen under load, only moving to idle. Makes me want to get at it sooner than this weekend. Really appreciate your help.


----------



## zanegrey (Dec 5, 2005)

the egr can seem to function correctly yet still be carboned up on its plunger...


----------



## apmason (Jul 21, 2004)

To save a little effort and expense, is it possible to disconnect the two smaller nuts and spray the plunger with some kind of cleaner? The spray would get into the tube that leads back to the exhaust mani. Since I have the part already, would it be best to just replace the unit?


----------



## zanegrey (Dec 5, 2005)

no cleaner that i know of will decarbonize it..

i think that you are going to find that when you get after that nut ..it is not going to come off easy..

it is tight back there and it gets as much heat as the exhaust mani..

so it may be on there fairly good..

that is why i just assumed you would remove the exhaust mani..

the 2 bolts will seperate it from the intake mani..


----------



## apmason (Jul 21, 2004)

Thanks Zane. I'm gonna give it a shot, taking the unit off without the mani. I'll let you know how it goes and if my problem stops. Once again, I appreciate your assistance.


----------



## zanegrey (Dec 5, 2005)

good luck......


----------



## apmason (Jul 21, 2004)

Replaced the EGR and the fuel filter for good measure. The nut is a 30mm. Came off with no problems. Problem solved! Thanks again!


----------



## apmason (Jul 21, 2004)

So, the problem persists. The egr replacement has helped the overall performance and gotten rid of the cel, but the low idle remains. I did a compression test and it seems a bit low (high 130's-150). Not sure if that could cause the problem. Do I need to start thinking about the maf again? iac?


----------

