Engine is revving itself in neutral...

[Deadrodent]

Well, this problem has happened off and on over the past few weeks but today it's been happening all day...my idle is super high - 1800rpm~ and if it's not idling high it's revving from 1100 - 2000 by itself every 2-3 seconds....it sometimes stops if i just mash the gas and rev it in neutral but if i just let it continue it practically goes on forever....what do u guys think could be the problem?

this isn't really a random fluctuation...the engine is doing a clean rev from 1100 - 2000 rpm as if i'm pushing the gas then letting off then pushing the gas..etc....

[da40]

it can be a vac leak even a small one can do that,or ur iacv valve can be going out on u or just really dirty check those maybe even try to get another maf to see if it changes anything starters

[Deadrodent]

would a dirty iacv really cause this problem? i thought it usually causes small fluctuations in idle?

[Deadrodent]

checked vacuum...it's following the engine's rev pattern - it's bouncing between 22-25 vacuum....i smell a burning smell - it's a sweet burning smell....also there is a major power loss....

i unplugged the maf and the car ran like **** so it's not the maf....

i unplugged the tps and the car searched for an idle....

i checked all electrical connections and everything seems fine...

at first startup there is a small amount of black smoke that comes out of the exhaust...usually it's white....

what should i check for? does anyone know how to read a vac gauge to find a specific problem? could it be a mechanical problem (bad valve?)...?

i need help fast people!!

[Deadrodent]

someone please help me!!!

[S14-NEO]

do you have a boost gauge on your car, if so check it and see where the vaccum on the gauge is at..if its high or near 0, chances are you have a vaccum leak...best way to check for a vaccum leak is get a few cans of brake clean and spray around all the vaccum lines, intake manifold, throttle body and if you have vaccum lines going into the cockpit check and make sure they are still properly conenected...i think you def have a vaccum leak..the IAC valve is a huge cource for a vaccum leak if its not closing properly. the reason for that is that the hose going to the intercooler pipe is outside the intake manifold track...if you have the means to clamp off the hose, try that to see if the engine changes the idle. if it does chances ar eth IAC valve is not closing properly.

also i would perform a leakdown test, check compression and also while cranking when its cold, remove the raciator cap and see if see bubbles or a coolant shooting out...if any of the above is happening then you coudl have a head gasket problem

[S13240]

If it's a sweet smell the it's definitely burning coolant. Got a leak somewhere.

[Deadrodent]

a small coolant hose was shooting coolant out of it...i tried tightening it down and it had no effect...still shooting everywhere...i decided it was time to take the hose off to check for a small hole or crack...i ended up brute forcing it and ripping the end of the hose off...i got the rest of the hose off but i have no idea where i could find a replacement hose...the hose connects to the firewall and to a metal tube that runs under the intake manifold runners - the metal tube joins another rubber hose which connects to the intake piping in front of the head....

anyone know where i can find a replacement hose for this? i'll try to get a pic up soon...



btw my boost gauge is reading 22 vac at high stable idle....and when the engine revs itself to 2000 the vac actually INCREASES...it follows the exact rev pattern of the engine...when the engine revs up the vacuum increases to about 25 then falls when the engine lets off....

if my headgasket was blown i'd see a decrease in vacuum...
Modified by Deadrodent at 6:12 PM 6/4/2006

[nzmoman]

http://www.puentehillsnissan.com/

they are supposed to be able to get almost everything, but I never use them... they are to far from GA.