Thread: Fun Surging

***Update 6/12/2008:
Ok, so after fighting this issue for months I tried a few things, I unplugged the maf for a week, the surging remained, but the car didn't stall. So after talking to James and him stating that the VE tables in my PCM probably aren't that good(it is a off-the-shelf Bin). I figgured I would bite the bullet and purchase a new Maf, long story short, a the MAF was bad, which was further complicated by my off VE table

So props to toasty who was the first with the right answer
*******

Well this all started about 3 days ago, not a rough idle, but a hunting idle. Sometimes it drops to like 300 rpm then shoots back up to 1500 rom then levels out into the hunting idle. Then yesterday it started stalling out on me.
Finnaly last night it threw a code, so I went to autozone to get it read:

P0102- which could be like five different things, but pretty much low vacume in intake manifold.

What I have done,

Used carb cleaner to check for leaks around the UIM and Throttle body
Cleaned MAP and MAF
Checked all hoses and vac lines
Checked EGR(tried to clean but damn near impossible to get that thing clean)
Cleaned PCV and checked o-ring

Now it sounds a little like vacuum around the throttle body, could this be normal, or could it be the infamous cracked UIM.

The dealer is gonna take it on friday cause the warranty, but I have a deductible on my warranty and wish to avoid it, any other suggestions on what I should check

nice, the person at autozone was very disspleased that they had to help me, but the print out does say p0102

but when I unplug the maf the car doesn't run, it starts and revs to like 2k then dies, so there is some other issue as well

could a bad maf cause the surging and stalling?

I cleaned it spotless when I cleaned the maf, the tech at carmax is having a hell of a time finding it as well, I had to go there show him the problem, and explain to him all my mods so he knew what he was working around, but nice dude

Ok, got my car back from carmax, had to pay a hundred bux for them to run every test under the sun, but they couldn't find my problem, they eliminated:

Vacuum Leak
Fuel Issue
and some others, I don't wanna just throw parts at it, but I think a new or new/used MAF sensor is going on this week then we will go from there, any other Ideas?

Kind of sounds similar to my problem. I have swapped out all the throttle body sensors with known good ones and nothing changed. Are you running a maf screen, if not put it back in for starters. If I unplug my IAC my car idles perfectly but with it plugged in it hunts sometimes worse than others.

what do you mean by a bad LIM?

He probably means the gaskets, I haven't been loosing coolant or oil and all the plugs looked ok, but it may be leaking vacuum through the lim gasket?

You set a Maf code so start there, unplug it an look at the connectors in the plug if they look clean make sure the wires aren't damaged, if they appear fine then try replacing it, if the new one doesn't solve the problem then take it back off an return it. No harm done but then you can start thinking about other possibilities.

To help everyone help me here is a list of what I've done:

Checked function(unpluged and ran car, problems still remained)
MAF
MAP
TPS
EGR
EVAP
IAT

Ive, blocked off the following, no change:
EGR
EVAP

I've replaced with good and problem still exsists:
Coils
ICM
Plugs
Wires
Pcv

Notes:
Bouning vacuum, enging runs fine anytime mre than about 10% throttle is applied

If your intake gaskets were causing a vacuum leak the extra air (from the vacuum leak) be coming in through the PCV valve, correct? Just wondering because I have my pcv blocked off.

I have my crank case vented with a breather setup. If I were to run a pcv valve I would pressurize the crank case under boost.

What I was saying is if your intake gaskets were leaking (as in the ones that seal to the block and not the heads) then you would be drawing unmetered air in through the pcv valve. But if the gaskets weren't leaking then you would just pull a vacuum on the crank case and not be pulling in unmetered air.

Good point, the PCV does seem to be openin/closing very rapidly(it makes a fun ticking noise

Originally Posted by Andrew_99GTP

What I was saying is if your intake gaskets were leaking (as in the ones that seal to the block and not the heads) then you would be drawing unmetered air in through the pcv valve. But if the gaskets weren't leaking then you would just pull a vacuum on the crank case and not be pulling in unmetered air.

Leaking LIM gaskets could be pulling from the outside too. They're exposed.