My car is mad at me! Random stalling, rough idle

[dumpstafresh]

when you say it died on the freeway it sounds like the maf.
when most cars misfire they dont die they just jerk around alot and loose alot of power(like in one cyl.)
but i think ive read that the cam positioning sensor will do that before it goes bad that without throwing a code. that was going to be the next thing i changed if the maf wasn't the prob. the only time i threw a cam pos. sensor code was when i changed my timing belt.

it kinda still sound like bad maf. Ive gotten bad parts from junkyards many times.
Maby try this with the old maf. how-to-fix. and BAD MAF SYMPTOMS
http://www.subaru-svx.net/photos/files/How-To/41607.pdf

also, did you clean your IAC? i cleaned mine and it leveled out the idle alot. you can spray some parts cleaner in it and kind of clean it through the throttle body.
heres the post i used for instructions.
http://www.subaru-svx.net/forum/show...+control+valve
If you do take it off make sure you set it right and plug the connector in the right way.

I would try to clean it without taking it off as it prob is not your problem. but it couldnt hurt.
I'd try fixing the maf(its free). It sucks throwing $200 parts at a car, not knowing if thats your problem.

[macadamianut]

Update,

Car in neutral/park, revving and holding above 4000rpm smooths out the miss/shudder/etc.

So it is mostly when the car is at operating temp. and being run at low rpm. Does this help point to anything in particular??

I appreciate your help and suggestions
Thanks,
Mac

[StelthSvx]

a bad MAf can make the car feel like it has no power at rpm or like its missing. I think based on your symptoms (starts ok- idles ok cold- warm idle bad) could be your IAC -Idle air control Valve under the throttle body. I replaced mine and it did wonders for the idle. You might be able to get away with cleaning it with carb cleaner. Mine was gunked up pretty bad after 270k miles of use. Depending on how many miles on your MAf you might want to replace with a good used or wait for 10-15% off @ subaruparts.com for a new one. Then again it could be the Maf going bad, especially if its sputtering at 4k rpm.... Evan

[macadamianut]

I gave up, (with no heated work space,) and gave it to Hodges Subaru here in the Detroit area that Todd had recommended. They have diagnosed an Intake Gasket leak and have quoted $525.00 parts and labor. I am hoping this will solve the missing and random stalling issues. Does this sound possible? What do you guys think?

Thanks,
Mac

[Trevor]

Originally Posted by macadamianut

I gave up, (with no heated work space,) and gave it to Hodges Subaru here in the Detroit area that Todd had recommended. They have diagnosed an Intake Gasket leak and have quoted $525.00 parts and labor. I am hoping this will solve the missing and random stalling issues. Does this sound possible? What do you guys think?

Thanks,
Mac

Kia ora Mac,

Before you commit to the sort of money suggested, you surely deserve a more accurate diagnosis.

If they/you can be exactly specific regarding which/what gasket associated with the intake system is leaking, an opinion would be possible. Meantime the diagnosis is rather vague and very much subject to doubt.

Cheers, Trevor.

[SoCal LS-L]

Before committing to the work, you can verify their diagnosis by spraying starting fluid around the intake gaskets, most likely where they go into the heads. Any change in idle marks the location of a leak.

You can also be assured that they will be calling you to authorize more cost in your repair, as when they remove the intake they will probably want to replace all of the vacuum lines, clean, have broken something, etc..... and may tell you they wont warranty the repair unless you consent.

Unless you're already in it for a costly diag fee, get a 2nd opinion.

[macadamianut]

Thanks for the thoughts.

I am already in it for a $100.00 diag. fee. The idea of this being the issue seems probable to me in that; The intake leak leans out the cylinders on that bank causing a misfire. But of course, I am only an amateur mechanic. 15 years old with 82,000 miles, I'd like to replace everything below the manifold, but budget won't allow.

I suppose it would be wise to do a few of the "otherwise inaccessible" vacuum lines while it is off. I will ask in detail the services proposed.

Hopefully they are straightforward, honest and capable. They haven't told me I was low on blinker fluid yet. They also mentioned cleaning of the EGR pipe (valve tested ok) and IAC assy.

Thanks,
Mac

[sowise]

seems like they want quite a bit of money for intake gasket replacement? I would suggest doing what SoCal said (maybe use WD-40 if not starter fluid). Honestly if you are careful with the rubber hoses you could do this yourself. The gaskets are like $10, from there you can clean any of the intake parts you want, I found alot of oil in my intake manifold, and purchased silicone hose for the replacement vacuum lines, I don't think I got close to spending $500 to replace my IAC, and EGR valve and get the hose and gaskets. I also had to replace the black fuel box and order one of the pressure sensors under the manifold. Really save your $$ and try it yourself, take pictures or video as you disassemble so you can figure out where to put things back.

[SoCal LS-L]

Its a good sign they suggested cleaning the EGR pipe and IAC, means they know what they are doing in a subaru engine. Id go for it..... as my "eternal" code 56 is directly attributed to my EGR pipe being clogged.

The $525 is probably mostly labor charge, the intake manifold is not exactly easy to remove and reinstall..... especially out in the cold.

Id see how much more they want for replacing the vacuum lines.... maybe they will be nice and throw it in.... vacuum hoses are cheap.

[macadamianut]

Well, aaarrghhh!

So the dealer did the intake manifold gaskets and for a few days, no stalling. They claimed they also cleaned the EGR pipe and IAC and said the EGR valve tested okay.

But... the car idled very rough like it was running on only 5 cylinders and continued to misfire.

Now... the last two days I had started the car in the morning to warm it up before leaving, only to come out of the house and find that it had stalled. Furthermore, I was driving the car home from dinner last night and she stalled while driving again.

Was worse this time, I could get it to refire but would not accept any throttle. It would immediately stall when any throttle was applied. Eventually it decided to accept throttle and I drove it the rest of the way home.

I don't know if the mods could aggravate the situation but, just as a recap, the car is a 1995 with 82,000 miles and minimally modified with the following:
-Lightweight crank pulley
-Stebro muffler
-ECU tune 1.5
-K&N filter in factory airbox

Coil Pack? TPS? MAF? Dirty throttle body? Cat clogged? O2 sensor? I give up. It will be going back to the dealer of course because they chose the expensive fix that didn't work, but it would sure be nice to steer them in the right direction so they don't keep it for a year trying to figure it out.

Any help is greatly appreciated.

Mac

[SoCal LS-L]

Since its easy, clean the MAF to eliminate that since you have the K&N. Maybe switch it out w a known good one.

You can also look back behind the throttle body and make sure they connected all the vacuum hoses that run to the intake tube.

It almost sounds like you could have an EGR thing now they were in there messing with it, id take it back to them and have them re-diag your problem and fix it.

[Chip Hutchinson]

Hi,
I recently replaced my Throttle position sensor because the torque converter would lock and unlock when it wasn't supposed to. When I did this it also cured an occasional shuttering misfire that I would get when increasing the throttle slightly while driving. If I floored it, the misfire would not happen.
I would suggest checking your TPS calibration. The way I did it was to cut the tape away from the wiring, and install one of those trailer wiring splice connectors that are open like a clamshell with two knives that crimp and slice through the insulation when you close it. Splice onto the appropriate wire (White I believe) with your splice wire sticking out far enough to be be easily accessible. Once this is accomplished, you can proceed with the calibration and subsequent adjustment if needed. A reading of .5VDC + or - .05VDC. That is a half a volt DC with a tolerance + or - 10% to ground with the ignition switch on and engine not running. When finished, I capped the wire with a wire nut just in case I have to go there again.
A dirty TPS could theoretically give random symptoms, and I have heard that they can be cleaned, So cleaning it before calibrating it would be a good idea.

I hope this helps.

[SVXRide]

The engine was still misfiring when you picked it up?
You might want to check all of the bolts for the intake to make sure they're still tight (you've put a couple of thermal cycles on the new gaskets). Also make sure that the intake is correctly installed on the throttle body (i.e., you don't have an air leak).
If it feels like the engine is only running on 5 cylinders, I'd suggest you find out which cylinder(s) are contributing to this condition. Try disconnecting one injector at a time and see if you get a noticeable change in how the engine is running. No change = problem.
-Bill

[Trevor]

Originally Posted by Chip Hutchinson

Hi,
I recently replaced my Throttle position sensor because the torque converter would lock and unlock when it wasn't supposed to. When I did this it also cured an occasional shuttering misfire that I would get when increasing the throttle slightly while driving. If I floored it, the misfire would not happen.
I would suggest checking your TPS calibration. The way I did it was to cut the tape away from the wiring, and install one of those trailer wiring splice connectors that are open like a clamshell with two knives that crimp and slice through the insulation when you close it. Splice onto the appropriate wire (White I believe) with your splice wire sticking out far enough to be be easily accessible. Once this is accomplished, you can proceed with the calibration and subsequent adjustment if needed. A reading of .5VDC + or - .05VDC. That is a half a volt DC with a tolerance + or - 10% to ground with the ignition switch on and engine not running. When finished, I capped the wire with a wire nut just in case I have to go there again.
A dirty TPS could theoretically give random symptoms, and I have heard that they can be cleaned, So cleaning it before calibrating it would be a good idea.

I hope this helps.

You do not have to damage the wiring, stick a fine needle or pin through the insulation and conductor/wire to make a connection. Refer the how to section for details.

[Chip Hutchinson]

Hi Mac,
The TPS is not likely to be the cure to your problem. I mentioned it because I had unexpected good results that may be coincidental. However, due to the relative ease and low cost of this procedure, I believe it is worth trying.
If you do the TPS test and/or cleaning, the method you use is up to you. I would like to point out that the trailer wiring connector I mentioned is an approved wiring device that has been certified for use specifically in the automotive field. I'm no car expert, but I am a journeyman industrial electrician with 37 years of experience. I didn't just step out of a cow patty and start giving wiring advice. So, you shouldn't have any reservations about using one of those connectors on you vehicle.

Chip