mtx starts and stalls... daily

sidepipe87 · Post by **sidepipe87** » Wed Feb 02, 2011 9:10 pm

Ever since I've gotten this car, occasionally when I start it, it stalls out immediately. usually if I start it again it will start right up, but sometimes I have to give it gas for it to start. It generally NEVER happens first thing in the morning, yet it seems EVERY time I go to leave work after it sitting in the parking lot all day it happens.

Kyle said he had this issue and a catch can solved the problem for him but people said he was crazy and that wouldn't solve the issue. So what am I looking at here? IS it really oil in the intake? dirty IAC sensor?

OB · Post by OB » Wed Feb 02, 2011 9:19 pm

Sounds like the IAC solenoid to me. If the issue is fixed by hitting the throttle, I'd all but guarantee it. The plunger has a tendency to stick in the bore, thus suffocating the engine at idle speeds. Since such a low voltage is used to open the solenoid for idle speeds, the stickiness is enough to prevent it from opening enough to maintain a proper AF mixture, yada yada yada. I've had this issue on both 05's and have yet to replace one. The other day I was starting my car before leaving for work, and it would only run if I was on the throttle. Unlike most times however, it did NOT run on its own when I let off. It would idle on it's own for 2-3 secs then start to die, but I would catch it in time with the gas pedal, only to repeat it 4-5 times. I got out, tapped the IAC body with a deadblow a couple times, then it started right up first try with no throttle and not a bit of the gasping and choking it was doing prior. I've found that they're actually similar to starter solenoids, in that when you whack one with a hammer a few times, the problem will all but go away.

I've tested these on the bench with a 12v source, and the plunger snaps open like a bat outta hell. The first time I had this problem years ago is when I first decided to try this, and after zapping it with a full 12v the problem was gone until just the other day. I guess forcing a full stroke of the plunger in the bore was all that was needed. Interestingly enough, both times I've had the IAC out there was not a spec of dirt to be found. So the problem is not maintenance related, it's simply a design flaw. I hear of this happening to more and more people too, so it's not an isolated issue.

Post by **occasional demons** » Wed Feb 02, 2011 9:22 pm

I would look at the IAC first. Possibly it isn't opening when you key on. It should go full open when you tun the key to run, without cranking the engine. At least mine does. Then it auto adjusts once it fires. It should be audible, at least with the hood open. I can hear mine along with the fuel pump prime. Or it is overshooting once it fires, and closing too far. I would try cleaning, and lubing with penetrating oil, then reset the PCM to see if that does it.

But then I just thought about it, my IAC is mounted to the battery tray, so it does make a little more (unusual?) noise than normal....

heydockyle · Post by **heydockyle** » Wed Feb 02, 2011 9:24 pm

Catch can didn't fix the problem, more of a bandaid. Mine is doing it right now actually. I'm going to clean the map sensor tomorrow. I bet you that for the third time, it fixes the problem.

Not saying the IAC couldn't be your problem, as when people have these problems I suggest IAC and MAP. I just know what my problem is, and what has fixed it more then one time. So I know it's not a coincidence.

Post by **occasional demons** » Wed Feb 02, 2011 9:26 pm

OB wrote: I've tested these on the bench with a 12v source, and the plunger snaps open like a bat outta hell.

Considering that is 2.4 times the max operating voltage....

sidepipe87 · Post by **sidepipe87** » Wed Feb 02, 2011 9:48 pm

Is this an '05 only issue? My brother has an '05 and he occasionally has the same problem with his not starting as well. I'll try cleaning the IAC and MAP and see what happens.

Post by **occasional demons** » Wed Feb 02, 2011 9:52 pm

Mine will go as low as 300/400 rpm at times, but doesn't die, even when letting the clutch out, it will still sputter along. Then it will eventually take off and go, if I let it go that long.

sidepipe87 · Post by **sidepipe87** » Wed Feb 02, 2011 9:57 pm

I've never had the issue with the car running. once it's running, it idles fine. it's just initially starting the car that is difficult.

which sensor is the MAP anyway? I know where the IAC is. Is MAP the other one on the TB?

heydockyle · Post by **heydockyle** » Wed Feb 02, 2011 9:58 pm

MAP is in front, on the bottom, in between 2 and 3 runners of the intake manifold.
Has two torx screws holding it in.

Other sensor on the tb is the tps.

sidepipe87 · Post by **sidepipe87** » Wed Feb 02, 2011 10:04 pm

Ok. wasn't sure if it was that one on the manifold or not.

Post by **occasional demons** » Wed Feb 02, 2011 10:09 pm

Eh? Mine was in front of #1 runner. Disregard the Mag IM

heydockyle · Post by **heydockyle** » Wed Feb 02, 2011 10:15 pm

Maybe it is, idk been a while since I worked on 2.0 sohc. Srt and 1gn are in between 2 and 3 i'm pretty sure.

Post by **occasional demons** » Wed Feb 02, 2011 10:21 pm

1GN

Ghetto Blaster

Don't haz SRT IM pic.

heydockyle · Post by **heydockyle** » Wed Feb 02, 2011 10:24 pm

Dohc 1gn is at one too?

Edit

OB · Post by OB » Wed Feb 02, 2011 11:20 pm

I think there was a manifold revision at some point then. I've seen some with them on the front of the intake manifold, but the majority seem to be on the back like Kyle said. Mine is, and every other Neon engine bay I've seen (that I payed attention to). Is this already common knowledge?

At any rate, a failing MAP sensor will almost always set a CEL with an associated code. They're pretty sensitive too. Not ruling it out though, I've seen stranger things... Try tapping it like I was saying above, it's a good way to pinpoint the IAC problem, or eliminate it and go back to the drawing board. When it does it, how many attempted cranks does it go on for? Until you hit the throttle a bit, or does it start and run on its own after a few tries?

superdan · Post by **superdan** » Wed Feb 02, 2011 11:31 pm

be careful removing those torx screws of you decide to remove the MAP sensor...when I decided to change my MAP sensor one of the torx screws were so rusted the head snapped right off

OB · Post by OB » Wed Feb 02, 2011 11:33 pm

superdan wrote:be careful removing those torx screws of you decide to remove the MAP sensor...when I decided to change my MAP sensor one of the torx screws were so rusted the head snapped right off

That sucks!

superdan · Post by **superdan** » Wed Feb 02, 2011 11:51 pm

haha oh it did. definitely opened a whole new can of worms

sidepipe87 · Post by **sidepipe87** » Thu Feb 03, 2011 12:23 pm

Maybe I'll shoot some penetrating oil on them.

NickKo · Post by **NickKo** » Thu Feb 03, 2011 12:39 pm

occasional demons wrote:Eh? Mine was in front of #1 runner.

So if I am reading this correctly, Bill..... Your IAC is / was attached to the INTAKE, and NOT to the throttle body ??

That's the first time I've heard of that, and I've never seen one like it before.

sidepipe87 wrote:Maybe I'll shoot some penetrating oil on them.

I definitely would.

This is a very good idea.

Don't use "pretend" penetrants, like WD-40.
PB Blaster 'eats' the factory locktite.

I'd try applying some the night before, let it soak in, and apply it again, before removal.

- Nick

heydockyle · Post by **heydockyle** » Thu Feb 03, 2011 1:51 pm

The map sensor screws into plastic. Really surprised the head snapped off lol.

Just cleaned mine. Was completely covered in oil. Same on the inside too. Stuck a paper towel up in and cleaned it out.

Post by **occasional demons** » Thu Feb 03, 2011 2:05 pm

NickKo wrote:
So if I am reading this correctly, Bill..... Your IAC is / was attached to the INTAKE, and NOT to the throttle body ??

That's the first time I've heard of that, and I've never seen one like it before.
- Nick

No,

, it was in reference to the MAP location.

heydockyle wrote:MAP is in front, on the bottom, in between 2 and 3 runners of the intake manifold.

but he was thinking of the DOHC IM. It is just the regular 2gn IM but had/has silver paint on it. The part at the inlet end is a carry over casting for the EGR on early '00's.

gilly02le · Post by **gilly02le** » Thu Feb 03, 2011 6:40 pm

heydockyle wrote:The map sensor screws into plastic. Really surprised the head snapped off lol.

Just cleaned mine. Was completely covered in oil. Same on the inside too. Stuck a paper towel up in and cleaned it out.

Map sensors on mag manifold are actually torx head bolts, since its metal and not plastic. non-mag plastic uses the screws you showed.

OB · Post by OB » Thu Feb 03, 2011 8:48 pm

^I believe the ones in the pic are Torx. I'm pretty sure they're Torx on both the plastic AND aluminum...

Post by **occasional demons** » Thu Feb 03, 2011 10:01 pm

Yep, just the Aluminum IM screws are M4 x .7, IIRC.

heydockyle · Post by **heydockyle** » Fri Feb 04, 2011 9:35 am

Yea, they are all torx... I said that a few posts up.