Help me diagnose this

[NachtRitter84]

05 neon SXT ATX acting like it has a vacuum leak occasion and throwing a code p0441. Did the propane test and my mechanic did the carb cleaner test and neither of us found a vacuum leak. Replaced the gas cap, twice. Choppy vibrating idle at all speeds under 30mph and Idle sometimes drops to 400-500 and car chokes out but ONLY when in reverse. IAC has been cleaned repeatedly and this has not changed the effect at all. Replacing the IAC soon.

My questions are as follows:
Could this actually just be caused by a failing IAC alone?
Could it actually be the purge solenoid even though it’s like NEVER the purge solenoid?
Bad EGR valve?

I’m thinking of just taking the nuclear approach and replacing ALL the vacuum line, if I do this how much hose am I going to need and in what specs?

[04rebel]

An 05 with how many miles? 2.0? I'd pull the PCV valve and replace it. Then follow the line down to the rubberhose connection between the intake and throttle body. Oil fumes and residues collect there and deteriorate the rubber, it could have a hole or tear there.
IF a 2.0...I don't recall seeing an EGR valve on my 04.

[occasional demons]

Only some of the 2000 neons got an EGR valve, and those are pretty rare.

That's what the large round molded in part on the IM near the bellows tube was made for. They just never really used it, and didn't revise the manifold.

The purge solenoid gets it's vacuum source from the small nipple on the manifold side of the throttle body. there should be a line that goes from there around the factory air filter box and back behind the battery. if that line is cracked, it will leak vacuum, and cause an incorrect flow.

I had that line plugged off for a few years on my '01 after it got damaged when it was totalled. I didn't get in a hurry after I got the R title.

I would get a CEL and code about every 6 months. I only fixed the vacuum line because it bothered my wife when it would ding and the CEL would come on.

But it never was a constant issue. Once it was cleared, it would take another 4 to 6 months before it went off again.

You could try capping that nipple off, and see if it clears up the vacuum leak issue. If so, then you may need to do some digging around the engine bay, or under the car.

[NachtRitter84]

147k on it. Went down the list and nothing. Mechanic thinks it’s a floating blockage somewhere in the lines. Nothing for it but to blow them all out and/or replace them all. I’m thinking he may be right as the issue got much worse after I put in a granatelli coil pack - like the extra power pushed the blockage through faster.

[occasional demons]

I doubt the Granatelli makes any more power than the stock Mopar coil, unless it was dead.

Engine output would have zero effect on anything going on with the evap emissions system.

If the original coil was fine, I would put it back on. A quality set of plug wires will do far more for spark energy than any "performance" coil.

[NachtRitter84]

Right. Gone through everything. Almost entirely certain it’s a computer issue but my mechanic ran one of those performance Computer plugin devices, which I can’t justify dropping 2 grand to get one of, that lets you monitor performance and it wasn’t reading anything wrong(With idle, airflow, map function all exactly at factory tolerances) but still occasionally the idle runs down and chokes out unless I keep blipping it. Once it’s warmed up it becomes I need to hold the gas to keep the rpm above 500 at idle when fully warmed up. No codes at all for months now after I fixed out the plugs.

Done: evap lines, IAC, plugs, wires, coil pack, fuel pump, pressure regulator/filter, injectors. While I’m fairly certain it’s probably the pcm/tcm there are a few things:
1) I can’t find the TSB for the 05 neons that covers this exact issue although I’m positive there is one and I’ve seen it mentioned before

2) is it possible that this is a torque converter issue? Neons.org had a long thread about torque converter issues causing idle problems

3) the injectors were one of the most recent things I did. Mechanic said that two of them were starting to fail, I did the full replacement. With the problem ongoing maybe one of the pigtails is starting to go bad?

4) there is a... bellows pumping air hissing sound(sorry for that, best way I can think of to describe it) from my TB when I idle with the hood up and blip the gas you can hear it. Not sure if this is normal , googling it got me all sorts of posts about intentionally drilling holes in your TB for an LS or various fords and jeeps.

5) I’ve operated under the assumption that o2 and MAP sensors are vital enough that they would be throwing codes if either were the issue and haven’t visually inspected them. I’ve also assumed the TPS is fine since everything works fabulously.... except at idle when warmed up.

[04rebel]

Did you remove the "bellows" between the intake and throttle body and inspect it for cracks or PCV oil fume deterioration(holes) in it? An air leak there can cause symptoms you described... BTDT with a number of similar intake design vehicles and constantly check our 2.0 engined Neon for that due to the amount of "flexing" the bellows does during acceleration and deceleration airflow.

[NachtRitter84]

You mean that plastic accordion box? Anybody happen to have a part number for that?

[04rebel]

You mean that plastic accordion box? Anybody happen to have a part number for that?

Whatever descriptive title you care to use(bellows, tube, pipe, large hose) that connects from the intake manifold to the air cleaner mounted throttle body.
Sorry, but I don't have the part number handy without looking it up. Are you just throwing parts by suggestion of others or did you remove and inspect it and found as I described?

[occasional demons]

4) there is a... bellows pumping air hissing sound(sorry for that, best way I can think of to describe it) from my TB when I idle with the hood up and blip the gas you can hear it. Not sure if this is normal , googling it got me all sorts of posts about intentionally drilling holes in your TB for an LS or various fords and jeeps.

So it is just a sound that "oscillates" after the throttle is opened and shut quickly?

It could be the IAC valve fluttering, possibly over and under correcting. Unfortunately, I have no real idea how to correct that, if that is the case.

It could also be a leak in the bellow tube, and it is expanding and contracting, opening and closing the leak. But an air leak there may also raise the idle, because the air leaking in is just like the IAC opening up to raise the idle.

[NachtRitter84]

Plastic seems worn on it, no visible holes, but the sound always comes from there, seemingly centered in the blows contraption - roommate and I played with it a bit, it’s still the factory one so probably a pinhole. Dodge calls it a ‘throttle body duct’ and it’s $150. I’ll swap it out on Monday and see if it helps.

[occasional demons]

It is a two piece part. There should be an insert inside of it, that keeps the inside smooth, and keeps the bellows from attempting to pull the air box up to the IM under vacuum.

If everything is there, and there are no signs of any cracks/light shining through with the insert removed, then I wouldn't swap it out, especially if you are buying a new one. It would be $150 better spent elsewhere. For less than $10, you could cut some PVC, and duct tape the PVC to the IM and TB, and see if the issue persists. Not driving it of course, but this should hold together adequately to just blip the throttle idling in park with the hood up.

Just have a helper sitting in the car to shut off the ignition, in case you tear the duct tape loose. Otherwise you may test the rev limiter....

You could get a couple silicone couplers and clamp the PVC in place. But that will up the cost.

I bought something similar to this (just the tube and filter) years back at AutoZone for about $30 when I initially made my GhettoBlaster IM to mate the stock TB to it. IIRC, 2.5" tubing is what you need. If AZ still sells this stuff, they would have the couplers.

[occasional demons]

I originally cut part of it off and glued it to the inside, then later cut that off and put a flange on to direct mount the larger TB. That is why the IM is shorter in the later pictures. But originally I had the stock TB clamped to the IM.

Click
VVVV

viewtopic.php?f=67&t=25866

[NachtRitter84]

Tested with pvc and it’s definitely the part. I’ll grab the new mopar replacement since it’s ... the same price as an hour for them to inspect it, which was going to be my next step anyway. Been shooting for ‘stock within 10% of all factory limits’ as stage one on the project anyway. Afterward I get to start on bigger, or more extensive modification, Projects.

[04rebel]

Tested with pvc and it’s definitely the part. I’ll grab the new mopar replacement since it’s ... the same price as an hour for them to inspect it, which was going to be my next step anyway. Been shooting for ‘stock within 10% of all factory limits’ as stage one on the project anyway. Afterward I get to start on bigger, or more extensive modification, Projects.

Glad you did some "testing" and found the problem as I described. Enjoy your "little" car, they are a blast when they run correctly!

[occasional demons]

Tested with pvc and it’s definitely the part.

Good deal!

Better to spend that sort of coin having confidence it will actually cure the issue.








But for less $$$, you could have just sprayed it with "Flex Seal"!

[NachtRitter84]

Yeah. Then it came back again. /headdesk - I tested the compression when it first started doing this and we were a-ok but on a whim I tested again and I’m hosed. Bottom end on 2/4 cylinders.

[occasional demons]

If the body is in good shape, and you could do the work yourself, a JY engine would probably be cheaper than a replacement car. Being an '05, the engines have a bit more availability.

But if it is rotting out, I don't think I would dump the cash and effort into it.

IDK if you bought it new or used, but anymore, buying used can be a gamble, especially for some of the used car asking prices. And fixing up a used car anymore is harder to do for cheap, given the cost (read mark up) of technology they dump into them now.

Avoiding the higher tech stuff is beginning to be impossible, as the older cars are fading away, or you have to wait until the owner dies, and the relatives dump the car.

It's sad that a few repairs on a "lightly used" newer car will put you into new car pricing real fast. And then you have to cough up that money on top of the loan payment.



Best of luck...

[04rebel]

Yeah. Then it came back again. /headdesk - I tested the compression when it first started doing this and we were a-ok but on a whim I tested again and I’m hosed. Bottom end on 2/4 cylinders.

Sorry to hear that. Please let us know your plans and general area you're located. Might be able to help you out with a great running 04 2.0 motor that has 1 year old timing belt kit. Car is a runner but Buffalo,NY area RUST has done in the body. Neons around me are pretty scarce to find, I'd hate to just send it off to the "crusher" yards as that's about all that is around me, when this car of our's has so many good parts in it. It's being replaced by a 2011 Dodge Journey AWD.

[NachtRitter84]

Actually on the other coast but... you guys this thing is going to drive me insane. I’ve dropped a new block in(800 bucks from a wrecking yard delivered) and with all the other work you ready.... it’s. Still. Doing. This. Crap.
It’s narrower now - now it only happens if I have no accessories ON. Yes, weird right? I’m now choking out at 500 rpm if I don’t draw as much power as possible.

The rest of the stuff has cut out, it’s just idling down and choking out now. I mean: new tensioner(entire plate assembly because if you’ve ever done one you know...), new belts, timing/water pump, radiator, trans service, weird air assembly metal thingY that draws 4-1 that hooks in between the cat and the block whose name I can’t recall, new LDP, new vac pump, new vac lines(the hard plastic lead ins to the ldp and vp were cracked), plugs, wires, block, new pcm, new IAC, visual inspection and verification on all sensors(TPS, MAF, o2 up and down) and the cat after computer testing showed all fine. There’s nothing LEFT.

My mechanic is convinced we’re chasing a gremlin at this point. I’m debating on selling it off for two large and using the money for a down on a new Imprezas or dropping the same cash on a 2.4NA conversion

[occasional demons]

weird air assembly metal thingY that draws 4-1 that hooks in between the cat and the block whose name I can’t recall,

Exhaust manifold?

So basically it will not idle? Or just loses power when driving/low RPM?

Have you or your mechanic tried removing and cleaning every ground wire connection you can find?

Have you tried running it without the exhaust connected? Possibly there could be a blockage in the muffler or converter. Granted it should give you more trouble at higher RPM/loads, but at this point...


The new Impreza is a comparable car to the neon, maybe a bit tighter suspension, and a touch more perceived power than a 2.0 neon.

I drove a 2020 model as a loner for my wife's Forester for an airbag recall. I like my 2010 a bit more, but then it has a 2.5 vs a 2.0, so it has a bit more power and torque. But the 2.0 in the Impreza will get things going, you just have to push it a little more. But then I am also used to the 2.4 in my neon, so I might be a bit biased/spoiled.

But the sticker on that Impreza was pretty high, ($28,000) because it had all the bells and whistles. For the money, I would get a Forester over that trim level of Impreza. A Forester may not handle as well, but then that's what I have the neon for. Of course if you don't have the funds or space to park an extra "low budget fun car", you have to compromise somewhere.

In all honesty, that's why I keep the '99, because it only costs me for registration/insurance/oil changes to keep it. And it does come in handy if I need to work on the Impreza.

[occasional demons]

And honestly, you need to get the bugs figured out, if you are going to swap in a 2.4, because it will be no different than swapping in the different 2.0, if the issue is not engine related. You're just going to have more money into it, and the same issue. If not some more minor stuff, because the fuel and spark maps are better suited to a shorter stroke 2.0 displacement than a 2.4.

I put a Syked PCM in my '99 swap, and it runs so much more like a factory option now. It just has a better overall feel.

[NachtRitter84]

weird air assembly metal thingY that draws 4-1 that hooks in between the cat and the block whose name I can’t recall,

Exhaust manifold? that was it

So basically it will not idle? Or just loses power when driving/low RPM? it idles fine unless I turn off all the accessories. Then it idles down low(650ish and slowly drops to 500 and cuts out from there

Have you or your mechanic tried removing and cleaning every ground wire connection you can find? done

Have you tried running it without the exhaust connected? Possibly there could be a blockage in the muffler or converter. Granted it should give you more trouble at higher RPM/loads, but at this point...


The new Impreza is a comparable car to the neon, maybe a bit tighter suspension, and a touch more perceived power than a 2.0 neon.

I drove a 2020 model as a loner for my wife's Forester for an airbag recall. I like my 2010 a bit more, but then it has a 2.5 vs a 2.0, so it has a bit more power and torque. But the 2.0 in the Impreza will get things going, you just have to push it a little more. But then I am also used to the 2.4 in my neon, so I might be a bit biased/spoiled.

But the sticker on that Impreza was pretty high, ($28,000) because it had all the bells and whistles. For the money, I would get a Forester over that trim level of Impreza. A Forester may not handle as well, but then that's what I have the neon for. Of course if you don't have the funds or space to park an extra "low budget fun car", you have to compromise somewhere.

In all honesty, that's why I keep the '99, because it only costs me for registration/insurance/oil changes to keep it. And it does come in handy if I need to work on the Impreza.

Right. Done done done. I mean if it wasn’t for the new block I’d suspect faulty head gasket but the chances of that performing identically across two motors? I’m thinking maybe there’s something up with the tensioner assembly.

Backtrack 6 months or so and some... person put one of those concrete curbs from parking lots, painted yellow, in his driveway. Predictable results when my neon went over it thinking it was a speed bump when this dude ordered delivery. Which bent the tensioner plate assembly. I replaced it, the belt and the motor mounts all at the same time because of this. But I swear it FEELS like the belt is too loose, or slipping. The problem is intermittent and I can’t get t to do it on demand to make matters worse.

[04rebel]

OK, now that you've given a bit more history of the car and a general location....I'm not a Neon history expert.
But your description of an air assembly thingy...Is this a California emissions WITH an air pump that will send exhaust back into the Intake manifold for reburn?????? Don't recall that these came so equipped, but know that some 2.4's from the Avenger/Sebring/200 o7-10 did use these on California emission models. If so a malfunctioning pump and control vale WILL cause idle stalling out if the control valve is stuck open allowing exhaust gases into the Intake when it should NOT be doing so. Will wait on further responses to my query before offering more.

EDIT: Note that this is a system DIFFERENT than having an EGR Valve, which I think you asked about in a long ago previous post.

[manuelcherri]

have you been able to solve it?

[Midnight_Rider]

The last post is from three years ago.