Help me diagnose this

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NachtRitter84
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Help me diagnose this

Post by NachtRitter84 » Wed Apr 01, 2020 11:07 pm

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
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Re: Help me diagnose this

Post by 04rebel » Fri Apr 03, 2020 7:53 pm

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
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Re: Help me diagnose this

Post by occasional demons » Fri Apr 03, 2020 8:36 pm

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.
Bill
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Seriously people, this is 2019 not 1920.
Too much time spent here is a sign of a bad case of Ownaneonvirus.

2000 Neon MTX swap with '02 R/T PCM
1999 neon coupe 2.4 swap
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NachtRitter84
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Re: Help me diagnose this

Post by NachtRitter84 » Fri Apr 24, 2020 2:00 pm

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
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Re: Help me diagnose this

Post by occasional demons » Fri Apr 24, 2020 9:50 pm

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.
Bill
dblsg wrote:ya'll a bunch of post whores
Seriously people, this is 2019 not 1920.
Too much time spent here is a sign of a bad case of Ownaneonvirus.

2000 Neon MTX swap with '02 R/T PCM
1999 neon coupe 2.4 swap
Help support 2GN!

NachtRitter84
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Re: Help me diagnose this

Post by NachtRitter84 » Sun Jun 28, 2020 4:08 pm

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
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Re: Help me diagnose this

Post by 04rebel » Wed Jul 01, 2020 10:41 am

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
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Re: Help me diagnose this

Post by NachtRitter84 » Wed Jul 01, 2020 7:10 pm

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

04rebel
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Re: Help me diagnose this

Post by 04rebel » Wed Jul 01, 2020 8:57 pm

NachtRitter84 wrote:
Wed Jul 01, 2020 7:10 pm
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
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Re: Help me diagnose this

Post by occasional demons » Wed Jul 01, 2020 10:06 pm

NachtRitter84 wrote:
Sun Jun 28, 2020 4:08 pm


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.
Bill
dblsg wrote:ya'll a bunch of post whores
Seriously people, this is 2019 not 1920.
Too much time spent here is a sign of a bad case of Ownaneonvirus.

2000 Neon MTX swap with '02 R/T PCM
1999 neon coupe 2.4 swap
Help support 2GN!

NachtRitter84
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Posts: 21
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Re: Help me diagnose this

Post by NachtRitter84 » Thu Jul 02, 2020 11:59 am

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
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Re: Help me diagnose this

Post by occasional demons » Thu Jul 02, 2020 12:39 pm

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.

Image
Bill
dblsg wrote:ya'll a bunch of post whores
Seriously people, this is 2019 not 1920.
Too much time spent here is a sign of a bad case of Ownaneonvirus.

2000 Neon MTX swap with '02 R/T PCM
1999 neon coupe 2.4 swap
Help support 2GN!

occasional demons
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Re: Help me diagnose this

Post by occasional demons » Thu Jul 02, 2020 1:01 pm

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
Bill
dblsg wrote:ya'll a bunch of post whores
Seriously people, this is 2019 not 1920.
Too much time spent here is a sign of a bad case of Ownaneonvirus.

2000 Neon MTX swap with '02 R/T PCM
1999 neon coupe 2.4 swap
Help support 2GN!

NachtRitter84
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Joined: Mon Nov 25, 2019 3:27 pm

Re: Help me diagnose this

Post by NachtRitter84 » Sat Jul 04, 2020 9:49 am

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
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Re: Help me diagnose this

Post by 04rebel » Sat Jul 04, 2020 5:37 pm

NachtRitter84 wrote:
Sat Jul 04, 2020 9:49 am
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
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Re: Help me diagnose this

Post by occasional demons » Mon Jul 06, 2020 9:09 am

NachtRitter84 wrote:
Sat Jul 04, 2020 9:49 am
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"! :lol: :lol: :lol:
Bill
dblsg wrote:ya'll a bunch of post whores
Seriously people, this is 2019 not 1920.
Too much time spent here is a sign of a bad case of Ownaneonvirus.

2000 Neon MTX swap with '02 R/T PCM
1999 neon coupe 2.4 swap
Help support 2GN!

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