DANGEROUS to Drive! Ram Camper Van STALLS after Hot Soak - Part 1

hey everyone welcome back to Pine Hollow out of Diagnostics my neighbors here they brought their 2 000 Ram 3500 camper conversion van over they're gonna take it on a long trip and they're having a problem with starting it after a hot soak interesting this thing is absolutely mint Road Trek 190 it's popular but um I mean this is so cool only 90 000 miles on it everything is just gorgeous looking at some live data here uh well before we get into that what would you guys do in this case so the symptoms are they said cold star is fine they drive it for whatever into town half an hour leave it like at a store parking lot come back you said anywhere from five minutes later to an hour later it cranks it does not want to start it pushes the gas it fires up but it doesn't want to stay running he said for the first five minutes of driving after a hot start you have to be really careful at a traffic light or a stop sign the van will stall out so um he just has to like keep one foot on the brake the other one on the gas a little bit to keep it alive and after five minutes of driving it's back to normal I just took it for a test drive it runs absolutely perfect I mean this thing just rolled off the showroom floor I was looking at some live data while you know on the test drive our fuel trims are with it like zero percent oxygen sensor is doing great TPS map sensor engine coolant temp everything is great so what could explain these symptoms it's screaming to me you know if it's a hard start when high the intake manifold is filling up with you know fuel fumes gasoline fumes and it's basically choking itself out after those clear up it's perfect so what could cause the intake manifold to fill with gasoline fumes it could be for example a leaky injector or leaky fuel pressure regulator that if you let it sit in the you know there's pressure in the rail and it drips into the intake manifold fills the whole thing up with fumes and also the pressure in the rail drop so that could boil you'll definitely have a hard time starting it when it's hot the other variable is the perch solenoid coming from the EVAP system if that's stuck open you drive around for a while the gas in the tank is warmed up there's pressure in the tank and it needs to escape it goes into the charcoal canister and if that purge solenoid does not close when it's supposed to when the truck's just sitting the intake manifold may fill up with fumes Okay so a couple possibilities what would you check first my thought process is the customer said that it takes a while for this problem to clear up like almost five minutes of driving which is pretty crazy if it was a liquid fuel you know dripping like say an injector wasn't completely closing and just slightly leaking once it fires up that should clear right up I mean within a few seconds and the truck should run fine uh fuel pressure regulator on this design it's actually in the tank so it's just one line going to the fuel rail it's kind of like a returnless early returnless system so that's not even a variable uh purge solenoid let's say the purge solenoid just mechanically sticks full open and it sits in the parking lot and the thing fills up with fumes and charcoal canister is you know saturated with with fumes that I think is more likely because that would take a little while to clear up you'll need to purge the entire charcoal canister uh before it actually you know clears up and runs fine at idle so that would be my first check just to see you know right now it says 100 Purge duty cycle basically shut the truck off locate this purge solenoid and see if we can just blow through it with the truck off it should be closed if it's not closed that's the problem if it is closed we'll you know we'll keep going maybe do some field pressure checks so it should be a fairly quick diagnosis uh this thing the engine lives you know right here but luckily we don't have to remove the dog house because the purge solenoid is right there look for the green cap The Purge line going into the engine and the line from the tank is parallel to that so I can disconnect it right by that green cap and try to just blow through the perch solenoid and see if if it's stuck open hopefully it's just that give you a simple fix so let's shut the van off now I'm going to let it sit so it's 11 12 a.m right now let's let it sit for 10 minutes so 11 20 we'll come back read the live data try to start it up and if it's a hard start it should be running pretty rich the oxygen sensor should say hey we're way too rich it's going to take fuel away until that charcoal canister cleans up then we can unhook the purchase solenoid and do that flow test when the vehicle is off actually let's just speed up the process [Applause] start the truck up I guess the one with the green cap actually goes to the fuel tank okay well let me disconnect the other hose all right so now the purge duty cycle zero and is there vacuum on this hose right here no there is not that purge solenoid indeed is is working Let's uh Prime actuation test purge solenoid let's not be running okay what about purge solenoid percent so right now the per solenoid is not okay you can see the purge duty cycle is ramping up that solenoid's actually working building vacuum at my finger now okay so maybe we're barking up the wrong tree here so I'm going to reconnect that we have to recreate this complaint so I'm gonna let it sit for 10 minutes we're gonna pull up some live data start it up and see what happens okay so while we're letting the motorhome sit in hot soak what's the next dot it's not the purge solenoid verified that took a couple minutes that's conclusive it's not going to be leaky injector I'm sure of that because it doesn't match the symptoms you know if it was a fuel you know fumes problem in the intake manifold that would clear right up and the truck would run fine the owner says he has to feather the gas for like five minutes and then then it's okay last thing I can think of is the idle air control motor so it has you know traditional throttle cable throttle body and a separate idle air control motor I bet that thing is just sticking closed and when it's you know really hot it doesn't want to do its thing and then once the truck starts up and fresh air gets in there and cools it down a little bit then it works fine that's my uh that's my guess so we're gonna have to take this doghouse cover off you know inside the van and then find the IEC we can look at the data pids what the command is uh for opening it maybe do a little tap you know if the van acts up you tap it and it just you know the idle stabilizes then we're exactly on the right track uh is it going to be no parts required maybe maybe not maybe it's just a little dirty and sticky because it works most the time he said the problem has been getting progressively worse over the last year first it would happen once in a blue moon then a couple times a week now happens he said every time you do a hot soap so um yeah I think that's the next step okay so doing a little research on this idle air control motor it's four wires so it's going to be a stepper motor design with four separate drivers in the description and operation they'll say I see stepper Motors mounted to the throttle body or at least amount of air bypassing the control of the throttle plate so it's a pintle that moves in and out take a little screw so there are four circuits two of the wires are for 12 volts and grounds by electrical current to motor windings upgrades that promoter One Direction other two are for 12 volts and ground to go in the opposite direction okay so you can reverse the polarity in both windings if only one wire is open Ice you can only be moved one step this locks the AC motor in place icy motor control system every step of the motor is moved so the PCM is smart as the stepper motor program that learns appropriate steps for the IAC to maintain the RPM in different scenarios AC power steering Factory adjusted set screw okay cool so before we tear this dockhouse apart I wanna plot the IAC data on the scanner and see if the van stalls out if it tries to force the IEC open all the way and it can't like what's the command I assume I mean if it was a circuit problem instead of code for sure so this might be a mechanically stuck stepper motor perhaps it's been hot soaking here for 10 minutes so let's fire up the scanner try to start it see if it acts up for us for some reason in this data list I cannot find anything has to do with the idle air control motor or steps at all huh it's like an engine RPM air intake temperature map vacuum minimum TPS time install this is all speed control so it's cruise control stuff spark Advance Target Governor pressure know what that is there's no IAC let's see if it acts up runs absolutely perfectly foreign see if that has the IAC counts hmm interesting got the cover off the engine here and our idle air control motor is conveniently located right there four wires I don't know it doesn't look Factory to me it looks a little too clean has some numbers engraved on it um not sure about that but with the snap on Varys check this out we have Target IAC and IEC steps do not have that on the thing tool Pros it just proves that there's no perfect scanner on these older domestic cars it's hard to beat the Snap-on that's the you know it had 95 of the other data but this is what we really need for our diagnosis and there's no way you're gonna get that from you know from your scope you actually want the computer to tell you what you know what it wants and what is actually happening here so let's graph those icy steps and Target IAC what happens when we just cycle the key let's try Stir It Up okay about 90. okay so we're at 87 there ready to start lose communication we're at 80. we turn on some loads headlights fan air conditioning for 91. okay interesting [Music] so right now the truck's starting fine functional tests minimum airflow RPM ATM AIS what is AIS okay IAC is AIS motor let's try that and we just want the iacc Target and steps we click on you hear it foreign you can even unbolt it from the throttle body and see if it's moving freely tap on it okay to exit leave actually a test we're going to click resume foreign let's get out of here it kind of cranks really weakly cancel exit [Music] foreign 110 steps now what is that screeching sound wow if your headlights are on definitely won't forget to turn those off [Music] foreign before it was like 80 now it's 111. that's kind of strange why would that happen hmm so I don't like how the IAC had to go up like 30 almost 30 steps to maintain the same idle that doesn't make any sense to me I'm gonna shut it down see back to 87 now eon [Music] we're starting at 87. let's see what it does stalls out now I'm going to put my foot on the gas a little bit help it out look at that ayak is at 40. 20 30. 87. that is very strange why would the computer be commanding the IEC down so far let's try again keep my foot on the gas a little bit 56 steps is gonna stall I was gonna stall okay now it's happy back to 87. put on the gas oh almost stalled out you see that oh okay very very interesting so the computer is commanding the IEC and why is it commanding is so low when you when you're on the gas actually you should actually open it up more to prepare for a D cell event this is this is nuts this kind of blows my mind Let's uh try again [Music] we're at 70. step on the gas I don't like that it's dropping the IAC so low and when I let go of the gas is going to stall out that's not correct at all so you raise our hands a little bit let out the gas ooh stalls out so that's our issue definitely has to do with the logic of the idle air control motor why is it doing this that's the question of the day neb kind of blows my mind why would it be commanding the IEC down to 27 steps when you're on the gas a little bit so you can see the TPS and then you let off the gas it's stalled out because the IAC was not open far enough is there a relearn is there some kind of reset you can look on the scanner but here the varus really shines in terms of graphing and having the right data pids without this scanner you'd be completely dead in the water I am 100 honest you can get your scope out you can you know hook them up to the IEC you won't have any idea what the computer is commanding this thing think tool Pros you wouldn't have any idea we need this Factory OEM computer live data to do this diagnosis so just keep that in mind

Channel: Pine Hollow Auto Diagnostics

Views: 30,875

Keywords: Dodge, ram, truck, stall, idle, air, fuel, IAC, throttle, control, adjust, diagnose, body, cleaner

Id: ZmoMRLSdP3c

Length: 26min 31sec (1591 seconds)

Published: Sat Sep 24 2022