Ford 460 RV Surges, Runs Rough but Nothing's Wrong?

I've broken one of the most important rules for mechanics no boats and no RVs it's a Ford it's a 1994 it's an E350 chassis it's got all the excess problems of a van all the wiring problems of a plow truck plus there's a giant wooden box on the back that you can poop in yeah foreign let's get to it it's got a slight identity crisis but otherwise pretty clean I think it's only got 27 000 miles or something like that so 460 gas engine under the hood and the problem is he said it runs pretty good when it's cold but as it warms up it starts to kind of run rough and he said eventually the engine will actually die while it's sitting there idling [Music] it's got the insufferable for door dinger the cursory big block exhaust manifold leaks so that's the issue it runs rough and then it kind of gets worse as it warms up being a 94 this is OBD1 so there's our diagnostic connector right there the only scan tool I have that really works with OBD1 is the old Snap-on solace we have to have some adapters so we need this Ford that one down there and then we're gonna need this thing that adapts my old school connectors to this OBD2 cable and then we're also going to need this 12 volt power supply cable which has a cigar lighter end on it so we're also going to need this cigar lighter adapter okay it says we need the 1A or 1B adapter with the da5 cable adapter we've got the 1B with the da5 so we're all set and we'll go to the codes menu these Fords they just kind of suck they have What fast codes and slow codes and Kion engine off key on engine running so it's doing a self-test I guess oh boy no Faults present it's pretty helpful see if we have data yes okay this is great so before we had live data you know on the scan tool the only way to see the value of you know any of the sensors and stuff was to install these crazy breakout boxes between the the connectors and the the PCM and then read the voltages with the you know a volt meter it was not handy at all right let's see if we can identify anything that's kind of out of the ordinary look at the O2 sensor basically stuck low second there we had a little little blip yeah right there so it tried to go into closed loop fuel trims like 11 percent I don't know if that works when it's still an open loop so that looks like the problem to me the O2 sensor is just dead I'm pretty sure we got a bad O2 sensor this thing but I want to be sure before we fully commit to the parts Cannon these things are basically magic and the problem with magic is that it's very hard to understand and it's very unreliable it's actually amazing that these things work at all what I think is happening is the O2 sensor is Under reporting so it's saying that the engine is lean when it's not and when it tries to go into closed loop it just starts pouring fuel into the injectors and it spikes way up and then the computer says that's not right and it goes back to open loop we can test the heater circuit so we'll just put a test light from positive to negative and see if we have current here in the heater we can also test the signal ground we'll just put 12 volt power to this wire here if the test light lights we've got a good ground then we can put that same 12 volt power to the signal pin and we can watch our scan tool and if the voltage on the scan tool goes High then we know we have good wiring for the the positive side of the signal we can do the same thing with a test light to ground and pull this down to zero if the voltage goes down to zero then we've got good you know circuit integrity and chances are we just have a bad sensor keep an eye on the O2 sensor voltage is coming down which probably means the heater is working but we're going to find out I'm going under with the test light okay good good okay so I've got two good grounds and I was able to pull that down to zero actually totally different you only like 100 millivolts the last time I have no idea what's going on what just happened just went from high to low hit it now it's stuck high again all right I mean it was stuck High the O2 sensor was stuck High then it was stuck low but it didn't seem to really make any difference on the the fuel trim it was in closed loop then it was in open loop didn't really seem to make any difference sometimes it responded to an artificial rich condition sometimes it didn't this is interesting five volt reference but it's actually five Max can't you just tell me what the problem is be a lot easier good morning it's the following day we're going to kind of forget about yesterday everything I thought was a problem was not a problem and I have no idea what the problem is the big problem is I'm a terrible businessman 95 percent of shops you know they would have said no as soon as they found out it was an RV the other five percent of shops they would have worked on it for about 45 minutes maybe throwing some parts at it and when it didn't solve the problem they would have called the customer and said hey pay us for an hour of Labor take your RV home and they would have washed their hands of it but for some reason I can't do that when there's a problem like this that I can't solve it gets stuck in my craw and I have to figure it out and when I do figure it out it makes me happy but it typically doesn't make me money so there's your macroeconomics lesson for the day anyway we're gonna see if we can get to the bottom of it I've got some ideas I just I don't know if I've ever seen anything quite like this before it's been a while since I made one of my trademark drawings now let's talk about the problem and we'll go through some of my various theories and I think you're going to see that none of these are correct so the problem is the engine runs rough especially at idle it has kind of a popping almost a misfire sound in the exhaust and you know the engine kind of drops out and then it recovers and it just kind of drifts around it is not running right he said it'll actually die I haven't experienced that but I don't doubt him my first kind of fixation was on the O2 sensor it seemed to be stuck low which I thought was making the engine run rich and keeping it an open loop so when the engine starts and it's cold it works an open loop it uses the air temperature the manifold pressure the coolant temperature the throttle position RPM various sensors and then it uses known values to guess how much fuel to inject to get the engine running the coolant temperature sensor is kind of like your choke when the engine's cold it needs more fuel as it warms up it leans out and then eventually maybe after three or four minutes the O2 sensors are warm there's they start working and then that's the primary feedback to the computer and it should go into closed loop the reason that it's switching high to low like this and staying there is because this engine has secondary air injection which I forgot about so there's actually a pump belt drive off the front of the engine that pumps air into the exhaust and when it turns on it's blowing oxygen past the O2 sensor so the O2 sensor goes High when it turns off it goes back low now I'm not sure why when it turns off it doesn't go to 500 millivolts it seems to stick down around 1 100 millivolts not going to worry too much about that I think the O2 sensor is working and it seems to be working correctly so my next theory was that it just had a misfire so I took my fancy little pliers here and I popped each spark plug wire off [Music] and they're all contributing so I don't think it's a misfire at least it's not a dead Miss so then I thought maybe it had a vacuum leak but this is a speed density engine so it uses a map sensor it does not have a mass airflow sensor and generally speaking vacuum leaks don't really affect speed density engine so make the idle a little bit high but they won't affect the air fuel ratio the only thing that I can see that's left that seems weird to me is that the 5 volt reference on the scan tool shows like 6.63 volts and I measured it at the map sensor with a multimeter and it's right on 5 volts so I don't know why the scan tool value is different from what we're seeing at the sensor also the timing Advance it seems to drift back and forth between 24 and 32 degrees and it just sharply switches back and forth now in my research I learned that on these old Fords the idle control depends on two things the primary control is the IAC the idle air control solenoid it's actually a valve in the intake that opens and controls the idle RPM the the throttle stays closed the valve opens and you know if you have a load like the AC compressor comes on the valve opens more keep it maintains your your RPM that I believe is working but apparently it also uses the timing advance to control the idle to make small adjustments so this is kind of like your course adjustment and this is your fine adjustment and it's supposed to move the timing advance to keep the idle steady and if it's if it's jumping from 24 to 32 I wonder if that could be the cause of our problem it does almost act like the timing is off so I don't know how to test that I wonder if this has a spout connector we could take the spout connector off I think that disables the timing Advance we could see if it runs better I'm gonna have to research that but that's kind of the only thing I've got to go on right now these three things have been a dead end yeah like I said I've never seen anything quite like this well definitely runs different do I hear a straight pipe Bowl hauler oh Peterbilt could knock me over with a feather anyway it seems to run differently with the spout connector unplugged so that means that the computer must be controlling the timing so spout stands for spark output I believe and when you remove this little connector it basically stops the computer from being able to advance the timing and it puts you at your your base timing so when you set the timing you remove the spout connector but the timing Advance is completely controlled by the computer the pickup is in the distributor it goes through the ignition module which is over here goes back to the computer the computer reads it deciphers it translates it advances it and sends it back through the spout connector to the ignition module which actually fires the the coil so if it can't control this the ignition timing does that mean we have a computer issue a PCM issue kind of looks that way I also don't like that vref being 6.63 or whatever volts I feel like it should be 5 volts unless that means something that something other than what I think it does I don't know a computer is buried back here in the firewall I'm gonna pull it out we're gonna take a look at it something we're missing okay oh oh I'm gonna see a problem that'll do it I wonder if that filter cap is on the 5 volt reference circuit I wouldn't be surprised if it is so that's an electrolytic capacitor and the electrolyte has leaked out and it rotted off one of the legs of the capacitor that's got to be the problem or a problem let's see if we can fix that so that is a 16 volt 47 microfarad oh looks like I've got some 47s 25 volts that'll work and then the other two are well let's see another one is 63 volts 10 microfarads that might be a problem 100 volts that'd probably do it okay I'll order these 50 volts well shouldn't hurt to go higher voltage so 100 volts will work cool pays to be a hoarder try to make a little map of the capacitors with the the negative side marked so we're going to go ahead and try to to de-solder these components everybody always hates the way I do this and they hate the way that I pronounce solder so I'm just gonna do it the way I feel like it and I will deal with the consequences down in the comment section kindly viewer sent me some new Wick and some suckers and a soldering iron which I've I have used it seems to work pretty well but I like my old Weller it's a Wes d51 kind of bench top soldering iron and I've got this fancy little Gizmo to clean the tips and then to desolder I like this old heco 808 pump this thing is great it gets hot here it sucks here does a pretty good job I built this fancy stand for it I think kind of the big problem is we've got this conformal coating on the board so it's this sticky nasty stuff that they spray onto them supposed to protect them from moisture but it makes it really hard to to do anything with them so we're gonna get some flux we'll try adding some solder solder first see if that kind of helps us so got to get the legs bent back up we got to do it without disrupting any of these tiny surface mount components next to it foreign up about as about as good as it's gonna get I saw it peeled the solder mask off here the electrolyte did but I think we're still good so that must be the ground side kind of same deal over here ground side um but this one right here pretty messy so the good news is there's the plated through holes are still there and I don't think there's any connection on the top side on that one it's all on the bottom side so we're gonna Jam them in there we'll see what happens so that's the 10 microfarad and then 47 47. let me just double check 47 47 10 and all the negative sides should face that way a little bit of flux all right that's pretty good there I feel like it's either going to work or it's going to explode spectacularly [Music] I think we got it not the way I expected but I think we got it so our Idol now is pretty much Rock Solid right around 800. the O2 sensors all the way lean if I cover up the intake for the secondary air you should see that come up I think there it goes anyway it's working all right I had percentage is a little lower it was around 55 percent our spark Advance is lower well pretty much stays around 25 I don't know why this beer app is still 6.65 but I'm not going to look a gift horse in the mouth I think it's good I'm gonna go ahead and put this air box back in oh I'm trying to figure out how I can possibly edit this video to make it make sense because I mean I was here and I did it and it doesn't make sense to me so I don't know what we're gonna do I mean I guess it's a win it runs fine now so obviously that electrolytic capacitor was the problem but I have a lot of questions and not any answers I don't understand the O2 sensor I don't really understand how that works at all how does the computer ever know whether it's rich or lean if it's using the secondary air injection system to just blast air right past that O2 sensor I don't understand why it idles an open loop I've seen other vehicles like that usually it's because the O2 sensor doesn't stay hot enough that you know it drops back into open loop this one doesn't seem to ever even try to go into closed loop so not sure what the criteria are for that I don't understand that V ref why it was at 6.63 volts what the vrf even means and we measured it at 5 volts at the map sensor and that was before I even mess with the computer so obviously the capacitor didn't have anything to do with that I don't know I still don't really understand that timing advance to correct the idle that seems like a really weird thing to do but yeah I guess we're going to move on so don't feel bad if you didn't didn't follow this one or you got kind of lost I'm right there with you thanks for watching yeah it's fixed must be a lot of fun to drive one of these in a strong crosswind you can see my trash can went for a ride they farmed this field last year not this year [Music] can't resist yeah go sh it's fine the wind's gonna blow it back [Music] don't get in the water that was our number one fan foreign that's normally a nice tame Creek not today foreign

Channel: Watch Wes Work

Views: 213,784

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Id: 6hh7zv21XlI

Length: 31min 41sec (1901 seconds)

Published: Sun May 07 2023