Rough Engine Idle Dies and No Start DIY Diagnosis

greetings two percenters well it has been a while so let’s dust off those diagnostic skills and see if we can fix this what is a 1997 Mercury Villager that was actually towed in so the owner states that the vehicle has been running very very rough for well over a year and he’s never been able to get it fixed because of some funding issues he is actually going to some school for a home nursing home health nursing program and while he gets this certification he’s really tight on money so he’s never been able to fix it obviously after he gets this home health certification and gets a job in his career he still won’t be able to afford to fix it but that’s okay because we’re gonna help him anyway he states that the vehicle was running so rough that it would die at red lights and stop signs but he can keep it running if he puts it in neutral and gives the vehicle some gas the problem is twofold now and the reason the vehicle is here with me first of all that became a little bit short-lived when the vehicle now he states has a complete no start so the vehicle is completely non running had to be towed in here and he states he was doing some research on the internet and YouTube came across my channel found out that I was local to him he contacted me asking if I would take a look at it and I agreed to look at it so we’re going to basically not charge anything here except for parts if we need them and see if we can get a diagnosis on what’s going on so let’s see if we can reproduce the symptoms and we’ll see how this works out all right well battery is completely dead well maybe that’s the no start actually well let’s hope so so let me get this thing on a charger and then we’ll try again in a little bit all right let’s try this again and nothing batteries definitely on dashboard lights come on got a dome light on fuel pumps really strong boy you can definitely hear it but nothing so I guess I misinterpreted this is going to be a non cranking no start I was assuming a cranking no start especially given those symptoms with the rough idle and then eventually it becomes a no start so not sure how that be related but we have to deal with what we’ve got in front of us exclusively so that’ll be a non crank no start let’s take a look alright let’s start with visual inspection now let’s be scientific about this so actually there is the starter motor is right there on top of the engine which is pretty interesting so actually I could if I had a long enough screwdriver I might be able to stick that in there and touch those contacts together see if we’ve got a dead starter motor the other things sometimes I’ll do is just bang on the starter motor but I will admit it it could be a bad starter motor here let’s just see if we can um verify that but we know we don’t have to check battery connections and all that I’m sure you could hear that fuel pump running from inside the vehicle that’s only gonna happen with a really strong battery we can see there’s a dome light actually you can’t see it but there’s a dome light for the engine hood and it is just really bright so I think what I’m gonna do is it’ll be easiest if I just get in here alright let’s just see if we can bypass this oh you can okay so you can hear the starter motor works just fine so let’s see if we’ve got control to the starter next that would be my guess is what must be our problem here maybe ignition switch problem or something because the guy had to keep restarting and restarting and restarting so much so let’s see if we’ve got control do the starter alright real a box right here Wow who designs this the radiator right in the way of the relay box and let’s take a look here um no starter relay in there so it’s gonna be inside the car some models have that let me take a look inside the car alright no passenger compartment relay either so I missed something here and guess I didn’t I don’t know what the deal is there’s a couple of these relays I’m not familiar with the terminology let me do a little checking on this with me there’s an owner’s manual or something I’ll be right back alright apparently this inhibit relay is the one

I want so let’s that’s not coming out alright let me get something I’ll be right back alright this relay has a lot of pins so I am really not familiar with this at all it’s probably some type of anti-theft I’d imagine or something so let’s take a look at this relay map here and look at control side so let’s do a test and see if we’ve got a lack of control or a lack of load side or possibly bad relay 2 so let’s get a voltmeter see what happens um yeah I can’t see the contacts but just testing the control side here let me just double check power just take it I think it’s this one yes okay good so I am sure this is probably going to be ground side switch well actually the course it’s ground sites which has to be we know that now so quick way I want to make sure we’ve got control coming on this thing so I wish I had somebody else to help get this thing into the crank position actually let’s do this let’s do this by process of elimination so let’s do a load side alright maybe let’s give a little better indication what I’m doing here so now what I want we’ve got control power we need to verify that we’ve got the ground side switching there it’s a little hard for me to do myself without somebody cranking so what we’re gonna do is yeah process elimination alright so let’s see we want to do load side that’ll be six and seven with all these pins six seven okay so let’s go well this won’t give anything of course so let’s find out which one is power so going over to battery negative and nothing there and nothing there interesting unless this is power side switch so let’s find out it’s battery positive and nothing there and oh wow okay I’ll be I’ll be darned okay did not see that coming so in that case so I’m not going to be able to do my usual jump with a paperclip here because of what must be some anti-theft system so let’s go from whatever this inhibitor is he is power side switched to so let’s do this I just want to make sure that my integrity is there right now everything’s looking pretty good except I can’t really verified my power side switches so well but what we’re gonna do so let’s see if we can relocate this meter what I want to do is verify my power side switching on this goofy system alright since you guys are probably wondering what the hell I’m poking at here’s a little crude map that I drew of the circuit so this is our relay obviously and this is our port obviously we’ve got a little bit of a problem here and that the load side is power switched with the ignition so that’s what we’re looking at right now so let’s get back to the car alright so now using our map let’s see some should have let’s see whether this is power side control on this interrupter thing and it is okay because there’s a ground so let’s see so that means number three so four should be feeding power during a crank so let’s see if we get that to happen let’s start this and alright kind of looking bad for this relay I would say probably easier to just test the relay at this point so let’s go over to the workbench and test this relay let’s just start off the basic so let’s do a continuity test on the control side so let’s test our lead there that works great so make sure we’re in view here Wow check that out alright well we could also have a

problem in internal in the car but this relay definitely is bad so easy diagnosis there let’s go get another relay and this car should start we still haven’t ruled out everything internal but obviously no functioning control we’re not going to get power to the starter right so let’s go ahead and take care of that all right one thing by the way a lot of people just swap relays yeah well guess what you can’t that’s a unique relay in that car because of whatever this goofy system is so you’ve got to know how to do this stuff you can’t always just swap a relay look at that oh and this car runs terrible Wow listen to that get you listen at the engine hang on yeah that engine is running really bad alright well let’s see here because of the dead battery we we don’t have a check engine light on maybe there was a check engine light on before there is not one on now this car sounds like it’s gonna die yeah this car definitely sounds bad kind of sounds like misfire a little bit this guy says it runs better when you give it gas oh wow definitely does it runs perfectly smooth when you give it gas that’s that’s going to be a vacuum leak no doubt about it so unrelated with whatever that starting issue with solenoid was but you know what I’m thinking that no start diagnosis was pretty quick and a no start diagnosis especially a non cranking one usually is really fast so let’s just continue on in this video and see if we can find this vacuum leak here at least I’m assuming it is one all right we’re gonna go old school here well old school for this channel remember Auto tap the very first skin tool that I ever had in the started the channel with and got it keep this thing running before it dies but God it does run terrible so let’s see what data we want to pull here one of the things I’m looking at is a negative long term fuel trim now this is probably still an open-loop and also remember the battery was dead so let me let this warm up for a little bit get the engine coolant temperature yeah so let’s warm up for a little bit here all right just inner closed loop so let’s get some data and obviously no-brainer here we’re going right for that fuel trim we are gonna want long term and short term so let’s get long term there and let’s get short term I saw earlier okay and I’d like to get a pink one oxygen sensor on here too so let’s do that on a different graph that’s one of the things I really like uh toe taps still the best user interface of any scan tool I’ve ever seen yeah it’s no longer supported in everything but we just need a sensor one obviously and looks like we’re gonna have oscillation huh okay let’s bring up that fuel trim because I’m a little concerned here because we don’t have a vacuum leak all right well as you can see this is not indicative of a vacuum leak at all so well that saves some time with the visual inspection doesn’t it man we would have been looking all over for a vacuum leak to no avail it actually gets richer with throttle so again not a vacuum leak here I am very surprised by that but just goes to show you know that that that getting this data before you do your visual tells you where to do the visual we’ve been looking all over for vacuum leaks spraying it down the brake cleaner or blah blah this is not a vacuum leak it’s definitely not a vacuum leak so what the hell is going on here so this looks like probably a fuel pressure problem so let’s look at fuel pressure regulator so what probably is happening is fuel pressure regulation problem let’s go over the fuel pressure regulator okay you’ll pressure regulator right here so what’s probably happening is we’re not getting vacuum to it or there’s some issue with it well there’s definitely

vacuum to it no doubt about that let’s me see if I can get a vacuum pump real quick so what I’m doing is getting a vacuum line on to the fuel pressure regulator right now okay and I’m going to apply vacuum okay we can see it holds vacuum see that and we’ll eventually get stabilization of that fuel trim again like that okay this is not a fuel pressure regulator problem Wow all right got that fuel pressure regulator vacuum hose back on and you can see that we’re normalizing again back to before and it’s not overly rich and also notice my long-term trim is not changing I just noticed that so what’s going on with my long-term trim let’s see if we can get reaction no it does it does function so so long-term trim and only negative seven and we see the short term obviously we’re ruling out regulator problem fuel pressure is kind of coming to mind except for one problem and that is that it actually runs a lot better under load that would not be indicative of a problem with fuel pressure but I am inclined let’s see if we’ve got a Schrader valve on this thing we do not there’s no Schrader valve but I I don’t see a reason to measure fuel pressure given this let’s try getting the throttle up again that is not a fuel pressure problem all right well obviously your parts cannon pirates gonna put some plugs and wires in this thing right now ignition problem not indicated here again the RPM increase it could be but I can tell you them it’s definitely not and the other thing too is we’re not running lean we would be running lean with with an ignition misfire here what I wanted to do let’s see if the check engine light might have come on no check engine light but one of the things I do want to do is uh let’s get on some mass airflow reading here actually let’s make it nice and big gosh another nice thing about Auto taps so let’s see what we want to do this could be a timing problem for sure let’s actually check that we want to change this gage okay this will be timing advance that looks good so I don’t believe we have an issue there I am quite convinced we don’t have an issue there let’s like to get a map reading um have map up here but we do have math so let’s get a map reading and that’s gonna be about right yeah all right I’m running out of ideas here let’s look at throttle position see if we can graph that that I doubt is going to be an issue but let’s see if we’ve got that available we do okay a little bit slow on the feedback for sure let’s get a wide open throttle blip here yep good well almost anybody else is gonna say you know hey you got a smoke machine you

put smoke machine on it why why would I put a smoke machine on a car that does not have a vacuum leak it makes no logical sense it makes no logical sense in the same way that putting plugs and wires in this thing is going to make no difference what are some variables like this could be maybe some high fuel pressure so instead of low fuel pressure causing this maybe there’s a really really high fuel pressure for some reason and that’s why it’s running better under load but not with idle I think of fuel pressure test is in order here and this car is going to be too old to have a kid for that and we don’t have a straighter valve either galley but fuel pressure is really on my mind right now so I’m just double checking again and I do not see a Schrader valve here following up there’s a fuel line others EGR valve I guess we could try that so hang on a sec let’s unplug that valve okay so there’s EGR hose right there and then let me connect something up to that EGR valve and let’s just see what’s going on there okay so connect it up to the EGR valve right behind this hose right there let’s just see if we can kill this engine and well it holds pressure and there’s absolutely no change in the engine absolutely none whatsoever this is gonna be a stuck open EGR valve the diaphragm still works but the EGR valve is stuck open let me see if I can um sometimes you can really open these up and then snap it closed ooh do you hear the change there let’s try that a couple times still running a little rough that’s better still a little rough though yeah this is definitely an EGR valve problem well we got lucky there didn’t we hear that idle change so we definitely have a problem here because the EGR valve is not working all the way this should kill the engine this car needs an EGR valve it’s not a blockage obviously of the port or anything it’s just that the diaphragm is not closing all the way at idle is what’s happening actually that sounds really good now Wow let’s check our fuel trim oh yeah check it out engine sounds really good now we can see that we’re bringing our fuel trim back up let’s see where it zeros at hope beautiful that is awesome all right well obviously we’re gonna carry our long term trim up there we’re at four on the short term quite honestly this car may well be fixed I guess we’ll just kind of see what happens if it if we get a reoccurrence of the problem we’ll replace that EGR valve but that’s a fix wow that’s beautiful that is just gorgeous I would wait for awhile to get this long-term up but quite honestly I got a flight to catch so we can see clearly we don’t need any further validation stuck EGR valve all right well I wonder how many guesses it would have taken a parts changer before they finally got around to EGR valve I guess it wouldn’t be first on their list or even fifth but we did get a little bit lucky there it just happened to be as I was gonna put the fuel pressure gauge on I saw the EGR valve made me think that’s a viable variable and ya had the EGR valve been located somewhere on the back of the engine I would have put a fuel pressure test on seen that’s not the problem but we still would have got there eventually but that’s science for you science it works [ __ ] wait a minute science it works [ __ ] because of our scientific methodological approach we changed only the parts that needed to be changed in fact we probably will get away with no parts on the rough idle thing we’ll see how the EGR valve holds up but all we spent was just a few bucks for the relay for the starter that’s it so that’s how we do it on this channel no guessing no parts cannon just get right to the source of the matter fix it and let’s move on speaking of which I will try to be back with another video sooner rather than later I know some of you guys are wondering what’s up with the pay channel

we’ll catch you up on that as soon as I get some free time so hang in there with me don’t do anything different and I’ll be back you