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Hey all,
Longtime watcher of Eric’s videos here, and I can’t seem to figure my problem out. I reached the edge of my knowledge, watched some of his videos and learned a bit more, but I’m stuck again. Since I’ve got an older car that I work on pretty often, I figured I should finally just register for the forum community and see if I can learn some more. I have no formal training, but I can read a manual and know my way around a toolbox with no issues taking things apart and then putting them back together. So here’s the rundown (apologies, it’s going to get a bit long as this is a bit of saga):
1997 Altima GXE – standard issue, no mechanical or trim customization
2.4L 4-cylinder automatic
162,000 milesI found this ETCG video which helped me eliminate some causes:
Last July, it began to stall out every so often. It had probably been running a little rough for some time before that, but I may not have noticed – it’s been a while since the problem began. My Check Engine light never came on. The problem felt like a misfire – jerky acceleration, sputtering and rough idle, and the occasional stall while idling. I bought the car at 111,000 miles and the mileage was up to 152,000 when the problem began and the plugs hadn’t been replaced since 110,000. So I checked them, they seemed to work OK when tested but were dirty enough that I couldn’t tell if they were corroded, so I replaced the plugs/wires. No change in performance.
Next up, I checked the distributor cap and ignition rotor – no carbon streaks on the cap, and the terminals looked OK. I brushed what little buildup there was off of them. The problem persisted, so at this point I’m thinking it’s fuel or air. Again, no check engine light is on so I have no idea yet.
Fuel filter is a cheap part and I knew the original one from 1997 was still in there, so I replaced it. That wasn’t it either, and at this point I’m just dealing with the car running awfully – gas mileage down to about 18 MPG from a normal 23 MPG for my usage. Then it starts behaving mostly normal for a few months, until last October when it gets really bad. It would stall out almost all the time at stoplights, and have poor performance even at highway speeds, with jerking acceleration and surging. After a stall, when I got it restarted, it would smell like a go-cart. Nowadays after a particularly bad stall, it can take over a minute to restart as the engine sounds starved and once it does, a cloud of smoke comes out of the tailpipe and it REALLY smells – more like fuel than like sulfur, but it’s hard to tell exactly what I’m smelling.
Last month, I got sick of trying to troubleshoot it on my own and took it to a mechanic. They found and repaired an air leak in one of my intake manifolds, which I could actually hear but didn’t have the time or daylight to fix myself during the winter. They also replaced another vacuum hose but did not tell me where, and my knock sensor (the check engine light came on the day before I took it in for repairs, and it was the knock sensor code). However, the problem persisted! Still no check engine light related to the issue. I took it back to the mechanic and they told me it was the MAF sensor. Being unwilling to pay $200 for a part I could get for $45 online, I decided to do it myself. I put the new MAF sensor in and the vehicle wouldn’t even stay running after 3 seconds, so I put the old one back in to get back to where I started. Visually checking the MAF, it appears to be fine and not dirty. The air filter is also pretty clean. I checked the harness connector for the MAF, and got 26 Volts – this seemed to be really high, but the repair manual just says that I should get a reading, any reading.
I checked my fuel injectors next (following the ETCG video, of course), and they all clocked in at 11.6 or 11.7 Ohms, which is normal. Unplugging the connectors to the injectors makes the engine perform worse for each one, so I’m pretty sure it isn’t an injector. We’ll call it 98% sure.
This gets me to thinking it’s a dirty throttle plate, and while researching that I discover the EGR valve. I take that off first as my throttle body is somewhat hard to get to. The EGR valve is absolutely caked in black carbon, so I clean it out really good, including the little mount that it connects to. Really dirty work! I didn’t get it perfect, but I wanted to see if there would be a change with as much black crud as I took out of it. The valve does hold a vacuum and the plunger moves/returns when I depress by hand. I also cleaned the throttle, but it wasn’t very dirty to begin with. I put it all back together and…. the problem persisted.
However, this time I got a check engine light. The code is P0400 and P0302, which means exhaust and multiple misfire. The repair manual has checks for me to do for these codes, and I’ve tried the first one which involves manually checking the EGR valve while revving the engine from 2000 to 4000 RPM. The plunger does not move, and when I depress it by hand while the engine is running I can stall out the engine. The repair manual says that this means I should replace the valve, however if there is no vacuum leak and the plunger doesn’t get stuck when I manually depress, shouldn’t this be fine? There is a solenoid valve that controls the EGR… but I have not been able to test it and am in fact a bit confused at this part.
A friend of mine suspects it could be the catalytic converter, but I’d like to stay focused on the EGR valve and EGRC-BPT for the moment as that’s what the error code refers to. There is a separate error code for the cat., which is P0402. I suspect my cat. is welded on rather than bolted/clamped, and I don’t have the tools to deal with that right now.
Any insight, tips, or links appreciated! Near as I can tell, I have it narrowed down to an exhaust problem of some kind, where exhaust is building up in the engine and choking it. I need to maintain pressure on the accelerator to prevent stalls, and sometimes pumping the accelerator will temporarily clear the problem (for a few seconds to a few minutes, at random).
TL;DR / summary:
Vehicle is stalling frequently at low RPMs, typically not until operating temperature has been reached, and has a smell while sputtering or restarting from a stall. I need to keep my foot on the accelerator quite often in order to prevent the vehicle from stalling out while driving in traffic, which is less than ideal and not very safe. Repair measures taken:
-replaced spark plugs/wires
-confirmed condition of distributor cap/rotor
-fixed intake manifold leak
-checked resistance on fuel injectors
-replaced fuel filter
-checked MAF connector voltage, and visually inspected MAF
-swapped MAF with OEM part and problem got worse, vehicle actually runs with old MAF installed
-checked vacuum on EGR valve and cleaned EGR valveDTC given is P0400 and P0302, but only recently.
Tools available to me:
-basic wrenches/sockets
-OBD II scanner arrives Tuesday/Wednesday of this week
-multimeter
-anything you can get from an auto parts storeI can provide reference to the repair manual (including screenshots/images) also.
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Just as a quick look over the post, (Excellent documentation of events, and attempted repairs, this should help those with the proper knowledge help you quicker!), I read this:
“The repair manual has checks for me to do for these codes, and I’ve tried the first one which involves manually checking the EGR valve while revving the engine from 2000 to 4000 RPM. The plunger does not move, and when I depress it by hand while the engine is running I can stall out the engine. The repair manual says that this means I should replace the valve, however if there is no vacuum leak and the plunger doesn’t get stuck when I manually depress, shouldn’t this be fine? ”
It would seem to me you found at least part of the issue. The book (If its an FSM, it was written by the people that built it, or otherwise, someone who knows what they are doing [hopefully!]) recommends replacing the valve if you can stall out the engine. It could be something else other then vacuum involved with the valve.
I’d probably start there, at this point. You’ve found an issue that needs replacing according to the book!
Thanks for the response! My issue with just buying an EGR valve and hoping it solves the problem is that the manual says I should replace if the plunger doesn’t move. However, if I move the plunger on my own, as soon as I make it start moving the engine begins running worse. This makes me think that it may not actually be the problem? Am I understanding incorrectly here? Here is my understanding:
When “at rest”, EGR valve is closed (plunger is not depressed). When it receives a vacuum signal from the solenoid valve (my EGR is 100% mechanical, not electric at all), it should open the valve – meaning the plunger will depress. I guess I’m not understanding how if I simulate by hand the functioning of the EGR, and it makes the idle worse, that means the EGR isn’t functioning properly?
Update: EGR Valve test
OK, as an update… while I was making a few short videos of what’s going on, from inside the cab and under the hood, I was able to properly test the EGR valve. I held 2 fingers under the valve to feel the plunger while I revved using the throttle cables. I had previously tested with a coworker, and she must not have revved the engine high enough.
As I revved using the cables, I could feel the plunger depress on its own, so the valve is working. Also, it got really, really hot!
Another update. I’d already watched this ETCG video last week, since my friend had been telling me of catalytic converter symptoms (http://youtu.be/9VZ5K8n5jj0)
I got my scanner on Tuesday – an Autel MS509. On Tuesday while I was driving home, I hooked it up and loaded up several custom data sets including ETC temp, O2 sensor 1, O2 sensor 2, RPM, MAF sensor flow (I actually don’t know what the “g / s” unit is…), and Load %. Unfortunately, the data print outs from the scanner aren’t that useful as they update slower than the data itself updates while driving the car, but here is what I found:
My operating temperature is in the mid-80s Celsius. (Is that hot? Seems like it is, but it’s been running at these same temps for 2 years)
While driving at operating temperature, and while experiencing the sputtering/poor performance, I noticed that the O2 sensor 2 jumps around a bit (from 0.4V to 0.8V, but not as rapidly as in Eric’s video) while the O2 sensor 1 doesn’t change a whole lot. It starts around 0.6V when I first start the engine, and gets up to 0.8V – 0.9V at operating temperature. It pretty much hovers around the same value the entire time.
Does this test tell me anything? The O2 sensor 1 should be showing rich/lean changes, correct? But it is not, so does this point to a problem prior to this point in the exhaust system, basically confirming that my problem is in the EGR system?
I still have the P0400 code and no others. I made a few videos on Monday evening, however need to load them onto the computer and edit together, all that jazz. Now that I have the scanner, I can show what I see with the scanner also.
OK, I have some updates. I have more documentation on my phone (pictures/video), but I think I have nailed down the problem. I’d like to think out loud here, and maybe somebody can tell me if I’m off base? All I know is what I’ve “learned” on the internet, and my education could be incorrect…
I went ahead and replaced my EGR valve with an OEM I ordered on Amazon. The car immediately performed differently. In some respects, it was better – smoother idle, sometimes, however it still stalled out about 30 seconds after the second time I started it. I drove it later that night to get my girlfriend from the Metro station, and the CE Light came on. Maybe strange to some folks, but I was actually really excited that I finally got an error code so I could continue troubleshooting. Once again, it was the EGR system code. So I put in the EGR-BPT valve (at least that’s what Nissan calls it – in universal terms, I think it’s the solenoid/valve that controls the EGR valve), another OEM part I had ordered on Amazon as that’s the only place I could find it.
Again, the car ran differently. The EGR code (P0400) is gone and hasn’t come back, so I know that was part of my problem. However, I was still stalling out and I couldn’t figure out exactly what was going on. The O2 sensor readings didn’t seem conclusive, at least from the previous videos I’d watched on the catalytic converter diagnosis. About a week went by before the car started running very roughly, intermittently, just like before – however it caused the muffler to disconnect from the exhaust system. (Awesome :unsure:) So now I rattle and rumble down the street. Pic attached… am I correct in assuming that I can take that anywhere and they’ll be able to weld it back together? It’s worth noting that there is a TON of black stuff immediately following this breach. You can see it in the pic.
I then bought an IR thermometer (along with a vacuum gauge) and this also seems to be inconclusive when I look at the catalytic converter, however I noticed that my car seems to have the California emissions system – and so it has a “pre-cat” up under the exhaust manifold. After some googling, it seems to be a common problem that these things overheat and fall apart, causing exhaust restrictions/misfires/engine damage.
I am still getting an error code almost every time I commute now. P0301 misfire. Looking in my repair manual, I see this:
When the code comes on for the first time, about 50% of the time, it blinks 5 times before staying on. Other times, it simply comes on and doesn’t blink. It took forever to find this in the manual, and I just found it by browsing. Looking up by code doesn’t mention the “three way catalyst” at all for codes P0300-P0304, and of course I can’t search the text of the manual as it is all hyperlinked.
So my thoughts are this: I should take the so-called “pre-cat” off of my engine, bang it around and get all the melted bits out, and then put it back on. Since I’m not in California, I don’t need it. However, since there’s so much black crap getting spat out onto the front side of the muffler, maybe I need to also replace the actual catalytic converter? Given the length of time I have been experiencing this problem (basically because no shop I went to could properly diagnose it, much less fix it), I think the entire exhaust system was basically FUBARed.
TL;DR –
1) Replaced EGR and BPT valves. EGR and multiple misfire codes fixed.
2) Bought IR thermometer, measured in front of and behind catalytic converter. Temperature is right around 350-370 degrees F at both ends…
3) Excessive rough running made my muffler disconnect from the rest of the exhaust.Read through as best I could One thing I would of done is blanked the EGR off yes this would introduce a fault code in the system but you would be able to see if there was any difference in the running of the vehicle that will give you a good indication of how the EGR is functioning if you are unable/unsure how to test it properly.
One thing that caught my eye is the MAF sensor and installing a new one causing a no start condition that is something I might investigate further.
precats can collapse internally causing a build up of back pressure which will stall the engine
Honestly looking the time and energy you’ve put into this car I’d of sold it a long time ago
[quote=”Fmxvxx” post=132586]Read through as best I could One thing I would of done is blanked the EGR off yes this would introduce a fault code in the system but you would be able to see if there was any difference in the running of the vehicle that will give you a good indication of how the EGR is functioning if you are unable/unsure how to test it properly.
One thing that caught my eye is the MAF sensor and installing a new one causing a no start condition that is something I might investigate further.
precats can collapse internally causing a build up of back pressure which will stall the engine
Honestly looking the time and energy you’ve put into this car I’d of sold it a long time ago[/quote]
Thanks. Judging from how badly clogged my EGR valve was and all that, I think that while the EGR valve wasn’t my original problem it definitely needed to be replaced.
I will be hooking it up to the vacuum gauge tonight, assuming I can get the front O2 sensor out to check the back pressure. I’m 99% sure I’m going to see a pretty high back pressure reading… but the O2 sensor has a 22mm or 23mm nut, and I only have a 19mm wrench as my biggest. The manifold’s heat shield is in the way to get a pair of grips on it, so that will have to wait until I get home from work.
Unfortunately, the problems began and continued through a period of time when I had to use all extra cash to pay off emergency trips (deaths in the family) and medical bills, so I just couldn’t get together the couple thousand bucks for a new car – especially since it would only be a couple hundred bucks to fix it. Even harder to sell instead of fix when it would be cutting into the price I could get for this car, which is cash I’d need to pay for the replacement. Being poor with an old car really sucks.
That said, I’ve learned a ton throughout all of this and given that I’m 28, assuming that I can put the knowledge to future use… I judge it worth it, even though it’s painful right now. I just want to get the thing fixed.
I used to own a 97 altima. I had the same issue with mine. Turned out the cat and the.muffler were.bad. my gas mileage stayed poor until I replaced the gas cap also.
Knock on the cat like its a door. Do you hear stuff rattling around? Replace.it. when I took the muffler off my altima, it weighed 86 pounds. It was THAT full of black soot and carbon. I was also the first owner to do any maintenance on it, so it ran dirty for years. After I changed.the cat things.improved a bit, but the.muffler being so incredibly full of carbon was my biggest problem.
Alright, updates, since I still have the thing and am actually working on it (slowly…).
I did test “knocking” on the cat when I was first trying to figure this out. I don’t recall it making any rattling noises – sounded solid but hollow.
The muffler is actually disconnected from the rest of the exhaust line at the moment – the shaking from the misfires caused the weld to break, so the exhaust effectively exits the system just prior to the muffler now. So I think I can rule that out as being clogged. Besides that, the front side of the muffler is caked with black crap, so it’s clearly “upstream.”
I bought a 2001 Accord 3.0L V6 at the beginning of May, and have since bought/moved into a house (which needed project time also), so haven’t really done much on the Altima until recently. However, in order to drive it the 4 miles to the new house, I tried to fix it again at the old apartment. All I did was take the heat shield off of the front of the engine block, and attempt to get the exhaust manifold off (there is a hairline crack in the front of that as well), as replacing that piece is relatively inexpensive via Amazon and I suspected that the clog might be in the “pre-cat” (I seem to have a so-called California model).
During this process, I removed the front O2 sensor that is seated in the exhaust manifold, and had a look at the “pre-cat” guts. It appeared clean/fine – the latticework was not melted, and I didn’t notice any soot or anything, with what little I could see with a flashlight and peering around.
So I put the thing back together…and it ran “fine”, albeit loudly, for a while. I drove it to the new house and started it up every 3 weeks or so to keep the old battery charged (it was slowly losing charge). The battery has since failed (2011 when I bought that), but I’ve got the Accord handy if I want to jump it. When I started it up the last time, about 3 weeks ago, it was back to misfiring and running rough.
Also, while it was sitting for 6 weeks at the apartment, the fickle left front brake caliper seized up and I have to fix that too :whistle:
Last weekend it was rather warm, so I went out with the goal of getting to the EGR passageways to see if they are completely clogged up for one or more cylinders. Thus far, I’ve removed the EGR valve assembly and some of the other stuff at the top of the engine there, taking pictures as I go so I can be sure to get it put back together exactly the same. I have yet to take the fuel rail off, but that’s next. I have some more learning to do. The thing isn’t really worth much in the condition that it’s in, even with car prices around the DC area, so my plan is to slowly work on it. I’ll replace the caliper for sure, but am starting with the engine troubles.
Paying for registration/insurance on the extra car is only costing me about $15-20/mo in total. If I can resolve the engine issues, then I am fairly certain that the car will pass the state inspection once I also fix the caliper and have the muffler welded back onto the exhaust, and I would be able to sell for $900 – 1100 ($1100 being the KBB “fair” price). If I can’t resolve the engine issues, I could junk the car for about $250 or maybe fix the caliper and then try to sell to someone who could repair/replace the engine for hopefully $400-500. I’d love to fix it and sell it (or even hang onto it, as I’m somewhat sentimental about it), it’s just a matter of finding the time to learn and then do. I might be able to get out into the driveway tonight, after I work on our bedroom closet first B).
Amusingly, the Honda had a clogged EGR when I bought it, but I knew that on the first day that I saw it and did my research that night. Bought it the next day and cleaned it out, no issues with the EGR in it since then, although I am having general “old car” problems with it now.
Well my friend, it appears that you are having all the fun!
Your exhaust issues seem like a pita. I had the same locked caliper issue on mine. It was actually the caliper mount. The mount has the caliper guide pins and all Nissans are known for those to freeze up solid regularly. A new caliper mount at Autozone is likely around $20ish.
The other thoughts I have on your exhaust, is that the manifold leak may create too much free flow, confusing the ecm to react oddly. I know a giant myth with small engine enthusiasts, is that a fart pipe is a good thing. I’ve seen real dyno numbers and those things are proven to lower performance, unless your running N0X which most of us don’t. Multicam engines rely on some back pressure to make power. Reduce the back pressure and it runs poorly and uses way more fuel with lowered performance. I did a lot on my altima to bring it up to spec. I even tried the fart pipe out, but ditched it for a new stock unit and loved the return of power. When those engines have regular maintenance done with decent parts, they run like a beast for a small car. If you ever have questions on good parts to get for it and which ones to avoid, just ask.
My only other suggestion after replacing the manifold, is maybe do a back pressure test at a muffler shop. Many will do that for free or nearly free.
Let me know how it turns out, I’m happy to help!Thanks. It’s definitely possible that there’s an issue with the muffler being blocked, but even if so there’s definitely an issue farther up as well. I wouldn’t be surprised if the issue farther up caused a lot of buildup in the muffler, but I’ll get to that if/when I fix the other stuff.
This occurred to me on the way home today, but I could have just taken the O2 sensor out again when it started running rough a few weeks ago to determine if the problem was exhaust manifold and beyond, or pre-manifold. I might reassemble it and test that out first, because taking the engine apart to get to the EGR passages. It might be inconclusive, but it would give me another data point at least. When I was posting earlier, I forgot that I had actually done something similar to this before. On the exhaust manifold, there are mounting screws…and 2 of them actually plug up holes into the exhaust itself. When I opened those up, I think it ran better. I put them back in so I wouldn’t lose the bolts. There’s something weird about the manifold also – there are only 4 bolts holding it in, but holes for at least 6. Here’s what looks to be an OEM replacement for the manifold itself (not a bad price, if my problem is in here I wouldn’t be displeased):
http://www.amazon.com/Dorman-674-508-Exhaust-Manifold-Kit/dp/B000E35VRA/ref=sr_1_6In that picture you can see where there are placeholders in the heat shield for where bolts/screws would go. Towards the bottom (right) end is where the 2 bolts are that I took out and clearly felt exhaust leaving from the holes. I thought this was weird.
One thing that peeves me about this is that I paid several places several hundred bucks to fix various things, most notably an intake gasket leak (who knows if that actually existed… I’m not sure that shop is very good – they just told me it was the MAF sensor after the gasket “fix” didn’t fix it), and got nowhere. They basically had no idea, or it would happen to run fine while they had it. The last place I took it just unhooked the EGR valve hose which made it run fine, but I had to pay them for “diagnostic time” as they spent several hours fooling around with it. I wish places would just listen to me when I tell the guy who’s going to be working on my car, directly, exactly what I did and what I found. I didn’t plug the EGR hose, so there was a potential vacuum leak there, but it ran smoothly for a week or so and then began misfiring again.
So at this point I’m treating it as a learning experience/potential project car. Good point about the caliper – when I bought this car, the same caliper locked up about a week after I got it home. I noticed when checking this one out that there’s no way that’s a 4-year-old caliper on there now, so it was either rebuilt or it was the mounting pins that locked up rather than the caliper itself (I paid a guy to do it). When we moved, I priced out the caliper parts. I want to say it was $30 for a caliper WITH bracket at Advance.
I agree also that, if the engine were maintained properly, it would keep going for quite a while and be a good little car. It’s only got ~140K miles on it. I suppose I’ll keep posting as I investigate and learn things. Don’t have time tonight to put it back together and check it by taking the O2 sensor out. I actually have a vacuum gauge, but can’t seem to use it properly to test for back pressure at the manifold.
Alright, I’ve been able to get back under the hood. I made sure I knew where everything went in order to put it back together first, and then went about figuring out how to get the fuel rail off and what I would need to do in order to get at the EGR passageways. Unfortunately, it looks to be a near-impossible job.
Why am I even doing this? Because if it’s the EGR passages being clogged, then all I need to do is clean those out, replace the front right caliper, and have the muffler welded back on… and then the car should pass MD inspection, meaning it would sell for $1100 or thereabouts. I’m looking at $48 from Autozone for the caliper and a few hours of labor on my part. I already have a set of front pads, as I know those are low. I don’t know what a welding/exhaust shop would charge me for the muffler work, but I’m hoping $200 or less. So that’s $250 plus my time, if it’s the EGR passageways… and without getting it to pass inspection, we’re looking at $300 or so to sell it. Maybe $500 if I’m lucky enough that someone who can fix it on their own springs for it, but in MD you can’t register a vehicle unless it passes inspection. So that’s why I want to fix it. I have until the end of June before it costs me another $65 in tags registration (which I’ve already paid, but would be refunded). Oh, and it needs a battery, so another $120 or so brings the estimated total to $370 plus time, against about $600-800 difference in sale price (there are a few ’97 Altimas on craigslist right now in my area for $500 that also need repairs, but they all run, allegedly…).
Going to upload a few pics here in a moment.
Circled in these pics are some bolts/nuts I am going to have an awful time getting to in order to get this thing off. From the linked picture in question 2, it actually appears as if the thing that holds the throttle cables is not a separate piece of metal, as I had assumed, even though I’ve circled the bolts. To put it simply, here’s what I’m wondering right now:
1) Am I even in the right place? It’s my understanding that the EGR valve and solenoid do the whole EGR thing through these intakes, which are clearly for air.
2) I do need to take this thing off in order to clean it, right? This is the part (from a 2000 Altima) that I’ve been thinking I need to get off: http://images.hollandersolutions.com/I65/65E/4CW/3TI/U.jpg
3) You can see into the EGR holes in these pictures – am I mistaken in thinking that there are places deeper than this that I’d need to get at? You can see they’re pretty gunked up (although not clogged, at least at a glance).
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