- This topic has 32 replies, 6 voices, and was last updated 8 years, 3 months ago by .
-
Topic
-
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.
- You must be logged in to reply to this topic.