Acura MDX SUV Forums banner

MDX stalls while driving

50K views 52 replies 16 participants last post by  kenpet 
#1 ·
Hi all, first time poster to this forum and unfortunately did not see a lot on this topic. My 2002 MDX is stalling randomly while the vehicle is moving. I am concerned that this is going to be an expensive part swapping exercise. Has anyone else had a similar issue?

Vehicle: 2002 MDX, 153K miles.

Symptoms/Scenario:

MDX stalled several times in the past month while driving at speeds greater than 40 miles per hour. When the condition occurs, the engine becomes non responsive to accelerator changes, engine RPM slowly bleeds down to zero. Power steering and brakes are lost. After putting the transmission in park and attempting a restart, the engine will not start anywhere from 2 to 10 minutes. The engine will turn over, but will not start (not a battery problem). After this time, the vehicle will start and operate normally with no fault codes displayed whatsoever. All electrical systems appear to be functioning properly when this event occurs (not an electrical power disruption, at least not in the cabin).
The problem seems to be random, it occurred with the transmission set in 5th gear, 4th gear, and 3rd gear.
Timeline:
1. First occurrence, after running for about 30 minutes, engine died and restarted 10 minutes later. Drove vehicle home and tried several engine starts. Engine sputtered but would not start in driveway. Next morning, the vehicle was fine.
2. Second occurrence was about a week later. Vehicle was running for at least 30 minutes when it happened.
3. Replaced the EGR valve and added a can of seafoam to the tank. I was thinking perhaps I had bad gas. I have had two EGR valves replaced already on this car, thought it might be the problem again.
4. Problem did not occur for two weeks, I thought I had it solved.
5. Problem reoccurred about 1.5 hours into a drive to North Carolina.
6. On trip back from North Carolina through high elevation and hilly terrain, problem occurred 4 times, about 20 minutes apart. After this period, problem did not reoccur for the remainder of the drive to Atlanta (about 1.5 hours).
7. Dealer replaced fuel pump due to low fuel pressure and debris in the pump.
8. Vehicle stalled 45 minutes into the drive home from the dealer, but this time the vehicle died while accelerating through a stop light. The engine would sputter when a restart was attempted, then would not sputter at all. Engine restarted 5 minutes later.

Any insight would be appreciated!
Shack
 
See less See more
#3 ·
Your problem has similarity to Main Fuel Relay problem common on other Honda/Acura products. When no-start condition is present, turn keyswitch to ON and listen carefully for fuel pump to run for 2-3 secs and cut-off. If you don't hear fuel pump, engine won't start.

MDX has two fuel relays that couple power to the fuel pump. One of these may be the problem if you don't hear fuel pump.

If you hear the fuel pump, problem may be an ignition power problem which would suggest a ignition switch assy problem,...another common honda/acura problem. In this case, you should notice whether Alt, Check Engine, and Oil Pressure lights come on when engine dies. If not, ignition switch assy is likely.

good luck
 
#21 ·
Your problem has similarity to Main Fuel Relay problem common on other Honda/Acura products. When no-start condition is present, turn keyswitch to ON and listen carefully for fuel pump to run for 2-3 secs and cut-off. If you don't hear fuel pump, engine won't start.

MDX has two fuel relays that couple power to the fuel pump. One of these may be the problem if you don't hear fuel pump.

If you hear the fuel pump, problem may be an ignition power problem which would suggest a ignition switch assy problem,...another common honda/acura problem. In this case, you should notice whether Alt, Check Engine, and Oil Pressure lights come on when engine dies. If not, ignition switch assy is likely.

good luck
Texas Honda is correct fuel relay switch is most likely issue , same issue with my 01 MDX we just bought , replaced relay very simple and so far so good.
 
#4 ·
Thanks, if it happens again I will attempt to listen for the pump; usually I am too busy trying to get the M off the road and not getting run over. I dont think it is ignition because the RPM does not drop to 0 instantaneously, its like a slow death. My thought is that the ECU is getting bad feedback from sensors causing it to screw up the air/fuel mixture and stall. But I dont understand why waiting for a few minutes clears the problem. Anyway, back to the dealer. Talking to the service rep, I think they are going to start looking at grounding and electrical related to fuel, since they already replaced the pump. If and when this gets solved, I will post.
 
#6 ·
Thanks, if it happens again I will attempt to listen for the pump; usually I am too busy trying to get the M off the road and not getting run over. I dont think it is ignition because the RPM does not drop to 0 instantaneously, its like a slow death. My thought is that the ECU is getting bad feedback from sensors causing it to screw up the air/fuel mixture and stall. But I dont understand why waiting for a few minutes clears the problem. Anyway, back to the dealer. Talking to the service rep, I think they are going to start looking at grounding and electrical related to fuel, since they already replaced the pump. If and when this gets solved, I will post.
Definitely post back once you have a diagnosis of this issue. I've never heard of this happening but it certainly sounds like a potentially dangerous scenario.
 
#8 ·
I drove the car to work today (about 35 minutes) without incident. Just for fun, I tried a restart after I parked. There was no fuel pump sound after I turned the ignition on, and no start either. Turned the ignition off and removed the key. Repeated several more times with the same result. After about 5 minutes, I tried again. This time I heard the pump start and the engine started too. I took the car to the dealer during lunch and shared this info with the service rep, they haven't gotten back to me yet with their diagnosis. BTW I checked on the price for a new main relay from a different Acura dealer - 75 bucks.
 
#9 ·
Update - I took the car back to the dealer. They called me two days later and said the main relay worked fine and they were still looking for the problem. They even took the relay apart and inspected per my suggestion. I told him to replace the relay and save it for me. A day later, he calls again and says all they did was replace the main relay and reattached the grounds for the pump. The tech drove it to and from his home one night without incident so they think they fixed it. I picked it up yesterday and so far so good. I took the relay apart and attached the photo. In it you can see a "cold" solder joint in the center of the relay, and some discoloration where it may have overheated. Time will tell if this was the problem but this is clearly not in good condition. I will post back after a "problem free" period.

Shack
 

Attachments

#10 ·
Poor/failed solder jts are not obvious. You need a really powerful magnifying glass to examine. Usually, just a dark circle around a vertical wire is all you can see. Repair usually consists of re-solder all the jts rather than trying to detect bad jts.

I did a bit of experimenting w/ an Accord MFR and found that temps of certain jts reach 140F when operating. Not surprising these jts fail in time.

good luck
 
#11 ·
We have powerful magnifying glasses at work so I plan on taking a closer look (just for fun), but if you zoom in on the photo at the center contacts you can see the joint is definitely malformed; this is the relay contact that is in series with the pump (no surprise there). Also, I googled "honda main relay schematic" and found all kinds of useful information on this problem.

The original diagnosis was debris in the fuel pump and low fuel pressure. I do wonder if the pump was indeed going bad or clogged causing more current draw, ultimately accelerating the failure of the solder joints. Or, was it a complete waste of time and money to replace the pump. My advice to anyone with an MDX of this vintage would be to preemptively reflow or replace the relay to avoid this serious problem. Thanks TexasHonda!
 
#12 ·
Your fuel pump could have been faulty. They are very reliable, but do occasionally fail.

I had a fuel pump fault on my 94EX Accord that took a lot of diagnosis, replacement of MFR, and hand wringing before I finally determined the pump was "hanging" when first powered on. I rigged a tell-tale light to power supply feed in the trunk and found pump was not running w/ power supplied. If I turned keyswitch on/off/on/off...it would eventually catch and run. New fuel pump resolved long running intermittent no-start issue.

Fuel tank was pristine on this now almost 20 yr old Accord. My "backup" car currently.

good luck
 
#13 ·
Hi, glad you found your problem without enduring an expensive part swapping exercise. Thought I'd mention for future reference that there is a useful procedure for diagnosing weak fuel pumps; the speed of the motor can be figured out by using an ammeter clamp probe around the power feed wire and looking at the waveform pattern on an oscilloscope (such as the Snap On Vantage power graphing meter)

I know this is probably a bit advanced for the average owner, but your local repair shop should have a driveability technician that has the equipment and knowledge.

This test is very useful for intermittent problems, where the fuel pump pressure and volume are within specs.
 
#14 ·
I am having a very similar issue as Shack. 2001 Acura MDX with 155,000 miles. Vehicle randomly dies. Once it does die, multiple attempts are required to restart. Electrical system is fine with no warning lights. After reading this post, I listened for the fuel pump after the next time the vehicle died, and I don't believe I could hear it. Would the sound be coming from under the dash/hood of the vehicle or elsewhere? The vehicle always restarts after several attempts (and several minutes) and seems to drive fine until suddenly dying at another random time. Could be when accelerating, could be when coasting to a stop....doesn't seem to be any patter to it.

How difficult is it to replace this fuel pump relay? Sounds like if it is an inexpensive part, it might be worth a shot for me to replace it just to see if that is the problem, especially since the problem is random and cannot be duplicated for a mechanic to experience.
 
#16 ·
I am having a very similar issue as Shack. 2001 Acura MDX with 155,000 miles. Vehicle randomly dies. Once it does die, multiple attempts are required to restart. Electrical system is fine with no warning lights. After reading this post, I listened for the fuel pump after the next time the vehicle died, and I don't believe I could hear it. Would the sound be coming from under the dash/hood of the vehicle or elsewhere? The vehicle always restarts after several attempts (and several minutes) and seems to drive fine until suddenly dying at another random time. Could be when accelerating, could be when coasting to a stop....doesn't seem to be any patter to it.

How difficult is it to replace this fuel pump relay? Sounds like if it is an inexpensive part, it might be worth a shot for me to replace it just to see if that is the problem, especially since the problem is random and cannot be duplicated for a mechanic to experience.
Fuel pump noise is from the fuel tank where the pump is located. It is easy to hear in quiet conditions. You may also hear some clicks from under the dash (main fuel relays). If you don't hear the fuel pump, the problem is either main fuel relay or fuel pump itself as discussed above.

Replacement is fairly easy, but you have to find the relay which can be tricky.

good luck
 
#15 ·
I had a MFR fail on a '99RL once, no notice, just hauling butt down the freeway, then nothing, no restart, not hot cold, or in the middle. Not only did my MFR fail, I burnt the wire leads into it as well. I took all kinds of current readings, thinking my pump must be drawing too much, but nope!! re-soldered the joints, put on new wire leads, and never installed the new relay. Ran another year or so before I sold it, never another problem with it.

This is not an absolute, but a no start on todays highly computer controlled vehicles where no codes or lights are thrown, is commonly a fuel rail pressure problem, either a fuel pump, or in a Honda vehicle the darned main relay.
 
#18 ·
Few months ago same thing occurs to me. All of a sudden My car was shut off. Fortunately nobody was behind me. I was able to restart the car with no problems and no check engine lights came on. I have no idea what happened. battery was good, connections good... No problems since.
 
#20 ·
Hi all, first time poster to this forum and unfortunately did not see a lot on this topic. My 2002 MDX is stalling randomly while the vehicle is moving. I am concerned that this is going to be an expensive part swapping exercise. Has anyone else had a similar issue?

Vehicle: 2002 MDX, 153K miles.

Symptoms/Scenario:

MDX stalled several times in the past month while driving at speeds greater than 40 miles per hour. When the condition occurs, the engine becomes non responsive to accelerator changes, engine RPM slowly bleeds down to zero. Power steering and brakes are lost. After putting the transmission in park and attempting a restart, the engine will not start anywhere from 2 to 10 minutes. The engine will turn over, but will not start (not a battery problem). After this time, the vehicle will start and operate normally with no fault codes displayed whatsoever. All electrical systems appear to be functioning properly when this event occurs (not an electrical power disruption, at least not in the cabin).
The problem seems to be random, it occurred with the transmission set in 5th gear, 4th gear, and 3rd gear.
Timeline:
1. First occurrence, after running for about 30 minutes, engine died and restarted 10 minutes later. Drove vehicle home and tried several engine starts. Engine sputtered but would not start in driveway. Next morning, the vehicle was fine.
2. Second occurrence was about a week later. Vehicle was running for at least 30 minutes when it happened.
3. Replaced the EGR valve and added a can of seafoam to the tank. I was thinking perhaps I had bad gas. I have had two EGR valves replaced already on this car, thought it might be the problem again.
4. Problem did not occur for two weeks, I thought I had it solved.
5. Problem reoccurred about 1.5 hours into a drive to North Carolina.
6. On trip back from North Carolina through high elevation and hilly terrain, problem occurred 4 times, about 20 minutes apart. After this period, problem did not reoccur for the remainder of the drive to Atlanta (about 1.5 hours).
7. Dealer replaced fuel pump due to low fuel pressure and debris in the pump.
8. Vehicle stalled 45 minutes into the drive home from the dealer, but this time the vehicle died while accelerating through a stop light. The engine would sputter when a restart was attempted, then would not sputter at all. Engine restarted 5 minutes later.

Any insight would be appreciated!
Shack
Just bought an 01 MDX , beautiful car , same issue , driving and stalling, restart not possible right away , replace Fuel relay switch under dash , starts and does not stall yet, will let you know. When in driveway after stall it wouldn't restart , but after replace it seems fixed , another forum said connections in relay deteriorate over time , makes sence due to restart after stall , not a fuel pump issue because a pump usually just fails , easy to get to relay on passenger side of drivers side under dash with brown connection to black box , push up on it to release from bracket and lower down to disconnect wire clip , 5 minute job , thanks to others on this info , $76 for part , see how Napa product holds up for now.
 
#23 ·
Fuel pump noise is from the fuel tank where the pump is located. It is easy to hear in quiet conditions. You may also hear some clicks from under the dash (main fuel relays). If you don't hear the fuel pump, the problem is either main fuel relay or fuel pump itself as discussed above.

Replacement is fairly easy, but you have to find the relay which can be tricky.

good luck
I have 2002 MDX with 181K miles. It started stalling on me yesterday. When I started the car, it started ok. But then it stalled within 0.2 miles. The engine would start, but then stop immediately. If I press the gas pedal, it would stay on. I pulled in my drive way with both gas and brake pedals pressed...just to avoid engine shut off. I started the car this morning...it started, but a lot of hesitation....as if it will die any moment. Once I shut off, it won't start right away...unless I really press the gas pedal. Does this look like fuel relay switch issue? Thanks a lot.
 
#24 ·
Doesn't sound like a relay. Those failures are almost always "binary" (works 100%, or not at all). Your problem sounds more like:
1) Fuel issue
2) Slipped timing belt

On the fuel - get a can of starting fluid. Next time your car doesn't want to start, give it a shot of starting fluid into the air box (the one that holds the air filter). If it then fires right up for a few seconds (even if it dies or stumbles immediately after), you know you have a fuel issue.

On the timing belt - if it's never been done, it's way, way, way overdue - both mileage and age-wise. If the belt slips a tooth or two, it acts a lot like your car is. If it slips ANY MORE, you have reduced the engine to a large paperweight, and will have effectively totaled it (or at the very least, forced you to spend more than it's probably worth to fix). You can move the plastic timing belt cover on the front of the engine (near the passenger-side fender) - a bolt or two will loosen it up IIRC. If the belt shows ANY signs of damage, you want to get this done post-haste.
 
#25 ·
Thank you for the response. If i wait a few minutes, the car would start. It would keep running (don't know how long)...even without pressing any gas pedal. It hesitates so it is certainly not smooth like it was before. If I take it out for a drive..it would stall in 0.2-0.3 miles.

Timing belt was replaced 35K miles ago.

Since the car is starting every few minutes, do you think I need the starting fluid. If yes, I open the air filter box and spray it directly into the pipe? Is it to help with the throttle plate? When you say fuel issue, does it mean fuel filter, fuel pump, etc?

Thanks
 
#27 ·
The starting fluid trick only helps if the car is doing something "wrong" when you start it (sounds like it's not really idling smoothly). If it fires up normally, it's not going to tell you anything.

Fuel issues could be almost anything - fuel pump, filter, lines, injectors, etc.

I also remember hearing about folks who had clogged catalytic converters - the car would usually start up, but with the application of any gas, it would just choke on itself. That also sounds a lot like your symptom. You might want to read up on that here: Clogged Catalytic Converters - Diagnosing Bad Catalytic Converters

Thing is, a clogged cat will usually throw a code - you really need to get the codes read, even if only with a generic OBD reader (like the ones they use to give free readings at many auto parts store). That will likely tell you the general vicinity of the problem, at least. If possible a Honda-specific code reader will give you a much more detailed analysis of the problems.
 
#28 ·
The starting fluid trick only helps if the car is doing something "wrong" when you start it (sounds like it's not really idling smoothly). If it fires up normally, it's not going to tell you anything.

Fuel issues could be almost anything - fuel pump, filter, lines, injectors, etc.

I also remember hearing about folks who had clogged catalytic converters - the car would usually start up, but with the application of any gas, it would just choke on itself. That also sounds a lot like your symptom. You might want to read up on that here: Clogged Catalytic Converters - Diagnosing Bad Catalytic Converters

Thing is, a clogged cat will usually throw a code - you really need to get the codes read, even if only with a generic OBD reader (like the ones they use to give free readings at many auto parts store). That will likely tell you the general vicinity of the problem, at least. If possible a Honda-specific code reader will give you a much more detailed analysis of the problems.
Thanks. How easy it is to check fuel pressure on MDX 2002. Auto Zone would lend the equipment for free (need to pay upfront which will be refunded upon return). That way I can rule out Fuel related stuff... Could it be Mass Air Flow sensor?

The puzzling part is there are no codes reported. Fuel pump doesn't report a code if there is a problem.

There are people in this thread that reported stalling several times and the issue was fixed with the Main Fuel Relay...any reason you feel I don't have the same root cause as an issue? Thanks a lot.
 
#31 ·
It is possible that the relay is intermittent, but generally it's back to that "binary thing" - though it can come and go. I suppose a failure mode that's "kinda/sorta bad" could occur, basically if the contacts that are held closed when the relay is energized are dirty / corroded / intermittent. At any rate, the part is pretty cheap and easy enough to swap, so at worst case you'll have replaced a part that might have failed in the future.

I'm not sure about checking fuel pressure though - my manual covers 2003 and up, and IIRC the 2001-2 are different in the fuel rail area. Most fuel rails have a Schraeder valve (similar to your tires) that you can plug a gauge onto. I know that my Torque Pro app (running on my Droid phone, using a cheap OBD Bluetooth dongle) reports fuel pressure. Might be a good addition to your toolbox (if you don't have a droid or similar phone, there are similar apps - the total outlay is around $20 for the app and dongle). Of course, a laptop running HDS will be the best possible answer, and will let you get into the minutiae of your car's many systems and computers.
 
#33 ·
Shouldn't be necessary. As far as that goes, you could just pull the connector off and temporarily plug in a new relay. If that fixes it, then bother removing the original (otherwise, why bother?).

FWIW, it looks like the quick and easy way to remove the relay would be to stick a long, skinny flat-blade screwdriver between the metal bracket it hangs on and the relay body. That should allow the little tab that engages a small slot in the metal tab to clear, allowing the relay to move.
 
#35 ·
Just incase you do want to remove the entire relay from the metal tab; It is release by pushing up once you stick the small screw driver to relieve the plastic nub. Figured it out after watching many vids and advise from a Honda tech. I originally had a hell of a time figuring that out while replacing mine.
What I did was removed the internals of the relay and swapped the new internals into the original box housing while it was still attached to the metal bracket. That was really easy.
 
#36 ·
Just incase you do want to remove the entire relay from the metal tab; It is release by pushing up once you stick the small screw driver to relieve the plastic nub. Figured it out after watching many vids and advise from a Honda tech. I originally had a hell of a time figuring that out while replacing mine.
What I did was removed the internals of the relay and swapped the new internals into the original box housing while it was still attached to the metal bracket. That was really easy.
Thanks for the feedback. What you are saying is use small screw driver to push down on the center lock tab on the top and then slide the entire relay out. Another option (which is what you did) is to push on the side tabs of the relay and break free the internal unit of the relay. Did u do this while the wire connector was still attached? Or did u remove the connector first? Did you remove any lower dash panel? If I could, may be it would be easier. I am still struggling to just disconnect the wire connector...that way I can buy a new one and try it out. Hard for me to get underneath the dashboard and use left hand...while I am righty...any other suggestions? Thanks
 
#38 ·
Gee, if only someone had suggested trying that starting fluid trick... ;-)

The throttle body IS one thing that could be a culprit, but there are a host of things that can cause a car to not want to run without a little throttle application OTHER than the throttle body. They do get dirty, and if so, cleaning can help. But a dirty throttle body isn't going to cause the car to stop running "just driving along".

You really (!) need to get the car scanned to see what it's trying to tell you. Trying to throw parts at it is going to get frustratingly expensive and time-consuming, trust me.
 
#39 ·
Thanks a lot for your guidance.

Cross-checking with you for my understanding - since the fuel pump was clicking, it is not MFR issue, correct?

I agree with you regarding the throttle body replacement. The dealer price is 1150 (retail price is 731). I rather just clean it than to replace it. It shouldn't stall while driving. Maybe it stalled with low speed or stop at the light? Would throttle body (where the plate gets sticky) throw an error code? I didn't have any.

Are u suggesting to have dealer scan the car?

Thanks a lot.
 
#41 ·
FWIW, I don't recall a whole lot of issues with the throttle bodies on these cars. It's such a simple device (really just a big tube with a rotating disc) that cleaning it should restore it to good standing. I remember doing that to mine, and don't recall it being a big deal (had to take the TB off to do something else - maybe valve cover gasket or valve timing?).

These docs may help a bit (I didn't include the removal - AIR, it's pretty straightforward)...
Jaw Gesture Font Writing Paper



Font Number
 
#42 · (Edited)
FWIW, I don't recall a whole lot of issues with the throttle bodies on these cars. It's such a simple device (really just a big tube with a rotating disc) that cleaning it should restore it to good standing. I remember doing that to mine, and don't recall it being a big deal (had to take the TB off to do something else - maybe valve cover gasket or valve timing?).

These docs may help a bit (I didn't include the removal - AIR, it's pretty straightforward)...
View attachment 123077


View attachment 123079
Thanks for the info. I am still puzzled at to why IACV or sticky Throttle Plate won't throw any CEL codes...

I am going to check Throttle Body Assembly part at a local junkyard....if it looks good...i will give it a shot. At this point I am not clear what exactly the issue is, but for $75 I will try it and see how it goes. The mechanic seems ok. As soon as I told him I wanted to change MFR, he went to the fuel tank and checked the fuel pump clicks...several times...so he knew his way.
 
#43 ·
To get an error code, there has to be some sort of sensor providing data that something's not right. If the gap in the throttle body plate is gunked up with carbon, there's nothing reporting that to a computer, so it doesn't throw a code (unless the problem causes an issue that DOES create a situation that is reported, like misfires, etc.).

Yeah, for $75 there's not a whole lot of risk. That way, if you do remove the TB and find it's got a fatal flaw, you're not going to have to put it all back together while you wait for a new part!

Of course, do let us all know how it goes!
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top