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Discussion Starter #1
newbie here . spent alot of time searching the forums but couldn't find a similar problem ....

2001 mdx with 225k kms . this problem started two weeks ago . i got in and started the truck . realized i forgot my sunglasses in the house . shut it down ran inside . when i tried to start the truck 2 mins later it just cranked over like there was no spark . tried several times but to no avail . popped the hood but all looked well . jumped in and tried again and it started right up . this reoccurred once every 2 days . weather it was hot or cold it seemed to make no difference . it seemed like once out of ten starts it would just spin over and if i had a smoke ( five mins would pass) it would start right up . once it was running i was good to go . used my obd scanner and got no codes . took to my mechanix and he seemed to hint with no codes he would be down to throwing money at it by buying new parts ... lmao so thats not ideal ... could live with it untill yesterday . driving down the highway when i heard a slight click and the truck went dead but dash lights and radio working . coasted to the side of the road . had a smoke and it would not start . another smoke and vroom it started right up . drove for 6-8 minutes then again it stalled . 7-8 minutes of patiently and calmly praying lol it started up again and drove it home (15 minutes away) where im afraid to get stuck somewhere so now it sits ..... doesnt give any notice nor does it seem like its fuel related as there is no struggle .just dies .....
 

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I would check my Key Ignition Assembly,
The TL and CL side had a lot of problems in those years with faulty Key Ignition assembly´s. Solution is to change it.

But before you do that make sure the Immobilizer system is detecting your key. When you put the key on position II (Before crank) the green key light in the dashboard should go off.. If it stays on then your key isn't being recognized and thus wont start the car.. You can crank it though but there will be no start because the immobilizer shuts down Ignition and Fuel.
 

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Discussion Starter #3
i have two keys and two fobs . i checked and when cranking the green key light does go out . so immobilizer should be ok . ignition assembly eh ? thanks i will check it and update ....
 

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Check your ground cables. Better yet, put in an extra ground cable to the engine and one to the frame.

Either that or buy a lot of cigarettes since that seems to work each time. :laugh:

Good luck
 

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Discussion Starter #7
ok so i took out my old ignition switch . cleaned it up inside . re-installed and made no difference . went to acura and bought a new switch swapt it out and it made no difference . drove the truck around for 20 mins before it just died again . after 8 minutes it started right up .

this is an electrical issue forsure . the truck runs perfect when it runs . no sign of struggle or bogging . it is not a valve problem as there are no symptoms that point that way . truck runs smooth , no engine vibration . idles perfectly . maybe a cps ? must be a bad sensor but still not throwing any codes .
 

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Discussion Starter #8
another day pulling out my hair here lol . pulled the fuel pump relay . under dash left of steering column . black box with white cap and a brown clip going into it .... pulled the relay apart , all the soldiering looks good , checked with a magnifying glass for hairline cracks , found nothing wrong with it. all looked well .....

arrrgghhh lol :)
 

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Conventional wisdom says that an internal combustion engine needs three things to run - fuel, spark and compression. There are a few subtle variations (like valve timing), but I think it's 100% safe to say you don't have a compression / timing problem (these things tend not to move around).

At the very least, you need to narrow down the problem to ignition or fuel (sounds like you're shotgunning your efforts between both). Next time your engine dies, try spraying starter fluid into the air filter housing. If it runs until the starter fluid dissipates, you know you're dealing with a fuel problem. If the engine won't fire on starter fluid (an oxymoron since it's actually an aerosol), then you know you've got no spark.

There are more variables that can kill the spark / ignition, and it's unlikely you're going to find the gremlin without doing a bit of testing while the engine is throwing a fit.

Here are a couple things that might help - at least it'll be fairly easy to check - the location of the ignition relay (which you should be able to swap with one of the similar ones next to it, though you'll want to check that theory), and the wiring that supplies power to the coil packs... and last, it wouldn't be a bad idea to replace both ignition-related fuses, just for grins #46 and #8). Good luck!


 

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Discussion Starter #12
i think ur right on the money . thanks for pointing me in this direction ..... i will tackle this some more tomaro .... thanks also for the pix ... it all helps :) will update soon
 

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another day pulling out my hair here lol . pulled the fuel pump relay . under dash left of steering column . black box with white cap and a brown clip going into it .... pulled the relay apart , all the soldiering looks good , checked with a magnifying glass for hairline cracks , found nothing wrong with it. all looked well .....

arrrgghhh lol :)
You're on the right track. Sure you checked the proper relay?

Want to verify? Next time it no starts, no smoke break...reach under the dash and tap on those relays and see if it immediately starts.
 

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Why do you think it isn't a valve adjustment?
Is this one of those models that doesn't need one?

In my 2005 Honda it had starting problems when cold. One started, it was beautiful.
After a while it was starting harder and harder. I even had my mechanic change my Idle Air Control Valve

Turned out it just needed a valve adjustment...which is what he recommended before I decided to diagnose it on my own.
 

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No one is saying that it's not possible that the OP's MDX does need a valve adjustment, just that there's no (NO) way that out-of-adjustment valves would be causing the symptoms he's experiencing. Loss of horsepower or mileage, sure... but not an engine that runs fine and shuts down suddenly.
 

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Why do you think it isn't a valve adjustment?
Key word with the OP...intermittent. Valves don't come in and out of spec randomly. When they're bad, they stay bad until you adjust them. Relays on the other hand? When they start going bad, they sometimes stick open/closed intermittently.

And valve clearance so far out of spec that it could cause a stall would certainly trigger a MIL and have misfire and/or fuel trim codes.
 

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Discussion Starter #17
hey guys sorry for the delay with an update . lol yes bro i tried to sort of smack/tap on fuel relay , no changes . no heat omitting from it .

well i started the truck for the first time in almost a week today . started up and ran great . took me an hour and a half to make the symptoms return . once it shut itself off (died) , i sprayed starter fluid in the intake and she fired although very ruffly lol . waited two mins and tried again and it would not start . took a few mins to get the air intake pipe re connected and then it started right up again . i have spark so this must be a fuel problem .....

i cant hear my fuel pump run at all . so im thinking that a super quite pump must be doing its job . i can sort of feel a vibration under the back seat so i think its running . i mean it must be if the truck runs great most of the time . is there another fuel relay ? or just the one under the dash ? im pretty sure i found the right relay . black box with white bottom and a brown clip into it ...... ? ( passenger side of drivers footwell but up under dash ? )
 

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Since your fuel problem seems to be binary (either fully on or fully off), I'd suspect the fuel pump, fuel pump relays, or wiring / PCM computer.

I don't think you're really going to know what problem you have until you can monitor the condition / position of the two relays that control the fuel pump. Only when you know if the relay is being commanded on or not, and whether that command is being carried out (by the relay activating and sending battery voltage to its output) will you know where to look.

FYI - here's a one-page diagram that has pretty much everything you need to look at - there are two relays that could easily be causing the problem, as could the fuel pump. Or the wiring anywhere in the system, OR a bad ground to the pump or one of the relays.


The problem with an intermittent problem like this is that you can't troubleshoot it until the car stops running. If it was my car, I'd stick a skinny wire into one relay's input or output at the connector, and hook it up to a small lamp. Then when the car died, I'd check to see if that lamp was on or off. If the "lamp is in the right condition" when your car dies, you know to keep looking. There are a very limited number of places to use this approach - the input and output to two relays, and possibly to the actual fuel pump voltage input (not sure how accessible that connector is). The one thing I'd add is that this won't tell you if one of the grounds is bad.
 

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So, what happened?
 
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