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For about a couple weeks now my car has been dying intermittently for no apparent reason. It happens totally at random 1 to 3 times a week. Sometimes when I am driving at low speed it will shuts off. Other times, the car stumbles and the RPMs bounce around wildly before it conks out. When that happens, I get surging and dipping of the RPMs. I cannot replicate the problem for the life of me and I have taken it to the dealer and they have no idea either. They have given the car a clean bill of health.

I have also used my Dashhawk to obtain some maps but, I haven't been able to capture any data when it acts crazy. All data seems consistent to me, AFR's, as well. However, my spark advance seems to be all over the damn place (at least to me). I had the fuel pressue tested as well and it is great. My battery is also solid.

I haven't checked my plugs yet, perhaps they're fouled. I did change to 1 step colder a few months ago.

If anyone has a possible diagnosis, I'm eager to hear it.

Thanks in advance.
 

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It dies and bogs randomly, but have you had any trouble starting it or anything?
 

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It dies and bogs randomly, but have you had any trouble starting it or anything?
No trouble starting up except right after it dies. Then, it will start up again but, drop RPMs, sputter and die. After a couple starts, it's back to business (most of the time). No CEL's either.
 

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Fuel pressure was tested at what point in the system? How many miles on the car? Ever run Seafoam through the gas tank or vacuum lines? If it's not fuel related, it's going to be electrical and likely a bitch to find :( I would check the injectors to make sure they're looking good and don't have any build up, and definitely check the plugs as it sounds like the only change in your system recently.
 

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Fuel pressure was tested at what point in the system? How many miles on the car? Ever run Seafoam through the gas tank or vacuum lines? If it's not fuel related, it's going to be electrical and likely a bitch to find :( I would check the injectors to make sure they're looking good and don't have any build up, and definitely check the plugs as it sounds like the only change in your system recently.
Your name is so appropriate
 

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In my mind the MAF wouldn't cause the car to die. It can run without it. Just very poorly.
I'd pay closer attention to fuel.
I'd say a position sensor, but it seems a sensor would sury cause an MIL.
 

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Are you saying that Seafoam would cause the problem or help it?

Fuel pressure was tested at what point in the system? How many miles on the car? Ever run Seafoam through the gas tank or vacuum lines? If it's not fuel related, it's going to be electrical and likely a bitch to find :( I would check the injectors to make sure they're looking good and don't have any build up, and definitely check the plugs as it sounds like the only change in your system recently.
 

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usually dieing issues that dont throw faults are caused by the fuel system. could be a number of things in this fuel system. If it continues. I would replace a few relays, not sure how many we have, but in sure theres a fuel pump relay, and pcm relay not sure what else. just buy a few and put some new ones in. They dont cost that much and can cause a world of problems
 

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^There's two fuel pump relays and a fuel pump resistor. The resistor is a little pricey ~$115. OP could also test the voltage on the tank pump. It runs on two voltages... on/off idle. I wouldn't guess the tank pump though, but I forget the flow rates for on/off idle. He can get at them pretty easy to test them though. Just yank out the back seats (pops right out) and there are two covers under there with 3 bolts.

Another way to check is to let the car come to temp, and then do the following at idle:
1. make sure you are logging, or at least have the display up and set to fuel pressure
2. While the car is running, disconnect the wire harness plug going to the hpfp

The fuel pressure should drop to 50 or so as it's running solely off the tank pump. If it's way low or high, there's probably a voltage problem with the tank pump. I went through the entire fuel system trying to figure out my fueling dilemma! Those are the only things I can think off of the top of my head related to fueling that are easy/quick/cheap to test. Another suspect could be the wire harness OR the solenoid on top of the hpfp (the one checked in #2 above). I have no clue if it's fueling related, but those are some easy/quick tests you can check. I forget what the voltage should be at the tank pump atm, but it's in the shop manual if someone has it handy. Also, see if someone can go to the diagnostic section for your issue in the shop manual and see what the tests are.

GL

EDIT: the two relays are in the main fuse box under the hood. You may also consider the large black main relay, which is also under there. If you need the location of the resistor, I can take a pick for you. I'd check the maf like bova said, as that's a likely suspect, but I have not clue how to test that. Try cleaning it with maf cleaner at least, just be careful as it's delicate. It may have just gotten really dirty.
 

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If we don't hear from Forzda, I can consult my WSM for more ideas tomorrow.

I really don't think the MAF could be the culprit. I've unplugged my MAF before while the car was running and it sputtered and putted, but didn't die. Also threw like 3 different codes.
Faulty MAF will make it run poorly, but dying and trouble starting is like fuel or position sensor related.
 

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The WSM suggests it may be the throttle position sensor, crankshaft position sensor, camshaft position sensor, MAF or may be fuel quality, the HPFP solenoid, the HPFP...like, anything.
You should take a closer look at some of your PIDs, since you have a Dash Hawk. Do you have a stock high pressure fuel pump? Watch your pressure in different load situations. To check the MAF, observe the g/s. It should be ~2.72-2.94 at idle.
There's ways to inspect the other sensors. Let me know if you want to try.

Does the car stall out in motion? At idle, like in neutral? Or with load, when accelerating? Is it cranking normally when it isn't starting? Or, does it stumble or sputter? And finally, once it starts to turn over does it pick right up or run poorly for a while?
 

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When I swapped out my hard fuel rail for an even worse used one like a nob, I threw a CEL.... I forget the code (because, lucky me, my AP shit out again before I wrote it down). It was something like "APP voltage correlation problem, No. 1, No. 2." Looking over all the connections, I had plugged in the wire harness going to the throttle body, but I didn't push the little red clip back all the way. Once I did, the CEL disappeared (and never came back). That doesn't mean it's not that, but I threw a CEL because of it within about 30 secs - 1 min.

It almost sounds like his engine is getting flooded to the point of stalling at random times. We need to know exactly what is going on immediately before it dies as Groceries suggested. I remember DJ saying that a sick alternator can cause all kinds of F'd up problems that you wouldn't expect. Multimeter to +/- with engine running, should be 14.2-14.4 volts.

OP, have you checked the plugs yet???

Gremlin- What are you thinking in terms of sea foam? If his egr was all clogged up, he'd be throwing at least 1 CEL for that, but I have no clue what kind of symptoms that can cause.
 
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Discussion Starter #17 (Edited)
Fuel pressure was tested at what point in the system? How many miles on the car? Ever run Seafoam through the gas tank or vacuum lines? If it's not fuel related, it's going to be electrical and likely a bitch to find :( I would check the injectors to make sure they're looking good and don't have any build up, and definitely check the plugs as it sounds like the only change in your system recently.
Fuel was tested at the CDFP and the tank pump. No, I haven't run Seafoam, that's a good idea. I'm hoping it's not electrical. That would be a bitch! Guh! Injectors look great. I will pull the plugs tomorrow. I appreciate the tips. I'll pick up that Seafoam and run it this weekend.

maf sounds like it could be going bad
Maf is good but, needs a cleaning. I'll hit that up this weekend too.

In my mind the MAF wouldn't cause the car to die. It can run without it. Just very poorly.
I'd pay closer attention to fuel.
I'd say a position sensor, but it seems a sensor would sury cause an MIL.
Yeah, I'm thinking fuel somewhere. I just can't replicate it under any circumstance. It's so random. I have had the car back for over a day now and it hasn't occurred again as of yet.

usually dieing issues that dont throw faults are caused by the fuel system. could be a number of things in this fuel system. If it continues. I would replace a few relays, not sure how many we have, but in sure theres a fuel pump relay, and pcm relay not sure what else. just buy a few and put some new ones in. They dont cost that much and can cause a world of problems
This is good info. I appreciate it. If all else fails I'll look into this as a potential issue for sure.

^There's two fuel pump relays and a fuel pump resistor. The resistor is a little pricey ~$115. OP could also test the voltage on the tank pump. It runs on two voltages... on/off idle. I wouldn't guess the tank pump though, but I forget the flow rates for on/off idle. He can get at them pretty easy to test them though. Just yank out the back seats (pops right out) and there are two covers under there with 3 bolts.

Another way to check is to let the car come to temp, and then do the following at idle:
1. make sure you are logging, or at least have the display up and set to fuel pressure
2. While the car is running, disconnect the wire harness plug going to the hpfp

The fuel pressure should drop to 50 or so as it's running solely off the tank pump. If it's way low or high, there's probably a voltage problem with the tank pump. I went through the entire fuel system trying to figure out my fueling dilemma! Those are the only things I can think off of the top of my head related to fueling that are easy/quick/cheap to test. Another suspect could be the wire harness OR the solenoid on top of the hpfp (the one checked in #2 above). I have no clue if it's fueling related, but those are some easy/quick tests you can check. I forget what the voltage should be at the tank pump atm, but it's in the shop manual if someone has it handy. Also, see if someone can go to the diagnostic section for your issue in the shop manual and see what the tests are.

GL

EDIT: the two relays are in the main fuse box under the hood. You may also consider the large black main relay, which is also under there. If you need the location of the resistor, I can take a pick for you. I'd check the maf like bova said, as that's a likely suspect, but I have not clue how to test that. Try cleaning it with maf cleaner at least, just be careful as it's delicate. It may have just gotten really dirty.
Really great stuff douge. I'll keep this in mind as I sort though this issue. Although it hasn't happened again yet I am going to methodically go through everything you all are suggestion to rule it all out.

The WSM suggests it may be the throttle position sensor, crankshaft position sensor, camshaft position sensor, MAF or may be fuel quality, the HPFP solenoid, the HPFP...like, anything.
You should take a closer look at some of your PIDs, since you have a Dash Hawk. Do you have a stock high pressure fuel pump? Watch your pressure in different load situations. To check the MAF, observe the g/s. It should be ~2.72-2.94 at idle.
There's ways to inspect the other sensors. Let me know if you want to try.

Does the car stall out in motion? At idle, like in neutral? Or with load, when accelerating? Is it cranking normally when it isn't starting? Or, does it stumble or sputter? And finally, once it starts to turn over does it pick right up or run poorly for a while?
YES! It has stalled out in motion, at idle, and in neutral. It has only done it once under load when accelerating. Yes, when it dies it stumbles and sputters when it cranks up and when it does, it runs poorly for a little bit with the rampantly bouncing RPMs before it settles in and runs correctly. This sounds like the perfect description of what happens when it dies and I start it back up. I can't look at the PIDs with my DH. Well, at least I don't know how to do that with it. I'll look it up. Yes, I have the stock fuel pump and I'll check the MAF readings as well. I'll get back at you with the other sensor checks.

When I swapped out my hard fuel rail for an even worse used one like a nob, I threw a CEL.... I forget the code (because, lucky me, my AP shit out again before I wrote it down). It was something like "APP voltage correlation problem, No. 1, No. 2." Looking over all the connections, I had plugged in the wire harness going to the throttle body, but I didn't push the little red clip back all the way. Once I did, the CEL disappeared (and never came back). That doesn't mean it's not that, but I threw a CEL because of it within about 30 secs - 1 min.

It almost sounds like his engine is getting flooded to the point of stalling at random times. We need to know exactly what is going on immediately before it dies as Groceries suggested. I remember DJ saying that a sick alternator can cause all kinds of F'd up problems that you wouldn't expect. Multimeter to +/- with engine running, should be 14.2-14.4 volts.

OP, have you checked the plugs yet???

Gremlin- What are you thinking in terms of sea foam? If his egr was all clogged up, he'd be throwing at least 1 CEL for that, but I have no clue what kind of symptoms that can cause.
The alternator checked out fine. I had Mazda check it as well as an independent garage where a friend of mine works. No, I haven't checked the plugs yet but, I will soon. It sounds like Groceries nailed the symptoms.

Crazy that I went to "professionals" and they had my car for two days and I got nothing. Here I am with my trusted club6 members and I have received all kinds of great information and potential causes and cures. Thank you guys a ton! I'll get back to you all with what I find out after some extensive trouble shooting. Now, if I can just get the car to do it again. I'm sure it will happen tomorrow.
 

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just a thought-
What's your fuel level when experiencing the stall/rough restart?

low, say below 1/4 tank?

generally, I'm wondering about debris in the gas tank
 

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Discussion Starter #19
just a thought-
What's your fuel level when experiencing the stall/rough restart?

low, say below 1/4 tank?

generally, I'm wondering about debris in the gas tank
It happens with all levels of fuel. 3/4, 1/4, under, etc. The car still hasn't done it again since I got it back from the dealership. It stumbled slightly yesterday. I'm going to wrench on it now, drive, run maps, etc. I'll get back to you guys on what I find.
 

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Discussion Starter #20
Okay. Here's the update:

I checked it out this weekend and I found one issue. I pulled the intercooler and went to check the spark plugs. They looked fine but, I noticed that the plastic sheathing around the harness had been either eaten through (had a rat try to nest in my ride a couple years ago). There were multiple exposed harness wires and it appeared that they might have been touching when the engine moves around. So, I fixed that. But, that was all that I found based on my visual inspection. I also purchased Seafoam and I am running that through the tank now. I haven't cleaned the MAF yet. I'll do that this evening for sure. There's a good chance it is pretty dirty.

I do not see where my Dashhawk will read Mazda PIDs in order to obtain the fuel pressure. Does anyone know how to do that and if it will? My DH is 2nd generation.

Up until the day before yesterday I had not experienced any of the symptoms as far as the RPM surge and/or studdering problems. However, I did get one small surge yesterday at low speeds yesterday and the car has simply died twice over the past two days. Once it died right after a lenghty highway drive after I slowed down and exited onto the off ramp. Then, it died again this morning at about 40mph. It was a silent shut off. No drama or warning whatsoever. Totally random.

Groceries, you said that there are ways to test the sensors. I'd like to know please. I would appreciate it if you could hit me up when you get a chance.
 
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