P5 Won't Start & Rough Idle

[The_big_dill]

I feel like if it was bad coils, it would still kick, his sounds like it doesn't even try to start, but all the electronics seem to be in good working order.

I would be looking at the crank sensor as well as the gap it has from the timing wheel.

 

[pcb]

Maybe try plugging in a code reader (the kind that broadcasts to your phone) to see what it's doing or not doing while it isn't starting.

You'd think it would throw a misfire code ??

 

[The_big_dill]

Maybe try plugging in a code reader (the kind that broadcasts to your phone) to see what it's doing or not doing while it isn't starting.

You'd think it would throw a misfire code ??

I only rely on the codes for hints, besides that engine light is there mainly for emissions purposes.

Look up how to diagnose the crank sensor, then check the gap and make sure there is nothing in between the sensor and the wheel.

The reason I say crank sensor is because it is the most important sensor for you engine, without it the ECU is clueless. If you have a chance to catch it giving you this problem at home, pull out a plug and see if it sparks.

This could also mean a bad ECU, but I would leave that to a later possibility as those are pretty robust.

 

[pcb]

I just re-read this thread and it sounds like your still using old used coils....

Get new coils,... go OEM to be sure they're good. I went with BeckArnley (from RockAuto) and they have been fine for me for two years now.


All of your symptoms can be caused by coils and our cars are notorious for coil issues. (especially weird Gremlin type activity)



This is what one guy wrote in,..


Hey,

just a shout out of thanks to all your guys who contribute to this forum.

I finally solved my stuttering P5 issue after like 2.5 years. The Fix for me seemed to be removing the connectors to the VITC and other electronics, cleaning with contact cleaner and connecting back. I also replaced the coils.

Check engine light is off. Runs nice. The dealer couldn't fix it, Pep boys or a monkey mechanic. But since someone on this site posted the connector fix, it is solved.

Paul

 

[Hank3]

I brought it into the shop yesterday. They troubleshooted for a while during the day and it shut off on them at one point after it idled for a while. It also had difficulty starting one time. But other than that it started fine countless times. He charged the battery and then all was fine. Well, when I went to go pick it up, it started up (kinda roughly) and then stalled within a sec. I called the shop manager out and told him it was not starting. I tried cracking it for him and it wouldn't start (same thing as my original video). I tried cranking it maybe 4 or 5 more times after that but the battery was starting to get weak. One of the times, he checked the spark of the leftmost connector from the coil and he could hear it sparking. The shop was getting ready to close so we left it. He said he was going to troubleshoot more today, but now that he has experienced the issue, it'll give him a better idea. We'll see what happens. I could tell he was stumped...the P5 gremlins are out at full strength

If he doesn't find anything, I'll definitely consider what you guys have chimed in with (new coils and crank sensor) - thank you, BTW, for the additional suggestions and info. I mean at this point, he feels like it's ignition related and not fuel related. He was able to drive it around some yesterday and it didn't exhibit any weird behavior. It seems like there's a good amount of "it could be this" right now" even though I've hopefully eliminated a couple of possibilities. I hope the fix eventually doesn't turn out to be expensive fix because the P5 is in great shape overall and would hate to cut my losses.

 

[pcb]

I remember PM'ing a guy for two weeks trying to help him with his car.
His car would only act weird after a full heat soak. He even had an oscilloscope to measure different outputs from his ECU.
It turned out to be his brand new set of coils, he replaced them again and his car was fine.

It seems weird that your car doesn't throw any codes.... I would think that you would throw a misfire code you're getting gas and its not firing.

I replaced my coils but had no issues with the old ones at all. I wouldn't do that was something like an IAC or EGR valve but coils are different so I just went ahead and replaced them.

 

[i12drivemyMP5]

Does OP car have oem alarm? Maybe the starter kill part of the alarm module is going out and randomly causing this issue? Could unplug alarm module from wiring harness and plug harness back together bypassing the alarm module and see if issue stops. Only other thing I could think of not already covered by others................

 

[Hank3]

I do not have an OEM alarm. And I did purchase a bluetooth OBDII reader. I've checked it for codes (even at the shop parking lot yesterday) and nothing shows up...other than the P0453 (Evaporative Emissions Control System Pressure Sensor High Input) CEL that popped up this past weekend...which I cleared.

 

[The_big_dill]

Hmmm, what about the clutch switch?

 

[Hank3]

Car started and ran fine for the shop today so they couldn't troubleshoot it. Talk about annoying and frustrating. So I'll pick up the car in a little bit and attempt to drive it home. I'm sure these symptoms will start happening again soon since they haven't done anything to fix the issue. Will check MAF tonight and consider all of the other things mentioned in this thread. I hate that I have to throw money at fixes that aren't certain. I have to stop at some point and just call it quits if this problem persists. Can't be throwing money randomly at this for too long...

 

[The_big_dill]

Highly doubt its the maf. Could it be the ECU?

 

[Hank3]

Highly doubt its the maf. Could it be the ECU?

The ECU is pretty robust. Been reading up on crankshaft sensors and the symptoms I'm having are within the scope of those sensors starting to go bad or already gone bad.

 

[The_big_dill]

I'm just throwing ideas at this point, but the crank sensor is the first thing I would check at this point. The cam sensor may affect it, but typically it's only got sequential fueling since our cars run wasted spark

 

[Hank3]

I certainly appreciate the throwing of ideas...they're free!

Filled up this morning on the way to work to F. As I started the car, it felt like it wanted to stall afterwards then was fine. As I pulled into my work, I could feel the car stumble a little bit right before I shut it off. I was reading about testing to see if the crack sensor is good/bad. I hooked up my OBD2 tool to the car this morning for a 3 cranks, and they all registered between 2200-2800 RPMs.

 

[The_big_dill]

I thought about it some more myself and I think if the sensor went bad it wouldn't be intermittent unless it was a poor contact.

The key words to your problem would be: starts and runs great most of the time. When it doesn't start it cranks over healthy and everything works but the engine.

Look into your emissions system. I know its a pita, but my friends Mazda 3 use to have a hard time starting after filling up all the way and it was part of the emissions system.

 

[Hank3]

I thought about it some more myself and I think if the sensor went bad it wouldn't be intermittent unless it was a poor contact.

The key words to your problem would be: starts and runs great most of the time. When it doesn't start it cranks over healthy and everything works but the engine.

Look into your emissions system. I know its a pita, but my friends Mazda 3 use to have a hard time starting after filling up all the way and it was part of the emissions system.

Yeah...been thinking about that too. It's a natural progression of trying to logically guess at what could be wrong I want to say that I don't think it's the crank sensor either since "most" of the time the car runs great. And I don't even mind it not starting every so often because it always starts after it sits for 5-10 mins. But things went to another concern level this past Friday when it stalled while cruising on a two-lane road. Now it's posing a danger to me and the cars around me. And I have to consider our new baby because she will on occasion ride in the P5.

Don't know really much about emissions systems, so not quite sure what to check/troubleshoot. I cleaned the MAF last night because it was easy and had the cleaner on hand.

 

[The_big_dill]

Yeah...been thinking about that too. It's a natural progression of trying to logically guess at what could be wrong I want to say that I don't think it's the crank sensor either since "most" of the time the car runs great. And I don't even mind it not starting every so often because it always starts after it sits for 5-10 mins. But things went to another concern level this past Friday when it stalled while cruising on a two-lane road. Now it's posing a danger to me and the cars around me. And I have to consider our new baby because she will on occasion ride in the P5.

Don't know really much about emissions systems, so not quite sure what to check/troubleshoot. I cleaned the MAF last night because it was easy and had the cleaner on hand.

Google and service manual are your answers, Think of your efforts as helping out the greater good, next time someone has this issue, I will know exactly what to tell them

I too believe its the coils though. The reason they fail on these cars in the first place is due to overheating. when you are driving, they get some air flow, but after you park it, they get heat-soaked pretty badly because the engine is hot and will continue increasing in temperature as there is no coolant circulating nor is there air flow and the coils are in direct contact with the engine.

I say get a set of coils if you haven't already.

 

[pcb]

Here's the short list of possible causes,...

 

[Hank3]

I purchased and installed a set of used OEM coils that had around 50K miles on them about two weeks ago. I thought the likelihood of two sets being bad were pretty small, but I guess there's no certainty like new. I didn't fare too well with an aftermarket brand about a year back. It triggered a CEL so I returned them and went back to stock.

Thank you for posting the service manual sheets. Was gonna look through it at some point. At this point, if I were to purchase another set of coils, I might go with OEM...but there so pricy. Probably $150-$200...and l probably should get new wires as well.

 

[The_big_dill]

Don't need OEM coils, go with a set of aftermarket ones from a good supplier.

I will be honest, I have seen these coils give so much grief for many people, but I have the original coils on my car at 230,000km... So I am basing off what others have experienced.

I have also seen a situation where the coil wire was bad in the harness, but that caused a mis-fire.