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Discussion Starter #1 (Edited)
Specs: Saab 07 Aero 2.8 84k miles (I have put on about 7k)

Parts Replaced: Battery (was failing over winter), Vacuum lines from master cylinder, spark plugs ((NGK #1959 (Double Platinum) gapped 0.035), all 6 coils (bosch),

Previous History I have found: Car has had its upper intake gaskets replaced (I could see fel-pro which probably aren't stock). Previous owner also had a fuel injector cleaning at pepboys a few years back. Also 3 back coils were replaced (no clue when) plugs didn't look old at all. I suspect this misfire issue was happening in the past.

History: During the winter while warming up, car was occasionally shutting off (no codes). It would also happen sometimes at stop signs. Eventually I got misfire codes while driving (p0306 p0305 p0304 0303 p0301 p0300). So I changed the plugs and the car ran fine for a week then misfires again. When changing the plugs, I noticed the previous owner changed the back 3 coils with non Bosch ones. So figured it was probably the coils. Changed out all the coils and made the gaps the smallest gap size as per the sticker on car (0.035). Car ran fine for few days and again misfires while on the highway. So I thought it was probably a bad connection at the coil wire since the car was running perfect for a few days. Took each coil and depinned and cleaned them 1 by 1 all 6 oil connections. Used some fine sandpaper and and de-xoit dn5. I also sprayed the pin connectors for the ecm(*see for more on why I cleaned each wire). Car ran perfect for about a week even in heavy traffic. Then one night coming back from the city, we pulled up to a spot to get a snack and the car shut off while in drive. The next day it also shut off while I was leaving a drive-thru and on then while on the highway, boom blinking misfires and non blinking again (this data log is used in the misfire charts). While the misfires were happening on the highway, I looked at torque and noticed that my short and long term fuel trim were no longer adjusting itself and my evap pressure was no longer adjusting either and the o2 sensors were also flat lined. I am not sure if once the car detects misfires is this has anything to do with limp mode perhaps?!?

Following day, I needed to move the car into the driveway. I turned on the car, it was running terrible with check engine light as expected. Moved the car before it was even able to fully warm up. Then shut the car off popped the hood. It was at that point that I heard the electronic Boost pressure control valve (179a) still clicking with the car off (**see video). I have not noticed and issue with the boost.

* Reason I decided to clean the connectors was because over the winter my headlight, my fog light (even my exterior temp sensor) was not always turning on and if you hit it, it would turn on aka bad electrical connection. So I depinned the connector wiring by the window washer fluid and cleaned all the wires. Never had an issue after that with the lights again. The pins for looked clean, no visible rust or gunk but there must have been some gunk on there invisible to the eye.

** ((Video of Boost pressure control valve (179a) Clicking While is Car Off (
)

Thoughts and analysis:
I downloaded and plotted my good and bad rides from Torque Pro to examine (See attached). When the misfires happened on the highway, torque stopped showing changes to long and short term fuel trim. The o2 sensors seemed to also flat line and the evap was no longer fluctuating like when the car was running normal.

I used torque for my logging because it was much easier to do with the tablet and bluetooth dongle. The car stopped misfiring for over a week and then just did again.

The three times I have disconnected the coils and plugs and ecu (ME9), afterwards the car has worked normally meaning no misfires. Which makes me believe the issue is electronic but that is just me thinking out loud. After everything that happened and looking at the torque data seems like it could be my 02 sensors and/or something with the evap because data stops changing immediately after the misfires. :roll:









 

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Evap an fuel trims might be normal to shut during a misfire condition(i will have to look at WIS), however O2 should operate normal for sure unless there is smthn wrong with the app, but if they r flat down, that could be ur issue (lean running)
Im sorry, the data is too blurry i cant see nthn .. pm plz
 

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When it dies, does it start right away ?
Does it die when u r coasting, or when u try to demand more power ?
 

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Bad ECU my guess.
 

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Discussion Starter #6
Evap an fuel trims might be normal to shut during a misfire condition(i will have to look at WIS), however O2 should operate normal for sure unless there is smthn wrong with the app, but if they r flat down, that could be ur issue (lean running)
Im sorry, the data is too blurry i cant see nthn .. pm plz
Hush thanks for pointing this out, the forum shrunk my photos. I just put them on another host. Answers to your question below.

Q: When it dies, does it start right away ?
yes starts without any problem

Q: Does it die when u r coasting, or when u try to demand more power ?
When it has shut off its been when I have been in drive and with the brakes on.

Point: Ground and ECU. This is what I am starting to suspect. I noticed this in the wiring harness btw. Previous owner or mechanic spliced a wire here, but why just makes no sense. My ECU is also only attached by 1 screw to the engine. The mechanic must have lost/dropped screws when he was working on the car. One is broken (see photo) the lower one on the bracket is missing. Not sure if that could be part of the issue. I have to look at the wiring diagram and figure out what that yellow wire was for. I have no clue why it was spliced, the black wire was added in between the yellow.

@Diggs, yes I am starting to think this is the issue. I am going to have to first have to check all my grounds.



 

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Not sure how the V6 ECU works but the 2.0 has a grounding wire on one of the bolts. Perhaps replace all the missing bolts as that is cheap and see how it does. Pop that one out and take to home depot/lowes to get right thread and pitch. Should be easy to mimic. And see if there is a ground wire supposed to be somewhere as well.
 

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The grounds on the 2.8 ECU are smaller bolts down between the ECU and the firewall. They attach to the bracket, and there is one on each side of the ECU. I doubt your missing bolt is causing a grounding problem.

Just something to check, but I recently got a bad batch of spark plugs. Everything was normal while I was driving, then I asked for power, and suddenly had horrible (blinking CEL) misfires, and the car went into open loop mode (ignores all sensors/fuel trims) while running on three cylinders. The next morning, I started the car, and everything seemed ok, but the problem resurfaced later in the day.

Turns out the plugs I got were not properly bonded at the ceramic to metal bolt head interface. Three of them could actually move in/out by shaking the part, which effectively allowed the gap to vary between almost 0, and way too big. The other three I could actually spin the ceramic section in the metal part, but it took a little force, think about the force it takes to sharpen a pencil in one of those little handheld sharpeners.

I replaced all my plugs, and no more problems since. This may not be it, but is worth checking.
 

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The grounds on the 2.8 ECU are smaller bolts down between the ECU and the firewall. They attach to the bracket, and there is one on each side of the ECU. I doubt your missing bolt is causing a grounding problem.

Just something to check, but I recently got a bad batch of spark plugs. Everything was normal while I was driving, then I asked for power, and suddenly had horrible (blinking CEL) misfires, and the car went into open loop mode (ignores all sensors/fuel trims) while running on three cylinders. The next morning, I started the car, and everything seemed ok, but the problem resurfaced later in the day.

Turns out the plugs I got were not properly bonded at the ceramic to metal bolt head interface. Three of them could actually move in/out by shaking the part, which effectively allowed the gap to vary between almost 0, and way too big. The other three I could actually spin the ceramic section in the metal part, but it took a little force, think about the force it takes to sharpen a pencil in one of those little handheld sharpeners.

I replaced all my plugs, and no more problems since. This may not be it, but is worth checking.
Interested in what plugs and where they were bought.
 

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Do u have the two ground wires attached at both sides of the ECU ?

Add links to the data images..

Provide more data on that slice..

Where did u buy the coils from ?
And spark plugs as well ?
 

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Discussion Starter #12
Point on Grounds: the ecu has 2 ground wires on each side as mentioned that are tied into the bracket which are attached via 3 bolts via the bracket to engine. My only top bolt is nice and tight.

@JBarstad
You lost me here, so when these engines get misfires, they ignore the sensors and data and go into open loop? I have pulled out the plugs 3 times so far, nothing that would indicate any physical failure. I'll look again.

@diggs, I went with NGK#1959 based on info in this forum and also went to the NGK web site and confirmed the info said OEM. Figured these would be better since they are double platinum. I got the plugs and coils from rockauto. 4 coils came in the bosch blue box and the other two in some bosch yellow box. Originally I only got two coils to replace the non oem ones.

@hus_sho, looking at the wis I haven't been able to figure out what happens when the engine detects misfires. I love the wis but sometimes the search leaves a lot to desire.

Q: Are the ecu grounds attached
A: Yes 100%

Q:Add links to the data images/Provide more data on that slice..
R: Do mean to upload my torque csv file?

Q: Where did I buy plugs and coils.
A: rockauto

Now that the car is misfiring I want to connect the tech2 but I am afraid of what damage I could be causing even if parked. What do you guys think on that point?
 

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Misfires on all 6 cylinders is not a coil or plug problem, no point going down that hole (I was just curious where you bought them). Both O2 sensors flatlining is not normal and I don't think they have anything in common in regards to wiring. The flatlining would absolutely lead to all the misfires.

All points back to ECU IMO.
 

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Misfires on all 6 cylinders is not a coil or plug problem, no point going down that hole (I was just curious where you bought them). Both O2 sensors flatlining is not normal and I don't think they have anything in common in regards to wiring. The flatlining would absolutely lead to all the misfires.

All points back to ECU IMO.
Totally agree. One coil or plug bad, MAYBE two at any one time...ok. But not all 6 at once.

Edit: just saw the butt connectors in your harness in the pics above. Can’t say I’m a fan... I’d soldier and heatshrink them IMO.
 

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Discussion Starter #16
So today I hooked up the tech2 and pulled the codes. Sure enough same as previous p0306 p0305 p0304 p0302 p0301 p0300 all cylinders except #3. So then I disconnected the ecm top connector and reconnected it. Then checked for codes, and they were gone. Assuming that the ecm gets reset when you pull the top connector.

I then started the car and ran it for 12 minutes and the car ran normal. Monitored the data on the tech 2. Short term fuel trim was changing normally. I didn't see a long term fuel trim in the data maybe it was named something else.

Suspect the ecm and/or the wiring coming from the UEC to the ecm.

Also the tech2 has a cool function under ALL/BUS/ ECU Response Test. Basically it will send commands to the ecu repeatedly and you can wiggle the wires to see if you get an error. I didn't get any errors while pushing and flexing the wires connected to the top ecm connector.
 

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Discussion Starter #17
Grey Connector

Does anyone know what this grey connector is for? Searched all the connectors in the WIS and can't seem to find it. The wires go into the plastic rails in the back (where the fuel injector wires also run) But that thick yellow wire that is spliced is not related to the injectors and no clue why someone would double butt splice it.
 

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I believe this is the main wiring harness for the injectors, it should be sitting under the bracket for the atmospheric pressure sensor .
U need to dig in this issue, where is this sliced wire going !!??
 

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Discussion Starter #19
@Hus_sho I haven't been able to find it in the wis. I thought it was the injectors but then looked at the wis and the injector harness is close by but not that one in the back. Its just floating there mind you which is somewhat weird unless the previous dummy just didn't bother putting into its correct holder. Attached is the injector harness.

Anyone have a clean stock photo of that area to share?

 

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Do u know where the atmospheric sensor is? Reach it with ur hand from underneath its bracket and move 2 inches toward the driver side of the car, is there a connector attached to the bracket ?
The problem with WIS is that it is showing it a little bit off its location.
Do u actually see the injectors connector as described by WIS !! I dont think soo
 
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