2003 Vue FWD 4CL. P0302 Misfire. Spontaneous recovery, then back to problem

[Rogerrp]

Dear Saturn fans,

2003 Vue FWD 4CL. Manual. 125k miles. P0302 Misfire. Spontaneous recovery, then back to problem.

Suddenly last Monday engine started misfiring as I start the car, happens at idle and any gear, hot and cold engine. Tank half full. Always Premium 93 gas.
OBDII sees p0300 with one reader and p0302 with another reader. No other codes.

Clues:
For a few months smell of fuel at start. Decided to work on fuel line this next Spring (fuel filter change, techron cleaner liquid, leak checks, injector checks,...) but now I can't wait (assuming fuel line is the guilty player). Spark plugs are new, coil is new, wires may be old (I have no record of when they were changed). Bought the car last summer, have done some basic tune ups.

The puzzling event is that last night, I added the techron fuel line cleaner liquid and filled up on gas (First time I use fuel cleaners ever but I had to try this time). No immediate change (obviously). 1 hour later I opened the hood and disconnected a vacuum hose (intake manifold port I think and hope) wanting to check for vacuum leaks. Could not even get a proper reading with the vacuum gauge. But, in 30 seconds of the engine being on, and misfiring/shaking, the engine misfires dropped in frequency. I reconnected the vacuum hose that I had disconnected and the engine continued to behave better and better. At that point I guessed that the techron cleaner was magically starting to act. Got in the car, drove around the block, perfect car behavior. Noticed the rpms at idle were lower than usual (800 instead of 1000). Drove again 5 minutes later and no problems either.
This morning, started the car and misfires again. As bad as before.
Dropped the car at a garage so they can have their guess.
Is the spontaneous but temporary recovery that I saw last night a clue at all? Does anything else that I have written give you a hint?

Thanks in advance for your input.

Roger

[far2grumpy]

Roger ... see the thumbnail and try to locate the hose you removed (or general area).

This diagram does not have fresh air intake tube to throttle bode so perhaps the line was part of that.

[Rogerrp]

The one that plugs in where the arrow points. From the air duct to there.
Thanks,

R

[far2grumpy]

Originally Posted by Rogerrp

The one that plugs in where the arrow points. From the air duct to there.
Thanks,

R

That fitting is for the positive crankcase ventilation (PCV) system. A good quality hose should run from that fitting to a nipple on the intake air duct.

PCV establishes a closed loop where engine fumes are "sucked" into the air intake to be burned during the ignition processes and passed through the exhaust system.

If engine runs better with hose removed it could mean the hose is clogged, which means pressure will build in engine and affect operation.

Another downside of a clogged PCV hose is internal pressure will build to distort the valve cover gasket causing oil leaks.

One way to check for a properly operating PCV system is to rev engine to 1500-1600 RPM and pull the oil dipstick. A vacuum should be felt at dipstick hole. Pressure could mean the PCV system is clogged or you have excessive blow-by (bad rings in one or more cylinder).

[Rogerrp]

Thanks for the info.
My first follow up question is where is the intake manifold vacuum? Not even looking at the picture in the Haynes manual can I tell which hose it is.

Concerning the PCV:

I left the car at a mechanic this morning and he has been vague as to what he checked but in the end he could not even identify the problem. I did not tell him about the PCV hose as I am still skeptic that the solution revolves around it. Mechanic failed and problem persists. After dinner tried to replicate my experience from last night by removing that PCV hose again and certainly, the engine stopped misfiring at idle. Checked hose and connection and is not clogged. Reconnected hose. Took car for a ride and misfired in 3rd gear and up. Less misfiring than usual.
Could I have something blocking the throttle and that messes up the pressure in the entire system in such a way that with the PCV hose off, that pressure comes back or it is relieved through the disconnected air intake duct?
Here is the thing. I have not even run the proper control for the pcv hose disconnection experiment were I turn on the car and let it idle for 5 minutes to see whether it is just a matter of waiting before the misfires present at start are reduced.
Plan for tomorrow, snow storm or not:
Check vacuum pressure (if I can find the right hose)
Check spark plugs and wires, maybe swap them around and see if the DTC follows a spark plug or wire set.
Check fuel pressure.
Think and read your answers.

Good night and thanks again far2g.

R

[far2grumpy]

Check the thumbnail ... item 4 is the EVAP purge valve ... one end is traceable back to carbon canister and the other (front) is tied to intake manifold vacuum.

I can't put a finer point on where the vacuum hose is routed to because I've not dealt with a 2.2.

A smooth idle with the PCV hose removed is probably a good clue for some one familiar with the 2.2. I assume when you unplug the hose from valve cover you let it dangle in free space. Or, do you crimp the hose to limit airflow into intake duct?

The ignition module and coil pack will limit swapping plug leads - but you can swap plugs. I use a Sharpie to number sparkplugs removed from any engine to keep track of how each plug is working.

If you find your Vue misfires after engine has warmed you could disconnect the electrical lead to the upstream O2 sensor. Its OK to run without this sensor for awhile so you could try to see if engine runs smoothly.

Don't do for extended period since engine will run open loop and the injectors will tend to inject too much fuel to each cylinder ... this could eventually harm the catalytic converter.

[Rogerrp]

Updates:

Busy weekend:
1) Checked spark plug gaps.
2) Cleaned throttle body (dirtiest thing ever).
3) Changed o-rings in fuel injectors cleaned their tips with B-12.
4) Checked vacuum and no leaks at idle. Acceleration drops pressure very quickly and even if I am still accelerating pressure returns to a steady normal. Letting go of accelerator raises pressure to 25-27 and in a couple of seconds it is back to normal (~19 or so). By the way, needle vibrates fast 0.25 mmHg either way, maybe less (I attribute this to normal engine vibration or is the needle supposed to stay put without any flickering?).
5) There is no PCV valve to clean in Ecotec 2.2l and the trick of disconnecting the PCV hose does not work (probably never did, it was just a matter of letting the engine warm up).

Symptoms have not changed but I can describe them better:

Idle cold:
Turning engine on brings 1200 rpm, sometimes it starts at 1500 rpms (never done that before and is another symptom of this problem). 15 seconds to drop to 1000 rpm. 1 or 2 minutes to drop to 800 rpms. Even at idle and as rpms slowly drop, engine skips, misses, randomly, once every 10 seconds or so. brrrrrrrrrrrrrrrrr-pr-brrrrrrrrrr-pr-brrrrr ... I can feel the problem/vibration through the clutch pedal (this is normal, I know).
No SES lights blink or turn on.

Idle warm:
700 to 800 rpms, no missing.

Cold engine, 2nd but mostly 3rd and 4th gear, less than 1500 rpms:
Missing, skipping, no acceleration, hesitation, whatever you want to call it. If I do not lower the gear, sometimes SES light flashes, then stops, but SES light does not stay on. I do not try this often = I avoid reaching the point where the SES light flashes by driving in lower gears than I used to.
Also, without the car being too hot, sometimes (not often, once every 100 miles) I can hear the coolant pump on for no apparent reason.

Warm engine:
Much much much better, barely any hesitation. Also, not speed related: I can drive in 5th gear at 50 or 60 mph very smoothly.

Plan for next weekend:
-Test coilpack.
-test MAP sensor
-test Engine coolant temperature sensor.
-test fuel pressure.
-Run b12 on fuel lines.

What else? Any further ideas?

Thanks in advance.

Roger

[far2grumpy]

A few thoughts - vacuum gauge will oscillate rapidly if there's an engine problem - say leaky valve(s).

Did you connect gauge to EVAP purge valve using a T-fitting? If yes, you can crimp the large hose leading back to carbon canister which should eliminate needle wiggle.

Engine startup RPM does not sound too bad to me - my two 3.5 Vue's do basically same as you describe - on a very cold morning.

The amount of fuel delivered to a cold engine is based on ECT, MAP and TPS. But wait - I'll attach a service manual extract explaining fuel delivery scheme for cold start through shutdown.

It sounds like the engine miss you report happens infrequent enough to not cause a MIL misfire condition. Root cause could be fuel or ignition related and you intend to check fuel pressure and coil so you might know more after those tests.

[Rogerrp]

Thanks for the tips.
Vacuum gauge connected without T. Vibration of less than .1inHg. I know larger regular and fast vibration would mean valve problem but this shaking did not look like that. I think. I have been looking for videos of vacuum tests as I only have some pictures in the Haynes manual to go by.
Last night after dinner I recorded OBDlink data, attached as zipped csv file in the hope that people more experienced can make sense of some sensor data.

During recording, engine was cold when I started and still, problem did not manifest itself. I had to "race" around the block and get into 4th gear low rpms in order to feel the hesitation. I wish it ran this way in the mornings too. Assuming everything was as cold as the ECT sensor shows, could it be that the difference last night was that the battery had not been sitting in the cold overnight? I shall add a battery check to the list of things to do even though in November I got the battery checked and they said it was in good condition.

I hope the sensor data helps.

R

[fdryer]

I think this is an intermittent ignition issue. I would disconnect and remove the ignition control module, coil pack, and coil on plugs for close examination of any corrosion on terminals or break down of the coil pack. Some dielectric grease in appropriate areas can prevent future corrosion. Inspect the coil pack and COP's for carbon arc tracking, indicating an incorrect path for high voltage.

[Rogerrp]

I have the dielectric grease ready.

Snow storm today and tomorrow. Daughters birthday on Saturday. Car fun postponed til Sunday.

What is the COP's for carbon arc tracking?

Thanks,

R

[Rogerrp]

Update:
Spark plug boots removed, coil tips gently cleaned with sand paper, dielectric grease everywhere. Spark plug boot 2 had a spring like wire inside twisted. I swapped 2 for 3 while I order new ones.

Problem still present. Will wait to see what misfire code pops up this time, with luck it switches to cyl 3, then I know it is the boot.

In the meantime, I recorded and uploaded a video on the vacuum readings that I am getting. Let me know if the vacuum looks normal to you:

Just realized I cannot post links to external websites yet. Search youtube for "saturn vue 2003 vacuum" I should be top hit ("Intake Vacuum Saturn Vue 2003 FWD Ecotec 2.2l Misfiring" is the title)

I could not do more today.

R

[mellissam]

You know Roger, your problems sound very similar to mine...a dirty throttle body (and dirty IAT sensor), bad battery and very small cracks in PCV hose (not convinced it was that though). I changed PCV hose anyways. Changed battery.

Novice thoughts: The recovery of engine on your vid makes me think your throttle body isn't clean enough (seafoam)...like it is still not closing all the way or you have a leak somewhere (also saw a vid recently of how to clean the TB and making sure the evap line into TB is clean too). My battery also contributed to my problems, as the engine will compensate for flaky battery.

Anyways, once everything is clean and good to go, do the relearn process...was posted here recently. Disconnect battery, wait (press gas pedal to remove any charge), reconnect battery, turn to on (but not start) for one minute, turn off, start engine, drive around with AC/heater on, lights etc. to create high load. My Vue then reset and it has been running much better. Heck, almost the best it has ever been...lol. I also started using 93 and my mileage has been great...the ticking noise I used to get is muted now too...

[Rogerrp]

I seafoamed the engine last night (half a can). Much much much better this morning.
I never took the TB apart to clean it. Probably left gunk behind the butterfly. Will take TB out this weekend and clean it.
Engine still hesitated at low rpms when cold. It behaves better than ever when it warms up.
Other half of seafoam in with the oil as I am due for an oil change (will wait 100 miles/ a week). I always use synthetic high mileage oil. Also always 93 octane gas (but cheap Hess).
No seafoam in fuel tank as I still have B-12 in there.
Should have seafoamed before the winter started!
Can I keep seafoaming the engine to see if it gets progressively better? How much is too much seafoam? At less than $10 could I do this once a week until I see no further improvement?
Thanks for all your tips.

R

[far2grumpy]

I watched video - vacuum does jitter a bit - but could be EVAP system unless you disconnected to install gauge.

Does engine still misfire - and did you determine if moving the plug lead spring between 2 and 3 made difference?

I'm not a big fan of dumping lots of chemicals into the intake - potential results look good on paper but burned and unburned junk moves from engine into exhaust system and first obstacle is catalytic converter.

You say hesitates at low RPM when cold ... what is RPM soon after cold engine start with no pressure on accelerator pedal?

You've probably seen but here's service manual extract to explain which sensors control fuel flow after engine start:

Run Mode

The run mode has 2 conditions called Open Loop and Closed Loop. When the engine is first started and the engine speed is above a predetermined RPM, the system begins Open Loop operation. The control module ignores the signal from the heated oxygen sensor (HO2S). The control module calculates the air/fuel ratio based on inputs from the ECT, MAP, and TP sensors. The system stays in Open Loop until meeting the following conditions:


The HO2S has varying voltage output, showing that the HO2S is hot enough to operate properly.


The ECT sensor is above a specified temperature.


A specific amount of time has elapsed after starting the engine.

Specific values for the above conditions exist for this engine, and are stored in the electrically erasable programmable read-only memory (EEPROM). The system begins Closed Loop operation after reaching these values. In Closed Loop, the control module calculates the air/fuel ratio, injector ON time, based
upon the signal from various sensors, but mainly from the HO2S. This allows the air/fuel ratio to stay very close to 14.7:1.

[Rogerrp]

Will take all this in consideration. EVAP was disconnected.

Also, I had the misfires yesterday before seafoaming and they were still in cylinder 2 even though I had swapped the boots.

I have not done the relearn process that mellissam described.

As I said, I will keep an eye on how things develop in the next few days. Without misfires, I am more comfortable driving around and slowly getting this car in shape.

Also, SEL turned itself off this morning too, so I will be paying attention to it if it comes back.

Battery showed 12V but that is all the testing I did to it.

R

[fdryer]

Originally Posted by Rogerrp

........ What is the COP's for carbon arc tracking?

My bad. Coil-on-plug boot, The insulated plug boot and spring between the ignition coil pack and spark plugs. Carbon arcing would be high voltage arcing incorrectly through the boot insulation to the engine block instead of through the spark plug and jumping across the gap. Carbon arc tracking would be a very thin trail of burned insulation or one spot that may or may not be seen easily on the plug boots. Ensuring the springs makes good contact on the coil terminals and top of each spark plug helps to direct the high voltage.

[Rogerrp]

Thanks for the explanation.
I am changing the spark plug boots and springs too this weekend. Did not see arcing when I checked two days ago.

R

[mellissam]

Originally Posted by Rogerrp

...
I have not done the relearn process that mellissam described.

....

Battery showed 12V but that is all the testing I did to it.

R

I wish I knew what the ECM relearns when doing a 'relearn', but it changed something or many things, as the I4 behaves totally different than before.
That battery voltage number seems low...imho...12.5v or higher should be number...near 14v when running (alt supplied voltage).

[fdryer]

^ The relearn procedure is basically for GM's Passlock theft deterrent system. The separate EFI system modules, pcm and bcm are 'married' electronically with an initialization process that lets the bcm recognize and accept the pcm for a fuel password. Once married, the theft deterrent program from the body control module receives the remote door Lock/Unlock command to tell the bcm to perform door lock service while enabling or disabling Passlock security. With Lock, Passlock security disables fuel injectors from operating - anyone trying to start the engine will only hear the starter cranking the engine. The fuel injectors being disabled won't allow the engine to run. The relearn procedure allows replacing an ecm, pcm, bcm or tcm in vehicles having these modules otherwise simply attempting plug n' play won't work as the security light either flashes or stays on and the fuel password isn't learned.