Brand new problem (scary!)

[NikFu S.]

Went to go pick the car up today even though they said it "wasn't idling right". I figured it was just being temperamental so I go to give it a run and no, it's still running the way it was before.

The guy said "at speed it's fine", which I am going to take with a few grains and just assume they didn't fix anything.

[EdWindows]

Sooooooooo did you ever inspect your cats??

[NikFu S.]

Cats have not been pulled.
We did a pressure test on the exhaust and found there was little back pressure. The engine is running very rich though, so I think if the cats are clogged there is another problem causing that.

Suspect of the moment is the z32 maf. Looking for a good one to swap in.

Today I found my intake snorkus is falling apart more than usual at the cam breather, but I would think a leak would cause a lean condition.

[NikFu S.]

I'm at the shop right now, threw a new maf in, no change.

The guy says they put a scope into the cats and visually inspected them. They look ok.

I put in some new chips a couple weeks before this went to ****, so today I swapped the old chips in and when the battery charges we'll run it again to see how things go. Don't have high hopes but we're just out of ideas.

[michael]

Do you have a spare computer laying around?

[NikFu S.]

Switching back to the old ECUTune chips had no effect. Visually inspected ECU, looks OK.

I don't have a spare.

Video from today: https://www.youtube.com/watch?v=hWEL...ature=youtu.be

Very wobbly at idle, steady at higher RPMs. I think that is what he meant by "at speed it's fine". I don't think he actually drove it but I assumed he did before.
The tach is reading the idle as normal. It's not wobbly from dropping to a low idle.

[Blacky]

It sounds like it's running on about 4 cylinders. Also are you sure the engine mounts are alright? That engine sure is jumping around a lot.

[ShiuludeSVX]

Sure sounds {and looks} like only 4 cylinders to me.

[NikFu S.]

Engine mounts are practically brand new. They were replaced when the head gaskets were done in November 2013, and the car sat for literally all of 2014. This year it's just been bouncing between shops for upgrades and repairs for 4 months straight.

I will agree it sounds like some cyls aren't firing. I'm going to go back over and pull injectors to see what it does. Last time it did nothing but it's running differently than when the problem arose so maybe we'll find a clue.

[michael]

Did you check for voltage leaks from the coils?

[Tapani]

There's another member on the forum who looses spark on all passenger side coils when heat soaked in heavy traffic.... replacing the ignitor is of no help. This happens only on idle - higher revs all is fine....

The +12V feed for the coils is separate for the drivers side and the passenger side. The ignitor controls the grounds.....

Have you checked that all coils do get juice?

/T

[longassname]

For reliable diagnostic connections on an SVX you should get one of my select monitor adapters.

I looked at your log and noticed the following.

Your o2 sensor is bad and is being ignored..isn't your problem

Your left o2 readings are consistently rich. Normally you would see your readings flicker back and forth between rich and lean. Since they are not that means the ECU is not able to get the get the exhaust readings to stoichiometric by shortening the injector on time. This is probably not because you are actually running rich. You are reading unburned oxygen because of the missfire.

I would probably put in a good right o2 sensor now for the following reason. If you put in a good right o2 sensor and log again you should see the afr readings on that side flicker around stoichiometric. If that proves to be the case that will tell you that you have a discrete missfire on a cylinder in the left bank. If it also reads steady rich then you will know you have something more nefarious that is effecting the whole system.

For now you will probably find unplugging the oxygen sensors will greatly improve how the engine runs. It is currently pulling out a lot of fuel because of all the oxygen it is reading on the left side. So you probably have 1 cylinder not firing and 5 cylinders running extremely lean.

To be quick about things and not have to wait for parts I would immediately swap the o2 sensors from left to right so you can get readings on the the right bank. Leave the bad o2 sensor unplugged. Just install it on the left to plug the hole.

...let me know what you find and I'll help you with the next step

Originally Posted by NikFu S.

So I got JECScan working, watched the numbers change as the engine ran, and what I learned is I have no idea how to use this.

I downloaded EVOScan and got that working as well, actually drove it up and down the street once and created a small datalog. It seemed as though the ECU has trouble keeping up with the logger as it attempted to reconnect 185 times. The car also felt as though it didn't want to move. It kept idle alright, but if I gave it more than a little gas it would bog down. Temperature readings seemed normal after actually moving the vehicle.

In the image below you can see the O2 readings are a bit strange. The numbers slant downward like that because I was shutting those readings down in an attempt to reduce the read load.

If anyone can make heads or tails of this I would appreciate it. In the meantime I suppose I'm either going to go learn to use a multimeter or go eat a cheeseburger and cry a lot.

[NikFu S.]

I tried to get readings today but it's all garbage. There was some sort of error, the computer restarted while it was logging, and after that Evoscan would not load properly and the battery was low anyway.

We disconnected the O2s and the car started without having to push the pedal, but it ran the same otherwise. We were not able to swap the sensors yet. I advised the shop to just install new ones since I seem to have no record of having them replaced.

We pulled injector connectors and observed the same behavior that I reported the first time. Pulling 1, 2, 3, and 5 does nothing. Pulling 4 slowly bogs the engine, pulling 6 bogs it quickly.

The idle seemed to deteriorate even though the tach read normal revs. It seemed by the time we were done scratching our heads it was running on two cylinders.
Judge that for yourself here: https://youtu.be/Adx9T8yJd5U
The revs seem to increase alright when throttle is applied, though I can tell it still isn't 100%.

I'm going to have them run continuity tests on the injector wires.

Originally Posted by longassname

For reliable diagnostic connections on an SVX you should get one of my select monitor adapters.

You mean this or something else?

[fasteract7]

"Four cylinders are decompressed (one only slightly, three on one side) and there's nothing left to check without going into the engine.

Even though they said the spark is good the guy actually doing the work said there is little or no combustion occurring."


Where does this previous info. fit in the scheme of things ? BTW, kudos for your tenaciousness !

[NikFu S.]

Originally Posted by fasteract7

"Four cylinders are decompressed (one only slightly, three on one side) and there's nothing left to check without going into the engine.

Even though they said the spark is good the guy actually doing the work said there is little or no combustion occurring."


Where does this previous info. fit in the scheme of things ? BTW, kudos for your tenaciousness !

I will have to ask very specifically when I check in next week, but I think compression returned when the timing was fixed. The prevailing theory so far is when this problem occurred it caused the belt to skip teeth and the resulting fuel dump killed the 02 sensor or it was gone already.