Falling on its face - EJ22

Last fall it was running good.

New lic plates today and off to get an inspection. Holly buck'in bronco, loss of cowboy hat buck'in. Made it the 2 miles there, got the sticker, and made it back. Bucking all the way. No Emissions testing, its now in a Kelmark bodied 73 bug chassis. Checked for codes when I pulled in for the sticker, the only one there was the speed sensor. Not running one. I was expecting to see the code for the 2nd o2 also, but that was not there, guessing I have not driven far enough to trip it yet. Rechecked at home, still just the speed sensor.

So back in the garage, at idle it surges about 100-150 rpm, and if you crack the throttle, it falls on its face, then revs and and stumbles/ surges. If you try to hold it at 2K, does the stumble and serge of about 300 rpm.

Where do I look first with out any codes ?

Its a 95 OBD2, running everything from the Subaru except the auto trans and evap canister lines from the engine are looped.

Thanks

My 96 Legacy EJ22 would act like that when it wasn't happy with the knock sensor, unlike the newer cars that would just pull a little but of timing to make things happy it would pull all of it all at once resulting in no power. In my case it usually meant I had run it low enough on oil that the hydraulic lifters would stop lifting and start making a racket, I'd top it up with a quart or two and 25-50km later everything was good again. 

Adam

Checking the knock sensor now, in the mean time here is a video of the issue.

In case the imbedded vid does not work you can find it here..

https://youtu.be/hgDajst_JeQ

Basics!

What is the fuel pressure, are there any leaks downstream of the MAF sensor?

The knock sensor issue isn't a "knock sensor" issue as much as it is a worn out engine issue, and the knock sensor triggers off of piston slap.  The computer is adaptive and will make semi-permanent changes to ignition timing as a result, mainly at the lower end.  You can see this easily on a scan tool if you watch ignition timing, and usually goes away like a lightswitch at 2200rpm or so when the computer goes into a different cell.  You can watch timing jump from 7btdc or so to 22btdc or so at the switchover point when it goes from "gutless" to "hey I feel great!!" mode.   Interestingly, clearing the computer with a scantool won't reset this, you have to disconnect the battery.  And then it will run great until it re-adapts again.  Moving the knock sensor to the bellhousing will accomodate a worn engine.

But it doesn't sound like this problem is the piston slap faking out the knock sensor issue, it sounds more like a lack of fuel/incorrectly measuring air issue.

Subbed for good info, hope you easily find your issue!

No leaks down stream of the MAF, but I will check again. I don't know the FP, torque lite is stating no data for fp. I will have to see if I can get my hands on a gauge to test it.

The fuel pump is chineseium, said to be the equivalent to a WALBRO GSL. No brand, just a part number on the box, E180-392. Its driven by the original Subaru circuit.

I just pulled the plugs, nothing out of the ordinary to my eyes, although the last time I was good at reading plugs was back in the 80 when everything was still carborated and plugs had some color.  

I will watch the timing to see whats going on there. When done tonight I will pull the neg from the battery to see what happens when I get back to it one night this week.

Edit: while there where some fluctuations in the timing nothing like what is described above.  I do have a second pump. I will swap that in at some point this week and see what happens.

Thanks for the input.

First time running it since last fall? Did you check the simple things like fuel being stale?

I've seen dirty MAF sensors cause similar issues. 

Fresh fuel last fall treated with stabil just before rolling into the garage. 

Cleaned the maf sensor yeaterday before taking the vid, no change. 

Today's update, not a lot accomplished, but good progress. 

A friend stopped by and interrupted the work so I did not get a lot done, but as chance will have it, we got something figured out.

Still no codes, so he said lets make it trip a code. So I unplugged the MAF when it was running, that killed the engine and no code. Fired it back up, unplugged the O2 sensor and let it run for a bit waiting for the check engine light to come on, it still had the same symptoms, surging idle, big pause when throttle cracked and wont hold an RPM. Thinking it was like a lean stumble (thanks Knurled), I crimped the return fuel line to get the system to full pressure. That did it, it idled better, it reved as it should, BUT plugging in O2 sensor with the return line crimped, and the issue returned, and still no codes. Guess I need to run it more to get the codes to trip.

Next course of action is to check the pressure get some real numbers, get that sorted out. Then figure out why plugging in the O2 sensor makes the issue return when the fuel pressure is up.

......Huh.

So, I have a friend who has/had an Impreza 2.5i (totally different species, it has 2.5l with drive by wire and pseudo-VTEC and it has widebands for O2s, and to be honest I don't even know if he still owns it)  and it had this weird problem where it ran like crap unless you unplugged the O2 sensors and then it ran just fine, except for the cruise control not working because cruise doesn't work on a Subaru if the MIL is on.

Long story short, I couldn't figure out what was wrong with it in the maybe 5 minutes I had my little baby MAC generic scantool plugged into it, and I really wish I could have had it at work with our big-boy get-E36 M3-done scantools and multi-channel 'scopes, but he has a repaired-Dieselgate Jetta Sportwagen now and he's registered at the next rallycross with one of his Miatas instead of the Subaru so I don't think I'll ever know what happened with that Impreza.

But my gut feeling is corroded connection in the bulkhead connector in the engine harness, because widebands are sensitive to current changes in the tenths of a milliamp range and he did have the engine harness open to atmosphere for a few months...

(Also:  Multiple Miatas, Jetta Sportwagen, he couldn't be more GRM unless he had some old British car and a 944.  Except he does have those things.  And an Esprit Turbo, because super-cheap supercar)

"did have the engine harness open to atmosphere for a few months"

My harness was open for about a year, maybe more, while I was in the swap process.   Another thing to check. 

Thanks

Got it.

Did a visual flow test on the pump that was installed with a steady 12 volts from my 10 amp charger. Weak stream and anything but steady, wonder of this is the type of activity Dr.s are talking about when they ask during your physical....

So anyway, I have another chinesium pump and an MSD pump from when I bought a used grease car kit for the 300D that I had. The pump was good, ran diesel through for 20 minutes back when building the grease car so it would not be gummed up with old veggie oil when needed as it was not needed for the 300D project. I went with the MSD. All installed and nothing, the pump was dead, not even a spark with connecting the charger to the terminals. Thus on to the 2nd chinesium pump. Bingo, what a stream, steady and powerful, like your first leak after three beers and holding it for 20 minutes.

Connected everything back up and its running good. Out for a drive and no bucking, no surging at idle or when holding a rpm.

Thanks to all for the input. Hopefully I remember this if the problem returns.

Now back to all the small stuff that needs doing, like adjusting a radiator hose before it rubs through.