Spark Plug analysis ... again :) - Hesitation Solution !!?!

[morgie]

Tonight I did couple of things on my car, for fun.. hehe what else to do by a -20°C evening other that playing with the car

so among the things i did, I once again changed the plugs, because the BOSH ones i putted into the car 3 weeks ago were SOOOOOOOOOOOOOO Crappy and sucking a lot of gas !.

So when I removed them, i was Surprised how DIRTY they were !! 3 weeks old, got a lot of High-Revving (lot of snow) lately so lot of heat to clean them, and despite all that, they looked very dirty. black. totally black.





I replaced them with NGK V-Power. Went for a test-drive. WHOAHHH What a difference !!!! after driving it hard for 10-15 mins, the car started to pull like it was meant to !!! Ah ! but, not all the time. in 2nd, sometimes the car pull really great, sometimes not so great. like if the engine is still verry warm, it pulls ok, but if i let him 15 seconds to cool down, then it wont pull as hard.


The bosh plugs revealed that my engine runs very rich. the new NGK might have a better facillity to burn that mixture. But, what is causing the car to run so rich ???


I'm close to my goal, but not there yet, but now, the car is more fun to drive !! hehe


thanx for your help

[Legacy777]

For one.......subarus run rich in general.........two.....turbo cars run rich.......three......subaru + turbo car runs really rich.

I would suggest some sort of fuel management/boost controller to help dial in a/f mixture better.

I would say that the a/f ratio and the fact subarus run rather rich is a pretty reasonable cause for some of the hesitation issues A LOT of subaru owners get.

However dave put it best......."you can always rich.....however you can only run lean once"

[IggDawg]

Morgie!!! Check the sticky at the top of this forum . I had the same EXACT plugs that you're showing. Read the hesitation problem I was having. I bet my left nut it was misfiring in my case. I pulled my plugs, and they were totally clean for the most part. but then I only had them in for 2 months and I know I'm not burning any oil. I had the same weird white deposits on the electrode that yours appear to have. I put in the NGKs, and WEEEEEEEEE!! It pulls now like it used to with a gallon of xylene and 11 lbs of boost. holy fock what a difference. I'm never putting those POS bosch plugs in anything I own ever again.

But yeah, I had those same plugs and they just filled my engine to the brim with suck. If your hesitation was the same as what I describe in teh sticky, I think we've found the answer to a lot of peoples' hesitation issues.

Another Legacy Turbo gets rid of the hesitation!! w00t!!

[morgie]

In fact, for my case it's a partial victory ...

I've read the sticky and found that your problem is very similar to mine.

I'll try to soak my engine into xylene to see if i can get the same results as yours ..


Yesterday, along with changing my plugs, I installed a "termal probe / sensor" into my intake, just in front of the throttle body to monitor temp. at the intake and how the car is reacting. (this is no rocket science, just a 10$ Electronic thermometer bought at home-depo).

This morning, I wasn't getting hard accelerations like i was yesterday. I noticed that the temp. in my intake was peaking at about 41-44°C, WOT in 2nd at 10psi. Then the car continued to warm up, and the car was starting to pull better and better. Temps. in the intake was then peaking at around 51-52°C.

I'm realy starting to think that my car have difficulties to ignite the mix (in fact, i'm pretty sure it's that since a long time..) .. and that i'm getting lot of missfire leading to dirty plugs and poor accelerations.

But i don't know what approach to take to be sure that this is my problem (and not something else like a very dirty engine... or else) and how to solve it whitout replacing a lot of parts 'just for fun' ..


in the area, subaru techs are 75$/hrs + 15% tax (grr) wich is very expensive, and there is no other "subaru specialits" here, so.. i'm kinda left to myself into finding and solving that prob. (but i might decide to let a subaru tech. inspect it if i cant find any solutions.. :\ )

[boostjunkie]

What are your plugs gapped at? Are you throwing any codes? My other guess would be that your o2 sensor might be on it's way out. The sensor is a non-heated element which requires the exhaust gas to warm it up. That might be why you're seeing problems at start up. Perhaps once the car goes into closed loop (and taking values from the o2 sensor), that it starts overcompensating with fuel for bad values from the o2 sensor.

FWIW, I wouldn't run full boost anyway until the car has sufficiently warmed up.

[entirelyturbo]

Well, I'm glad to see all you turbo people have resolved your hesitation issues, but for us N/A people that have them, I hope I've narrowed it down to one thing... the knock sensor...

After I replace my motor mounts, I'm going to replace that sucker, and if that doesn't do it, I'm going to curse very loud, probably kick the car, and change my mechanical engineering major to journalism !

I have NGK V-powers, I have a new coilpack and wires (which are attached correctly this time ), I use 89 octane, I have a good MAF (good mileage and all), I have new-car compression, I have no codes, and I floss regularly...

[boostjunkie]

Also try a S-AFC and a good tune from a dyno. I'm willing to bet you're running CRAZY RICH as well . . . might be cause for your hesitation as well. Yup, it's costly, but you'll be able to find out on the dyno what the hell is goin on with your car.

[Legacy777]

Couple things.

Morgie......couple suggestions.......I do think you are running rich. Couple things you could do is get an MSD Dis 2 ignition to increase spark. Other thought would be go with a hotter plug......however that may cause other issues like pre-ignition.

Michael, knock sensor may fix it....however I doubt it will fix it completely.

I do think the S-AFC will probably help......however only seems to help in open loop mode. In closed loop, the ecu seems to learn around it.

[morgie]

MSD DIS-2 = 700$ CAN + install + tax.

I already have a broken exaust Manifold and up-pipe to change, wich are not very cheap.

S-AFC is 850$CAN + install + tax...


Put i'm wondering... why i have that problem, and i only run 10psi, that's not a LOOOOOOTTt more ! . should be something not working properly on my car... :\ no ?
hehe

Me hoping for miracle solution. I KNOW !!! I'LL pour Oxy-Clean into my intake!! that will clean all things up ! hehe .. or maybe i'll need some orange-clean.

[vrg3]

I do think the S-AFC will probably help......however only seems to help in open loop mode. In closed loop, the ecu seems to learn around it.

If you're using an S-AFC, you should probably unplug the oxygen sensor. Our engines are happy to run in open loop all the time. On my car it doesn't even throw a CEL; the code only comes up if I do a D-check.

[boostjunkie]

Even with the o2 sensor hooked up, the car runs in open loop at anything even remotely close to boost. In the lower rpms, around 8-10% throttle, at the higer rpms, well, I'm usually in boost

[Legacy777]

I do think the S-AFC will probably help......however only seems to help in open loop mode. In closed loop, the ecu seems to learn around it.

If you're using an S-AFC, you should probably unplug the oxygen sensor. Our engines are happy to run in open loop all the time. On my car it doesn't even throw a CEL; the code only comes up if I do a D-check.

You know this would explain a lot. I've done some tests, and it didn't seem to matter whether the O2 sensor was unplugged or not. I didn't get any check engine lights. Maybe when I'm on the highway it'd be in closed loop.....

Is there any way to check/tell if the computer is in closed loop vs. open loop?

Remembering too....I have a n/a not turbo model.

[boostjunkie]

Legacy777, if you have a volt meter you can test the O2 sensor wire while driving. At closed loop your readings will fluctuate between .01 and 1 volt. When in open loop, your reading should stay ALOT steadier . . . maybe within .08 and 1 volt. That's pretty much what my A/F gauge does . . .

[Legacy777]

ahh ok......if I get ambitious.....I'll play