So I got this bucking issue, and maybe you guys have an idea of whats going on.
After I start it up I go to drive away and if I try to go 1/2 to full throttle then it falls on its face like its starving for fuel. I figured out if I shut the engine off then start it back up it goes away and drives fine "weird right".
Im trying to narrow it down in my head, maybe its fuel delivery, spark misfire? I need some ideas guys.....
Could it be computer related because shutting it off then starting it fixes the issue??
If anyone out there has any ideas or has had the same problem, please let me know. Im thinking of taking it to a specialists cause I dont have tools or time right now to figure this out.
I do have a brand new coil pack as well........planning a 8 hour trip this weekend. I hope everything goes well, Im a little nervous the subie wont make the trip.
Hi,
Does it only do it when it's cold or even after it's warmed up? I'm thinking it could be the CTS - coolant temp sensor. Although the fact that it 'fixes itself' on the restart isn't consistent.....?
Td
Turbo Subies:
'87 GL-10 Turbo - SOLD
'90 BJ EJ22T/DOHC & 5speed swap - SOLD
'04 FXT, Forged internals, VF39, STI TMIC, Cobb AP- SOLD
'93 Legacy SS - 5-speed, SOLD :-(
'02 WRX -SOLD
'96 BD-turbo'd-SOLD
'98 SF - NA-T
Hey thanks for the reply.......It almost does it off the cold start every time and yes after I restart it, it fixes itself. What boggles my mind is it does it more at high elevation. I work at a ski-resort at about 8000 elevation. I live at around 4000 elevation and it does the "bucking" only 1/2 the time.
At work even if I let it warm up for a 1/2 hour before I leave, I still have to shut it off and fire it back up again and it runs fine.
Im pretty confused about it, what would elevation have to do with it?? Not sure whats up.
I have had it running and driving fine to the grocery store and then when I go to leave it starts acting up again. So I dont think having the car at warm running temperature makes a difference.
It seems like its choking......maybe its leaning itself out at WOT. The elevation is a big factor with the air going in right? If I feather the throttle its fine. As soon as I open the throttle close to all the way "BAM" doesn't want to get up and go.
It doesn't stall either....some funky stuff going on.
You need a metal hitachi turbo MAF, the NA MAF will make you run really lean which honestly may be your issue, when I was running lean (due to my fuel pressure reg) it would buck hard and stutter.
I have a turbo MAF if you're interested.
the guy who had the really low winestone SS on the corvette wheels
This is a picture I pulled of the internet, but this is the MAF im running right now....
So I have the right MAF......Im interested in buying one, but at the same time I dont want spend money that I dont need to spend.
I was up late lastnight doing some research and what I came up with, with this bucking and hesitation issue could be a bunch of things going wrong. Its got to be a bad sensor because when I restart the car the problem fixes itself.
It could be.....
-knock sensor
-o2 sensor
-MAF
-TPS
-CTS
Now before I start throwing parts at her, is there a way to test the sensors or figure out how to narrow it down to which one is the problem??
-Robert Im interested in your MAF for sure, I just need to come up with a game plain cause my MAF might still be good and it might be another sensor thats bad.
I seriously think it could be a throttle position sensor! Of course thats the most expensive to replace out of all the sensors I listed but it kinda makes sense.
The subie idles weird (and I have checked and cleaned the IACV). It starts idling weird after I let of the throttle in gear BUT when I start it with out touching the throttle it idles fine. Its never a consistent idle after driving in gear threw stop lights around town, it just either idles high or low, and sometime hesitates at 8th throttle (very light throttle). It comes out of the hesitation if I punch it a bit, or drop the clutch.
Does this make any sense guys or am I wasting my thoughts?
Can I pull the old unplug trick to see if the car runs better?? Or is there a better way to diagnose the TPS?????????
I would lean more towards your MAF sensor. If the throttle response is ok during times when the engine is running ok, then I really doubt it's your throttle sensor.
You can try cleaning your MAF with MAF cleaner to see if that changes anything, but if you can find a replacement MAF that's probably what I'd recommend.
Yea Josh, Ive cleaned it a few times sense i bought it back in June. I actually have a can of cleaner sitting on my passenger seat. I will see what I can do and get back to you guys....My custom intake may be affecting it I think.
My set up from the air filter to turbo is...
FILTER-MAF-90* elbow-"coffee can" with cam breather connections, IACV, PCV, and boost solenoid vac lines connected-TURBO.
Also while driving when I push the clutch in, it idles high....Like pulling out of the driveway Ill go first to second, then push the clutch and it will idle up.
The MAF really doesn't care too much about what is downstream of it as long as there are no air leaks in the intake piping.
The stock setup has a 90 degree elbow directly after the MAF, so unless your 90 degree elbow is drastically different I wouldn't be concerned about the intake piping configuration.
So I tried messing with the diagnostic wires under the dash and the 2 green "T" plugs were plugged in already. I have a whole mess of wires under there and it seems at some point someone was messing with them and didnt know what was going on (like me).
So I couldnt find the right wires to run the tests to check for trouble codes. The 2 green T plugs seem to be were the problem is. I unplugged them and the bucking and hesitation stops.
I actually did this while I was driving- The car would start bucking while the plugs were plugged in and then I would unplug them while going down the road and the issue would stop.
What exactly are those green T plug wires for?????
Also when I turn the key to on with out turning over the engine with the green plugs plugged in the radiator fans kick on and off, on and off.
So I got some electrical badness going on! I think Im going to take it in to my mechanic, but Ill take all the help I can get on here for sure.
As stated those are the diagnostic connectors. Please re-read the LINK Josh provided. When the Green connectors are connected, the car is in Diagnostic mode. Part of what it does is cycle the sensors, etc. (incl. fans) to help ID what is/not working.
They can also be used to Clear codes in the ECU.
They should NOT be connected for normal driving.
TD
Turbo Subies:
'87 GL-10 Turbo - SOLD
'90 BJ EJ22T/DOHC & 5speed swap - SOLD
'04 FXT, Forged internals, VF39, STI TMIC, Cobb AP- SOLD
'93 Legacy SS - 5-speed, SOLD :-(
'02 WRX -SOLD
'96 BD-turbo'd-SOLD
'98 SF - NA-T
The green plugs are for diagnostic mode. The will cycle the fans and the BCS will start clicking under the hood. What these do, is they out the car in a fail safe type mode, and when you drive them plugged in, it scans a little harder to find a problem. For example: I was having issues in boost, but no CEL. I used the green diagnostic plugs, and it flashed a code for the o2 sensor because it was an intermittent problem.
If the car is running fine now, and the green plugs are unplugged. I would assume it has to do with the ECU being in a safe mode map.
the guy who had the really low winestone SS on the corvette wheels
So boys Im finely getting to the bottom of my problems with my 94 SS!
I took a drive over to my mechanics shop (good friends of mine). The guy thats been doing work to my car has a soft spot for old 90-94 subaru legacy sport sedans and is determined to get this thing healthy! I kinda feel like Im cheating getting help from a pro, but I have tried everything to find out whats going on with it.
So today we tested every sensor the car has, check for vacuum leaks, checked compression ect. Turns out most if not all the sensors have been replaced including the MAF.
After tracking down the past 4 PO's I emailed, called to ask what problems they have had with the vehicle. They all told me "The car has idle/running issues". With pretty much new sensors on the car from the past owners it seems like those PO's tried to figure out the issues.
My mechanic and I narrowed it down to the computer. The computer is getting the right information but it wont cycle it back to the injectors. We also checked the injectors of course.
The big task next is "what made the computer fault"? So Im going to take it back so he can run more tests. Most likely Im going to have to replace the computer, but before I drop some big money on that I hope he finds what caused the problem.
IF ANYONE HAS A SPARE EJ22T ECU FOR SALE [THAT DOESN'T HAVE ANY PROBLEMS!] LET ME KNOW!!!!
Mean while Im headed to Truckee, CA with the broken computer (8 hour drive) to shred some powder (4 to 6 inch's there calling!) wish me luck I hope the car makes it with out problems......
Last edited by Tbly89 on Mon Dec 15, 2014 7:54 am, edited 1 time in total.
When you had the green diagnostic connectors connected did the check engine light flash at all? With the green diagnostic connectors unplugged does the CEL come on with the key in the ON position and the engine not running?
I'm very interested in this as my car is doing the same exact thing and I've done basically everything you've done to this point as well. My car only does it when the connectors are plugged in, otherwise it runs great.
The (green) connectors are for diagnosing. They shouldn't be plugged in while daily driving. I noticed the car running much better after I found those were plugged in. They were plugged in all the way back when I bought the car. So I think the PO kept them plugged in for some reason.
Most of my issues are my ECU. The hard part is finding out what made the computer go bad.
