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Hard/no start with stumble when engine cold

20K views 44 replies 7 participants last post by  titter 
#1 ·
Hey guys,

Some of you are familiar with my 04 WRX. My stepson blew the engine and tore it down... several years later I was stuck with rebuilding it from pieces in boxes. I got it built and had to find a few parts that were missing like the turbo, MAF and air filter box, driver's side exhaust manifold, vibration damper, TMIC with BOV, and that seems to be it for replacement parts.

After getting it all together it would crank and pop and try to fire off. After 30+ seconds of this it would eventually start. RPMs would be up at 1000-1500. Sometimes the idle would hunt. After a few minutes things would settle down, idle would smooth out and be down around 800 rpm. I'm thinking this was about the time the ECU came out of the cold engine cycle. Some days it would fire right up after 5-10 seconds of cranking but still have the rough idle. Other days, and what I'm experiencing right now, is that no matter what I do it will not fire off. It'll crank all day and I "might" get a pop like it wanted to start but then right back to cranking. I pulled one coil and put in a spare plug to test for spark and I get spark. It's a bit yellow, it seems, but there is spark. And looking back at the video I took, there is a few seconds where there is no spark. 20151127_112215_zpshigmsbqb.mp4 Video by smolikmd | Photobucket

Here's what I don't know... There is most likely a tune. I don't know what all addons my stepson put on. He's not in a position for me to ask him. I believe there was a larger turbo. Possibly injectors. There's a stock turbo on it now. The injectors are whatever was on the fuel rail. I've another set in bubble wrap in a box, possibly the stock injectors. It was, at one point, getting fuel because I had to reseal the #4 injector due to a leak. I know it's getting air.

I can also hear the fuel pump prime on every key cycle.

Here's where I may be playing the idiot because the fuel is old, 3+ years old, but it ran with that fuel...

So with spark, fuel, and air.... what am I missing? There is no CEL. Could the engine actually be flooding? It does blow white smoke "if" it starts but then quickly clears up.

I may be playing idiot with this, too; starting fluid has no effect which makes me think, once again, that the engine is flooding.

I looked by the fuse box and see at least 3 connectors hanging down, 2 green and 1 white, if memory serves. I'm guessing that's an AP? How can I find out who may have tuned it and how to return it to a base tune? Or should any speed shop be able to do this?

Any thoughts would be greatly appreciated.

Thanks,
Michael
 
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#2 ·
I would pull the fuel pump and siphon all that old fuel out that you can through the hole the fuel pump goes in. It's on the passenger side right behind the back seat. The green connectors are the test mode connectors. they should only be plugged in while flashing the ecu or during diagnostics. Not sure about the white one. Do you have a way to flash a new map? I think I MIGHT have a stock tune for an 04 saved on my laptop. If I don't @psinuse might. You def need the ecu reflashed back to stock.
 
#3 ·
you could always try to find an ECU out of a junk yard for cheap and plug it in shee what happens.

oem wrx injectors are 440cc and teal/cyan in color: http://thumbs.ebaystatic.com/images/g/gNYAAOSwuWVWEsoT/s-l225.jpg
what color are the ones in the box?

if those are not the ones currently installed, then swap them out. larger un-tuned injectors can cause lots of problems

definitely shounds like an ECU problem. you cant really go any further without knowing what tune you have.

also i second boo-key's suggestion of cleaning out all that old gas.

also a few things:
are your plugs gapped to .028 - .030? thats stock gap measurement.
clean your MAF. its possible its sending fasle info from being dirty.

good luck :D
 
#7 ·
regapped the plugs, dried them all and getting great spark.

20151128_145018_zpsydwv5mbg.mp4 Video by smolikmd | Photobucket

Put them back. pulled the fuel pump relay connector and cranked and cranked to purge the intake/cylinders of fuel. shot some ether in the intake but couldn't get it to fire.. wth? one would think that the ether would at least ignite. plugged the fuel relay back in. cranked some more. pulled the #2, it was damp again but not dripping like before... ECT could be a part of it, too. but what bugs me is I could get it to start.. now I can't hardly even get it to pop occasionally like it's even attempting to start.

If I found a Subaru at a junk yard for an ECU.. is there another model car that would work? Or does it have to be a WRX? They're not that common around here.
 
#9 ·
sounds like your suffering from bore wash / cylinder wash. as for the cause, it is still pointing towards the ecu. i have heard its a byproduct of an ecu failsafe preventing extreme detonation, which again could point to a cam sensor leaving the intake valve open too long?

sadly, im pretty sure it has to be a WRX ecu, but i think you can get away with an 02-07 as most everything from those years are interchangeable.

your other option is still a Tactrix cable and RomRaider/ECUflash and try to get yourself a stock map to flash on your car. the romraider fourms might have one. RomRaider ? View forum - WRX Base Maps maybe if there isnt one posted you can request for one.

also, if its not starting in cold weather... try a new battery. if its been sitting for a few years, probably a good idea for a new one anyways.

and yes, you can turn on the fuel pump to drain the tank.
 
#27 ·
sadly, im pretty sure it has to be a WRX ecu, but i think you can get away with an 02-07 as most everything from those years are interchangeable.
06 was a huge change to the fuel system. 02-05 WRX's use a 16-bit ECU and a drive by cable. 06+ WRX's are drive by wire and have a 32-bit ECU much more similar to the 04+ USDM STi.
 
#10 ·
battery's brand new, cranks well, well enough to turn off the oil pressure light if that means anything. It seems to be cranking around the same RPMs as when OAT was warmer. Been doing some reading, seems only an 04-05 WRX ECU will work. But used online are $200... I need to find out when shops open tomorrow what someone would charge to put a base MAP back on. This thing's turning into a money pit. :(
 
#11 ·
I've run cars on old gas before and never an issue. Pumped out 4 1/2 gallons of junk all the way up to the fuel rail, put in 5 gallons of high test, primed it, and BAM!! First crank she fired right up!

Now to figure out the CEL and the stumble/bog/hesitation at light throttle... but that's for another day.
 
#12 ·
Hell yeah! I'm excited for you! Now get that stock tune or a stage 1 tune on there. Do you have a laptop? A laptop and tactrix cable might be a cheaper option than a new ecu and would provide reflash capabilities and be a good diagnostic tool.
 
#13 ·
boo-key and titter, thank you, sincerely. I'm an old iron head/block/carburetor guy. This has been a learning experience and even dusting off the cobwebs on 35+ years of tinkering and trying to apply old school knowledge because, in the end, it's really all the same. Just a lot more variables with the new stuff. Not sure I want to buy a cable and adapter and whatnot or find someone that can put stock tune back for cheap. Once running as it should a for sale sign is going in the window. Long story short... it's what's best for all concerned. I hate having put so much blood, sweat, and tears into this thing but it was either that and get a better sale price or sell a rolling chassis and a huge loss. As it is I'm only $2500 or so into it since I've done 90% of the work. Far better than selling a paper weight on wheels for half what a running car will get.
 
#14 ·
all good bud! glad its sorted for ya :D im in the same boat with all this new tech. untill i joined the subie world, last time i "tuned" anything i was swapping venturi's and float valves.

what CEL's are being thrown?

and i'll second the laptop and tactrix cable. you should be able to fix your problem and then you can keep the cable and laptop for further use since youre selling the car.

http://www.tactrix.com/index.php?op...duct_details&product_id=17&vmcchk=1&Itemid=53

and a cheap netbook will work fine. or if you already have a laptop use that with ecuflash / romraider. its more time and learning, but definitely the cheaper and probably better option.
 
#16 ·
Ran up to Autozone and pulled codes. MAF, IAT, HEGO codes. They must've been set during the no start issue because I cleared them and they haven't returned yet. Still runs crappy under moderate to heavy acceleration. The shop that I suspect did the tune was closed today. Will call them tomorrow to see what they say.
 
#17 ·
#19 ·
These are the 6 codes from last night. And the CEL came on this morning on my way to work. I'll pull those on my way home.

Hard:
P0102 Mass or Volume Air Flow Circuit Low Input
P0113 Intake Air Temperature Circuit High Input
P0546 Exhaust Gas Temperature Sensor Circuit High Bank 1 Sensor 1
P0134 HO2S11 No Activity Detected

Soft:
P0171 System Too Lean Bank 1
P0546 Exhaust Gas Temperature Sensor Circuit High Bank 1 Sensor 1
 
#20 ·
P0171 is probably the most famous code for subaru's.

P0171 CEL Thread - Everything you ever wanted to know? - NASIOC

P0546 is the EGT sensor in the up-pipe, whether its non-existant, non-funtioning, or a few other things.

never seen P0134 but here is what the internet says:
P0134 Subaru HO2S11 No Activity Detected OBDII Engine Light Trouble Code | AutoCodes.com
- Faulty Front Heated Oxygen Sensor Bank 1
- Front Heated Oxygen Sensor Bank 1 harness is open or shorted
- Front Heated Oxygen Sensor Bank 1 circuit poor electrical connection
- Inappropriate fuel pressure
- Faulty fuel injectors
- Intake air leaks may be faulty
- Exhaust gas leaks
 
#23 ·
yea if the ECU still thinks it has the bigger injectors, thats a problem. that just proves the ECU's definitely been tuned. need that stock tune back on there. (sorry i thought that bad been done already)
 
#24 ·
I wasn't able to talk to the shop until this AM about the tune but have to call them back. i had taken the larger injectors out thinking it was part of my no start problem. Just got off the horn with the guy who would do the tune/flash back to stock and he recommended that with all the changes to do 1 of 2 things, flash it back to stock (since the only change now is maybe a cat back) or if I put the bigger injectors back in it would have to be retuned and dyno'd since it doesn't have the bigger turbo anymore nor the aftermarket TMIC and BOV, etc. He'll flash back to stock for free... I like free! LOL
 
#25 · (Edited)
** My Bad ** I totally Missed Pg 2 ** My Bad **

CEL stands for Check Engine Light. Good luck with the MAF, I strongly reccommend keeping a bottle of MAF cleaner on hand. Cleaning the MAF is a quick trouble shooting tip and a good preventative when you swap your engine air filter.
 
#26 ·
This is all 100% due to the fact you don't have the right tune for the parts you have in there. Your ECU is getting all the wrong reading. Figure out what parts you want in the car, leave it alone, and go get a tune. BAM your good to go.
 
#29 ·
I think it was mostly related to the engine. The WRX was based on the japanese WRX pretty closely (DBC,16-bit) but they made an entirely new engine for the USDM STi in 04 out of the well established EJ25 block (which had never seen a turbo before) and a bunch of trimmings from the JDM STi, notably the newer ECU. When they wanted to ditch the EJ205 in favor of the EJ255 for the 06 WRX, it was easier to scale down the STi than scale up the older WRX IMHO.
 
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