Thanks in advance for any help you may give. I did some searching and didn't come up with any solutions. Car: '04 WRX wagon, 5MT. Mods: Perrin Y-pipe, gutted UP, Bosal Shorty DP, STi CBE, basic Cobb stage 2 map. Almost 60,000 miles. The problem: This has happened 4-5 times the past couple weeks and twice yesterday. Under light to moderate throttle (pretty normal acceleration from a dead stop) my car will hesitate for a split second and then resume normal acceleration. The hesitation is enough to make me lurch forward a bit (like during a gear change) and when it reengages it's enough to make the clunk in the trunk occur. Almost feels like if you were to let off the throttle during high RPMs and then get on it again without shifting. It all occurs in about a half-second. Also, I'm not 100% positive about this, but I think every time it's happened it's been during rainy/snowy conditions (as you all know, yesterday was a messy rain/snow mix here in Minnesota and it happened twice). My first instinct is that this is an electrical or fuel delivery problem. But I'm also concerned it might be in the drivetrain as well. Any ideas? The car is still under warranty. Keeping in mind my dealer is pretty lenient about this stuff, do you think it's something that could reasonably be blamed on my mods? Or is it just a routine maintenance thing (spark plugs, coil pack, fuel filter, etc.)? Thanks a lot for any help.
I had that happened in my car as well. Have not come back since a few weeks ago. You might want to check if your car is knocking at partial throttle. I can do it for you with Romraider if you want. Another thing it could be electrical, but i know nothing about that so i will not comment.
I posted on NASIOC as well. Someone there thought maybe a coil pack. I just wanted to post here and see what the locals thought too. I haven't logged in a while, but last time I did we didn't see anything terribly unusual, except my advanced multiplier was down to around 13 I think. I'd like to get that up a bit. Waiting on a couple of parts to get a tune. But now I don't want to do that until I get this problem figured out. Thanks for the help.
I know, I've been taking it easy on my car until I can get a tune. But as I said above, I think I need to solve this problem before I get that tune.
Your problem could be your tune, possibly. However by logging a few different parameters you can narrow down the possible problems. You could have a pre turbo leak. Like i had. Check your turbo inlet hose and BPV area. Maybe up-pipe?
rainy snowy conditions when it happens? Did you or the previous owner delete the intake snokus? Mines does that too once in a great great while...maf getting moisture on it briefly. i don't believe it's the tune....
I also had this happen to me, just the way you describe. I think at first I had a 3/16" mod - took that out asap. But I do think I remember it happening after that as well. I have not had the problem since I went from AP to a custom tune by w_o_tboy. I was AP stage 2 with pretty much the same mods as you. Cold weather seemed to be a factor as well.
Also, it was not predictable as to when this would occure. Just seemed random on long trips - after the car was warmed up. Maybe would happen 2-3 times on my 170 mile trip to my parents in winter.
You can buy a can of MAF sensor cleaner or use non-chlorinated brake cleaner, take out your MAF, spray it.
Yes, it can get dirty fast If cleaning the MAF sensor doesn't help, at least you cleaned it. Doesn't hurt to clean the sensor, especially if it hasn't been cleaned before, might get a little more MPG out of it also.
Go to any auto store and buy a spray bottle of MAF cleaner. Locate MAF housing on intake. Unclip MAF wire harnass from sensor. Unscrew the two phillips screws holding MAF to intake. CAREFULLY pull MAF straight up and out of intake. Look inside the keyhole thingy and spray according to directions on bottle. allow to dry, replace in intake.
Wow, I step away for lunch and to get a little work done and return to all this great advice. Thanks. I don't know if it would be my current tune, which is an off-the-shelf Cobb Stage 2 tune. Always thought Cobb tunes were pretty conservative so as to not cause any problems. I am a little worried about it being a pre-turbo leak. I think the guy that put my up-pipe in forgot to replace the gaskets (that was about 20k miles ago). But I actually just had one of my Dad's employees get under the car to listen for a leak. I was hearing a low rumbling noise during wide open throttle in the higher gears at low RPMs. Wasn't sure if it just started happening or if I just started to notice it and it was there the whole time. Wanted to make sure it wasn't a leak. Guy said he couldn't hear anything. Intake is stock. Snorkus and all. I'm using the OEM paper filter. Idles fine for the most part. Ever once in a while the idle RPMs will drop a little too low (seems like the car is about to stall but never does). Does not happen very often at all. Regardless of whether this is the problem or not, I'll do this for sure anyway. Thanks again for all the great advice.
If your IAM is down to 13, the map is likely not working well with your setup. I would pull some timing based logs while you experience this trouble spot to see what's really going on.
Running less then 16/1.0 IAM is fairly normal for Cobb maps. Doesn't necessarily mean anything other then that the Cobb OTS map learned some timing corrections for his car.
