My car developed a pretty bad hesitation/bucking yesterday. Basically, it idles fine, but when I get on the gas, even a little, it bogs and bucks until I bring the RPMs above say 3k. Then it surges forward. On the freeway, it'll start bogging when I keep it at a constant rpm. I had to keep jabbing the throttle to maintain my speed.

I'd like to see what code(s) I pull. Hopefully it's nothing too bad.

I have already:

1. Took apart intake and cleaned it out
2. Cleaned MAF sensor
3. Checked spark plug wires for oil (none)
4. Reset ECU
5. Filled up with 92 octane (usually use 87)

Still need to:

1. Pull the plugs and inspect
2. Check bushings to see if anything's torn
3. Change fuel filter
4. Adjust TPS (don't really know how)
5. Replace front 02 sensor

I figure pulling a code(s) would be a good place to start so if anybody in the Kapolei area is free and would like to help, I'd greatly appreciate it. Input on the issue is also welcome.

Thanks in advance!

 

no reader with me but im off today can help if needed

 

Call me up, bulleh! 389-2162

 

i got a reader in my car if you want to swing by my office (red hill), or can get it to you later - you'll need an android phone though

 

I got one Josh, i'm off work here soon as well, let me know if you want me to drop it/meet.

 

sounds like fuel or electrical. if i had to guess i'd say fuel. sounds like it's running lean. pull the plugs and see if they are grey. clean the IACV and see if that helps. if you need help still i can also swing by after work and help a brother out.

 

Thanks to Shaggy, Brett, and Justin for the help. Last week, I replaced the fuel filter, inspected the wires/plugs, checked for vacuum leaks, cleaned anything to do with the intake, including the MAF sensor, and reset the ECU. No luck.

I then drove over to ****'s and we pulled the o2 sensor. Was pretty grimey with greasy ****, so I wiped it off and reinstalled. Shaggy noted that the sensor was very loose when he first tried to take it out. Brett then came by with an OBDII scanner and my car had 5 codes.

Misfires in all 4 cylinders and the P0507 code for the IACV (IACV running higher than expected).

We cleared the codes and did 2 laps of the block to see how it'd run with the wiped-down o2 sensor. Ran fine.....for a bit. Ran like @$$ on the way back to Kapolei.

This morning, I took off my IACV (kind of a btch on the EJ25D compared to the rest of you SOHC and turbo guys) and cleaned it out. Ugly. It was pretty nasty in there. I shot it thoroughly with throttle body cleaner and then took a rag and wiped it up pretty good as far in as I could go. I also sanded the flat surface clean as it was caked with gunk. I replaced the gasket with a new one and reinstalled. I also loosened my throttle cable just a bit as my RPMs previously read high.

I reset the ECU once again and started it up. It idled like it was freaking out for a few minutes, then it settled and smoothed out. I checked for codes again and pulled a P1507 (Idle Control System Malfunction). I shut the car down, cleared the code, and restarted. SMOOTH again! I took the car out to test it. Runs like new! Not throwing any codes for now, but I'll keep an eye on it. Hope this problem stays away. I'll keep you guys posted.

 

Here's a shot of my dirty IACV.

 

awesome! glad you found the problem man; diag is sometimes my favorite part of the process (when i actually find the problem that way)

 

where did you get your iacv gasket? subaru stealerships here want you to buy the entire IACV which comes with gasket.
Thanks,
-J

 

I actually hate not knowing what the problem is right away. It bugs me to no end. I say it may be a bit soon to call it fixed. I'll keep driving and monitoring to see how it goes. For now, it's good and I'm happy for that.

 

I actually got it from Rick at Servco. Gasket was sold individually for $9.50.

 

I also should add that IACV gaskets for most of your motors are different from mine. I have an EJ25D which has the IACV on the side if the intake manifold rather than sitting atop the throttle body. Dunno if that matters.

 

I've got a couple spare IACV gaskets if anybody needs one. Once you do the coolant bypass mod they quit swelling up so bad.

 

Good job buddy, glad to hear the car is running smooth again after all that. Fairly cheap fix is a bonus too!

-b