Cascade Crew

aaron_sK · Posted: Fri Jul 13, 2007 1:26 pm Post subject: Mmm... Hydrocarbons

Took the IROC to emissions today...

blue89 · Posted: Fri Jul 13, 2007 1:48 pm Post subject:

Bad injector dumping fuel through? Junk cat?

aaron_sK · Posted: Fri Jul 13, 2007 1:50 pm Post subject:

It will hold 40psi at the rail with the engine off for more than five minutes, so I doubt the injectors are leaking.

Wouldn't a bad cat cause an increase across the board, and not just at idle?

blue89 · Posted: Fri Jul 13, 2007 1:53 pm Post subject:

Dunno. Raw HC count should be caused by unspent fuel going through the engine, which i interpet as either incomplete burn, poor atomization, too much valve overlap, or the cat is dirty.

Does the car think its running rich at idle? Whats the o2 sensor thinking?

aaron_sK · Posted: Fri Jul 13, 2007 1:55 pm Post subject:

It's not throwing any codes, but I don't have a reader for it.

Could the AFPR be causing it?

blue89 · Posted: Fri Jul 13, 2007 2:11 pm Post subject:

Potentially? Depends I guess. Hopefully Dewey can comment on that. If the pressure is increased than engine will get more fuel than the computer intends, but it should compensate. If it can't compensate enough then it should throw a code. Just speculating. But if its higher/lower than stock I would return it to as close to stock as possible. Adjusting for larger injectors if need be.

Dewey316 · Posted: Fri Jul 13, 2007 2:15 pm Post subject:

it may or may not.

It also depends on if the engine is actulay idling in closed loop. If you have more than stock pressure, go back to stock rating.

It is the same thing everyone else has said, the cat is suspect. It could just be that you are not getting enough heat into the cat at idle, to get the process to work in there. I would give it a tune up (new plugs, etc) and put the fuel pressure back to stock, and see what it does. You might also consider unplugging the cooling fan, to make sure that your temps are nice and hot when you test.

--John

aaron_sK · Posted: Fri Jul 13, 2007 2:16 pm Post subject:

Hmm... okay.

My AFPR was installed and adjusted by some previous owner, and I haven't touched it since. With the vacuum applied it is around 43psi when the car is cold, and closer to 39 psi when it's hot. However when I pull the vacuum the pressure jumps up to around 55psi at the rail, and the car bogs.

No idea if the injectors or the pump are stock. There have been quite a few people through this car before I got it, and only some of them knew their stuff. Rolling Eyes

blue89 · Posted: Fri Jul 13, 2007 2:36 pm Post subject:

Hmm. Just reading what you posted, sounds like you have a fuel related problem. Here's another one, how far away is your o2 sensor? Your headers may not be getting it hot enough (like dewey said).

If the V8's are like the V6's, you should be around 43 psi at idle. At 55psi with no vacuum, I would hope the engine would bog! Thats a huge difference in fuel pressure. Especially coming from 39psi at warm idle!

You can do the paperclip jumper test between A-B ports on the ALDL port with the car off. Start the car and the light should stay lite until it gets warm. Once its warm it will go off when the car is lean, on when rich. This will tell you if your in open loop or closed loop at idle.

aaron_sK · Posted: Fri Jul 13, 2007 2:41 pm Post subject:

O2 is in a welded bung in the drivers side header, about an inch above the collector gasket.

A and B on the ALDL are 1 and 2, or the upper left pins, right?

Quasi-Traction · Posted: Fri Jul 13, 2007 3:26 pm Post subject:

test the 1-2 pins and see what the sensor tells your, arron.

aaron_sK · Posted: Fri Jul 13, 2007 6:17 pm Post subject:

Okay, back with the results...

Jumped the ALDL, and started the car. SES light blinked rapidly till the car hit about 170F then started blinking slowly. For about a minute it switched between the two, going fast and then slow. After that it settled down and just blinked slowly. I then killed the car a couple times and restarted it, and it blinked slowly from the start each time.

Timing is at 6* btdc with no advance, but plugging the ETC plug back in pulls it way back. I'd guess it's hitting maybe 14* at idle with the ECM control.

Watched the leakdown on the fuel rail, it's worse than I thought. These numbers are with the engine hot:

Immediate: 45psi
45 seconds: 40psi
90 seconds: 30psi
2 1/2 minutes: 20psi

Seems a little fast to me, but what do I know...

Tomorrow I'm pulling the plugs to see if any of them are fouled by extra gas.

*Edit: Pulled the codes, and nothing abnormal. 12, 24, and 42. VSS is fixed now, and ETC is cause I set the timing. Vac gauge says it's pulling about 22hg of vacuum.

Twilightoptics · Posted: Fri Jul 13, 2007 10:04 pm Post subject:

Cat and or O2

Sellmanb · Member Joined: 30 Nov 2004 Posts: 727 Location: Tigard, OR

Before you go throwing anything at the car that you speculate it needs, figure out where you're losing fuel pressure that rapidly at. Pull the rails with injectors and fuel lines attached, and watch the injectors after you pressurize (not start) the system. Find the leakers. After that's fixed you can find if you passed DEQ, or if you need to go further. With leaky injectors I've seen them eat up cats (and foul O2s) rather quickly.

All I'm saying is fix the reason why your cat and O2 probably needs replaced before you replace them Wink

BigDaddyVu · Posted: Sat Jul 14, 2007 10:33 am Post subject:

you'll get raw fuel mixture at idle if you got an aftermarket cam (cam overlap) where the the intake and exhaust are open at the same time. Can they test your car at a lil higher idle speed?

redlava · Posted: Sat Jul 14, 2007 11:34 am Post subject:

my vote is the cat to get past deq, I tried so many things to get my car threw that stuipid thing, non of them worked. I just ended up with a new cat and it passed with flying colors.

aaron_sK · Posted: Sat Jul 14, 2007 6:15 pm Post subject:

Sellmanb · Member Joined: 30 Nov 2004 Posts: 727 Location: Tigard, OR

aaron, that way isnt fully accurate. Remember, the intake valve has to be open in order to have fuel get into the combustion chamber (hopefully lol)

aaron_sK · Posted: Sat Jul 14, 2007 7:36 pm Post subject:

Yeah, I figured that I couldn't rule out leaking injectors by doing that, but I could probably rule them in as a the probable cause.

BTW, Sellman, would it be a better idea to put the O2 just past the Y-pipe, or would that cause it to not get hot fast enough?

Sellmanb · Member Joined: 30 Nov 2004 Posts: 727 Location: Tigard, OR

I'm a firm believer that O2's (and other sensors) are designed to be in specific places for a reason. Right at the collector on the manifold/header seems like the best place for it to me. You get a reading from all of the cylinders on that bank, plus having all 4 exhaust pulses run through that joining spot lets the O2 get warmer than anywhere else downstream.