Please help, Apex still fouling plugs (Long Thread)

←snow∞motion→ · Mar 26, 2012

Went out again this weekend after putting another set of plugs in (fourth set in 300 miles), decided to try a little hotter plug (didn’t work though).

Just to give a background, I’m fouling stock plugs CR9EB’s on one ride, and have even fouled an O2 sensor. When at idle through mid-range the sled runs EXTREMELY rich (wideband gauge reads 10.0) and WILL NOT run without feathering the throttle. This feels and acts much like being on full choke on a carbureted sled and is running so rich I burned through 16 gallons of fuel on a 68 mile ride.

I have taken the entire rail off and have checked all of the hoses for vacuum leaks and have glued and reset the throttle body boots. The only vacuum leak that is obvious is out of the bottom of the Idle Air control valve assembly. On the left side of the fuel rail there are two fittings about ½ inch in diameter that come out the front of the IAC. These run into two vacuum hoses that bend 90 degrees downward and go into a black plastic chamber that is zip-tied to the front of the fuel rail (this is right between the rail and the #1 intercooler boot). Then from the chamber is another single 90 degree vacuum tube that is vented to atmosphere (this used to be connected to the stock airbox, but was left open to air as per the MPI instructions for the supercharger and intercooler installation).

When doing a vacuum or a boost leak test air leaks through this port quite freely. When I start the sled and hold my finger over the open hose, it will stall the sled so I assume this is supposed to be open somewhat, but I’m not sure how much. I’ve asked the dealer about this being bad, and was told that they never go bad and if it did it would throw a code.

This is a problem from the “stock” side of my sled though. I have tried disconnecting the fuel controller and this still is happening. I have also noticed that when the presence of boost comes on and there isn’t any vacuum the AFR’s are perfect and the sled runs great.

Please help, this is getting EXTREMELY frustrating and we’re running out of riding days.

Thanks

tjc · Mar 26, 2012

are there upgrades to the fuel pump/regulator/injectors? or is it stock

←snow∞motion→ · Mar 26, 2012

tjc said:
are there upgrades to the fuel pump/regulator/injectors? or is it stock

Fuel pump is MSD high volume pump.
Stock fuel regulator
Injectors are stock but additional 330cc injectors for second fuel rail (Boost-it)

summitboy · Mar 26, 2012

Have you checked all the injectors to see if you have a stuck injector ? Is the oil getting contaminated ? Sounds like a injector is stuck ??

←snow∞motion→ · Mar 26, 2012

summitboy said:
Have you checked all the injectors to see if you have a stuck injector ? Is the oil getting contaminated ? Sounds like a injector is stuck ??

How can you check this? Do you just unhook the injector and watch it spray?

BOOSTD · Mar 26, 2012

A couple things to look into that were once a problem on some apex's. The stock tps( throttle position sensor) can get out of wack and just start dumping fuel, much like you described. It was more common on the 06's but did happen in later year models. Very rare to have injector issues but still a possibility so that wouldn't be a bad place to look either, or at least test the injectors to make sure try are firing correctly, there is a test in the service manual to do so.

←snow∞motion→ · Mar 26, 2012

I can see a voltage change on the TPS on my XIC box. So it seems to be at least changing. What should the voltage be?

mattymac · Mar 26, 2012

if your fouling all 4 plugs I think its safe to say you can rule out the injectors. Check the TPS settings at idle and WOT and make sure the values are within spec. Also you need to manually pull codes from the sled, sometimes they trip codes but dont show up on the gauge until you run the diagnostics check, theres a bunch of threads that cover how to pull codes.

←snow∞motion→ · Mar 26, 2012

Ok, I'll pull codes tonight. Thanks

kinger9 · Mar 26, 2012

←snow∞motion→;3037732 said:
I can see a voltage change on the TPS on my XIC box. So it seems to be at least changing. What should the voltage be?

On the GEMS at least this voltage is NOT correct and to get the true voltage you have to disconnect it and go back to stock.

So do that then it should read 15-18 FULLY CLOSED and 95-100 FULLY OPEN. To do this just put the key on and go into diagnostic then see what #01 is showing, move the throttle to WOT and see it change. If it works perfect then your TPS is good.

Your open hose is correct that is what feeds the engine air since the throttle blades are stuck shut.

With the engine off on start up the fuel pump should kick on and 'pressurize' the system before cranking it. Maybe you can make sure all the plugs are dry the reinstall them, then cycle the key a few times and try to hear if the injector is spraying, once doen DONT start it pull the plugs to see if any are wet that would help you find a leaky injector.

My money is on the boost it system not properly set up and its giving fuel off boost when it shouldn't ie improper set up or bad boost sensor thinking its seeing boost ALL the time and not when it really is on boost. It would explain why it runs so good in boost. Get the best way to check that from Boost-It.

←snow∞motion→ · Mar 26, 2012

I printed a bunch of pages out of the manual, and I'm gonna check them tonight. Hopefully I can find the gremlin.

tjc · Mar 26, 2012

what about something simple like checking the fuel pressure. Does the boost it use 2 pumps or just the high pressure. Maybe the base pressure is too high?

BigFish BC · Mar 26, 2012

so is it fouling the plugs at idle or while riding a little more info on how it happening.it almost sounds like you have the box injecting to soon with no boost.

BigFish BC · Mar 26, 2012

another thing if you have a boost leak it will go fuel lean usually & sounds like its hitting the limiter because the box will not want to add fuel if its not seeing enough boost pressure.the other thing to look at is if you are getting enough spark if your not getting a strong enough spark it wont burn the fuel proper.

←snow∞motion→ · Mar 27, 2012

Thanks for all the replies.

Checked the fuel pressure last night, and it's at 43 psi so I think I'm good there, needs to be between 43-45 as per Boost-it specs.

TPS position on the diag 01 setting was 65 at closed, which according to the manual is supposed to be 15-18. So apparently while butterfiles are closed it's still pushing nearly 3/4 throttle at it.

Bought a new TPS sensor, plugged it in and it read 45 at closed, was stumped again (thinking I'd found the gremlin).

Called and talked to Neil at Boost-it. Found that the XIC box wasn't grounded good enough and was feeding voltage back to the TPS. Got a better ground and now it's reading correct on the diagnostic.

So fingers crossed, I'll try it out again this weekend and see how she does and follow up.

kinger9 · Mar 27, 2012

That'll do it! Enjoy the ride 70 degrees here in the midwest i'm jealous!

←snow∞motion→ · Mar 27, 2012

I'll try, weather is still warm here too but on 70+ inch base at least it's still rideable. Kind of slushy though.

Still waiting for the big spring storm that seems to come every year around Easter, hopefully it slams us.

kinger9 · Mar 27, 2012

Did you start the sled and see if its idling at 13 afr?

←snow∞motion→ · Mar 27, 2012

I did, but if it's like the other sets of plugs I put in, all seemed well in the garage.

Once I started riding after about 20 minutes is when it started going to crap, so knock on wood it stays this time.

←snow∞motion→ · Apr 2, 2012

Thanks to all who have helped with advice!!

Took her out this weekend with the new TPS sensor installed. Ran like a top, with no bobbles or fouling. The exhaust even smelled much better, if that makes any sense.

Hopefully she stays put, considering I've dang near wasted a season of riding (which is quickly coming to an end) trying to figure this out.

Thanks again. :face-icon-small-hap

Please help, Apex still fouling plugs (Long Thread)

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