Fuel Running Extremely Rich at 5500+

[RiceBurner98sC]

I decided to get my car dyno'd at a local shop, where as baseline dyno pull was $20. I strapped her down came out with some really terrible #'s across the board. Did it a second time with a/f, and found out that around 5500rpm my motor was dumping fuel and running extremely rich.

NOW...my car idles perfectly, runs strong, boosts just right. I am running a Redtop SR, GReddy DP, RSPL FMIC, Stock Recirc, Apexi N1, walbro. Also I am running on stock boost. I was told I should put down at least or around 175+whp. Needless to say, that was happening in my case. My car however was running very hot due to the weather and realizing that one of my fan's wasnt working and I was low on coolant.

I've never got on the car, but when we dyno'd it, it was breaking up at the mentioned rpms, which I had never noticed before.I was told that it could either be my spark plugs or my fpr, which is stock. Does anyone have any info/suggestions that I could look into. I was running very old plugs, and changed them out with the correct plugs and the car seems to run better, but Im not quite ready to kick out my cash to see if in fact its putting out the numbers it should. I know my recirc valve isnt leaking because it held boost all the way to redline.

[RiceBurner98sC]

-UPDATE--

Went out to the ol Gandy Bridge to see if I could feel/hear the breakup at 5k rpm like we heard on the dyno. I changed my plugs, and during driving around today the car felt alot better.I took it out on the bridge and on my run into St.Pete I simulated my dyno run by cruising through 1st, second, then into 3rd at low rpms, then at about 3k(30ish)mph I floored it, getting quick response/spool at 7psi and a strong pull. I watched my boost gauge and was listening for the loud breakup upwards of 5k, when I hit 5700ish I hit what appeared to be a boost limiter/cut off? I had never hit that before, though I had never run it that hard either. I had to shift out of gear as I had zero throttle response while in gear(which makes be think it had something to do with my transmission/speed sensor)and shift back into 5th with no problems.

On the way back over the bridge, I took the u turn right after the bridge, so I had some rpms turning, and pegged it in second, hitting full boost early, pulling all the way to 7K+, then into 3rd, where I started to pull pretty well until I hit the same limiter, but at 6k, which either time I dont think I ever hit on the dyno.

Has anyone experienced this before, or did I miss an article that already discuss a boost/speed/gear limiter? Also I noticed on the second run, the boost dropped down to 5psi when it cut out. Recirc Valve maybe?

[SpeedRacer1]

A dead, or non-functioning O2 sensor can cause you to run rich, but that would cause it across the RPM band. But at idle it will make the car run lean.

[Dori Dori]

There is no limiter that would stop you from pulling all the way in 3rd. Something else is wrong...check all your vacuum lines and try a different MAF if you have access to one.

[Phax]

I'm guessing you are having ignition problems. What kind of plugs did you get? I recommend Bosch F5DTCs. I have a similar setup to you, minus the FMIC. I had very similar problems, which ended up being a result of using the wrong plugs.

[RiceBurner98sC]

Dori, I was thinking the same thing about checking my maf...I noticed that my car runs like garbage when it rains here in FL, for no apparent reason. Its not too bad, but when I try to boost at 4k rpm, no dice.

Phax, I am running the recommended NGK BRE-6(something like that)plugs gapped to what XAT suggested at .028. Im going to check the fuel pressure regulator to see if its at fault. Havent thought of it being a bad injector as of yet because it runs fine during normal driving and even if I slowly take it up in the upper powerband.

[DriftS14]

I had a small accident with my front mount a few months ago. I thought there might have been damage but I checked and everything looked ok. The car drove just fine. A day later, those exact same symptoms were occurring on my car. The car would not rev past 5500 RPM. It steadily got worse. That's when I saw them, 2 two inch long holes in the intercooler. It was a boost leak the whole time. Sorry for the long story for a quick answer. But I'm betting it's that.

[RiceBurner98sC]

I've been thinking about that as well...but I wonder if a boost leak would cause me to run THAT rich.

[msaskin]

What fuel pump are you running? Sounds like possible fuel cut to me.

~matt

[DriftS14]

I've been thinking about that as well...but I wonder if a boost leak would cause me to run THAT rich.

The ecu is compensating for air that is metered, but isn't there. This would definitely cause a very rich state.

[s13sr20chris]

i blew off my tb hose one time and it did that. i could hear it though so i knew instantly that something was going on.

[RiceBurner98sC]

The ecu is compensating for air that is metered, but isn't there. This would definitely cause a very rich state.

Drift. I now are leaning back towards the notoriously leaking stock recirc valve. I changed out my plugs and my car ran alot better. I took it out for some testing .

My original problem is that I am hitting a "limiter" at high rpms(55-7000K)depending on what gear I am in. I am using the KA speed sensor.

It is running better and the "wall" I am hitting seems to be at a higher rpm after I switched back to my SMIC and changed of plugs. What I did notice was that when I am at WOT in starting at 3k and boosting at 7psi, I will pull pretty hard up to about 5500ish and I noticed my Boost gauge dipping from 7psi to 6 to 5, then "Wall".

Is this an indication of a notoriously leaking stock Recirc valve? When I hit this "wall" I have power, but if I stay in the same gear I have ZERO throttle response and the rpms come down slowly and smoothly. If I switched into a lower gear all is well. So Im wondering if the bov is holding boost for a little while, but after a ton of load it leaks at high end leaving it stuck open then when I let off the gas to switch gears creating a vacumn, it pulls it back shut?

[DriftS14]

I don't have experience with the stock side-mount or recirculation valve, but if you have checked every hose clamp and all other possible leak points, I'm willing to bet it is that. The symptoms you describe are word for word boost leak. The fact that your turbo can spool up 7 then slowly drop to 5 could definitely be the recirc valve. I know the "wall" you are talking about. It is an extremely rich state that the motor can't rev past. Sorta lika a limiter but it isn't.

[RiceBurner98sC]

I know the "wall" you are talking about. It is an extremely rich state that the motor can't rev past. Sorta lika a limiter but it isn't.

Exactly...well Im going to go with that for now. Tuesday Im picking up a HKS SSQV so I can elimate the recirc valve as a possible problem area.

[RiceBurner98sC]

Also, I ran the recirc valve with the GReddy RSPL as well, which I'm assuming is why at a lower RPM, I would break up sooner vs the SMIC which I break up at a higher rpm.

[RiceBurner98sC]

Today I will find out if my stock bov/recirc valve is the culprit. I'll be adding a HKS SSQV and a GReddy Hotpipe to the mix and see what happens.

[electricproblem]

any results??

[RiceBurner98sC]

Didnt pick up the hotpipe, but did add the BOV...still have the problem. Guess its time to make a boost leak checker then onto the FPR.