Way too much fuel!!! O2 or Map (F.A.S.T)

[Fast GN]

I was making my first pass down the track and half way the engine lost all power, did not die though. Now at an idle it is just dumping a lot of fuel puffing some black smoke. You can give it some gas and it clears up but just for a little bit as soon as it starts to build boost it just kills over and tries to die. I have a FAST computer. With the car running it is about 10 on the a/f ratio, and my O2 correction % just shows 0.0 all the time. Is there any way to test and see if my O2 is bad? Or could it be my 3 bar map? The stupid O2 sensor is $500.00 bucks!! Alot just to be guessing. Thanks in advance. Please help.

 

[HighPSI]

Look at what the sensors are reading. That will tell you what, if anything, is bad. Check the vacuum line to MAP sensor and verify your coolant temp and air temp are correct. I doubt the O2 is the problem, but if it is, you can buy them for under $200.

 

[Fast GN]

Checked Sensors

Ok, The coolant and air temp are correct. The WB O2 reads 1 all the time, the O2 correction percentage reads 0.0 all the time. The Map is at 101 and it also never changes no matter how much gas you give it is stuck on 101. So basically the O2 and the Map never change. Checked the vacum connection to the Map and it is fine. Please let me know your thoughts. Thanks!!

 

[HighPSI]

The Map is at 101 and it also never changes no matter how much gas you give it is stuck on 101.

You found the main problem. Try unplugging it and see if the FAST reads "0". Also, make sure you are running a dedicated line to the MAP.

 

[Fast GN]

Ok, do I unplug the vaccum line or the electric plug or both?? I don't know what you mean (dedicated line?) You tuned the Car at Wild Cat Engines about 2 months ago so I am not sure how it is hooked up. I spoke with you couple of times about 3 weeks ago trying to diagnose another problem, well I fixed it. A piece of teflon tape was hung up in the #4 injector. And when we removed it that joker ran like a top, until now.

Please let me know.

Thanks,

 

[HighPSI]

Unplug the electrical connector and see if the MAP drops. By dedicated line, I mean a vacuum line that runs from the engine to the MAP sensor without any "T"'s or other vacuum lines branching off.

 

[Fast GN]

OK, well when I went looking for the dedicated line I found the line was off where is attaches under the hood. It is not a dedicated line it is T'ed in with the Boost controller. (is that bad?) Ok so now I fired her up and she kinda sounds worse. Plugged up the FAST and the Map is now working (of course it always helps to be plugged in ) anyway but the O2 is still on 0.0 so I decided to go for a drive to see if it would clear up. After about 3 minutes the 02 started working it would go from -5 to 8 just putting around. A/F is now from 13 to 15. But it never cleared up. When I got home I started pulling plug wires cause I knew it was not hitting on all 6 and I know for sure the back hole on the right is not firing and I think the back hole on the left is not either. Now I drove this thing about 45 miles home from the track without a map, have I fouled a plug? Do I need to replace all of the plugs if so. Or do I have another problem? Please let me know where to go from here.

Thanks,

 

[Otto J]

replace the plugs first ,its cheap.
If this vacuum line fell off under heavy boost your COULD have hurt the motor.
Like Cal said make sure the line to the map is dedicated,
and put pull ties around both ends to ensure they dont come off again.

 

[HighPSI]

Try what Otto said. Additionally, the reason the O2 correction doesn't work immediatly, is because the engine has to get up to a certain coolant temp before it will start correcting. It also won't work until the afterstart fueling is completed.

 

[Fast GN]

Ok, I will put new plugs in this evening. Where is another place I can pull the vacuum from to make the map a dedicated line. I am getting if off one of the lines on the intake now. And it is going to the Map and the Boost controler. Thanks,

 

[Fast GN]

Ok I got the new plugs in and it seems to have fixed the problem. I took it for a spin and everything worked great all the sensors looked good. I did not give it much boost cause I don't have the Map on a dedicated line yet. Can I T into the vacuum on the cruse to run my boost controller, so the Map will be dedicated?

Also I set the plugs at 32 to 34 is that too tight?

Please let me know,

Thanks for all your help so far. :smile:

 

[Otto J]

PLugs are fine at that gap if you find you have no misfires at high rpm/boost.

The reason for a dedicated line is so that you take away the chance of any other line blowing off from the map circuit causing the problem you have.

 

[Fast GN]

Ok cool,

Thanks again for your help

 

[Bent6]

Can I T into the vacuum on the cruse to run my boost controller, so the Map will be dedicated?

QUOTE]

DO NOT T into the cruise vac line - it has a check valve to prevent boost from damaging the diaphragm on the cruise actuator - the MAP sensor would never see positive boost. I usually just hit the hard vac line off the top of the plenum that went to the stock MAP on the pass side fender.