I'm trying to find a large vacuum leak and I was thinking of bypassing the fmic. Is it ok to just bypass the fmic with a short tube.

 

That's not vacuum. Vacuum is between the engine and throttle body. Anything between the filter and throttle body is just intake, and will cause an issue with idling and starting on a stock ECU that retains the AFM, but just so the record shows, that area is not vacuum.

 

You may run a short pipe to bypass the FMIC... Don't let it run too long, though.

 

But if you think you have an issue there, replacing it with a piece of pipe is fine, so long as you don't plan on driving it with that there.

 

yes.
I have found vacuum leaks with a little contraption that was found on www.fighters-garage.com
Basically it is a Cap with a schrader valve(tire valve) and a gauge on it, that you can put on one of the pipe couplings at the turbo( I put it BEFORE the turbo),and then you pump about 15psi into you system and listen for leaks.
Very handy tool.

 

Thanks for the tip but I could not find the contraption. Do you remember what it was called?

 

Thanks for the help. We just put the engine back together again. This is the third time that this engine has been installed in this 7.
The engine will not idle, in fact it runs like crap. Its almost impossible to keep it running more than 1 minute and then I have to keep pumping the accelerator to get it to run that long.
I just want to bypass the fmic to take that section out of the equation.

 

OK, thanks for the input.

 

Thanks. I can't keep the engine running long enough to get out of the drivers seat as to make a visual inspection so I'm just trying to eliminate possibilities.


ash

 

You don't buy it, you make it.

Here is how to make one of these. Just get a piece of PVC pipe the size of one of the intake's, preferably before the afm. Glue on a cap. Drill and tap a 1/4" MPT hole. Install a male air quick-connect. Clamp this tool onto the intake pipe using a rubber gasket. Set your air pressure regulator to 10 psi. Hook up the hose and let the entire intake pressurize.

You should find the leak easily-if that is the problem.

Good Luck!

-Jack

 

Here

 

^ That would be better than bypassing the FMIC with a short tube.

I've seen those things for sale for such ridiculous prices. Like Jack is saying... Make one. It's a pretty self explanatory design.

 

Did you properly install the crank angle sensor? Does it seem to bog down, or just die off as if it's not getting enough fuel? How's the fuel pressure? What injectors are you using? Are the spark plug wires connected properly?

 

Thanks Jack, I don't remember anybody talking about these. Sounds simple.
I'll definitely make one.

 

Yes, I'm sure the CAS is installed correctly, I've rechecked it several times and the spark plugs wires are correct, I've had them off several times.

IDK about the fuel, maybe it is starving. It starts right up but it is very hard to keep running. I have to keep pumping the gas and that only works for less than for a minute, and it just dies.
If I can get it to hold idle at 2000 it will slowly creep up to about 2800 and immediately drop back to 2000 and then repeat. TPS has been checked several times and is currently set at 1k ohms.

 

How old is the gas in the tank?

 

About 1/2 of it is from last November but I added about 5 gallons of premix to it. The premix was mixed at 50:1 using a high quality 2 stroke oil. I figured that when the old gas already in the tank and the new premix were combined that the overall premix in the tank would be approx 100:1.

I'm going to fabricate the leak detector gadget. I would be really nice if I found a really bad leak some place.

ash

 

Most likely, you now have 10 gallons of useless fuel. You probably should have drained that gas first. I always drive my car to empty before letting it sit for a while (I know it's not something you could do at the time with a busted engine). I get deployed pretty often, and when I come back after about 90 days, I literally have to limp my car to the gas station. Not saying that's the absolute issue here, but 7 month old gas.... eek.

 

OK, I see. If I don't find anything with the leak tester, I'll just drain the gas.

thanks