I was driving home from school friday night racing a RX-8. When I hit 4th gear, he's bearing see in my rear view mirror. Then I hit 5th gear with boost still on. I heard a pop. After that night, each and every time I reach to 0.5 bar or 7.4 lbs of boost, there's no power and alot of backfiring. It's like an air leak somewhere, but I can't find any vaccuum loose. I also checked everything connects to the IC and nothing seems to be loose. I done a search but didn't see anything relates to my issue. I still have boost, but only under 7.4 lbs. Please help!

 

car smoke alot?

 

How fast were you racing where you needed to shift into 5th? Anyways, what were you boosting prior to this experience?

 

The intercooler piping couplers don't look 'loose' when they are leaking. Remove each one completely, and turn it inside out. You're looking for a small gash or slit.

Dave

 

Yes, smoke alot from exhaust ...

 

I do not remember the RPM, but I was at around 80mph. I used to have a 10-8-10 boost pattern.

 

If you're going to be racing someone at 80mph, you shouldn't shift into 5th gear. Anyways, did you check to see that your MAP sensor has a vaccum hose connected to it?

 

Actually, the racing ended already. It's not a drag race, it's only a highway chasing cutting race type. I checked the MAP sensor and the Boost sensor the first thing. There is vaccum connected.

Don't concert too much about the race guys. I just want to give a little back ground of how this happened. And thankyou for all your reply.

 

Just to let you know, the boost sensor, and MAP sensor are the same thing.

Now, i'd assume you havn't tried taking off your UIM to see if any hoses are off under their? If not do so. Look at every hose going to the twins and and through the LIM and check them over. Don't forget to take off every coupler to see if there is any slits in them, and that they are nice and tight. Also double check the MAP, it might not be disconnected right at the sensor, it could be disconnected somewhere a ways down from the sensor. After you've checked all that report back, but i'd assume you have a hose that has popped off somewhere, or a slit in one of the couplers. Usually if one of your couplers is slit, you'll hear air rushing out when boost starts coming on, and you normally won't even hit close to 7psi.

-Alex

 

Chances are it will be one of the small vaccum. I will take off the UIM and check everything out ASAP. Once again, thanks guys for all your help!

Also, any link or site that I can purchase vaccum lines? I think it's time to change all of them.

 

I got a set in silicone that i'll sell you for cheap, I was going to switch mine out but decided to do a custom twin setup so I don't need them anymore. Just shoot me a PM if your interested.

-Alex

 

While you are at it, check your spark plug connections (and I would recommend changing the spark plugs themselves while you are there).

 

Just a little update on my nightmare. The problem is still unsolve. I already check every vaccum under the UIM, nothing is loose. I had a flood on my engine last night for the first time. Unflood it today and the car runs fine. I replace all new spark plugs and it starts way better than before. The worse now comes, once I boost the car=no power, alot of smoke coming out from the rear, and the car shakes a little. Before the flood, I can go up to 7.4 lbs and now once it pass 0, things happen. Please help me out with my N/A FD3S =*(

 

Have you done a compression test recently? I wouldn't think thats it, but you never know. Also, if all you've done is fiddle with the vac. lines, and your car won't make it over 0psi then I'd say you put something back on wrong. Just because the vac. lines are on tight doesnt mean one doesn't have a slit in it or what not.

-Alex

 

Got it Alex, I'll try to have the vaccum diagram next to me tomorrow and open up the UIM again to take a look. I might put back something the wrong way.

 

Have you checked to see if there are any stored engine codes yet?

 

Sorry, I didn't get you. Are you talking about that thingie that a computer connecting to our cars and shows codes? If yes, I do not have the machine.

 

Look in the engine bay, you should see a little black box that says "diagnostics." Search around and you'll figure out how to pull codes from it.

-Alex

Edit: Here ya go, this will tell you how to get the codes. If you don't have a shop manual to tell you what the codes are, search around and you should be able to find your answer, theres also an online shop manual.

http://www.scuderiaciriani.com/rx7/engine_codes.html

 

I got 4 error codes:

11 - Intake air themosensor
12 - Throttle sensor (full range)
13 - Pressure sensor
18 - Throttle sensor (narrow range)


Does any of them relates to my boost problem? I cannot start my car today as well. Keeps cranking but it wouldn't start. I took off the vaccum under the boost sensor and start the car with my foot on the gas pedal. While my foot is still on the pedal, I ask a friend of mind to put the vaccum back on. The car starts fine except when the engine gets cold. Any advise guys?

Anyone lives in NYC and willing to let me testing my car use your sensors for a minute or two?

 

Update:

I find out that I put back the check valve in the wrong direction. I fixed it today and all the codes are gone. But my problem is still there.