Ok, the background, recently put a new engine into the car after the old blew. Also full emissions removal and TB mod, induction kit and atmospheric BOV.

After that it started and run fine althought did need to fit new water pump.

had a few other jobs to do so 3 days ago I went on the first drive. I started testing all apects of the car seemed fine then a problem surfaced about 10 mins in.

The problem is, when you press the throttle more than 10% the engine cuts out, and doesn't kick back in until the throttle is let off. And would backfire then run normally.

Driving under 10% throttle would allow the revs to rise, but still more than 10% throttle it would cut out.

Also notice a wooshing noise as if the turbo was spinning fast but no boost. All the pipes are still on and attached.

I thought it could be the BOV with a weak spring fitted. Trouble is under greater thottle setting the pressures on both sides are more equal, so in theory the more throttle the better the BOV can seal itself.

HAs anyone got any other suggestions, I have just bought a Spring kit with 4 diff springs for the BOV to try, but I cant help but think it's something else.

Thanks Guys

 

Well, the whoosing noise would indicate a boost leak to me.

 

Yeah me too, hence the focus on the BOV

Would a boost leak, cause the total cut out then?

 

Sounds like the fuel pump. Mine did that about 3 months ago.

 

Hummmm the Fuel Pump

I was also thinking about my FPR, because it has 2 vacuum ports, And no one on the forum seemed to know why so I just hooked them both up to the same location on the LIM, I do have a S4 one to replace it.

could it be any other fuel issues as well.

What ever it is, it did work fine for 10mins ???

 

I am hav ing this EXACT same problem. If i press the gas more then i would say 20 - 30% when the rpms are above 3000 - 4000 all power is lost. If i hold it in, it will start to backfire and run bad but if i let off power comes back.

I am thinking it is a fuel problem with mine, if it was spark it would bouncethe RPM's like a rev limiter.

If it was air, it should not effect anything at WOT.

So only thing left is fuel. the question is then, is it eletronic or mechanical. For me i just replaced the pump so i doubt it is that.

So today i made an ECU code reader (i have an S4) and found that i have this code:

Code 09 - Atmospheric Pressure sensor.
DCC1: LSSSS P ... (1 long light ... 4 short lights ... long pause ... repeat)
DCC2: does not light
Fail-safe mode: Maintains constant sea-level command (boost sensor)

Might be worth checking your codes and see if the error is the same, if not that would help me, if so that would us both lol.

If your fuel pump is old i second that is what it could be. also could be fuel filter.

 

Yeah it's not spark Def not.

Obviously All fuel delivery is stopped when it cuts out.
I thought it was the BOV that created a massive leak that made the ECU kill the fuel. But as i dont know how the ECU works it was only a guess.

On the fuel side, the fuel filter is new so lets rule that out.
The fuel pump could be at fault, it's probably as old as the car. If replacing i'd try a WALBRO, are the ebay ones I see the real deal? And is it much work to fit?

The code reader sounds interesting, I'll have to research them, You say you made one yourself, is it just an LED?

 

http://www.teamfc3s.org/info/article...odes/main.html

That is how to make one for the S4, the S5 cars don't need it, see the link on that site for how to check S5's.

Cost me $8 from radio shack and about 3 mins to put it together. Also works as a TPS setting light.

And yes, if i have to replace my pump again i will be getting an ebay pump. There are some off brands but there is not much to a fuel pump, they should all work, though i would try for a real deal.

A BOV leak should not cause all power loss IMO, unless you are in high boost and all your boost goes by by. but then it should still have NA power, not cut out all the way.

 

Yeah I thought that the ECU cut the fuel as a fail safe if it detected a massive leak. On other turbo vehicles I've had when a pipes blows off you just lose power and not cut out.

Might try out the an ebay pump then anyway, just for the added flow rate. Must say though I am drawn to the FPR being the problem, i was unsure about it from the start hence the purchase of the S4 fuel rail and FPR. My FPR has 2 vacuum ports, and no one on the forum had an anwser as to why, think maybe wasn't on American models.

I'll have a look at the fault codes tomorrow

 

IIRC if that pressure sensor is bad it will also prevent your secondaries from coming on which would nuke your power above 3200 ish...

 

Are you thinking of the boost sensor?

This code is for the Atmospheric Pressure sensor. It is in the passange footwell by the ECU. From the reading i have done it looks like it just controls how much fuel is used to run the car. but i could very well be wrong.

 

Ok the news is, when the engine is cold it runs fine, once warm the problems start.

I now think the cutting out is the limp home mode, And for what ever reason once warm it goes into that mode. So Temp sensors spring to mind.

 

The famous 3800 Cutouts...lol

Quote from Shep when i had this issue.

"its pretty common. I would first try getting your injectors cleaned and flow tested. Then I would check all your grounds and test your TPS to make sure there aren't any dead spots."


I cleaned my injectors then grounded the crap outta my motor. I'm pretty sure it was just the ground wires that fixed my first vert. They sell kits for like 5 bucks on ebay but i just used power wires from when i used to install stereo's.

I cant remember ecatly how i ran the extra ground wires but the basics would be Alt. to block, block to firewall, 1 extra from battery to wherever (Block).

I pretty much just ran random ground wires. take your time and your motor will still look "Clean" Try it- Injectors and enough ground wire will run ya late 30 bucks if you do it all yourself.

 

Well it's is not like the 3800 lag problem exactly, i have that before and fixed it. This is quite differnt in that it used to go to 6000rpm fine, then it was 5000 then 4000 now 3000.
And at idle at WOT it will go to 5500 then sudenly stop and drop to 4000 and stay there as long as i have WOT. I think it is my brand new fuel pump, i am going to exchange it today and find out.

If it doesn't work then i only have 1 more ground to beef up.

Also, how would cleaning the injectors cost under $30? Cheapest i have seen is $75 for 4.

Is your car an S5? if so then it could very well be your problem. Though if yours is an S4 there was no limp mode on the S4.

 

What i ment by cleaning them is taking them out sprayin them off real good with injector cleaner and throwin them back in with new o-ring. how por people lke me do the job lol. what all have you done with your fuel system?

I dunno i was just throwin that out there tryin to help.

 

Except the injectors, it is ALL new. Pump (though i think i may have got a bad one, it seems to be going out) filter, hoses ect. and i cleaned the injectors like that before i installed them, though that doesn't actually do anything for how they work since you can't get the cleaner down inside of them without opening them.

 

IS THE PUMP A WALBRO>>! It would be interesting if it was. Seams like everyone's lately is defective somehow. I dunno man i'd honestly try grounding everything out before takin the new pump out. Hurray! 10 posts! lol

 

Well on the box it said bosce i think but it sure looked like the Walbro i put in my truck a while back.

Either way, it is getting power fine, i can hear it running. In fact that is the problem, it has been getting louder and louder to the point where now i can hear it outside the car over the leaking exahust. Somethings got to be wrong with it when that happens.

 

If I had a atmospheric pressure sensor code on a series four, I'd go to the item and see if its elect plug is on or not. If it's on, then see if it has a input voltage on the brown/white wire of approx 4.5vdc, the gnd is good and the output to the ECU is good or not. I mean, that sucker just sits there all by itself and it's hard to see one failing.

IF its plug is off it defaults to sealevel. Meaning it MIGHT cause a little bit richer fuel mixture thru the full range from idle on up if you live at a high altitude. Tx does not have high altitudes. humor

Depending on where you live in Tx, I could give you the output of mine vs yours. But then again, the ECU isn't seeing the output so it's throwing a code. Plugs off.

 

I will check that out, later today if i get a chance.

Right now i just found the problem with my high-rpm power loss. It was indeed my fuel pump, well kinda:





The sock got clogged and this would be my problem. but then i got thinking, if it clogged that fast then something has to be wrong.

So i looked into the tank and was shocked to see this thick layer of junk everywhere. So i am not swapping the fuel tanks between the parts car and mine, should fix the problem.

Oh, and that last picture with the other fuel pump, the PO of the parts car had swapped the pump to run a turbo, is that an FD pump or any ideas? i might just return my pump and use that.

 

I seem to remember that there is a resistor "pill" in the vacuum line for the pressure sensor.... Perhaps the line was replaced and the pill was left out and that is putting you into a limp mode? You can disconnect the vacuum line at the sensor and probe the vacuum line to see if the "pill" is in there. I know mine had one and I swapped the "pill" into a new vacuum line. I seem to remember the original line has a small white dot on the sensor end.

Ramses666

 

Yeah I have deffinatly not got that pill in, so does that restrict flow and damp out any unwanted occilations of pressure?

I'll have a look to find that old pipe may have ended in the bin!

 

Yeah S5, only sold the S5 in turbo verson in the UK. Thing is I dont have a Engine Check light! UK cars dont have them!!!!

So going to make the Check light thing and see what I get.

 

Actually if you have an S5 then you don't need to make a light, look at that site i posted above, they have instuctions for S5's.

Also, if you do have an S5 then limp mode does sound like it might be your problem. Read the site and pull the codes, i bet it tells you.

 

Yeah Like I said, I dont have an Engine Check Light, Its not on the UK models so I will need to make one