im running a norris designs T28/T3 hybrid and normally it would spike hard up to maybe 0.80-0.85bar for a second or so and level out at .75 til i let off. recently i took my car in to have the timing adjusted, IC leaks fixed, vacume lines cleaned up, TPS and idle set. Well the i noticed when i got the car back that the breather line from the intake to the leftside valve cover was missing (facing the front of the engine). its possible that i lost it when i was working on my car a day prior to bringing it in or that they lost it thats not the point. when i got my car back earlier today i drove back with the line pluged up on the intake side but open on the valve cover side and was not pushing my car whatsoever since i have no idea what adverse effects this could cause. anyways i wanted to see if the transition into boost was better (it had been a problem before) and so i gave it maybe 45% throttle to about 4500 and hit what felt like fuel cut, looked down to my horror to see id hit a peak of 1.12bar! not that much but way to much on stock injectors/mafs. so my question is could the breather line have in any way caused this or should i be looking around for other offenders (ie my restrictive nipple on the vacume line from turbo going to actuator). one more question. i had been advised by many with SR's to completely disconnect the boost control solinoid valve (is mounted directly on top of the ignitor chip). but the mechanic at the shop said that my car is running very lean and is probably do to the fact that this is disconnected. he said it is responsible for raising fuel pressure while in positive boost to prevent lean conditions. anyways i appreciate any help.

The fuel pressure is set directly off the intake manifold (on the back near the brake booster vacume line). It just goes straight into the fuel pressure regulator. The thing above the ignitor chip has nothing to do with fuel pressure.

The valve cover breathers being open isn't going to kill anything, I've got mine like that (with a filter attached) and I've done it for like 10,000miles.

I'd look into where your wastegate actuator is getting it's pressure from, make sure you have a good solid boost signal from the manifold leading into it, and make sure your hose is good and not leaking. It sounds to me like you have a leak somwhere in the system. I had that same problem on my turbo, since the stock rubber hose has a T fitting in it and the other end of that fitting was open.

Also somthing I've found that makes transition to boost a bit easier is to bump the timing up from 15 to 20 (which is stock on the SR and KA). I did that and it really woke the car up. CA's stock use a LOT of timing, 37 is what it runs at WOT 8,000rpm full boost! Adding more really seems to wake the motor up.

I'm also assuming that you capped off the boost control solonoid when you disconnected it? Even if you did I'd just go out and buy some vacume line and re-do everything from scratch, that has helped 2 of my other freinds who had drivibility problems.

later,

Paul

Quote »make sure you have a good solid boost signal from the manifold leading into it[/quote] shouldnt the actuator get the boost signal directly from the compressor side of the turbo not the intake manifold?

That's what I recomend that way your working off what's in the manifold, not what's in the turbo. I've always run mine that way and never had any problems with it. If worse comes to worse the problem might be in the O2 sensor housing, mine was WAY ported out, and then welded up to flow like twice as much as the original. That will help the wastegate flow, eleminating boost spike (if that is in fact your problem).

After your sure the new vacume stuff is done right, then I'd start looking into porting out the wastegate hole and O2 housing.

later,

PaulOrlando, FL

well i bypassed the solinoid valve and ran the shortest hose i could from the compressor to the actuator. i also opened and closed the actuator a few times to make sure it wasnt stuck and still does it. i did a couple different runs in different situations to assess the problem. and even in a WOT boost build in 5th gear it just keeps climbing and i let off at around 4600 where boost has climbed up to 0.9 bar. this was not a problem before i took my car in so i can only come up with 3 possibilities:1. big coincidence that my actuator gave out at the exact same time i got my car back... highly unlikely since this turbo has less then 5k miles on it.2. the AVC-R (which i use as my boost gauge as well) is not correctly displaying the correct manifold pressure after the vacume lines were changed around. this also seems unlikely since its reading out correctly at idle and seems to build boost and show correctly for the rpm/throttle position. the hoses now are setup from a direct line on the very back of the intake manifold T'd off to the pressure sensor with the other side of the T branching off to the BOV. but then again my S-AFC's MAFS air peak readings dont seem to match up with the amount of air it says i am pulling in. also doesnt the stock ecu kick in fuel cut at 14psi?3. the actuator is opening but not all the way, or is actually working but too little too late.

Try getting rid of the boost controller all together, and run a straight line to the actuator. Also try sucking on the line coming out of the acutator, if you don't get any vacume the thing's toast.

The boost cut happens at 5 volts on the MAF, on the stock car that's right around 15-16psi, but upgrade the turbo, intake, and exhaust and you'll be hitting it much lower (somtimes as low as 7psi). Everybody refers to it as a boost cut, but it's really an 'airflow cut'.

If you disconect the harness on the avc -r it will run stock boost.

I have hit fuel cut (boost cut what ever) as well recently. The car was driving fine for quite some time and then it just got sloppy. Its now running way rich. Maybe we have similar problems. What do you guys mean by breather on the left side? Are you guys refering to the huge line that runs out the side and then goes back into the intake somewhere? Mine has come disconected fromt eh valve cover. The owner of our shop has suggested that in turn it acts as a large boost leak and is most likely the problem with my car running rich and hitting fuel cut. I changed my plugs. One reason was becaues they had not yet been changed and the other reason was becuase i wanted to see just how rich the car was runnning. Mine were extremely black. There was more unburned fuel on my plugs than in my gas tank. The owner called them "SHAFT BLACK" (like the movie shaft) they were so black. Anyways, we are going to Weld the piece back onto the valve cover soon and hopefully that will take care of the problem. I will let you know if anything else is figured out.

Actually that line coming off the lower back side of the valve cover leads down into a crank case vent that's located right behind the oil filter. There's a little metal plate in the oil sump that blocks this off, and a rubber flapper valve to keep oil from getting in there (don't ask how I know all this). It vents the crankcase into the valve cover, and the valvecover vents out though the other breather. So having that uncovered wouldn't cause you to loose any pressure through the manifold.

I had VERY similar problems in my CA18 powered capri for a while, check to see what your vaccum is at idle, if it is higher(well lower really) than usual (instead of 15 it is 10 or 8) then you have a leak somewhere. thats was a fix once, then i was hitting a similar fuel/air cut, check your dropping resistor resistance/voltage as discribed in the manual, check throttle position sensor, do a diagnosis on the ecu and see what errors you are getting. I did all of those and fiddled with the throttle sensor, used some electrical cleaner on all the sensors and it was sorted out.

and clean out your Air Flow Meter with some carburetor spray or something, that usually help out allot. it could be that your air filter got dirty or greasy.. and if they changed around your breather system you may be getting oil blow by into the intake and it fouled your AFM... that happened to me after topping up with too much oil and i changed around my breather system...''hope that helps

thanks for all the help guys. i went thru and examined all my vacume lines and found that the actuator wasnt getting a correct pressure signal. i ran one from the intake manifold and am now getting only slight spikes (up to about .85 from a .75 limit) but at least the boost is regulated now. im still trying to find a way to eliminate the spikes by using different hoses and trying to shorten everything up.