[Petik]

Good evening, folks. I finally installed the SVT JRSC BBK on my Zetec powered kit car. I had been running the zetec JRSC BBK for a couple of years now and wanted a bit more power and a bit less IATs...

If you're interested in how the zetec JRSC ran, see this thread: http://forums.focaljet.com/showthread.php/677455-Zetec-JRSC-no-boost

Anyway, so...I bought a beat-up old SVT Focus that had it installed, took the JRSC out and shipped it to Stiegemeier for full rebuild and porting.

Per some great advice here http://forums.focaljet.com/showthread.php/680930-Zetec-vs-SVT-intake-flange-mating-for-JRSC, I then had a machine shop slot the mounting holes on the SVT JRSC to drop the whole assembly slightly and have the ports align. Seemed to do the job.

As part of the swap, I also switched to using the fuel rail which came the JRSC and thus switched to the SVT fuel pressure sensor and FPR.

Pretty much everything else remains the same, at least for now: same intake tube/MAF, same 42lb injectors, same ECU tune, etc. Figured I may need to retune afr slightly and possibly upgrade the fuel pump if it runs out of steam, but it should run reasonably well as is.

Finished the installation this evening and went to fire up the car. First it wouldn't run at all and threw P0190 and P0193 - realized the pinout on the SVT fuel pressure sensor is not the same order as the Zetec - the white and yellow are swapped in case you ever run into this. Once that was fixed, the car would idle happily.

Now for the problem...the second I give it almost any gas, the car dies. As I move the throttle body lever, I can see the bypass actuator close the bypass valve on the JRSC and as that happens, the car dies - as though all air was shut off.

I checked that the belt routing I used is was the same as the one on the zetec JRSC (can't think of any other way to route it and it matches the installation manual anyway), so I don't think it's spinning backwards.
I haven't measured boost, but it happens so quickly I doubt I'd measure anything anyway.

I have an xcal2 so went ahead and measured a bunch of PIDs, everything looks in order until I give it throttle and then just nothing, car goes "off".

Appreciate any thoughts, things to try, etc....

 

[Petik]

Really looks like the car is getting air starved...here's a snapshot of the log. You can see how the air flow spikes just a tad after the throttle is opened, but then it plummets....is the SC running backwards?

 

[focusownerskid]

Sounds like your vacuum routing is off.

Bypass actuator shouldn't even consider moving until you see boost.

- Drew

 

[Petik]

Well I thought I had it resolved. After running for a while the car picked up rpms and idle was super smooth, then i was able to give it gas and rev up very nicely. I did this for a bit and then shut the car off. Next time i started it went back to crap. I re-checked vacuum routing and everything looks right. I swapped spark plugs and re-checked wiring to the coil and also checked intake. All looks right.

I disagree with you on the actuator. It's actuated by vacuum, not boost. Default state is ambient in which case the valve is closed. When you idle, engine pulls vacuum on the actuator which in turn opens the valve. As soon as vacuum is removed, the actuator returns to its natural condition and closes the valve. The actuator would work in the same way if you just had it hanging on a naturally aspirated engine doing nothing...

Something else worth noting...the car remains in open loop the whole time. STFTs immediately peg at 0.75 and then switch to 1.0 when the car goes to open loop. I think there's either an electrical issue or the car is running super rich. Reason why I suspect an electrical is because my wideband (Analog1) just sits at 0V. I checked the wiring on it and it looks fine. Also checked fuses and none are blown. Thinking maybe a ground issue...need to investigate further.

One last thought about the electrical...hope i didn't cook something on the ECU when I mis-wired the fuel pressure sensor - that said, the fuel pressure keeps reading well so I think it's unlikely...

 

[Petik]

Missed a switch on the wideband and got more data. When it runs like crap, it runs super lean, basically pegged lean (not rich like i thought). That said, i think it's because it's missing, not because it's actually not getting enough fuel. Going to try a different coil pack and plug wires - think i have spare set laying around somewhere...

 

[64Rambler]

Pete, did you ever figure this out?


Sent from my iPhone using Tapatalk

 

[Petik]

Pete, did you ever figure this out?


Sent from my iPhone using Tapatalk

I did indeed. The cobra maf i was using was sending erratic readings. Replaced the maf and everything was fine. Took me good two weeks to figure that out...

 

[64Rambler]

Cool! I too have had my car staying in open loop when it should be closed loop, or only showing a change from 1.0 on the STFT's when it changes widely to the far ends of the range, not seeing the small changes that should occur to the STFT in closed loop.


Sent from my iPhone using Tapatalk

 

[Petik]

Have you logged the sensor voltage output directly?

In general I find it hardest to tune idle or low throttle afr when running large injectors, especially 60s - so I run the smallest possible injectors that still satisfy my power needs. You can figure this out through calculations, but I find the best way is really to just get on a dyno and log the injector duty cycle. I like to see it in the upper 80% at its peak. Tells me that there's a bit of room if I were to hit colder temperatures, but no extra room to keep the lower airflow tune-able. On a track car this doesn't really matter since there it's running open loop nearly 100% of the time anyway. I've gone as far as completely disabling adaptive learning to avoid it messing with my tune. You can also use your wideband to tune the lower ranges - stfts help, but wideband is still valid there.

 

[[email protected]]

FYI, Focusownerskid is right. When the car is off and at idle the boost bypass actuator stays in the fully extended position and even at partial throttle it shouldn't move.

My SVT has been running the JRSC/BBK for 130k miles and it works perfectly, I can't make that actuator move at all just sitting in the driveway and revving it but I also won't rev the piss out of it to test it. I do know that mine makes a solid 10psi at WOT.

-Steve

 

[Petik]

Steve, what cams are you running? I'm running a pretty aggressive grind and in that setup vacuum goes away much quicker than on a stock cam - which means the actuator will close sooner. Found this out back when I still had a focus and did a bit of rally school - brakes wouldn't work as well when left-foot braking and using the throttle.

That said, after figuring out the maf issue, I was able to see a very nice 9psi (note it's a ford racing head so much higher flow = lower boost).

 

[[email protected]]

My engine is bone stock.

When the actuator diaphragm is fully extended (as mine is at idle and partial throttle, free revving) the boost bypass valve is closed and stays closed, when the actuator pulls the rod it opens the boost bypass valve.

-Steve

 

[Petik]

Steve, I believe that's backwards. Where are you pulling vacuum for the actuator from? The rod out of the actuator (diaphragm) should not be fully extended at idle - it should be retracted and holding the bypass valve open. I suspect that if your bypass valve is shut at idle, it probably never opens.

The bypass valve should stay open during idle and part throttle to provide a bypass for the engine to not have to pull air around the rotors which act as an obstruction at low rpm. When you get into throttle and increase load, vacuum goes away and the actuator/diaphragm shuts the bypass valve and prevents air from recirculating - this recirculating is what occurs when actuators fail and allow the bypass valve to remain open even in boost conditions and power drops off since the sc is just moving air in a loop. Note that the bypass valve should not act as a boost controller.

This is how it worked on my regular JRSC (m45) and also on this M62.

Please correct me if I'm wrong here, but I don't see how else the bypass valve would work...

 

[[email protected]]

edit

 

[[email protected]]

I'll see if I can get someone to go for a ride with me soon and shoot video of how the boost gauge behaves.

If mine isn't working right I can't imagine it could be much better but we'll see, will test my old actuator shortly.

-Steve

 

[Petik]

Steve, you wouldn't lose any boost if the actuator was pulling vacuum from the wrong place. As I mentioned, the bypass valve is not there to control boost, it's purely there to allow a bypass when boost is not needed. You can google this - it's pretty well documented.

Also, if your bypass valve never opened, you wouldn't actually notice anything terrible other than the car having a harder time idling - which tends to fix itself with adaptive learning turned on.

When you're taking that ride, could you check that your boost gauge is getting its vacuum from the same place as your bypass actuator? I'm curious if the actuator is seeing much vacuum. One of the things I recall Oscar mentioning many years back was that the original instructions for the jrsc had not entirely correctly described the hookup of all the vacuum lines - not sure if this is relevant.

 

[[email protected]]

Verified yesterday that my actuator is bad, will be installing a new one in the next couple days. I'd just seen so many people complain about loss of boost etc due to bad actuators that it didn't seem that anything could be wrong since it runs and drives so well.

And yes, the boost gauge and actuator get vacuum from the same source. Those barbed fittings on the back of the blower manifold.

-Steve

 

[Petik]

Well I'm glad I'm not completely crazy...sorry that you have to replace a part though.

 

[[email protected]]

Well I'm glad I'm not completely crazy...sorry that you have to replace a part though.

Made a half hearted attempt to replace it yesterday and found out that it's virtually impossible to do without taking the blower off due to the way the retainer tab on the actuator pushrod locks in the the lever on the bypass valve but I did come up with a solution.

On the new one I'm grinding off the tab and using a push on style retainer along the lines of what's used on the stock intake to hold the DSI lever to the intake. This will allow me to cut off the old pushrod and get the new one in without having to deal with that tab/slot that can't be done in the car.

-Steve

 

[[email protected]]

Got it swapped out, I did have to cut off the old actuator rod with a hacksaw but the new one is in and the hardware store had a perfect press on retainer that worked like a charm.

It's not any faster but it does idle a lot smoother and low end and partial throttle does feel smoother.

-Steve