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Join Date: Oct 2006
Location: MYR S.C.
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my SYNAPSE DV is leaking

well i actually found a problem that made a real difference once fixed.

skip down for results:
i was wanting to try to adjust the DV so it opened for a certain pressure instead of being opened by vacuum. thought it might shorten the open time and not dump all the boost pressure between shifts. well i could not adjust it enough or make it consistent for opening pressure so i started checking the vacuum ports to see where they opened. neither port would hold vacuum!
finally i took it apart. nothing but a piston with some O rings inside. but i also found that the piston is not moving smoothly. its like something is out-of-round inside. i could also see what looks like a wear spot on one side of the body.
so i put some oil on the Orings and put it back together.
the ports still leaked of course but if i block one, it will work. as it would open i could see the piston sticking at the bad spot then popping open the rest of the way. so with bith ports connected together it looks like it is working despite it not opening smoothly.

result:
BIG drop in idle. my idle has been pretty steady at 950. it dropped to 800.
i did not check the mixture since it was late. drove it to work next day and the idle was the same all day. (in the past symptoms have changed. one drive it was better, the next drive worse).
the other big change is mixture. i am WAY TOO RICH. part of this is my fault.
i had exhausted all my ideas and was down to having the FD rebuilt. so since i was going to send it off anyway i bumped all ports up a tad in fuel flow. even after doing that before fixing this air leak my mixture was still in the 15's no matter what i did. now i am in the 12's. BUT. the mixture seems to be steady across the RPM range.
i have rasied my system pressure to 6.5bar and raised my control pressure to 4.1 bar and still very rich.
sometimes the engine would sound like it was running on 5 cylinders or like it had a slight miss to it. i think #4 injector had an intermittent fuel leak. yes, i check them with the engine running. (this made me think if that dumb a$$ post robby did the other day about silicon) so last night i was removing the fuel head and i noticed a very very slight trickle of fuel coming off #4. this was after the engine was shut off too.

so the plan is to check fuel flow of thehead tonight and adjust it back some. i am not ready to send it off since the weather has turned nice and everytime the weather is nice the car has been on stands.

oh, the synopse is only about a year and a half old so i am not too impressed with its condition.

iside the synopse:
its like there are 2 "seperate" chambers for vacuum. one is smaller than the other so i think one port would have more "pull" on the piston. the top of the piston looks like the inside of a cap off of a can a spray paint.

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86 930 42kmiles [__] RUNNING:[__] NOT RUNNING: ____77 911S widebody: SOLD
88 BMW 325is 200K+ SOLD
05 BMW 330CI 130K:: [__] RUNNING: [__] NOT RUNNING:
08 VOLVO V70 190K:: [__] RUNNING: [__] NOT RUNNING:
90 B2200[__] RUNNING:[] NOT RUNNING:__2000 MER E320 WAGON [] WRECKED:[]RUNNING:

Last edited by T77911S; 10-29-2014 at 10:28 AM..
Old 10-29-2014, 07:23 AM
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i still dont suggest anyone do what i did. screwing with the FD is bad. i have had multiple little problems off and on for a long time and i had exhausted everything to the point the FD was all that was left. obviously i found one more thing, but not less than a week after i tweeked the FD. whcih sucks because i dont think the FD was bad.

i went thru somehting very similar with the 77s i had. i bought it with a problem. you could not rev it past about 3500 or floor it with out a lot of spark knock.
peope kept telling me it was the fuel head but i kept testing, and learniing until i found the cams were advanced 15 degrees and i had a defective injector fuel line that was restricting flow to one injector.

i talked to synapse. they are going to take a look at it under warranty. i am not sending it back yet. i will do that when i send the FD off.
this really sucks checking fuel flow on the 930.
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86 930 42kmiles [__] RUNNING:[__] NOT RUNNING: ____77 911S widebody: SOLD
88 BMW 325is 200K+ SOLD
05 BMW 330CI 130K:: [__] RUNNING: [__] NOT RUNNING:
08 VOLVO V70 190K:: [__] RUNNING: [__] NOT RUNNING:
90 B2200[__] RUNNING:[] NOT RUNNING:__2000 MER E320 WAGON [] WRECKED:[]RUNNING:
Old 10-29-2014, 10:39 AM
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Bypass valves aren't really designed to work that way. The theory behind them is during shifts it dumps the pressure as opposed to keeping boost, which would flow backwards through the turbo, effectively stopping or reversing it. By dumping the intake pressure between shifts it allows the turbo to maintain speed (because there is no resistance on it) so it reduces lag.
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Old 10-29-2014, 11:01 AM
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yea, i understand that. that is why i put one on. when i got the car it had a partial RUF conversion done. for some reason RUF removes the DV or BOV. i dont think it is a good idea but i can perhaps see why they remove it.
i was playing around with it to see if i could get it to open at a certain boost so that perhaps it would not dump all the pressure, then have to build back up. (this is why i think RUF removes them). i also wanted that, pop,pop,pop sound like the 962's did when they shifted. now i just get one long "pishhhhh" sound.


what i did to the FD did not really do anything to it. i did lots timed flow test. test were either 30 sec at WOT or 5min with the sensor plate open about 10mm.
my first few tests all the ports had very even flow. then i turned the adjustments CCW maybe just a little more than what i turned them CW originally.
the flow did not drop any great amount. first tests were at 5.1oz in the end they were 4.8.

when i fired it back up idle AFR was 17 2500 rpm was 12.5
control pressure bumped up to 3.9 bar (spec 3.65) idle mixture at 13 2500 rpm is 11.8
car runs great. no popping from exhaust, smooth across the RPM range.
AFR's are much more steady now. before AFR's could be 14.2 at one rpm, then 15.5 then back to 15. just all over the place.

i still think there is a problem with the FD. i wonder if the PO adjusted the FD to make it run richer because when i got the car it was in the 16's at 3k.

the car runs really good. boost comes in faster and harder. it accelertes smoother. i drove to work in 3rd in the low 3k's and it did not feel like it. i am finally gettting that smooth falt 6 back.
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86 930 42kmiles [__] RUNNING:[__] NOT RUNNING: ____77 911S widebody: SOLD
88 BMW 325is 200K+ SOLD
05 BMW 330CI 130K:: [__] RUNNING: [__] NOT RUNNING:
08 VOLVO V70 190K:: [__] RUNNING: [__] NOT RUNNING:
90 B2200[__] RUNNING:[] NOT RUNNING:__2000 MER E320 WAGON [] WRECKED:[]RUNNING:
Old 10-30-2014, 06:57 AM
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i up the system pressure .5bar to 6.7 and raised the CP to 4.4bar. its now in the upper 12's maybe 13.

i really think someone has adjusted the fuel head to flow more fuel. i have heard of a company that calibrates them on the high fuel flow rate side and people have had problems with their fuel heads, just cant remember who.

i would like to give all the adjustsments a half turn, but when i send it to flow tech i would like for then to test it to see if is one the rich side.
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86 930 42kmiles [__] RUNNING:[__] NOT RUNNING: ____77 911S widebody: SOLD
88 BMW 325is 200K+ SOLD
05 BMW 330CI 130K:: [__] RUNNING: [__] NOT RUNNING:
08 VOLVO V70 190K:: [__] RUNNING: [__] NOT RUNNING:
90 B2200[__] RUNNING:[] NOT RUNNING:__2000 MER E320 WAGON [] WRECKED:[]RUNNING:
Old 10-31-2014, 02:59 AM
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iA used to sell CFT modified fuel heads which were turn up way too high and not tuned for the engine. I worked with Larry for several years collecting these and recalibrating.
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Old 10-31-2014, 03:59 AM
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thanks. i had read where there was someone that was doing that. i can only assume this has been done to mine because i cant explain why it would go so rich.
i had PM'd you a while back about my WUR going very rich under boost (9-10's) even with the CP set higher than spec. this could explain why that was going on too.

i was thinking i dont what to know what my boost AFR is since i am so rich now but i bet it is still the same.

you know what makes me feel really stupid is that i looked at the DV a long time ago and found this problem. i adjusted the tension on the spring and then it stopped leaking. i called synapse about it back then and they said it could not leak from one port to the other. so i doubted my tests and put it back on.

i am going to pull some plugs today and see what they look like
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86 930 42kmiles [__] RUNNING:[__] NOT RUNNING: ____77 911S widebody: SOLD
88 BMW 325is 200K+ SOLD
05 BMW 330CI 130K:: [__] RUNNING: [__] NOT RUNNING:
08 VOLVO V70 190K:: [__] RUNNING: [__] NOT RUNNING:
90 B2200[__] RUNNING:[] NOT RUNNING:__2000 MER E320 WAGON [] WRECKED:[]RUNNING:
Old 10-31-2014, 06:48 AM
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When Larry at CIS Flowtech modified the aluminum lambda fuel heads to flow more fuel he stamped the numbers 007 into the backside of them.

On the ones I've seen he also put a dab of paint on the edge of the button head adjustment cover screws next to the fuel line banjo fittings. It's brown paint on mine. I guess it's so he can tell if someone has adjusted it after it leaves his shop if he ever gets it back.

I have one on my car I bought from Imagine Auto around 7 years ago before I knew Larry Fletcher at CIS Flowtech was the one doing the modifications and adjustments to them.
After having Brian Leask make my CPR adjustable I was able to adjust control pressures a little higher than stock during idle and steady cruise so it works great all the time.
Mine idles perfectly smooth with 964 cams around 13.3:1 and during steady cruise it's usually around 14.9:1 depending on rpms and under boost it gets plenty of fuel. A little more than needed and that way it should be safe when running 1.1 to 1.2 bar of boost with 93 octane gas.

By raising control pressure around 3 or 4 psi during steady cruise you can tame a CIS Flowtech modified fuel head so AFR's are perfect and it will still flow a lot more fuel than stock under boost so you can run a high flowing modern ball bearing turbo with higher than stock boost and headers so the motor makes more power.

Take some time road testing and adjusting control pressures with an onboard wide band AFR gauge and you can get them dialed in so they run fantastic.
Old 10-31-2014, 07:09 PM
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i got the AFR's in the 14's. it did not like it. this is REALLY confusing because it use to run in the 15's, BUT, i had the air leak so i was still dumping a lot of fuel into it.

with the cruise AFR in the low 12's the car ran better than it ever has. great throttle response, especially off boost. only problem was when i let off the gas sometimes the RPM's dropped to nearly 0 and then back up, then down and up.

i have 2 new CIS gauge sets and they read different system pressure. one reads 6.1(spec) and the other reads 5.2bar. if it really is 5.2 that could explain why it is so rich.

i have some parts for sale and once they sell i am sending it to flowtech.

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86 930 42kmiles [__] RUNNING:[__] NOT RUNNING: ____77 911S widebody: SOLD
88 BMW 325is 200K+ SOLD
05 BMW 330CI 130K:: [__] RUNNING: [__] NOT RUNNING:
08 VOLVO V70 190K:: [__] RUNNING: [__] NOT RUNNING:
90 B2200[__] RUNNING:[] NOT RUNNING:__2000 MER E320 WAGON [] WRECKED:[]RUNNING:
Old 11-03-2014, 06:37 AM
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