[s-cars] Drastic Power Loss - Loong
Ian Duff
iduff at comcast.net
Thu Sep 20 07:01:57 PDT 2007
To what pressure did you test the intake plumbing?
Those Samcos are strong, if there's a leak, it could be effectively
sealed by their wall strength until you hit big boost numbers, then
dramatically/catastrophically blow open. If you tested to 27-ish PSI,
then this hypothesis is bunk. HTH.
-Ian Duff.
On 20 Sep, 2007, at 09:50, <manuelsanchez at starpower.net>
<manuelsanchez at starpower.net> wrote:
> This didn't post before, so sorry if it's duplicated
>
> S-Heads,
>
> I’ve run out of idea’s and I’m desperately seeking some insight
> into a power problem I am having, thus the looong explanation
> below. I hope some of you can take the few minutes to read this
> post and help me find the stupid thing I seem to be missing.
>
> Problem:
> Drastic Power Cut Out (neck snapping forward kinda cut out) at peak
> boost (We suspected intake leak but can’t find one, at least not yet).
> Around town driving is OK. Car generally does not feel as though
> it’s making as much power as it used to (confirmed by slower lap
> times at Driving School Events, and not being able to dust Bro-In-
> Law like I used to at previous events, and no he can’t possibly be
> getting better at a faster rate than I am )
>
> I’ve had the MRC software and RS2 bits on for about 3 years.
>
> I can build boost to about 27 psi (my gauge only reads to 25, so I
> am estimating based on the travel distance of the needle), in say a
> 2nd or 3rd gear pull and slightly after reaching it, 27 psi, it
> will feel like someone thru the Queen Mary’s anchor out of the tail
> gate, if I back of slightly on the throttle, the power will come
> back on and I can try to build boost again.
>
> When the engine is relatively cold (i.e. it has not reached the big
> hash mark indicating normal operating temp) this problem does not
> always occur. So I can hit 27 psi without the big cut out. I know I
> shouldn’t be boosting it like that before the oil is warm, but I’m
> desperate at this point to try and find out what the problem is.
> Seemingly after reaching normal temp (and it will stay at normal
> temp once there, just fine) I am now getting this new power cut off.
>
> Previous to this drastic power cut-off, the car hadn’t felt like
> it’s had all the power it used to have. I would be able to build
> boost, even to these peak 27 psi levels, but it wouldn’t feel like
> it wasn’t pulling as hard as it could be or used to be. It didn't
> used to cut off like this.
>
> So what did I change between the time it didn’t feel like it was
> running as strong as it could be, and when I would experience this
> drastic power cut off? These things:
>
> Injectors (swapped the Racetronix 37 lb/hr units with 034’s RS2
> clone injectors, I was trying to resolve that niggly check engine
> light that would flash on and off with this injector / software set-
> up. I believe others have solved this issue by installing the 034
> RS2 clone injectors, funny thing was, it didn’t seemingly solve the
> check engine light problem for me that would occur on very very
> light throttle)
> Replaced Stromung Test Pipe with Stromung Cat section
> Replaced Oxygen Sensor (the one I replaced was only a year old, but
> I thought with new injectors, why not)
> Installed Fuel Pressure Gauge
>
> With the exception of the Stromung Test Pipe, I swapped all the old
> bits back in, and I still have the problem (this included removing
> the Fuel Pressure Gauge). (Could it really be the Cat?, I’ve never
> mounted this Cat before, it was brand spankin new, and I drove the
> car around with the Cat and the Racetronix injectors for only about
> 100 miles before swapping in the slightly smaller 034 RS2 clone
> injectors.
>
> Patient:
> 95.5 UrS6A-125,000 miles
> RS2 Turbo
> RS2 EM
> Mihnea Custom Chipset
> Stock MAF (although also tested with a new RS2 MAF, same result),
> Racetronix 37lb/hr Injectors (Although also tested with 034EFI RS2
> Clone Injectors)
> Tom and Marc FMIC
> SAMCO Boost Hoses everywhere else
> Stromung Exhaust
> Forge 007 By Pass Valve
> RS2 WGFV
> Original Wastegate
> 034 DIS Coil System with new Ignition Wires
> New Plugs (Bosch Tri-Electrode Copper Plugs from 034, the kind they
> use on their monster motors)
> 044 Fuel Pump
> Newer Fuel Filter (2,000 miles)
> New Fuel Pressure Gauge
> New Adjustable Fuel Pressure Regulator set at 56 psi – 3.8 Bar
> (idle) (Is it supposed to be 4 bar for RS2, and if so would 2 PSI
> really make that much of a difference?)
> VDO Boost Gauge
> Original CPS (no trouble starting when hot)
> I've had Leakdown and Compression tests yielding acceptable levels
>
> I’m hoping the list wisdom can help with this one.
>
> We have suspected of course a boost leak, but have not found one.
>
>
> Pressure Tests of the Intake Tract:
>
> We have pressure tested the system just south of the MAF, by
> pressurizing that first hose that isn’t supposed to be pressurized
> and plugging the Idle Control Valve, Throttle Body, and the
> Crankcase Ventilation line on the turbo side of the engine, at the
> front of the head. There was not a big leak by any means, but we
> did notice that the swelling of that first hose, the MAF to turbo
> hose, would visibly reduce in a few seconds. I have tried
> pressurizing the system with the ISV and T-Body hoses connected, to
> see if those various bits of rubber pieces located under the
> Throttle body had torn (I replaced all those pieces last year), but
> no audible leaks.
>
> We have also tested the system just south of the turbo outlet, we
> have blanked off/plugged the Idle Control Valve, Throttle body and
> the crankcase ventilation line there on the turbo side of the
> engine. We have tried testing with the Idle Control Valve and the
> Throttle body connected. No audible leaks.
>
> Checked Moisture Trap (located at ECU in S6) – OK
>
> Flipped BPV connections around-no leak or seeming effect
>
> Swapped my BPV with another BPV – no leak (We have not tried
> running the car with this other BPV though, don't know if this
> would make a difference)
>
> ECU's
> I have swapped in a different stock ECU with stock chips and
> pressure transducer, as well as swapping in my original stock
> injectors from my pre-RS2 upgrade. Near peak boost for stock
> levels, I am getting this same drastic power cut-off, say around 13
> psi.
>
> So I somehow think both my ECU with RS2 software and a completely
> different stock ECU are “seeing” something similar, and throwing
> out the Queen Mary’s boat anchor.
>
> What we don’t think it is:
>
> Ignition
> Well, it’s a new 034 DIS System, with plugs only a few hundred
> miles old. We haven’t looked at the plugs this week, but we did
> look at them when I installed the DIS system several months ago. At
> the time I had the stock Bosch F5DPOR plugs. There was a slight
> grey/white residue at the tips, which I think is indicative of a
> lean condition, which is odd because MRC software is supposed to
> run rich. I swapped plugs because there was a slight crack in the
> ceramic housing one one of the plugs.
> I ran the car at a dyno day about 6-9 months ago, and they told me
> the car was running waaay too rich. Off the top of my head I can’t
> remember the A/F ratio at the dyno day. I just love the seemingly
> contradictory indicators.
>
> Knock Sensors
> The mechanic who has serviced this car since I’ve had it doesn’t
> think it would be knock sensors for a couple of reasons(which I
> don’t know enough about how they work to form an opinion, I guess I
> could say that about a lot of these issues):
> He thinks they would throw a code if they sensed something, and
> he hasn’t seen a code related to these
> He doesn’t think it would build up this amount of boost if there
> was knock
>
> Fuel
> I’ve got an 044 pump in there (3 months ago), new filter,
> adjustable fuel pressure regulator set to 56psi at idle (which I
> think is 3.8 bar) and a fuel pressure gauge. There was some chatter
> about someone running RS2 software and a stock pump, but not
> getting enough pressure at the rail, so since I needed a new pump I
> figured I’d go hog wild. Anyone know if 2 psi ( 0.14 bar) at idle
> is enough to throw things out of whack? I think RS2 pressure is
> supposed to be 4 bar but I’m not sure.
>
> The gauge is mounted in the engine compartment, so I can’t see the
> pressure under load. I suppose we could try to rig something so I
> can tape it to the windshield while driving to keep an eye on it.
> Anyone know what range in Psi I should see while under load or at
> full throttle with the pedal buried against the firewall? I assume
> it's not supposed to be a continuous pressure, but rather a
> variable one within some unknown to me limits, yesh?
>
> Codes:
> We have seen a few codes thrown. Whether or not they have anything
> to do with the loss of power or drastic power cut-off is the
> $64,000 question.
>
> They are:
> 00537 – Oxygen Sensor Control
> Maximum Control Level Exceeded
> Condition:
> Fuel Tank Low resulting in fuel system pressure less than 3.3 bar
> (48 psi) [Note tank was ¾ full as indicated on fuel gauge]
> Ignition System Failure
> Symptom:
> CO before 3 way catalytic converter less than 0.5% (Hmmm, what
> could this mean???)
> Fuel Consumption high
>
> Repair:
> Fill Fuel Tank (tank had plenty of gas, and fuel gauge reads
> accurately)
> 00537 – Oxygen Sensor Control
> Minimum Control Limit Exceeded
> Condition:
> Engine Intake Air Leak after Mass Air Flow Sensor-G-70
> Leak in Exhaust System in front of 3 way catalytic converter
> Heated Oxygen Sensor (HO2S)-G39-malfunctioning
> Fuel System Pressure greater than 4 bar (58 psi) [This is
> interesting, seems like I will throw this code all the time if I
> set the Fuel Pressure to 4 Bar/58 psi, which is what I believe I’ve
> been told is the Fuel Pressure for RS2’d cars. True?]
> Symptom:
> Rich Exhaust
> Spark Plug Fouling
> CO before 3 way catalytic converter greater than 3%
>
> Repair:
> Repair Leak
> Check HO2S-G39
> Check Fuel System Pressure
> 00561-Mixture Adjustment
> Adaptation Limit (mul) exceeded
> Condition:
> Fuel System Pressure too low
> Spark Plugs, ignition coil, ignition coil power output stage
> malfunctioning
> Symptom:
> Reduced Fuel Economy (no kidding)
> Sooty Exhaust (yeah, in spades)
> Repair:
> Fill Fuel Tank
> Repair Leakage
> Check Fuel System
> Check Fuel System Pressure
> Check G70 (Mass Air Flow Sensor) [We cleaned the OEM MAF with MAF
> Cleaner, and we also installed a brand new RS2 MAF-we still had the
> drastic engine cut-off]
>
> I’m not a mechanic(and I don’t play one on TV either), but I
> somehow think the ECU is seeing something it doesn’t like (duh). A
> few months back I surmised that since I was seeing plenty of boost
> on my gauge, but the car didn’t seem to be moving quite fast
> enough, the ECU must be retarding the timing for some reason. Now
> it must really not like what it’s seeing, and it’s throwing the big
> anchor out the back. SO , assuming it’s the ECU trying to save my
> motor, what kinds of things would cause the it to back off like
> that? I thought maybe knock, but my wrench says knock would throw a
> code (true?, what say ye?). Dyno guy says A/F is very rich, plugs
> had a little bit of white/grey deposits on the tips. Nuts.
>
> This has been really frustrating and we are running out of ideas.
> Any help is greatly appreciated.
>
> Thanks for reading.
>
> -Manny
>
> 95.5 UrS6 Avant (kickin my arse)
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