[s-cars] Drastic Power Loss - Loong

[Manuel Sanchez]

Bob,

You and Stott both offered up overboost as an avenue. I'll take a  
look there and see what I can find.

Regards,

-Manny




On Sep 20, 2007, at 10:18 AM, Robert Myers wrote:

>
> Manny,
>
> That sounds like you're hitting the overboost cut-out.  Boost gets  
> too high and the ECU shuts off the ignition and it feels like you  
> just hit a concrete wall.  Check the hose from the turbo outlet  
> WGFV and the bottom of the WG.  A blockage (or leak? - I forget)   
> there can give excessive boost.   Too high and you have s sore neck.
>
> Bob
>
> At 09:50 AM 9/20/2007, you 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 wouldnâ 
>> €™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 didnâ 
>> €™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 canâ 
>> €™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 Iâ 
>> €™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 itâ 
>> €™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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