Bad Harmonic w/ Comptech SC -> Is this normal?
Registered User
Joined: Jan 2001
Posts: 609
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From: Rockville
You guys get any feedback on what Comptech will be doing for us other poor souls with the girly-man valve? Does Shad want to wait a few days to see how it holds up, or are they building kits to ship out as we speak?
Do you get any sense that Comptech has any desire to incorporate the electronic solution (if it works as intended)?
Do you get any sense that Comptech has any desire to incorporate the electronic solution (if it works as intended)?
Registered User
Joined: Oct 2000
Posts: 1,664
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From: Santa Cruz, CA
Hi All, well i picked up my newly SCd S2K late Friday afternoon, Boy is this thing fast and responsive....
While bringing it back from Modacar there wasnt any hesitation at all during acceleration.... However,
During deceleration there is what must be a slight enrichment that occurs if you let up on the throttle. This only occurs when the manifold pressure is between 0 and about 3 lbs above 1 atm. It lasts about .5 seconds and causes the car to lurch at the start of decel.
I figure its due to the check valve taking a split second to close after being opened by boost and the resulting drop in pressure during decel not being great enough to snap it shut quickly. I think this small problem is can be lived with easily and not cause most people any dificulty. however if you are driving near the limit the resulting change in deceleration can be enough to unsettle the cars balance
Today, Saturday morning, i took my car out for my morning coffee... and I got a hesitation for the first several mile of driving. However after i got my coffee and got back in the car to drive home it was working like it should....
I believe the source of this problem is moisture... my car is parked in a car port in a coastal city and subjected to moisture condesning conditions early in the morning (fog, etc) and after a few miles the moisture is driven out and the car behaves as it should. Again if this is indeed what is going on then people may be able to live with it...
I'm not going to... i'll be installing the MAP sensor override circuit discussed in this thread later today. http://www.s2000online.com/forums/showthre...50&pagenumber=2
Sorry for the long post...
RT i'd like to here about your environmental conditions (fog, etc) and how they might seem to effect your SC.
I'll post an update later today after i install the override circuit.
While bringing it back from Modacar there wasnt any hesitation at all during acceleration.... However,
During deceleration there is what must be a slight enrichment that occurs if you let up on the throttle. This only occurs when the manifold pressure is between 0 and about 3 lbs above 1 atm. It lasts about .5 seconds and causes the car to lurch at the start of decel.
I figure its due to the check valve taking a split second to close after being opened by boost and the resulting drop in pressure during decel not being great enough to snap it shut quickly. I think this small problem is can be lived with easily and not cause most people any dificulty. however if you are driving near the limit the resulting change in deceleration can be enough to unsettle the cars balance
Today, Saturday morning, i took my car out for my morning coffee... and I got a hesitation for the first several mile of driving. However after i got my coffee and got back in the car to drive home it was working like it should....
I believe the source of this problem is moisture... my car is parked in a car port in a coastal city and subjected to moisture condesning conditions early in the morning (fog, etc) and after a few miles the moisture is driven out and the car behaves as it should. Again if this is indeed what is going on then people may be able to live with it...
I'm not going to... i'll be installing the MAP sensor override circuit discussed in this thread later today. http://www.s2000online.com/forums/showthre...50&pagenumber=2
Sorry for the long post...
RT i'd like to here about your environmental conditions (fog, etc) and how they might seem to effect your SC.
I'll post an update later today after i install the override circuit.
Joined: Oct 2000
Posts: 14,269
Likes: 42
From: Redmond, WA
dave,
Barometric Pressure is around 30" inHg,
Relative Humidity has been high 80's,
Temp has been in the 50's and the weather Wet.
Installed the "newest" check and it does indeed flow enough to keep the Computer from retarding the timing, but the drivability is not the best.
Only seeing a little of what davepk is experiencing but more of a problem for me on quick acceleration from neutral throttle. I still get a pronounced flat spot (non-RPM specific) analogous to the feeling of a bad accelerator pump on a carbureted vehicle. My best guess is that it's a split second lean condition caused by a spike in the MAP sensor signal caused by the pressure required to pop the check valve open.
I'm able to rectify the problem by simply installing one of my super low cracking pressure fish tank valves in parallel to the new check valve.
I'll run it this way (two valves in parallel) through the weekend and see.
Barometric Pressure is around 30" inHg,
Relative Humidity has been high 80's,
Temp has been in the 50's and the weather Wet.
Installed the "newest" check and it does indeed flow enough to keep the Computer from retarding the timing, but the drivability is not the best.
Only seeing a little of what davepk is experiencing but more of a problem for me on quick acceleration from neutral throttle. I still get a pronounced flat spot (non-RPM specific) analogous to the feeling of a bad accelerator pump on a carbureted vehicle. My best guess is that it's a split second lean condition caused by a spike in the MAP sensor signal caused by the pressure required to pop the check valve open.
I'm able to rectify the problem by simply installing one of my super low cracking pressure fish tank valves in parallel to the new check valve.
I'll run it this way (two valves in parallel) through the weekend and see.
Registered User
Joined: Oct 2000
Posts: 2,670
Likes: 1
From: Scotts Valley
My car is still performing quite well. I have noticed the flat spot from neutral throttle though when applying full throttle in 4th or 5th. Anything less than full throttle seems to be fine. I can't wait to feel how Dave's car responds with the electronic fix.
Registered User
Joined: Oct 2000
Posts: 1,664
Likes: 0
From: Santa Cruz, CA
Ok heres an update, Sorry for taking so long... i've been out driving around 
I installed the MAP Sensor Override Circuit this morning....
Yes it works... it works very well indeed... The throttle response is very very smooth... You cant tell you are transitioning into or out of boost (manifold pressure > 1 atm). There has always been some funkiness in the way the engine responds to various changes in throttle position, non of that is there any longer. I installed the Override circuit right next to the ECU as i didnt think the various components were up to the engine bay temps... be carefull removeing the kick panel... it looks like its 2 peices but its not... you need to lift up the door sill to remove the kick panel.
I installed the MAP Sensor Override Circuit this morning....
Yes it works... it works very well indeed... The throttle response is very very smooth... You cant tell you are transitioning into or out of boost (manifold pressure > 1 atm). There has always been some funkiness in the way the engine responds to various changes in throttle position, non of that is there any longer. I installed the Override circuit right next to the ECU as i didnt think the various components were up to the engine bay temps... be carefull removeing the kick panel... it looks like its 2 peices but its not... you need to lift up the door sill to remove the kick panel.