03-06-2017, 04:48 AM
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#1
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Registered User
Join Date: Aug 2015
Location: Callahan, FL
Posts: 462
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Cps fail?
My 99 Boxes half of the time during either a a cold or warm start will require me to crank it several times before it fires up. Once fired up, it struggles (low RPM) for a moment or two. If I apply the gas, it will catch, but if it dies, it will fire up then idle normally. I've never had the P0335 CEL code, but my tach does not move at all during cranking. Is my CPS on the verge of failure or do I have a different problem.
-Plugs and coil were replaced <10K miles ago
Please advise before I start spending money on parts I don't need.
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99 Boxster base
1966 912 3 gauge
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03-06-2017, 06:09 AM
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#2
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I am my own mechanic....
Join Date: Feb 2013
Location: Salt Lake City, UT
Posts: 3,432
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Just saw this. Sounds like:
CPS iffy but not sure if they go bad intermittently.
Fuel pump.
MAF
__________________
'04 Boxster S 50 Jahre 550 Spyder Anniversary Special Edition, 851 of 1953, 6-sp, IMS/RMS, GT Metallic silver, cocoa brown leather SOLD to member Broken Linkage.
'08 VW Touareg T-3 wife's car
'13 F150 Super Crew long bed 4x4 w/ Ego Boost
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03-06-2017, 06:48 AM
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#3
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Registered User
Join Date: Aug 2015
Location: Callahan, FL
Posts: 462
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MAF appears to be working; when I disconnect the connector, the engine bogs down. The only other change I made recently is changing out the fuel filter since I thought that might be part of the problem. PO did not take care of the car.
In your other post you mentioned to check the fuel rail pressure. Will look that up to see how its done. What should the pressure be? Will low pressure indicate failing fuel pump?
Thanks
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99 Boxster base
1966 912 3 gauge
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03-06-2017, 07:16 AM
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#4
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I am my own mechanic....
Join Date: Feb 2013
Location: Salt Lake City, UT
Posts: 3,432
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Quote:
Originally Posted by flouese
MAF appears to be working; when I disconnect the connector, the engine bogs down. The only other change I made recently is changing out the fuel filter since I thought that might be part of the problem. PO did not take care of the car.
In your other post you mentioned to check the fuel rail pressure. Will look that up to see how its done. What should the pressure be? Will low pressure indicate failing fuel pump?
Thanks
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Yep. I don't recall pressure but if it ain't there with key turned over it's a bad FP. Mine had zero pressure. Fuel rail port is same as AC ports.
__________________
'04 Boxster S 50 Jahre 550 Spyder Anniversary Special Edition, 851 of 1953, 6-sp, IMS/RMS, GT Metallic silver, cocoa brown leather SOLD to member Broken Linkage.
'08 VW Touareg T-3 wife's car
'13 F150 Super Crew long bed 4x4 w/ Ego Boost
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03-06-2017, 07:16 AM
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#5
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Registered User
Join Date: May 2014
Location: S.California
Posts: 2,029
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There is one definitive, simple electrical test for a suspect CPS given in full in the previous Thread.
Last edited by Gelbster; 03-08-2017 at 07:14 AM.
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03-06-2017, 07:18 AM
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#6
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I am my own mechanic....
Join Date: Feb 2013
Location: Salt Lake City, UT
Posts: 3,432
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Quote:
Originally Posted by Gelbster
There is one definitive, simple electrical test for a suspect CPS given in full in the previous Thread.
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You're wrong.
__________________
'04 Boxster S 50 Jahre 550 Spyder Anniversary Special Edition, 851 of 1953, 6-sp, IMS/RMS, GT Metallic silver, cocoa brown leather SOLD to member Broken Linkage.
'08 VW Touareg T-3 wife's car
'13 F150 Super Crew long bed 4x4 w/ Ego Boost
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03-06-2017, 07:27 AM
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#7
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Registered User
Join Date: Nov 2016
Location: London
Posts: 234
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Quote:
Originally Posted by flouese
MAF appears to be working; when I disconnect the connector, the engine bogs down. The only other change I made recently is changing out the fuel filter since I thought that might be part of the problem. PO did not take care of the car.
In your other post you mentioned to check the fuel rail pressure. Will look that up to see how its done. What should the pressure be? Will low pressure indicate failing fuel pump?
Thanks
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Did you install the fuel filter the right way round?
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03-06-2017, 07:31 AM
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#8
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Registered User
Join Date: May 2014
Location: S.California
Posts: 2,029
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Quote:
Originally Posted by Timco
You're wrong.
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Please tell JFP directly that his CPS Test is "wrong" & why.We don't want incorrect info here.
Last edited by Gelbster; 03-08-2017 at 07:14 AM.
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03-06-2017, 07:31 AM
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#9
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2003 S, Arctic Silver, M6
Join Date: Oct 2014
Location: Winnipeg, MB, Canada
Posts: 1,346
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Quote:
Originally Posted by Timco
You're wrong.
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Timco you are hilarious!
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03-06-2017, 07:50 AM
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#10
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I am my own mechanic....
Join Date: Feb 2013
Location: Salt Lake City, UT
Posts: 3,432
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Quote:
Originally Posted by Gelbster
Please tell JFP directly that his CPS Test is "wrong" & why.We don't want incorrect info here.
Here is the definitive test from JFP:
"Remove the CPS sensor connector, connect your multimeter to pin #1 and pin#2, at 68F it should read 0.8-1.0K ohms; then connect the multimeter to pin #1 and pin #3 and it should read infinite ohms; if it does not read correctly in either range, can the sensor and replace it."
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Nope. Still wrong.
Guess again.
__________________
'04 Boxster S 50 Jahre 550 Spyder Anniversary Special Edition, 851 of 1953, 6-sp, IMS/RMS, GT Metallic silver, cocoa brown leather SOLD to member Broken Linkage.
'08 VW Touareg T-3 wife's car
'13 F150 Super Crew long bed 4x4 w/ Ego Boost
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03-07-2017, 02:48 AM
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#11
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Registered User
Join Date: Aug 2015
Location: Callahan, FL
Posts: 462
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Quote:
Originally Posted by That986
Did you install the fuel filter the right way round?
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YES! The hard start issue has been going on for several weeks. Ignored this problem until intermittent stalling at idle started. The stalling happened only on one drive. Another hidden gremlin. The hard start issue is hit and miss. Some days I can go out and it will fire right up, other days, it takes a few try's. On those days, it idles rough for a few moments, sounds/feels like it going to die until I apply the gas, then it settles out.
__________________
99 Boxster base
1966 912 3 gauge
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03-07-2017, 05:35 AM
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#12
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Registered User
Join Date: Nov 2016
Location: London
Posts: 234
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Quote:
Originally Posted by flouese
YES! The hard start issue has been going on for several weeks. Ignored this problem until intermittent stalling at idle started. The stalling happened only on one drive. Another hidden gremlin. The hard start issue is hit and miss. Some days I can go out and it will fire right up, other days, it takes a few try's. On those days, it idles rough for a few moments, sounds/feels like it going to die until I apply the gas, then it settles out.
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Sounds like a fuel pump issue to me.
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03-07-2017, 06:20 AM
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#13
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Registered User
Join Date: Dec 2012
Location: FL
Posts: 4,144
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I had the CPS fail on me one time, car shut off as I was driving and would not crank, but if I let it sit 20-30 minutes it would crank. Then it would shut off again 10-15 minutes later. Rinse and repeat.
If your car cranks up and runs rough and then smooths out, that doesn't sound like CPS to me, unless maybe it is doing some very rapid intermittent failure. Usually it just cuts off and then won't start until it cools down a little.
Last edited by steved0x; 03-07-2017 at 06:23 AM.
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03-07-2017, 06:27 AM
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#14
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Registered User
Join Date: Aug 2015
Location: Callahan, FL
Posts: 462
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All,
Thanks for the responses. Will check fuel pressure this weekend. See if Advance Auto has a loaner rig. Now to figure out how to do it...
Of course all this will take place after I go to the 20th anniversary shin-dig at Amelia Island.
__________________
99 Boxster base
1966 912 3 gauge
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03-07-2017, 10:30 AM
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#15
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Registered User
Join Date: Oct 2014
Location: California Central Coast
Posts: 1,476
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A FP relay is a common spare carried in older Porsches. They do not always completely fail and can cause intermittent issues such as yours. The problem is you can check fuel pressure and it works fine and can cause you to look elsewhere. If you haven't already I'd replace it with a new one, they're cheap <$20.
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03-08-2017, 08:23 AM
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#16
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Registered User
Join Date: Aug 2015
Location: Callahan, FL
Posts: 462
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Quote:
Originally Posted by 911monty
A FP relay is a common spare carried in older Porsches. They do not always completely fail and can cause intermittent issues such as yours. The problem is you can check fuel pressure and it works fine and can cause you to look elsewhere. If you haven't already I'd replace it with a new one, they're cheap <$20.
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Thanks for the input. I will order the relay today. Will follow up after install to let you know if that fixed the problem.
__________________
99 Boxster base
1966 912 3 gauge
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1998 Porsche Boxster
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