 2.7L CIS surges at idle when warm, UPDATED with pressure readings 7/6/15 |
|
|
|
Porsche, and the Porsche crest are registered trademarks of Dr. Ing. h.c. F. Porsche AG.
This site is not affiliated with Porsche in any way. Its only purpose is to provide an online forum for car enthusiasts. All other trademarks are property of their respective owners. |
|
|
  |
| Kansas 914 |
 May 8 2015, 10:29 AM
Post
#21
|
|
Advanced Member  Group: Members Posts: 2,999 Joined: 1-March 03 From: Durango, Colorado Member No.: 373 Region Association: Rocky Mountains 
 |
QUOTE(SLITS @ May 8 2015, 10:25 AM)  Yes .... With your 2.7L you will either have an 017 or 033 WUR. For these WURs, the (ambient) cold pressure is: 50 F ....1.2 - 1.6 bar (17,64 - 23.52 psig) 68 F ....1.8 - 2.1 bar (26.46 - 30.87 psig) 86 F ....2.4 - 2.8 bar (35,38 - 41,16 psig) 104 F .... 3.0 - 3.4 bar (44.1 - 49.98 paig) Control pressure warm (engine hot) 2.7 - 3.1 bar (39,69 - 45.57 psig) High idle speed (1800 rpm) 3.4 - 3.8 bar (49.98 - 55.86 psig) Your initial system pressure (from fuel pump) is regulated between 4.5 - 5.2 bar (66.15 - 76.44 psig) Leak down test (engine shutdown) 10 minutes - 1.3 bar (19.11 psig) 20 minutes - 1.1 bar (14.7 psig) If you have any other WUR the control ranges are different. Bosh WUR numbers are 0 438 140 XXX Great info - thanks for taking the time to document this. PS: "Fireball" says hello... |
   |
 
|
| SLITS |
May 8 2015, 10:43 AM
Post
#22
|
|
"This Utah shit is HARSH!" Group: Benefactors Posts: 13,602 Joined: 22-February 04 From: SoCal Mountains ... Member No.: 1,696 Region Association: None  |
Hi Fireball ...... wish I were in Durango right now ... it snowed 5" last night while I was asleep.
Mike, remember when you are testing "cold" you must remove the electrical connector to the WUR so it won't heat up for the test. After that you plug it back in 'cause it has constant power when the key is on. Between the heating of the bi-metallic strip and the heat of the engine, the fuel pressure will vary. |
|
|
|
| Kansas 914 |
May 8 2015, 10:51 AM
Post
#23
|
|
Advanced Member Group: Members Posts: 2,999 Joined: 1-March 03 From: Durango, Colorado Member No.: 373 Region Association: Rocky Mountains
|
QUOTE(SLITS @ May 8 2015, 10:43 AM) Hi Fireball ...... wish I were in Durango right now ... it snowed 5" last night while I was asleep. Mike, remember when you are testing "cold" you must remove the electrical connector to the WUR so it won't heat up for the test. After that you plug it back in 'cause it has constant power when the key is on. Between the heating of the bi-metallic strip and the heat of the engine, the fuel pressure will vary. Got it - good info as I would probably have failed to do that. Denver is getting snow this weekend. Durango is gorgeous today - but that stuff you got last night is moving our way. Looks like a shitty weekend here. |
|
|
|
| rick 918-S |
May 8 2015, 03:23 PM
Post
#24
|
|
Hey nice rack! -Celette Group: Members Posts: 20,489 Joined: 30-December 02 From: Now in Superior WI Member No.: 43 Region Association: Northstar Region 
|
It took me years to finally learn CIS. I couldn't get the old Volvo guys to touch it with anything but an allen wrench. (IMG:style_emoticons/default/dry.gif) It was so screwed up! I ended up reading enough about it to figure out that the sensor plate is never the issue. I was offered a Volvo turbo WUR for parts. I ended up gutting mine and the Volvo unit and swapping in the 928 bi-metal spring setup as the Volvo unit has an adjustable plunger. You will read about "knocking or tapping" the plunger to adjust the bi-metal spring.
An old Volvo mechanic that wouldn't touch the car borrowed me his gauge setup. I set the cold and warm pressures ( they were way off) and then went about undoing the inaccurate adjustments to the sensor plate. I cranked the allen out about a full turn. If you have ever adjusted a sensor plate you are sitting there with your jaw in your lap. The allen adjustment is a verrrry fine movement. Not turns, just movements by a hair. Oh and were home now. (IMG:style_emoticons/default/biggrin.gif) |
|
|
|
| Kansas 914 |
May 8 2015, 04:08 PM
Post
#25
|
|
Advanced Member Group: Members Posts: 2,999 Joined: 1-March 03 From: Durango, Colorado Member No.: 373 Region Association: Rocky Mountains
|
QUOTE(rick 918-S @ May 8 2015, 03:23 PM) It took me years to finally learn CIS. I couldn't get the old Volvo guys to touch it with anything but an allen wrench. (IMG:style_emoticons/default/dry.gif) It was so screwed up! I ended up reading enough about it to figure out that the sensor plate is never the issue. I was offered a Volvo turbo WUR for parts. I ended up gutting mine and the Volvo unit and swapping in the 928 bi-metal spring setup as the Volvo unit has an adjustable plunger. You will read about "knocking or tapping" the plunger to adjust the bi-metal spring. An old Volvo mechanic that wouldn't touch the car borrowed me his gauge setup. I set the cold and warm pressures ( they were way off) and then went about undoing the inaccurate adjustments to the sensor plate. I cranked the allen out about a full turn. If you have ever adjusted a sensor plate you are sitting there with your jaw in your lap. The allen adjustment is a verrrry fine movement. Not turns, just movements by a hair. Oh and were home now. (IMG:style_emoticons/default/biggrin.gif) Glad you guys are home safe! Was there's book you read on CIS that helped you? I learned a ton from Ron just today. |
|
|
|
| sixnotfour |
May 9 2015, 11:19 AM
Post
#26
|
|
914 Wizard Group: Members Posts: 10,434 Joined: 12-September 04 From: Life Elevated..planet UT. Member No.: 2,744 Region Association: Rocky Mountains
|
QUOTE There are several threads on the Bird Board about this and how to adjust - most starting with "Get a 5mm Allen wrench"... dry.gif simple easy to try , make note of wich way you turn 1/8 turn is a lot ... then if needed you can become an expert.. |
|
|
|
| rick 918-S |
May 10 2015, 06:05 AM
Post
#27
|
|
Hey nice rack! -Celette Group: Members Posts: 20,489 Joined: 30-December 02 From: Now in Superior WI Member No.: 43 Region Association: Northstar Region
|
|
|
|
|
| Kansas 914 |
May 10 2015, 06:15 AM
Post
#28
|
|
Advanced Member Group: Members Posts: 2,999 Joined: 1-March 03 From: Durango, Colorado Member No.: 373 Region Association: Rocky Mountains
|
QUOTE(sixnotfour @ May 9 2015, 11:19 AM) QUOTE There are several threads on the Bird Board about this and how to adjust - most starting with "Get a 5mm Allen wrench"... dry.gif simple easy to try , make note of wich way you turn 1/8 turn is a lot ... then if needed you can become an expert.. Thanks Jeff, I have more reading to do. This CIS is so new to this old carb guy! |
|
|
|
| Kansas 914 |
May 10 2015, 06:17 AM
Post
#29
|
|
Advanced Member Group: Members Posts: 2,999 Joined: 1-March 03 From: Durango, Colorado Member No.: 373 Region Association: Rocky Mountains
|
QUOTE(rick 918-S @ May 10 2015, 06:05 AM) Thanks Rick, Looks some great information. I will dig into the data right after the Formula 1 race this morning. Cheers! |
|
|
|
| Kansas 914 |
Jul 6 2015, 09:26 AM
Post
#30
|
|
Advanced Member Group: Members Posts: 2,999 Joined: 1-March 03 From: Durango, Colorado Member No.: 373 Region Association: Rocky Mountains
|
UPDATE:
I borrowed CIS fuel gauges from a friend and here is what I get. I have a 033 WUR. Ambient Temperature was 68 degrees F. Cold Control Pressure = 21PSI (Range 26 to 30) Warm System Pressure = 69PSI (Range 65 to 75) Control Pressure at Idle = 42psi (Range 39 to 45) Control Pressure at Partial throttle = 42psi (Range 39 to 45) Control Pressure WOT = 42psi (Range 39 to 45) Rest Pressure was 21psi after 20 minutes After the car warmed (temp above 120) the car started surging like it always does. What I discovered was if I pinched the return line from the fuel distributor the idle would smooth out perfectly - no more surging. What would I be doing by crimping the return from the fuel distributor? It is obviously changing pressure at the fuel head but what else? I don't have an O2 gauge. Is that the next piece of important data? |
|
|
|
| SLITS |
Jul 6 2015, 11:01 AM
Post
#31
|
|
"This Utah shit is HARSH!" Group: Benefactors Posts: 13,602 Joined: 22-February 04 From: SoCal Mountains ... Member No.: 1,696 Region Association: None |
If you crimp the return line, you are adding full fuel pump pressure to the fuel distributor. Maybe the fuel pump is weak even though the pressures you obtained are in the range.
With the 5mm allen tool, try going richer by turning it ONE CLICK at a time clockwise. Remember to remove the tool and let the engine stabilize prior to making any further adjustment. |
|
|
|
| jim912928 |
Jul 6 2015, 01:08 PM
Post
#32
|
|
Senior Member Group: Members Posts: 1,485 Joined: 8-January 04 From: Granger, IN Member No.: 1,536 Region Association: Upper MidWest |
My 80 911 did the exact same thing. There was a broken wire inside the control box/computer. Shop soldered it up and it was fine. Need to find a porsche shop comfortable opening that up.
|
|
|
|
| jcd914 |
Jul 6 2015, 02:15 PM
Post
#33
|
|
Advanced Member Group: Members Posts: 2,081 Joined: 7-February 08 From: Sacramento, CA Member No.: 8,684 Region Association: Northern California |
I agree with Slits except it should be a 3mm allen wrench and I don't recall any clicks in the adjustment. I make a very small adjustments (maybe an 1/8 of a turn) and blip the throttle after removing the allen wrench.
Jim, good info on the control unit wire, except it does not apply to a 2.7 with CIS. In 1980 the 911 w/CIS an Oxygen sensor and electronic controls, earlier cars did not have this. Jim |
|
|
|
| Kansas 914 |
Jul 6 2015, 03:45 PM
Post
#34
|
|
Advanced Member Group: Members Posts: 2,999 Joined: 1-March 03 From: Durango, Colorado Member No.: 373 Region Association: Rocky Mountains
|
QUOTE(SLITS @ Jul 6 2015, 11:01 AM) If you crimp the return line, you are adding full fuel pump pressure to the fuel distributor. Maybe the fuel pump is weak even though the pressures you obtained are in the range. With the 5mm allen tool, try going richer by turning it ONE CLICK at a time clockwise. Remember to remove the tool and let the engine stabilize prior to making any further adjustment. Thanks Ron - I will give it a try tomorrow! |
|
|
|
| rick 918-S |
Jul 6 2015, 07:29 PM
Post
#35
|
|
Hey nice rack! -Celette Group: Members Posts: 20,489 Joined: 30-December 02 From: Now in Superior WI Member No.: 43 Region Association: Northstar Region
|
QUOTE(Kansas 914 @ Jul 6 2015, 04:45 PM) QUOTE(SLITS @ Jul 6 2015, 11:01 AM) If you crimp the return line, you are adding full fuel pump pressure to the fuel distributor. Maybe the fuel pump is weak even though the pressures you obtained are in the range. With the 5mm allen tool, try going richer by turning it ONE CLICK at a time clockwise. Remember to remove the tool and let the engine stabilize prior to making any further adjustment. Thanks Ron - I will give it a try tomorrow! Mike did you check vacuum now that you pressures checked out? is the vacuum gauge in the range of 15-20 steady? regardless if it is 17 or 19 it should be fairly steady. If you are getting low readings or a funny tick in the gauge you need to look there before adjusting the sensor plate. Not intended to challenge the master I just wouldn't jump on that plate until I was sure I ruled out everything else. This is how I would proceed. Pressures, Vacuum, Valve adjustment, vacuum again then Timing, Then Sensor plate |
|
|
|
| Kansas 914 |
Jul 6 2015, 07:53 PM
Post
#36
|
|
Advanced Member Group: Members Posts: 2,999 Joined: 1-March 03 From: Durango, Colorado Member No.: 373 Region Association: Rocky Mountains
|
QUOTE(rick 918-S @ Jul 6 2015, 07:29 PM) Mike did you check vacuum now that you pressures checked out? is the vacuum gauge in the range of 15-20 steady? regardless if it is 17 or 19 it should be fairly steady. If you are getting low readings or a funny tick in the gauge you need to look there before adjusting the sensor plate. Not intended to challenge the master I just wouldn't jump on that plate until I was sure I ruled out everything else. This is how I would proceed. Pressures, Vacuum, Valve adjustment, vacuum again then Timing, Then Sensor plate Hi Rick I haven't seen any mention of testing vacuum in the documents I have read. Do you have a link to the procedure? Sounds like another gauge to borrow... Thanks! |
|
|
|
| rick 918-S |
Jul 6 2015, 08:02 PM
Post
#37
|
|
Hey nice rack! -Celette Group: Members Posts: 20,489 Joined: 30-December 02 From: Now in Superior WI Member No.: 43 Region Association: Northstar Region
|
QUOTE(Kansas 914 @ Jul 6 2015, 08:53 PM) QUOTE(rick 918-S @ Jul 6 2015, 07:29 PM) Mike did you check vacuum now that you pressures checked out? is the vacuum gauge in the range of 15-20 steady? regardless if it is 17 or 19 it should be fairly steady. If you are getting low readings or a funny tick in the gauge you need to look there before adjusting the sensor plate. Not intended to challenge the master I just wouldn't jump on that plate until I was sure I ruled out everything else. This is how I would proceed. Pressures, Vacuum, Valve adjustment, vacuum again then Timing, Then Sensor plate Hi Rick I haven't seen any mention of testing vacuum in the documents I have read. Do you have a link to the procedure? Sounds like another gauge to borrow... Thanks! http://www.tuneruniversity.com/blog/2011/0...a-vacuum-gauge/ http://www.gregsengine.com/using-a-vacuum-gauge.html |
|
|
|
| rick 918-S |
Jul 6 2015, 08:05 PM
Post
#38
|
|
Hey nice rack! -Celette Group: Members Posts: 20,489 Joined: 30-December 02 From: Now in Superior WI Member No.: 43 Region Association: Northstar Region
|
QUOTE(rick 918-S @ Jul 6 2015, 09:02 PM) QUOTE(Kansas 914 @ Jul 6 2015, 08:53 PM) QUOTE(rick 918-S @ Jul 6 2015, 07:29 PM) Mike did you check vacuum now that you pressures checked out? is the vacuum gauge in the range of 15-20 steady? regardless if it is 17 or 19 it should be fairly steady. If you are getting low readings or a funny tick in the gauge you need to look there before adjusting the sensor plate. Not intended to challenge the master I just wouldn't jump on that plate until I was sure I ruled out everything else. This is how I would proceed. Pressures, Vacuum, Valve adjustment, vacuum again then Timing, Then Sensor plate Hi Rick I haven't seen any mention of testing vacuum in the documents I have read. Do you have a link to the procedure? Sounds like another gauge to borrow... Thanks! http://www.tuneruniversity.com/blog/2011/0...a-vacuum-gauge/ http://www.gregsengine.com/using-a-vacuum-gauge.html A vacuum leak will cause your sensor plate to pulse. |
|
|
|
| Kansas 914 |
Jul 7 2015, 08:50 AM
Post
#39
|
|
Advanced Member Group: Members Posts: 2,999 Joined: 1-March 03 From: Durango, Colorado Member No.: 373 Region Association: Rocky Mountains
|
QUOTE(rick 918-S @ Jul 6 2015, 08:05 PM) A vacuum leak will cause your sensor plate to pulse. OK - this makes sense. It is a $30 part so I will go get one today. As long as I am connected to a vacuum line below the throttle plate I should be good right? Thanks again! |
|
|
|
| d914 |
Jul 7 2015, 12:53 PM
Post
#40
|
|
Advanced Member Group: Members Posts: 2,331 Joined: 12-July 03 From: Atlanta, ga Member No.: 904 Region Association: South East States |
I had a 79 with 3.0 cis......vacuum and seasonal changes drive it crazy.. What little I know I'm going with rick....check for vacuum leaks first.
|
|
|
|
|
1 User(s) are reading this topic (1 Guests and 0 Anonymous Users)
0 Members:
|
Lo-Fi Version | Time is now: 7th June 2024 - 01:43 PM |
Invision Power Board
v9.1.4 © 2024 IPS, Inc.