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914World.com _ 914World Garage _ 74 2.0 Idle/Stall remedy suggestions appreciated
Posted by: Jon Dugan Jan 3 2016, 02:17 AM
Hello fellow 914ers,
First post here... My 74 2.0 was my daily driver for the past 5 years until it decided not to be... Ran fine one night, parked it, next morning no so much. Starts right up no problem but rev above say 2000 RPM, it wants to bog out and stall. I do get an occasional smooth rev through to red line though. Tried advance/retard adj with the dist and can now only find idle around 1600 RPM (normal idle was about 600 RPM I think) but then lose it whwn I try to dial it back down. Dist checks out fine ($65 test by Porsche mech in Campbell). The guys at PH suggest maybe the fuel pressure sensor (grenade) has failed. I have limited troubleshooting skills and budget and was hoping to get back into AX this year after a long hiatus so any suggestions will be much appreciated. Thanks in advance !!
Posted by: ndfrigi Jan 3 2016, 03:18 AM
I'm sure members here will ask this, FI or Carb? If FI maybe vacuum leak.
Posted by: Jeff Bowlsby Jan 3 2016, 07:34 AM
Does it run rich or lean or just bog down?
Check the MPS to verify of it hold vacuum. 15 inHg.
Lube the dizzy weights by 1 drop of 30wt in the felt in the center of the dizzy shaft, annually.
Posted by: Jon Dugan Jan 3 2016, 09:38 AM
FI
It has run rich since I bought it. Run well too... I'll check the MPS and lube the felt next as suggested. Thx!
Posted by: Jason74914 Jan 9 2016, 09:35 AM
I have same issue with my 74. Will start and idle, but if you pull rpm's up, at about 2000 rpm it stalls back down to idle. (doesn't die). If I rev quickly it will go above 2000, but then fall back down.
I've checked everything. Checked pressure and seems good at idle, 40 psi. Someone else suggested a bad fuel pump, but seems odd since pressure is good. Fuel pressure regulator? I'm not sure how to test that.
Posted by: Jason74914 Jan 9 2016, 09:36 AM
Jeff, What are you referring to as MPS?
Posted by: Jeff Bowlsby Jan 9 2016, 10:18 AM
Manifold Pressure Sensor
What 'pressure' are you checking to get 40psi?
Attached image(s)
Posted by: Jason74914 Jan 9 2016, 10:33 AM
Manifold Pressure Sensor
What 'pressure' are you checking to get 40psi?
It was several months ago, but I think it was just before the fuel pressure regulator/fuel rail.
Posted by: Jason74914 Jan 9 2016, 10:43 AM
Manifold Pressure Sensor
What 'pressure' are you checking to get 40psi?
It was several months ago, but I think it was just before the fuel pressure regulator/fuel rail.
No wonder I didn't recognize the MPS...I have 1.8L with K-Jet.
Posted by: The Cabinetmaker Jan 9 2016, 10:50 AM
Kjet? 1.8s came with Ljet.
I had to read this thread twice to figure out Jeff was talking to 2 different posters. Lol.
Posted by: Jeff Bowlsby Jan 9 2016, 10:53 AM
Assuming your car is a stock 1.8L L-Jet, fuel pressure should be 32-38 psi. 40psi is too high.
This manual may be helpful to you:
http://bowlsby.net/914/Classic/zTN_Man12.pdf
Posted by: Jason74914 Jan 9 2016, 05:08 PM
Assuming your car is a stock 1.8L L-Jet, fuel pressure should be 32-38 psi. 40psi is too high.
This manual may be helpful to you:
http://bowlsby.net/914/Classic/zTN_Man12.pdf
Sorry, yes L-Jet (typo). I will re-check, but thanks for the link!
Posted by: achman_73_2.0 Jan 9 2016, 08:58 PM
I chased a similar issue for a year with my 2.0 FI '73
Turned out to be a small leak in intake manifold
Caused engine to run lean under load, and with a high idle to prevent stalling...
I would check that before the MPS (I wish I had!)
It's a cheaper fix than getting that rebuilt etc.
Posted by: Jon Dugan Mar 19 2016, 10:44 AM
Back for more suggestions... Just replaced the MAP with a New/Rebuilt one... Car started fine and idled @ 1800 rpm or so, lower than before, but still can't dial it in.. It still intermittently revs smoothly for a few revs then reverts back to a flutter rev @ 2000 RPM and above. Both at the same distributor position. I spent about an hour advancing/retarding the timing with the distributor and found a sweet spot for a smooth rev through to about 5000 RPM, but as soon as I tightened the distributor in that position, the flutter rev returned...Argh! Hoping one of you guys can offer any other troubleshooting suggestions and/or recommend a mechanic preferably in the Hayward area with good 914 experience that I could tow to and not be taken to the cleaners so-to-speak.... Thanks in advance !!!!
Posted by: Jeffs9146 Mar 19 2016, 12:38 PM
Have you checked the Aux Air Regulator or the CHTS?
Posted by: Jon Dugan Mar 19 2016, 12:56 PM
Have you checked the Aux Air Regulator or the CHTS?
Jeff, thanks for responding... What is CHTS? My abbreviation knowledge needs some work
Posted by: Jeffs9146 Mar 19 2016, 12:58 PM
Have you checked the Aux Air Regulator or the CHTS?
Jeff, thanks for responding... What is CHTS? My abbreviation knowledge needs some work
Cylinder Head Temp Sensor
Also Vacuum leaks are very bad!
Posted by: Jon Dugan Mar 19 2016, 01:10 PM
Have you checked the Aux Air Regulator or the CHTS?
Jeff, thanks for responding... What is CHTS? My abbreviation knowledge needs some work
Cylinder Head Temp Sensor
Also Vacuum leaks are very bad!
Makes perfect sense... Thanks for the suggestions !!! It's looking like I can use all the help I can get.. 5+ years as a daily driver with no real problems was too good to be true...
Posted by: The Cabinetmaker Mar 19 2016, 01:39 PM
No dwell adjustment in 5 years? I'm gonna assume that valves haven't been adjusted either. I'd do both. You can set the timing all day but if dwell is off it doesn't do any good. Valves first, then dwell, then timing. I'm betting your points are closed. Pop the diz cap, put the car in 5th gear, roll car forward till points rub block set on one of the 4 high points on the diz shaft, then set it to .017 (17 thousandths) clearance. Then check dwell and reset the points as many times as it takes to get the dwell to 47 degrees + or - 3 degrees.
Posted by: Jon Dugan Mar 19 2016, 02:22 PM
No dwell adjustment in 5 years? I'm gonna assume that valves haven't been adjusted either. I'd do both. You can set the timing all day but if dwell is off it doesn't do any good. Valves first, then dwell, then timing. I'm betting your points are closed. Pop the diz cap, put the car in 5th gear, roll car forward till points rub block set on one of the 4 high points on the diz shaft, then set it to .017 (17 thousandths) clearance. Then check dwell and reset the points as many times as it takes to get the dwell to 47 degrees + or - 3 degrees.
Thanks for the response!! I did have a valve adjustment/tune-up about 4 years ago so I'm no doubt overdue. I also went will optical in the diz.. I've been hoping to get it running well enough with a possible "obvious" fix per the symptoms, to drive it, rather than tow it, the 40 miles to the mechanic that did the work last time.... Good Times !!
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