1973 2.0 D-Jet Hesitation Stumble 2500-3300 RPM |
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1973 2.0 D-Jet Hesitation Stumble 2500-3300 RPM |
gonzo54 |
Aug 20 2023, 11:30 AM
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#1
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Orange Crush Group: Members Posts: 226 Joined: 10-May 19 From: Seal Beach, CA Member No.: 23,112 Region Association: Southern California |
I had this problem shortly after I purchased my car in 2019 and I solved it with a new 2.0 914 Rubber TPS Circuit Board.
Fall 2022 I rebuild the motor to a 2056 with a mild Webcam 73 (D Jet compatable) and The Hesitation Is Back. So far I have accomplished the following using PB Anders articles and with the help of Bob D @bob164 who has logged numerous hours on this project. -Checked the resistance of the entire engine wiring harness repairing and improving resistance on several connections. Checked all grounds. No Hesitation Fix -Smoke tested the intake which found a leak at the Cold Start Valve, fixed. I still have a minor leak at the Throttle Body shaft and #1,2 Intake Manifold (replaced gasket and added sealant - needs resurfacing) No Hesitation Fix -Fuel Injectors were sent to Mr Injector for cleaning and flow test during the rebuild. -The Dizzy was disassembled-Trigger Points cleaned, Weights cleaned and lubed, Vacuum advance checked. No Fix, so I bought a 123 Blue Tooth Dizzy after reading about Trigger Points possibly being the problem. No Hesitation Fix -The CHT sensor is within the paramaters of PB Anders data. -The MPS checked out and did hold vacuum withing the leakdown parameters but it decided to quit holding vacuum so we rebuild it with a Tangerine Racing Kit and PB Anders data. No Hesitation Fix -The ECU 0 280 000 037 that came with the car was replaced with ECU 0 0280 000 044. I've read that ECU's rarely fail. No Hesitation Fix -TPS: All of the 914 World threads regaring this problem takes me back to the TPS and TPS Circuit. I now own 2 complete TPS's 0 280 120 032 and 4 circuit boards. I've tried all combinations including the 914 Rubber TPS Circuit Board and the Throttle Switch has always been set up per Ralph Ricks Instructions. I still have the Hesitation. When I disconnect the harness plug to the TPS The Hesitation Does Not Occur! The car has a little lag with the TPS harness unpluged but accelerates through all RPM's with out a problem. This test continues to lead me back to a bad or dirty TPS Board. I have cleaned and sprayed the boards and sweep fingers with electronic cleaner numerous times, perhaps the gold plated contact fingers are too warn but a continuity test as the fingers run over the track appears good. I have rechecked the TPS harness wires to the ECU and they check good. I do not want to continue buying parts that may not fix this problem, so at this point I'm Stumped! Should I buy another Board or complete TPS or go in another direction? This is a great group with a wealth of information what do you think? Thanks in advance, |
emerygt350 |
Aug 24 2023, 12:22 PM
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#2
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Advanced Member Group: Members Posts: 2,147 Joined: 20-July 21 From: Upstate, NY Member No.: 25,740 Region Association: North East States |
It is hard to figure what Hesitation means... bogging is different from a hesitation in my book. You don't need advance with a 123. Really, you don't need it period on a type 4.
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914_teener |
Aug 24 2023, 01:53 PM
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#3
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914 Guru Group: Members Posts: 5,205 Joined: 31-August 08 From: So. Cal Member No.: 9,489 Region Association: Southern California |
It is hard to figure what Hesitation means... bogging is different from a hesitation in my book. You don't need advance with a 123. Really, you don't need it period on a type 4. Let's try and stay away from semantics and keep to engine theory of operation. In saying you don't need it is overly broad and doesn't mention engine induction or why an engine doesn't need it. Engine theory of operation say it's a mechanical truth...regardless of how it's achieved. To say you don't need it on a Type 4 engine depends on a lot of things: Induction, VE, distributor type, ect. IE: For carbs...if you have a mechanical andvanced dizzy...maybe not. But that's not what the OP says the engine has. He posted Stock D-jet, so how is the timing for a stock D-jet engine advanced on part load? OR..you could create a curve where at a certain RPM you've advanced the timing enough where it won't bog...hesitate or what ever it's called. But what about under 2,500 RPM where most driving happens? and what about 1,500 rpms? That becomes a dynamic situation which vacuum advance was invented and addresses. |
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