Car is running great, I drove it on tuesday, it was a light snow all day. Then it sat Wed. and today when i went out to start it, it cranked and cranked and cranked. Not catching. Battery is strong and its getting 30psi. fuel. Ignition is all in order. AAR is open.

I did notice that the red light was not on while cranking. Is that the problem.

What is the normal behavior of the 2 idiot lights on the dash.

insert key and turn to ON they both light up?

crank the engine, they should both stay lit till it starts?





I want to figure this one out, cause it happend once before back in October and left me stranded at work.

Check your grounds and fuse box....

I had the same problem but after cleaning all the connections in the fuse box in the engine bay it solved the problem. Good luck.

It was snowing/ wet most of the day, I will unplug everything tonight, make all the connections shine and put some jelly on the connections. I hope it works.

Thanks


As far as the fuse box, not exactly sure how to check for good grounds. I will remove all the fuses and shine the connectors.

Have you checked for spark? Personally I would do that first because it only takes a minute and then you know if the problem is fuel or spark, which drastically narrows down where you need to troubleshoot.

If the two you are referring to are the red and green, the green is oil pressure and should turn on when you turn the key to start (on cold engine or engine that the oil pressure has bled off). The red is the alternator light and the best description of the behavior is from the good Dr from his 700 Tips book:
Click to view attachment

Fuel is plentiful. The pump runs as it should and the smell of raw fuel comes from the tailpipe after excessive cranking. I had spark the day before, guess i could put my timing light on a wire when i crank it to make sure its still there.

Just pull a plug wire and hold it next to the tin and check for spark. Even with good spark, it may not start if running full rich.

Im no expert, but dosnt the d-jet design always start full rich. The head temp sensor is ice cold, the cold start injector kicks in, and the aar is to open to compensate. right???

my AFR gauge is always pegged full rich on startup. even when it did start great. is that not right ??!?

Not sure why it could be a problem from sitting, but also check the CHT. I had an intermittent issue where the car would run fine, die, crank, smell like gas out the tail pipe, but would not start. Then it would start another day, run for a while, and repeat... Of course I was troubleshooting and moving engine components around between these periods of running/not running.

Turned out to be a broken CHT lead on the FI harness - moving it would make/break contact. With an open connection (high resistance) on the CHT D-Jet sets enrichment high and thus floods out.

Ditto on checking the CHT,, had the same problem at the RRC in sept. It turned out to be a bad CHT.

Got it started, man was it tough, and running rough. Full rich pegged.

Spark is fine

Fuel pressure is 30

once it warmed up, it ran great. Now if it gets cold again, not so sure it will start again. How do I check the CHT with a meter ??

Function: Senses engine temperature and sends signal to the ECU to provide mixture compensation. Proper part for your application and proper functioning is extremely important!
Normal Value(s):
0 280 130 003 and 0 280 130 012: about 2.5 K ohms at 68 deg. F, less than 100 ohms with hot engine.
0 280 130 017: about 1.3 K ohms at 68 deg. F, less than 100 ohms with hot engine.
See Notes section below for more data on the resistance vs. temperature values of these sensors.
Failure Modes
Open: The ECU interprets an open sensor as a signal to greatly richen (e.g. I've measured an over 3X effect) the mixture. This usually makes the car impossible to start and causes it to stall if the sensor fails open while running. Check by disconnecting the sensor from the wiring harness and measuring the resistance to ground, refer to the values above.
Shorted: The ECU interprets a shorted sensor as a signal to lean out the mixture (about 30% leaner). The car may run and start in this condition, but will have poor idle and drivability. Check by disconnecting the sensor from the wiring harness and checking the resistance to ground. Note that shorts are often intermittent, caused by nicks in the sensor wire and by exposed contacts to the wiring harness touching ground. Check by inspection.
Stuck Value: I've heard of at least one case of the sensor being stuck at a value (e.g. 50 ohms) and not varying with temperature. Depending on the value it gets stuck at, it can result in either poor cold or hot performance, or both. Check by measuring with an ohmmeter as described above.
Mismatched: The 1973 2.0L's came with the 0 280 130 017 head temperature sensor, 039 971 762 A ballast resistor, 0 280 100 037 manifold pressure sensor, and the 022 906 021 E version of the ECU. This set of components must be used together. Any substitution will result in idle and part-load performance problems, and possible poor fuel economy. Additionally, use of any of these 1973 2.0L components with a 1974 2.0L setup will also cause problems. See the table above for the suggested setup for both 1973 or 1974 2.0L engines. If you have a 1973 2.0L and you want to keep the original setup, make absolutely certain that you have the correct combination of components. The 0 280 130 017 head temperature sensor's cold (70 deg F.) resistance is about 1200 ohms, compared to 2300 ohms for the 0 280 130 003 and 0 280 130 012 sensors. Use of the ...017 sensor with the 039 906 021 ECU (1974 model) will result in a lean mixture during warm up, causing low idle and/or backfiring on over-run. Use of the ...012 or ...003 sensor with the 022 906 021 E ECU (1973 model), with or without the ballast resistor, will result in a rich warm-up mixture. Take the extra time and determine exactly which head temperature sensor is installed in your car and make sure it matches the setup.
Notes: This resistance of this sensor is one of the primary factors in adjusting the mixture and it has a strong effect. An additional issue is the availability of the 0 280 130 012 sensor. I have found this sensor difficult to locate, and most shops substitute the 0 280 130 003 sensor for it. As far as I can tell, it is either exactly the same or nearly identical. Bosch even lists the ...003 sensor as being cross-referenced to the Porsche/VW part number 311 906 041 A. See the entry above for the intake air temperature sensor for theory on how these sensors work.
Fixes for Crappy Warm-Up: For whatever reason, VW/Porsche made the CHT sensor such that the warm-up mixture is usually too lean, resulting in poor idle and drivability. Two ways to fix this. First, you can add up to 150 ohms of ballast resistance to the sensor to bias the curve up towards a richer condition. Don't go over this amount of ballast because it will begin to affect the warmed-up mixture. Second, you can construct a spacer as described on Richard Atwell's page, that delays heat transfer from the head to the sensor, making the mixture richer during warm-up. I made mine using materials from my local ACE Hardware: a M10x1.0 tap and wrench, 11/32" drill bit, M10x1.0 bolt, and a M8x1.25 coupling nut w/13 MM hex. Drill out the coupling nut and tap it to M10x1.0. Cut it down to 16 MM length. Cut a 16 MM stud from the bolt, thread it into the coupling nut so that when you attach the sensor on the other end, it just jams the stud in place. Align the flats and install. BTW, you can also do both fixes in combination (like on my car!).
Installation Notes: Installing this sensor can be tricky. The best solution I've found is to buy a deep 13 mm socket and a 3" extension (I bought mine at Checker, about $5 for both). Use a Dremel tool with a cut-off wheel to cut off one of the corners of the four-sided end of the extension (the part that goes into the socket) to create a gap that the sensor wire can be threaded through. ALWAYS USE SAFETY GLASSES when doing this kind of work with a Dremel tool. Filing works, too, but it will take a very long time. Make sure to use the copper washer that comes with the sensor - the washer assures good thermal conductivity to the head and prevents loosening. Keeping the washer from falling off during installation can be difficult. First, to keep the sensor from being pushed back into the socket during installation (which will pop the washer off, and it'll fall into the head air fins), position the sensor so that it's sticking out a bit, then tape the wire with a single loop of masking tape to the extension. The wire will resist the sensor being pushed back into the socket. To keep the washer on the sensor, I use a couple of tiny drops of superglue to hold it in place. The glue bond will be broken when the sensor is tightened. DO NOT overtighten this sensor, just get it snug. It's easy to strip out the head threads and then you'll have to pull the engine to fix the problem.
More Data!!: Below is some characterization data I took on each sensor at three different temperatures (one data point missing). Note that these are representative readings - there is significant manufacturing variation in these sensors. All data measured with a freshly-calibrated Wavetek LCR55 meter.

o.k. thanks, just went outside. Engine was running 1 hour, fully warm

meter set to 2000 ?

positive lead to cht and negative lead to neg battery.

reading 403

can i tell wich sensor i have installed without removing it?

Seems to be higher than it should be, it should read <100 ohms or almost short.
Us the motor casing for your 2nd test lead incase you have a grounding strap issue. If you still read 400ohms I would get a new CHT

Resistance @ 212 degrees F is around 190 ohms - so your 400 ohm sounds high unless you also have an inline balast resistor (like the 73 djets have)

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