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How to test fuel injectors and trigger points using homemade NOID lights.
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- เผยแพร่เมื่อ 28 ก.พ. 2024
- This is a detailed video showing you how you can quickly make a set of NOID lights and use them to test the fuel injectors AND the trigger points in your car.
This method is quick and simple, and does not involve any soldering. At the end of the video, we show you where we got the parts from and how much they cost.
In this video, we are using NOID lights to test the injectors and trigger points on a 1975 Mercedes 280SL a the Bosch D Jetronic fuel system. This same system is used on numerous other cars of the same era including Porsche, Volvo, VW etc.
Wow. Very technically interesting. Always enjoy 1975 280SL D-Jetronic content. Not much around. When I got my motor running, it was running rough. I used a laser temperature meter on the exhaust side and found one cylinder to be cool. I swappped fuel injectors and the coolness moved so I knew I had a bad injector. A used injector from ebay had my car running smoooooth. My injector points looked really good. I call them the downstairs on the distributor. My car runs nice except I am 90% sure my valve seals are bad due to smoke.
Thanks for your comment. Leaking valve seals is a trick problem to fix. Is the smoke is blue and worst when you first start the cold car that is a sign of worn valve seals? If the smoke gets worse when you are coasting downhill that is another sign. I have yet to see how this engine will run - wish me luck! Mike
your conclusion would be that the injector was leaking or putting too much fuel that caused the cylinder temp to be lowwer?
@@MrFrambooise or it was not working thus not firing.
I think the opposite would be true - injector not squirting any (or enough) fuel into cylinder would mean spark plug didn't have enough fuel to combust and therefor that cylinder would be colder.
A 'leaking' injector could mean:
1. Leaking FUEL into the cylinder which would give a rich condition and result in rough running and difficult starting because the fuel pressure wasn't being maintained.
2. Leaking AIR into the cylinder via a faulty seal could also potentially resukt in a rich condition on a D Jetronic. An air (vacuum) leak would lead the MAP sensor to think there was too much air relative to fuel and thus the MAP sensor would signal the ECU to increase the duration of the injectors. firing@@MrFrambooise
Neither of the conditions above would lead to a cold cylinder.
Mike
@@MikesMercsandothercars Hello Mike, How did you conclude that neither of the situation would result in cold cylinder? I imagine that the injector was leaking so bad that the spark was not able to ignite the mixture or the combustion was not complete due to not enough oxygen therefore the cylinder would be cooler . On the other hand lean condition can lead to increased exaust temperature. Im not gonna pretend as if I know every possibility but thats the info I got. I dont understand how exacly MAP would be acting in case of leaky intake manifold, but that generally means lean condition. I assume you are talking about engine that only has MAP sensor no MAF sensor.
Excellent video! Thank you Mike!
Thanks. I'm in the process of trying to capture some injector waveforms using an oscilloscope, but it transpires that I need to put the fuel and vacuum system back together to get any meaningful readings. If you have an older SL maybe you can tell me something? If you turn the ignition key to start but don't crank the car, do you get any voltage at the injector plug for cylinder 1? Mike
Hey Mike. I have a 450SL 1973 with the M117 engine. The engine manual states that voltage is transmitted to the injectors when the key is in the crank position (engine turning) with cable 1 on the ignition coil disconnected (eliminate risk of fire). Hope this helps.@@MikesMercsandothercars
Thanks - that is helpful. By "cable 1" , I wonder if that means the top spark plug lead leading to the distributer or whether it means one of the electrical conections to the coil? Mike@@MBSLC
On my original Bosch blue coil, the " - " connection is where "cable 1" is attached.@@MikesMercsandothercars
Did you have connect the light unit to a power supply (car battery??) for it to work cheers
Hi Mark - so here was the arrangement for this test:
1. Fuel pump relay removed.
2. All 6 injectors unplugged
3. Car battery connected
4. No other power sources
5. Car turned over using the ignition key.
I had hoped for he next video to be showing how an oscilloscope can be used to measure wave duration and injector timing etc....but...it transpires that you need to reconnect the fuel system to do this. Mike