Porsche 924 K JET Tronic CIS injection system basics
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- čas přidán 15. 07. 2024
- Here is an explanation of how a Bosch K JET Tronic system works. Hope you will find some awnsers here, if not just ask me in the komments section.
- Auta a dopravní prostředky
And thanks for the video, quite helpful. Just got a ’79 and trying to learn everything about it.
Thanks. Will try to Make more when I'm done with customer work and I get back to working on my car.
Wonderful explanation. Many thanks 🙏🏼
You're welcome!
Great Video,
very well explained and visualized.
That was very interesting because my 83 Porsche 924 got a warm-start problem. It will cold-start perfectly and also after like 10mins of being warm. It just wont start after standing for like 30mins to 2 hours. I heard that air bubbles in the fuel lines make it hard to start the car. A solution would be to activate the cold-start injector over a manual switch. I know its not the best way of fixing it but the war start-components are quite expensive.
Without holding system pressure after hot shutoff, the Fuel BOILS in the injectors, overcomes the 50 psi holdback spring in the injectors and floods the engine. More fuel then makes it worse. I proved this on my 77 with a pressure gauge, the pressure bleeds off too soon and it takes a 30+ second crank with pedal on floor to clear it. Porsche has a time and psi spec for this. This is what the fuel accumulators and anti return check valve are for. It also can sneak past the pressure regulator o ring after shutoff thru the WUR and into the return line. There are tests for this.
Thank you! Amazing content👌
Can't wait for the rest of the video, thanks!
Your welkome. Coming soon! Good luck with your project!
Awesome Content 👌🏾😏
Thank you my friend!
Merci beaucoup
You using an LED light source? If so, that’s what’s causing the flicker.
Great explanation, thanks! Can you please tell me the type of your performance throttle body you show ~6:00? Does a standard '81 924 2.0 need significant mods to install it? What are the benefits? Thanks!
Thank you for video in English! And just the video I needed! I bought 924 in no start condition that was sitting for 10 years. I managed to get it started by changing fuel, fuel filter and pump. But at start up idle is very rough. Could it be due to WUR? Would you recomend buying rebuilt kits for WUR and distributor?
I will do more videos on that topics. I will also make a wideo on diagnostics and so on. The rebuild proces is not hard and can be easily done in a garage. The setting up is a different story as you need a fuel pressure gauge.
@@undergroundgarage Thank you! Looking forward to more videos!
Im having cold start problems with my 924 2.0, really curious about the thermo time switch! Loved the info in the video.
Thers more to come on that topic!
I’m having a nightmare with my 924.
Summary of symptoms:
Car runs either way to rich but srtarts and runs okay when cold, or if I set the mixture so its has correct CO when warm, its coughs, splutters and barely runs when cold.
So it must be the WUR then?
This is what I;ve done so far to try and find the issue.
Full system pressure check - all within Bosch spec when cold and warm, confirming WUR working.
Rebuilt and cleaned WUR just to make sure. No difference. Swapped out WUR, no change.
All new injectors.
All new injector seals / screw in bosses.
Flow check on all injectors - even and correct.
Cold start injector, tested, functional and working - issue of poor cold running exists long after cold start injector fires either way.
All new coil, distributor, plugs and leads.
Swapped out ignition module, no change
Stripped and rebuild metering head valve - new kit, fully ultrasonic clean etc, etc
Cleaned out and checked all the injector lines.
New fuel pump in tank and engine bay + filter
Fresh clean fuel
Inspected, cleaned and checked flow plate mechanism in metering head and test swapped ith a known working one, no change.
Replaced inlet manifold gasket and resealed.
New air filter.
Smoke check for vacuum leaks, small one found and corrected.
Timing checked and rechecked.
New timing belt fitted and timing checked.
Compression and leak down all within spec and even.
When warm, car runs great but coughs, splutters and barely runs when cold.
Make the mixture way to rich and car starts no issue, but then is poor when warm as too rich.
Pressures and WUR checked, rechecked and different WUR swapped in to test, no different,
All correct Porsche components fitted, nothing after market or high performance.
Only other issue is that the auxiliary air valve didn’t appear to work very well,m i.e did not increase cold idle speed so had to modify this to give a 1,500 rpm fast idle which sovced that problem. Cold start mixture was same before or after so dont believe related.
Lost as to what to do next?
This is a tough one. Have you considered excessive blow by ? Is your crankcase ventilation connected to the plastic coupler ? When yes, could it be when cold the rings let compression through, hence more not metered air, and good running cold when to rich. As soon as blow by reduces, due to thermal expantion of the rings, less air gets behind the metering plate. If your CCV is connected tho the air box than its not the case.
Da rade po polsku?
Kurde mogłeś po polsku mówić.
Po polsku to pym zrozumial a napewno ciekaee rzeczy mowisz.
K JET tronic ??? really ??? All my life i think it's K-jetronic...
Yawn.