Darkbound 7 Posted July 1, 2017 Report Share Posted July 1, 2017 (edited) Hey guys, I'm new here! I have recently did a rebuild on my VR6 and while we were rebuilding the engine, I had the injectors ultrasonically cleaned, now I have hard hot start issues. No error codes (the only error codes that I have are for the heaters on the post-cat o2 sensors, but I had these before the rebuild aswell, so I doubt this is the issue) I have replaced the coolant temp sensor, seems like the old one was fine And the car has hot start problems if it sits for 30+ minutes, if I press the accelerator pedal a little it starts easier The hard start can be explained as, the engine cranks for 1-2-3 seconds with almost nothing else happening, then it starts but runs very low RPM like 300-400 for 1-2 seconds and then goes up to normal RPM. Fuel pressure checked, 2.5 bars on idle, 3 bars with regulator vacuum out, 10 minutes after it was shut off the pressure was about 2.1 bars, after that it stopped dropping a little, after 30 mins it was 1.5 bars, but as soon as I opened the drivers door it went up to 3 bars, so I seriosly doubt its a pressure problem. If I take the fuel pump fuse out and start the car 5-10 times to burn the remaining fuel in the fuel rail/injectors, wait 30-40 mins, put the fuse back and start the car it starts with no problems, this is why I am suspecting a leaky injector, but leaking only when hot, because we did take them out and tested them with brake cleaner spray, all of them seemed to spray nicely and we didnt see any leaks, so this must be happening only when they are hot.... I have also tried starting the car 6 times in a row when it is cold (I don't let it warm up), I start the car in the morning, let it run for ~30 seconds, shut it off, come back after 40 mins start it again (starts flawlessly) and I did that 6 times, all 6 times it started as it should. So these are the only 2 cases in which I had a 100% success rate in starting the car properly Is there anything I can do to fix the injectors or should I start looking for another set of injectors? Vagcom: Edited July 13, 2017 by Darkbound Link to post Share on other sites
Darkbound 7 Posted July 13, 2017 Author Report Share Posted July 13, 2017 The problem is Solved, it was the Injectors (I changed all six). Ultrasound cleaning, never again. VR6Pete and blackwookie 2 Link to post Share on other sites
blackwookie 26 Posted July 13, 2017 Report Share Posted July 13, 2017 What was the issue with the injectors tho. My 12v hard starts when warm. Never cleaned the injectors or anything. Just always how its ben since i got it. Doesnt always happen tho Link to post Share on other sites
Darkbound 7 Posted July 18, 2017 Author Report Share Posted July 18, 2017 On 7/13/2017 at 7:12 PM, blackwookie said: What was the issue with the injectors tho. My 12v hard starts when warm. Never cleaned the injectors or anything. Just always how its ben since i got it. Doesnt always happen tho I really have no idea exactly what was wrong with the injectors. I suspect that they were leaking when they were hot as I had the issue only when the car was hot. I tried testing them on a bench both cold and while heating them with a heatgun, I just could not get them to show any sign of problem infront of me, yet after I changed them, the problem disappeared and the problem started after I had them cleaned ultrasonically. Your problem may be different, coolant temp sensor maybe? blackwookie 1 Link to post Share on other sites
blackwookie 26 Posted July 18, 2017 Report Share Posted July 18, 2017 Possibly. Last time i was in it before i took it apart again my temp gauge was acting funny Link to post Share on other sites
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