Thread: GA16DE Dieseling

Hey Fellas. I have a couple of problems I have to fix with my beater.

This post however just relates to one. The car is dieseling after I cut the ignition.

I've been reading about dieseling and it is only supposed to happen in cars that are non fuel injection.

I ran free conzult to monitor some things. While the car was idling at around 1500 rpm. The high idle is something else I have to fix, but yeah so at idle I see that the car does not fluctuate between lean and rich. It just stays on rich. Is this normal for idle? Normal for 1500rpm? I was able to get it to fluctuate Lean Rich once I stepped on the throttle.

Temp does not get past 200 F before the fans kick in, so I know the engine is not running super hot. A couple of things with the car. My father turned down the timing as low as it would go. His reason was the high idle. I let him know that it was the wrong thing to do. Lucky he didn't go in the opposite direction with the base timing.

So I have some questions regarding the dieseling. Will low timing cause a motor to diesel after ignition cut off?

What would cause the motor to run rich at idle?

My theory is that the cylinders get over filled with fuel because of the rich condition, and then on shut down that extra fuel in the cylinder burns itself off causing the dieseling after ignition cut off. Now if my theory is right I need to find out what is causing the rich condition.

Another thing the car has shown me is that when you stab the throttle 4-5 times in a row the motor starts bogging itself getting close to the point of a stall. I have to let it run for about 30 seconds for it to start idling at 1500rpm again. Again I think the cylinders are getting flooded and the extra fuel just has to get burned out.


If anybody has run into a dieseling situation with their GA16 or SR20 powered Sentra please post. Any knowlege is welcome.

I would suspect a leaky injector.

My car did that to me when I installed the ebay intake. It was all good except for the MAF adapter causing a TON of turbulence. You may want to see what the MAF thinks is going on.

It would idle SUPER high, 1500-2400 depending on what it felt like, sometimes it would stall out, but it had LIQUID gasoline coming out of the exhaust it was so rich... It also didn't shut off immediately, it'd keep running 10-15 seconds after it was turned off. I just assumed it was due to the insane amount of fuel somewhere that would keep it running. (I don't know if it really would be enough to do it, but I couldn't figure it out at all) But yeah, check the injectors and MAF, also I'd go ahead and check the coolant temp sensor.

Thanks for the posts. I'll look into those two possibilities. I also suspect it is injector related. Another problem the car was having was cylinder number 3 was not making power. I was just looking things over last night and I pressed on the #3 injector a bit an cylinder number 3 fired up again. I'm thinking that #3 not firing was maybe a loose connection to the injector.

Ok So I fixed the problems I was having.

The high idle was caused by the catch screw on the throttle body. It had worked itself up somehow and was keeping the throttle open.

I'm really not sure why the dieseling was happenning, but it was not a leaky injector or anything like that. Since my dad turned down the timing I decided to first put that back as it should be.

I put the timing back to 10 degrees BTDC and adjusted the idle back to where it should be. This got rid of the dieseling and the car would no longer stall with application of full throttle. I was very lucky I did not have to do anything else besides adjusting the timing and idle.

As for the #3 cylinder not making power. I'm going to attribute that to a wiring problem. Because ever since I jiggled that injector harness and pushed the wire in as far as I could the #3 cylinder has been working as it should.