91 Maxima SE Idle bounces between 1500 And 2000

Mattx4 · Oct 28th, 2009, 06:16 PM

My car idles high and bounces between 1500 and 2000 RPMs. The check engine light is on. Other than that it runs good. I ran a diagnostic on the ECU and it came back with codes 33 and 51. What do they mean? I have already replaced plugs and wires and I found a vacuum leak coming from the EGR. There may be another leak somewhere but I'm not sure. Any suggestions?

**JNCoRacer** · Oct 28th, 2009, 08:24 PM

The 33 is going to be the vacuum line for the EGR. I'm guessing since you said you found a leak that that is where the code for that came from. If you havent cleared the codes then it'll still show up.

51 is the Injector Circuit. To check to see if an injector has gone bad, check the resistance between then two terminals in the injector harness connector of the 2, 4, and 6 cylinders. When you unplug it, you'll see two terminals in the connector.... the resistance between them should be 10 - 14 ohms. If it's not, then replace the injector. For the 1, 3, and 5 cylinders, disconnect the sub-harness connector for injectors. Check the resistance between the terminals to see which one has gone bad. The sub-harness connector looks as follows:

a b
c d

The piece of plastic that juts out is the top of the connector. Ok, to check to see if Cylinder #1 injector has gone bad, check the resistance between terminal b and d. Cylinder #3 is terminal b and c. Cylinder #5 is b and a. The resistance should be 10 - 14 ohms.

If any of the readings are way off... then replace that injector.

Mattx4 · Oct 29th, 2009, 03:16 AM

Quote:

Originally Posted by JNCoRacer

The 33 is going to be the vacuum line for the EGR. I'm guessing since you said you found a leak that that is where the code for that came from. If you havent cleared the codes then it'll still show up.

51 is the Injector Circuit. To check to see if an injector has gone bad, check the resistance between then two terminals in the injector harness connector of the 2, 4, and 6 cylinders. When you unplug it, you'll see two terminals in the connector.... the resistance between them should be 10 - 14 ohms. If it's not, then replace the injector. For the 1, 3, and 5 cylinders, disconnect the sub-harness connector for injectors. Check the resistance between the terminals to see which one has gone bad. The sub-harness connector looks as follows:

a b
c d

The piece of plastic that juts out is the top of the connector. Ok, to check to see if Cylinder #1 injector has gone bad, check the resistance between terminal b and d. Cylinder #3 is terminal b and c. Cylinder #5 is b and a. The resistance should be 10 - 14 ohms.

If any of the readings are way off... then replace that injector.

I have already replaced two bad injectors. The rest were ok but the connections are corroded. I tried to clean them as well as i could but I might need to clean them better. Is there any way to service an injector besides a fuel additive? I also heard that code 33 could mean a bad o2 sensor. Is that true? I believe i reset the computer. it gave me a code 55 after but then i ran the diagnostic again and it gave me the same 33 and 51. Is there anything else i need to do with the ECU? The check engine light is also still on. I know to run the diagnostic you have to wait for the syncronized red and green flashes to reach 3x and they have to reach 4x to clear old codes but what does 1x, 2x, and 5x mean? Also on the little knob you turn with a flathead on the ECU, it says something about idle speed adjustment. What's that about? I really appreciate any help you can give me. I just got the car and all I know about it is what i read online and in my haynes manual. I haven't gotten any full explaination about the ECU. Again, I really appreciate any advice. Thanks.

**JNCoRacer** · Oct 29th, 2009, 01:24 PM

The 55 code could be related to the 51(injector signal) code. If its not spraying the fuel in properly then its just sucking and pushing air out through the exhaust, thus giving the O2 sensor more "oxygen" to detect.