Hello I know this is a CB7 website but I just purchased a 1993 NISSAN D21 PICK UP. My problem with it that it idles rough it has a 4 cylinder fuel injected engine I hope that I can find help with this on this website but if not it's fine sometimes when the truck is first started it will go down to 400-500 rpms even when it's warmed up it will sometimes do it even at 700 rpms it shakes hard/rough like it's not idling properly. Looks like to me the fuel filter,battery,spark plugs/wires,distributor and air filter was changed before the truck was sold. Please if anyone can help it would be greatly appreciated thank you. Also when you turn the key right before it starts and the fuel pump primes the engine you can hear like a leak around the area of the fuel injectors but it can't be heard when the truck is running could that be the problem with the rough idle?
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Originally posted by Kev1990 View Post
I had a D21 hardbody years ago. Frame rusted through and one day the passenger side started getting lower and lower going down the highway. Until it crinkled the fender against the door.
Anyways, I had similar problems with my Nissan pickup.
Unplug the MAF while it's running. If it clears up that's your issue. Once you unplug it it will go into limp mode which limits RPM to 2500ish as I recall. Try cleaning it before replacing it. Be careful with it by the way.
Do you happen to have a CEL?
My truck made a sound when the fuel pump was priming that sounded like a low pitched squeak. Are you hearing something similar?
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Hmm. Where is the MAF located on this truck? And I hear what sounds like a leaky fuel injector couldn't that cause idle problems with low fuel pressure? This morning I started it it idled at 250 and stalled a few times. I can hear the injector leaking too right before start up when it primes. No CEL light ether.Comment
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OK so I unplugged the MAF sensor to test it and it stalled every single time for about 3-5 times unless I press the gas as soon as it cranks/turns over. What does that mean?Comment
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The reason I suggested the MAF is because they are very problematic with those trucks. It could be a combination of issues and at this point I'm not sure if the MAF is bad or not. However if it were solely the MAF when you unplugged it it would run smoothly and normally.
If you have a fuel leak especially one large enough to hear that very well could cause an issue. Have a friend repetitively turn the key on while you look for the leak or source of the sound.
Even though the CEL isn't on it could still have a code that could help point you in the right direction.
Here is how to check the codes. You will likely have a code 12 which is from unplugging that MAF. But your looking for other codes as well.
http://infamousnissan.com/forum/showthread.php?t=14573
Also, if you have an injector leak it should tell you. Still, I would find the source of the noise you are hearing just to be sure.
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OK so were moving along here! I got codes 41,34,12,13 12 was most likely just for unplugging the MAF earlier. Would any of these engine codes/problems cause idle/stalling/rough idle problems?
13 Engine Coolant Temperature Sensor
34 Knock Sensor
41 Intake Air Temperature SensorComment
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What does the knock sensor do exactly? I was reading that a knock sensor wouldn't cause rough idle or stalling but code 41 and 13 would cause rough idle/stalling. Also the CEL is not solidly on so can't say for sure knock sensor is bad plus I was reading there's things that would set off the knock sensor code like the MAF OR OXYGEN SENSOR.Comment
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Its a sensor that is bolted to the block and senses for spark knock and detonation. The sensor sends a signal to the ECU to control the ignition timing. It is possible for the MAF or O2 sensor to set the knock sensor off but it is unlikely without any current codes for either the O2 sensor or the MAF.
EDIT... The knock sensor can in fact cause a rough idle. What I recommend now is for you to reset the codes then start it and let it run for a few minutes. Drive it around a bit if you are able. See if any codes come up. Does the CEL come on when the key is cycled to the on position but not the run position? I ask to verify that the CEL light works.
You are looking to rule out the MAF before considering replacing the knock sensor.
The IAT sensor is typically the culprit for not being able to pass emissions. If it is disconnected it can cause similar symptoms as you are experiencing (which happens to be an issue on those trucks). Sometime you can wiggle the wires going into the harness and hear it start to run better.
The engine coolant temp sensor could also be the culprit or play a part in it running poorly. I forgot those have two sensors. The one you are looking for is the one bellow the end of the fuel rail towards the front of the engine.Last edited by H311RA151N; 09-06-2014, 07:16 PM.
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Hmm I see would you say it's a hard job to replace?Comment
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I edited my post, I hit submit on my phone by accident before I was done. My apologies.
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None of those sensors are hard at all to replace I just don't see why its not throwing any current codes. Yet it pulls up the stored codes and it's running quite poorly.
You can test the MAF you have now with a voltmeter. So that will save you from buying something you don't need.
https://www.youtube.com/watch?v=xisjdjNskFc
I do not know how to test the intake air temperature sensor.
I also do not know how to test the coolant temp sensor.
I know both can be checked with a voltmeter but I do not know what reading to look for.Last edited by H311RA151N; 09-06-2014, 07:27 PM.
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OK just one more question could you help me find a good knock sensor like something that's possibly reviewed 4-5 stars for a good price under 100-150? And doesn't the intake manifold have to come off to replace the knock sensor? The codes 13 and 41 i'm just going to replace those sensors as they are the cheapest to start with. WAIIITTT! I am reading that engine KA24E does not have a knock sensor?Last edited by Kev1990; 09-06-2014, 07:45 PM.Comment
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Yeah, replace the coolant sensor and the intake air temperature sensor first then see how it runs.
If neither of those two items fix it then look into the MAF. They have MAF cleaner at parts stores. I would most definitely clean it then reinstall it to be certain it is not dirty before replacing it.
EDIT...Man, this is really pushing the limits of my memory as it's been almost a decade since I owned a D21.WAIIITTT! I am reading that engine KA24E does not have a knock sensor?
The 240SX has a K24DE as where the D21 has a K24E. The K24E which is what you have does not have a knock sensor so that is evidently not the issue. I'm starting to remember why I hated that truck...
Still yet, you have a code 34 unless you misread it which I'm thinking may have happened. If it does in fact read a code 34 and it never had a knock sensor then I don't know what the hell to tell you. Check the codes again if you have not erased them.
Check the codes to verify it is in fact "34" before doing anything else to be certain it isn't a different code and there is an issue you are unaware of.Last edited by H311RA151N; 09-06-2014, 08:15 PM.
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