# 1990 d21 running rough



## Firl (Aug 10, 2010)

Hello, I searched around the site a while and couldn't find too much too similar. later today I am going to be pulling the ECU code to see if it helps with any of the diagnostics. 

Problem:


> Right now the truck starts up great, but has a very rocky / rough idle.
> When the gas pedal is pushed down it dies just a little, but goes.
> 
> If the gas pedal is pushed more than 1/2 way it feels like it "catches" better and gives a lot more power, and sounds like a much more smooth acceleration.
> ...



I have worked on other cars, and from what it feels like, that if it had a 2 barrel carb it would be that the first carb might be junked up; Or that the timing might be off. 


Any suggestions / help would be greatly appreciated

- Firl


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## GeoBMX4Life (Mar 25, 2010)

It could be a number of things, the code will let you know. I'm thinking TPS or O2 sensor. 1990 should be EFI as well...so no carb(s).


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## Firl (Aug 10, 2010)

Thanks 


> I'm thinking TPS or O2 sensor.


I was thinking about cleaning the air filter out, checking the gaping of the plugs and just seeing if there is anything just out of place. I will post the codes once I get them.


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## clg82 (Jul 30, 2010)

How do you pull codes from the ecu if you don't mind me asking? And how do you know if there are any stored? Will some kind of a service enging soon light come on? thanks for any help, don't mean to jack your thread just thought I would ask.....


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## Firl (Aug 10, 2010)

there is a sticky on the forums that has it. I believe it is.

Ecu Self-diagnostics For 87-95 Pathfinder - Nissan Pathfinder Off-Road Association


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## clg82 (Jul 30, 2010)

Firl said:


> there is a sticky on the forums that has it. I believe it is.
> 
> Ecu Self-diagnostics For 87-95 Pathfinder - Nissan Pathfinder Off-Road Association


Best link ever thank you. So from what I'm reading on that website, I would be throwing some kind of a Service Engine Soon light if there was a code in it correct?


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## Firl (Aug 10, 2010)

clg82 said:


> Best link ever thank you. So from what I'm reading on that website, I would be throwing some kind of a Service Engine Soon light if there was a code in it correct?


I have no idea I haven't read it fully yet


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## GeoBMX4Life (Mar 25, 2010)

The codes will come in multiple blinks, then pauses, you need to write them down whenever there is a pause. 3 blinks then pause, 1 blink then pause, 5 blinks then pause would be code 315. Check engine light is for oil and oil pressure. The check engine light won't come on if there is a random sensor failure...hope this helps guys!


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## clg82 (Jul 30, 2010)

GeoBMX4Life said:


> The codes will come in multiple blinks, then pauses, you need to write them down whenever there is a pause. 3 blinks then pause, 1 blink then pause, 5 blinks then pause would be code 315. Check engine light is for oil and oil pressure. The check engine light won't come on if there is a random sensor failure...hope this helps guys!


Thankg geo....great post, I will have something to do this weekend and that is check my ECU codes lol I know i'm a :loser:


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## GeoBMX4Life (Mar 25, 2010)

*HAHA!!!*



clg82 said:


> Thankg geo....great post, I will have something to do this weekend and that is check my ECU codes lol I know i'm a :loser:


 LOL...just keep us updated!


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## Firl (Aug 10, 2010)

alright. so I was able to get the ecu to start giving codes off the unit itself. I was not able to get the ECU to turn the check engine / oil light. At one time it blinked green 5, red 5, which means nothing, but at that time I think it might have been cleared, so I tried to regenerate that after driving the car around.

By the end of it, my helper I think over rotated the screw and I am not able to get it into the diagnostics mode anymore. 


The engine is a 4 cylinder but it had a different ECU than the others in the link.











there MIGHT have been a chance that it blinked 5 green 3 red. MIGHT.


Any suggestions on what to do next?


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## Firl (Aug 10, 2010)

/bump... nothing?


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## zanegrey (Dec 5, 2005)

turn the key to the run position (but the engine is not running) then turn the ecm switch to on
then look at the ecm lights.. it will blink one time then 2 times then three times then 4 and then 5 times..

these are the modes..

after it blinks 3 times ( 3 is the stored trouble codes)

immeadiately turn the switch to off and then record the blinks...

then look up what code it gives you...


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## smj999smj (Jan 1, 2006)

Timing chains on the KA24E engines have been known to jump at times, which retards the cam, and subsequently, the ignition timing. Just something you may want to check if the basic checks turn up nothing. Also, check for vacuum leak at the intake manifold gasket with carb cleaner and the engine running; listen for a change in RPM while spraying the gasket.


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