# D21 Engine Rough Idle



## 89sentra1 (Nov 7, 2005)

I got a 1991 Nissan pickup Truck with a 2.4L engine. 99k. Idle is bad and getting worse. Ive done all the obvious checks and cleaning. All vaccum hoses and tps, maf, iac all clean and functioning. Egr functioning. O2 working. All wires and cap and timing fine. No Manifold leaks. 

Does anyone know if theres an issue with these engines and the idle going bad at some point and the fixes that were involved??? :nerd:

I dont want to have to go through the whole engine of sensors and test and such if someone knows what some of the obvious fixes were for this common problem or am I stuck checking each sensor now. Just trying to catch a short cut if this is a common issue as Ive read a few of the same problem but most dont post the fix. They just disappear, lol. 

Past idle the engine runs fantastic! Great power and perfect at cruise.

Thanks for any advice and all inputs or suggestions!!!


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## smj999smj (Jan 1, 2006)

Common problems are EGR valves that stick open and leaking intake gaskets. Do you notice any timing chain rattle? If so, the timing may have jumped.


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## jp2code (Jun 2, 2011)

Read over this thread:

FIX: erratic idle, low speed driveability, possibly more - Infamous Nissan - Hardbody / Frontier Forums


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## 89sentra1 (Nov 7, 2005)

Thank you guy very much! I will check into both advices. 
Probably take EGR apart and clean just for the heck of it. I had spayed carb cleaner all around the base and intake. There was no change in idle at all.
One or two Valve tappets just a bit noisy at idle, but no timing chain rattle.

I did also notice some time ago when I wiggled the wire harness near the back of firewall extending to the valve cover, the cars idle did change and jump every once in a while, although it didn't idle nearly this bad as its doing now, so I will probe into that again as well. Thanks for that link to the harness problem!

Only other thing I was considering was the exhaust pipe leak I have at the small mid pipe muffler now. I was wondering if it would be affecting the O2 reading although the leak is past the O2 sensor. Just a thought.

I will check into all this soon and post my results for those in the future. 

Thank you guys!!!
Now If I can only get my speedo needle to straighten out and not drag so I can see how fast Im going. Dam needle just flopped onto the face and drags. How cheap can u get with the speedometer needle. OK, sorry, off subject.

Will post finding.....
Thanks guys! =)


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## jp2code (Jun 2, 2011)

> Now If I can only get my speedo needle to straighten out

A lot of people take fingernail clippers and cut 1-2 inches off of the plastic needle.

I've also seen people cut it off flush, and then glue a toothpick in the direction it is supposed to point.

Either that, or you need to hit up eBay/Salvage Yards for replacement clusters.


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## 89sentra1 (Nov 7, 2005)

Todays Update:

So from the link above listed by jp2code , I found the B/G wires(3)of them that connect to the one(1)B/G wire in the wire harness when wiggled affected the idle and would make it surge up and come down. I cut the little clamped set of wires and soldered the (3) wires to the (1)wire. Although this affected the engine idle by the wiggle test, it hasn't fixed the problem. At least the wiggle test now passes and theres no more idle surge when wiggled. I wiggle every sensor in the engine. No change in the bad idle. I rechecked intake gasket, throttle body gasket with the carb cleaner. No change in idle.

I've pulled one sensor at a time and each did affect engine idle and some lit the check engine light. So, I guess Im now stuck checking each sensor, one at a time for voltage specs. UGGGH! NO check engine light is on. Just low bad idle still. Idle is low and unsteady. NO high surges. Just stays low and lousy. At least engine doesn't die. Im still thinking EGR sensor or Fuel Injector. I have to check that exhaust Filter as well. That thing has been a problem in the past. 

The Saga continues.....

PS..thanks jp2code for the tip on the speedo needle. I'd like to find a stock tack for this truck. It didnt come with one =(

OK, will post my next chapter as I continue to try to find the mystery to the crappy idle.


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## slizzzzard (Dec 16, 2007)

jp2code said:


> > Now If I can only get my speedo needle to straighten out


Howdy, I had to laugh when I read this. I have an 86.1/2 Hardbody. The speed-o needle is melted and curled like a mad dog. Only benefit is perhaps it will get me out of a speeding ticket one day!


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