# 96 4x4 idle surge



## Adamv7010 (Mar 20, 2016)

I've recently picked up a 96 4x4 5 speed, had about a month of no issues at all. 

I washed the truck the other day and rinsed off the underside of the hood. 

Ever since I've had an idle surge, surging from 500 ish to 900 ish pretty quickly. I've read a ton of posts about common surging issues but none of them seem to be common with my situation. The distributor cap is dry, no codes, and does it cold and when upto operating temp. 

Ideas? Iac? Tps? 

Thanks in advanced










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## rogoman (Dec 16, 2004)

Since washing the underside of the hood, one or more harness connectors got water inside it. You'll have to disconnect them and use a hair drier to dry them out.


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## jp2code (Jun 2, 2011)

...or a spark plug wire could have been loosely connected, and the power washer pushed that connection a little further off. Pop each connector off, then reconnect.

Where are you from? Is it sunny outside? If so, pop the hood and let the engine sit in the sun for a day. Here in Texas, it's already getting up to 80 during the day, so it'd be dry in no time.

If the issue continues, pull the codes. You could also have blown off a ground wire to one of the sensors.


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## Adamv7010 (Mar 20, 2016)

jp2code said:


> ...or a spark plug wire could have been loosely connected, and the power washer pushed that connection a little further off. Pop each connector off, then reconnect.
> 
> Where are you from? Is it sunny outside? If so, pop the hood and let the engine sit in the sun for a day. Here in Texas, it's already getting up to 80 during the day, so it'd be dry in no time.
> 
> If the issue continues, pull the codes. You could also have blown off a ground wire to one of the sensors.


Garden hose on the 'mist ' option. No real pressure. No codes and runs great until it warms up, so roughly 10 minutes or so of idle. Weathers been in the upper 70s to upper 80s here as well. 

It's probably due for some maintenance anyway. For less than 500 bucks, with a clean title...I don't mind spending a little on it. 

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## smj999smj (Jan 1, 2006)

Try wiggling the engine harness where it runs from the firewall down along the side of the valve cover with the engine running. If the engine surges as you do the wiggle test, it could be a poor grounding issue. Nissan used several crimp splices to connect multiple grounds. If this is the problem, you would need to cut open the harness and locate the grounds and then solder the crimp splices.


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## jp2code (Jun 2, 2011)

smj999smj said:


> Try wiggling the engine harness where it runs from the firewall down along the side of the valve cover with the engine running. If the engine surges as you do the wiggle test, it could be a poor grounding issue. Nissan used several crimp splices to connect multiple grounds. If this is the problem, you would need to *cut open the harness and locate the grounds and then solder the crimp splices*.


+1

I forgot about that.

There is actually a write-up on what is needed with detailed pics.

From my bookmarks:

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


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## Adamv7010 (Mar 20, 2016)

smj999smj said:


> Try wiggling the engine harness where it runs from the firewall down along the side of the valve cover with the engine running. If the engine surges as you do the wiggle test, it could be a poor grounding issue. Nissan used several crimp splices to connect multiple grounds. If this is the problem, you would need to cut open the harness and locate the grounds and then solder the crimp splices.


I'd read a few articles about that being a fairly common issue, and did as you said. It didn't seem to have any affect. Most of what I'd read about the 2 loose splices, guys had issues of jumping from 7-800 or so and spiking at 14-1500 and dropping back. But i suppose those cases couldve had a worse connection in those 2 splices than i do. This truck basically bounces between 800 and 900 rpm. It's just enough to be obnoxious. I haven't yet had it cut off. I'll probably pull the harness apart tomorrow for good measure anyway. I'm sure it can't hurt. 



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## jp2code (Jun 2, 2011)

Have you worked through the "idle issues" in the Factory Service Manual? As shown in the image below (took me about 30 minutes to create that, upload it to the web, and get it posted), there are several columns devoted to idling issues. Most of the things to check are redundant, so it isn't hard to work through all of the idling issues.










The free Factory Service Manual can be downloaded from this website (you'll have to type the link in manually because one of the words in the URL is treated as a filtered word):


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## Adamv7010 (Mar 20, 2016)

jp2code said:


> Have you worked through the "idle issues" in the Factory Service Manual? As shown in the image below (took me about 30 minutes to create that, upload it to the web, and get it posted), there are several columns devoted to idling issues. Most of the things to check are redundant, so it isn't hard to work through all of the idling issues.
> 
> 
> 
> ...


I have not, but will now. Lol. I hadn't been able to find a download online. Thanks a ton for that. 

As for my idle, here's a little video of my idle 

https://youtu.be/5G8gi2AYSnE

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## Adamv7010 (Mar 20, 2016)

Ok guys, I'm kinda baffled at the moment. I pulled the harness apart, all the way from the top of the bend on the firewall all the way down past the injectors to the front of the motor...there are no splices in it at all. Each set of injector wires are paired together in the harness with tape, but other than that, just individual wires. Ideas?

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## Adamv7010 (Mar 20, 2016)

Snapped 3 quick pics. It's just like this the whole way down 

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## jp2code (Jun 2, 2011)

I'm going to say you have a crack in an air hose somewhere.

However, you'll probably have to walk through all of those troubleshooting steps I posted earlier to find it.


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## Adamv7010 (Mar 20, 2016)

jp2code said:


> I'm going to say you have a crack in an air hose somewhere.
> 
> However, you'll probably have to walk through all of those troubleshooting steps I posted earlier to find it.


Kinda my thoughts as well, so I covered every piece of hose I could see with a propane torch with a rubber hose on it, looking for leaks and got absolutely no change in idle even around the intake manifold. 

I did however find that 2 manifold bolts for cylinders 1 and 2 are broken and the threads pulled out thus creating a upstream exhaust leak. Vacuum is around 18-19 in. At idle which is within oem spec. 

Different note, do all the trucks not have the splicing points mentioned in that link?

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## Adamv7010 (Mar 20, 2016)

Oh, and I put a new coolant temp sensor in since the old one had a broken connector on top. Also did plugs and wires today 

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## jp2code (Jun 2, 2011)

Adamv7010 said:


> do all the trucks not have the splicing points mentioned in that link?


It was a Service Bulletin fix on the older trucks. The newer year Hardbody trucks are supposed to have eliminated this.

It looks like yours is good.


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## Adamv7010 (Mar 20, 2016)

As far as that splicing issue goes. Lol


Well I went ahead and did a compression test, 100-100-75-100, which is well below whwre it needs to be. A little oil in #3 brought it up to 125 pretty quick. But I dont think that's where the idle issue is coming from. I imagine I'll look at the iac and go from there. 

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## Adamv7010 (Mar 20, 2016)

It finally set a soft code today, a p0105, map circuit malfunction 

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## jp2code (Jun 2, 2011)

Adamv7010 said:


> It finally set a soft code today, a p0105, map circuit malfunction


Visit this site:

http://www.obd-codes.com/p0105


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## Adamv7010 (Mar 20, 2016)

I cleaned the maf and iac today for shits and giggles. It idles 100x better that before. Every once in a while it'll stumble for a second or so then back to where it should. I'll give it a few days and see how it goes and react to what I see. The iac was clogged pretty good and the valve was sticking. The maf had carbon deposits on the sensors. 

The p0105 was later accompanied by a p1105, but neither have come back once reset. Vacuum is back upto around 19 inches as to where it drooped down below 18 for the majority of the time prior to cleaning the iac and maf. It's idling as smooth as can be expected at the moment. I'll probably start putting a motor together for it soon anyway. I may even have a good block and head on the shelf. 

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## jp2code (Jun 2, 2011)

Fingers crossed!


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## Adamv7010 (Mar 20, 2016)

jp2code said:


> Fingers crossed!


We'll see. I imagine this trucks been run hot at some point looking at the new radiator. I'll end up putting a motor in it anyway at some point. As for the idle issue, it's still not perfect, but 100x better. It's not trying to cut off anymore in neutral or between shifts. I'll keep this thread updated either way. Thanks for the help 

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## Adamv7010 (Mar 20, 2016)

Just an update...so far so good. 

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