# 96 XE bucking over 2500rpm, misfire?



## NavyDoc (Jun 30, 2010)

I'm going to list the complete history since I bought this truck back in Oct 09. I got it with 165,000 miles on it, KA24E, 5-speed. It had a blown head gasket that had been repaired but It drove great and didn't need anything worked on. 
About a month later the check engine light came on and the codes came up as EGR malfunction and O2 sensor. I never got around to fixing the issues since they wern't causing any drivability problems. Another month goes by and now the truck starts to bog down until fully warmed up but still no serious issues except for crap gas mileage. 
Early in June I started trying to improve on the truck and fix the 2 problems that were causing the CEL to come on. I started by seafoaming, cleaning the MAF, changing the spark plugs, wires, cap and rotor, oil plus 4cly engine restore and air filter. Never did take care of the O2 sensor but I started in on the EGR valve to get it off and clean it but discovered that it was more of a challenge than I was ready for. I went ahead and ordered a new egr valve and pipe. 
While waiting on the parts to come in I continued to drive it and a few days after doing this work the truck suddenly starts to drive horribly. It almost dies while idling, it cuts out/bucks/hesitates above 2500 rpms. It never stalls but it's almost impossible to drive. I have tried several things since: assuming it's bad gas I put in fuel injector cleaner, a water remover and 3 gallons of 93, changed the fuel filter then ran the tank through-no change; I changed the EGR valve and pipe- no change.
I pull my new spark plugs out (bosch platinum +4) and the are covered in icky blackness. I check the crankcase breather element and see more icky black junk.
After reading several threads that pointed in the direction of the throttle position sensor I replace with a new one and again no improvement.
So I go and have the codes read again. This time it's saying IAT sensor malfunction, MAF malfuntion and O2 sensor malfunction. I checked the wires on the IAT and MAF and can see nothing wrong. What is causing this problem? Please help!


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## GeoBMX4Life (Mar 25, 2010)

Check the continuity, from the MAF to the CPU. This sounds like a airflow meter/MAF malfunction, if the wires are comprimised, the codes will point to the MAF/airflow meter. As ZG would say, keep us posted!


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## dvdswanson (Nov 6, 2005)

check the TPS, it doesn't always set a code, I had the same symptoms on mine yrs ago.


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## NavyDoc (Jun 30, 2010)

Thanks for the replies so far. I was talking with my dad this morning going over the timeline of when this problem started and he has a theory that my catalitic converter is clogged. (he worked on cars for many years, long before everything was EFI). It make sense to me because this didn't start until after the seafoam treatment. I'm going to test the exhaust pressure cold vs hot and see if there is a difference.


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## NavyDoc (Jun 30, 2010)

I still need to get myself an ohmmeter...
I checked the exhaust output as best I could, just by feel of the hand. When first started w/ cold engine it's steady but after warming up it's erratic and seems to have less pressure, lots of black crap spraying out onto my hands as well. I don't really know if this determines anything. I guess the only way to really figure out if this is the problem is to have the exhaust replaced. Checked craigslist and there is a guy selling a flowmaster 40 series with 2.25 in/out. I'm thinking of picking this up and having it a local shop do pipe from the intermediate pipe back. No inspections in South Carolina so no worries about eliminating the cat. 
On a side note, wondering if anyone has done a setup like this on the KA24E? I don't know a lot about how back pressure is achieved but I imagine that the cat plays a role. Im concerned that the muffler alone wouldn't provide enough back pressure for the engine to run as it's intended. But the again what do I know. I still haven't changed the O2 sensor out but I didn't think that a bad O2 sensor could cause this many problems.


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## GeoBMX4Life (Mar 25, 2010)

Here's a link to another thread that may help.
http://www.nissanforums.com/hb-truck/160496-catlytic-converter-troubleshooting.html


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## NavyDoc (Jun 30, 2010)

That helps a lot! Thanks for that link. Hopefully I can get this thing off tomorrow and take a look.


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## GeoBMX4Life (Mar 25, 2010)

No worries, just let us know how you make out.


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## LOUD88 (May 6, 2010)

try changing back to factory plugs the factory plugs are what the engineer designed engine to run best with. Putting the (bosch platinum +4) in give no advantage and arent good from my experience with em causing missfire and poor running engine (lack of power) hope this info help bud.


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## NavyDoc (Jun 30, 2010)

I forgot to mention that once I pulled those plugs out they looked pretty bad so I put in new stock plugs. I carefully gapped each one to specks and that actually seemed to smooth out the idle a good deal but the problem persist once the engine is fully warmed up.


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## NavyDoc (Jun 30, 2010)

I changed the O2 today, all I had time for. The sensor was really messed up. The shroud was completely gone and the actual sensor tip was black and looked like it had been snapped off. Either i've been running very rich for a while or high amounts of ethanol have been making their way into my gas tank. Maybe i'm wrong. Either way im still having the same problem. I'll take off the cat tomorrow.


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## NavyDoc (Jun 30, 2010)

I pulled the cat off. I can see straight through it. Tried to run the truck without it the same thing is happening. As soon as it's warmed up I get the erratic hesitation and won't rev over 2500 rpm, it just cuts out. I still haven't gone the route of test the sensors or adjusting the TPS. I still need to do that before I completely give up.


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## GordonW (Jun 25, 2010)

I'd be tempted to try another ignition coil/power transistor on there. Sounds suspiciously like weak spark to me. 

Is there anywhere that you can take it, that can put it on one of those analyzers and tell if the ignition spark is strong enough from the coil? That might tell you something...


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## NavyDoc (Jun 30, 2010)

There's no ignition coil that I can see. There is wiring going from the distributor to the cab. I'm gonna have to take this thing somewhere to get it checked out.


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## GeoBMX4Life (Mar 25, 2010)

Take your airfilter out and take the entire air breathing case off...the airflow meter is on the left hand side, 3 philips screws and take the meter off, there are two wired diodes...if even one is gone, you need a new airflow meter. This sounds EXACTLY like what I just went thru.


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## NavyDoc (Jun 30, 2010)

I took a look and i only see one red diode. It is still connected as far as I can tell. i also took a look a pic of a new and there is also one red diode. I really hope that it's something as simple as needing a new sensor.


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## GeoBMX4Life (Mar 25, 2010)

*no color*



NavyDoc said:


> I took a look and i only see one red diode. It is still connected as far as I can tell. i also took a look a pic of a new and there is also one red diode. I really hope that it's something as simple as needing a new sensor.


 The airflow meter isn't colored... once you take the AF off of the side of the throttle body(TB), the sensor is is 2 1/4inch posts with 2 micro-wires(offset) with a diode in the middle...if the micro-wires on either side are broken, you will run SUPER RICH...and get nothing for power after 2500rpms.


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## dvdswanson (Nov 6, 2005)

check the TPS, if you replaced it then check to see if the tab is on the correct side on the pedal for the TPS. been there, done that.


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## GeoBMX4Life (Mar 25, 2010)

I thought the same, but the TPS will be a very inconsistant idle...AFM/MAF doesn't let the rpm above 2500...just my experience.


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## NavyDoc (Jun 30, 2010)

GeoBMX4Life said:


> The airflow meter isn't colored... once you take the AF off of the side of the throttle body(TB), the sensor is is 2 1/4inch posts with 2 micro-wires(offset) with a diode in the middle...if the micro-wires on either side are broken, you will run SUPER RICH...and get nothing for power after 2500rpms.


It was too late last night to think straight. I was thinking you meant the air temp sensor. I see now that you meant the mass airflow sensor. This all started the day after I cleaned the MAF. I used CRC MAF cleaner and followed the directions. Both wires appear to be intact. What could I have done to cause this? Also, my MAF is held on by 2 screws, not 3. Don't know if that makes a difference.
For the TPS, since I don't have a multimeter is there any other way to determine if it's properly adjusted? When I replaced it I tried to make sure it was at the same angle but from what I'm reading about TPS it's all about getting the proper reading on the multimeter by rotating it.


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## dvdswanson (Nov 6, 2005)

GeoBMX4Life said:


> I thought the same, but the TPS will be a very inconsistant idle...AFM/MAF doesn't let the rpm above 2500...just my experience.


actually no, mine idled fine and when I would accelerate it would crap out around 2200-2500 rpms because the sensor wasn't giving a correct throttle position reading so the ECM would put it into safe mode.


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## NavyDoc (Jun 30, 2010)

Sounds similar to my problem as well.
I checked the sensors again. A wire was disconnected to the air temp sensor. I reconnected it and disconnected the battery for 10 mins (i don't have a clue how long it takes to reset the computer). I started it up and still have a CEL on. Probably the MAF sensor still giving me problems.


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## NavyDoc (Jun 30, 2010)

Had my MAF sensor checked at a shop today. Guy said he was getting 1.0V after the engine was started and then it dropped 0.65V after it was warmed up. If the MAF sensor was moved or "wiggled" then the volts would jump all over the place. Looks like something is jacked up.
Here are pics of the MAF sensor.
Anyone see anything wrong?
Sorry the first pic is blurry.


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## GeoBMX4Life (Mar 25, 2010)

From the pic, the 2 wires look to be intact, but if the voltagfe is inconsistant, there has to be a break somewhere. PM Zanegrey, he said he has a few of these relatively cheap.


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## NavyDoc (Jun 30, 2010)

Thanks Geo. I sent him an e-mail yesterday. Just keeping my fingers crossed in hopes that he has one.


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## screamingscotty (Apr 28, 2006)

Sorry but having the same issue and was wondering if you ever got this fixed.


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## NavyDoc (Jun 30, 2010)

Yes, i had to get a new MAF, ended up finding one locally. It got the truck running but it's still messed up. The next thing I need to look at is the TPS. I messed with it during the time the truck wasn't running and I think it needs to be adjusted.


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## Nosyt (Sep 2, 2010)

Having the same issue - Truck bogs out at 2500 RPMs almost like it is hitting a governor. Wondering if you've been able to test/adjust the TPS properly and if it solved your problem.


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## SPEEDO (Jun 9, 2003)

sounds like the truck is in "safe mode", have you checked the codes?
(mine went into safe mode when I lost a injector)


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