# 97 4x4 missing at cruising speed, power loss



## mgiles (May 30, 2014)

I have a 97 XE King cab 4x4 and it has started missing at constant throttle and gas mileage is 15mpg. I have noticed that the miss seems to be worse once engine reaches operating temp or if outside temp is hot. This is when it loses power. It was throwing a EGR low or no flow code and found vacuum line from BPT disintegrated. I replaced it. I disconnected battery and it erased codes. I have scanned ECM but it has no stored codes. I did check operating data and this is what it showed:
Load value: 29.8%
MAP sensor: 9 in/hg
RPM: 775 but tach showed 1100
Ignition timing:10 deg
Intake air temp: 143 deg
Air Flow: 0.46lb/min
Throttle Position: 0% and didn't change every time I presses throttle
o2 sensor 1 bank 1: 0.200 to 0.800v
02 sensor 2 bank 1: 0.780v steady
sensor 1 rich-lean: 0.430v
lean-rich: 0.480v
sensor 2 same as 1
data checked at operating temp at idle
I have changed spark plugs, distr cap, rotor button, fuel filter, cleaned maf sensor, air filter, canister purge solenoid, timing chain, water pump, oil pump, front oil seal, belts, oil, and all drive fluids. Truck has 218,000 miles
Anyone have any suggestions as too what could be causing problem


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## jp2code (Jun 2, 2011)

mgiles said:


> I have changed spark plugs, distr cap, rotor button, fuel filter, cleaned maf sensor, air filter, canister purge solenoid, timing chain, water pump, oil pump, front oil seal, belts, oil, and all drive fluids.


Did these problems start before or after you changed the parts?

If AFTER, did you keep some of your old parts? Particularly parts like the distributor cap, rotor button and canister purge solenoid.

If so, try swapping parts back in. One of your new parts may not be too good. Did you buy Genuine Nissan parts or the cheapest thing the auto parts store carried (Chinese goods)?


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## mgiles (May 30, 2014)

I replaced with genuine Nissan parts. The only thing I have replaced since this problem started was distributor cap and rotor button, plugs (NGK), and the fuel filter. None of these helped. The purge solenoid was replaced due to evap code which cleared when replaced. The miss problem started after adding seafoam to the gas tank, but it may just be coincidence.


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## jp2code (Jun 2, 2011)

The SeaFoam could have loosened stuff in the gas tank or fuel line - clogging your fuel filter.

The fuel filter is easy to replace. It's a "mini soda can sized" canister in the engine bay between the battery and the back firewall.


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## mgiles (May 30, 2014)

I replaced the fuel filter this weekend and it did not help. I have seen on forum that the distributors are prone to failure. Could this be causing the problem? only reason I ask is the power loss after it reaches operating temp or during hot weather. I did drain the gas from the old filter and it was clean and not discolored.


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## jp2code (Jun 2, 2011)

I know some have replaced the distributor and it fixed their problem, but I don't understand what lead those people to ever suspect that component. If the ECU were throwing a Bad Crank Angle Position Sensor code, then I'd think to replace the distributor.

Is there anyone else in here? Hello? How do we test a distributor? That's a lot of coins.


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## TheRepairMan (Jun 30, 2009)

Well, I'm sure there are techies and test equipment out there to check a distributor's components, but not many shops that I know of actually do that sort of testing. I know how I test a distributor... I go get another one and drop it in to see if that fixes the problem. Most stores will tell you they won't take it back if it's been used, but just tell them you need to try it to make sure that's the problem. If they won't let me do that, I just tell them I'll go buy it somewhere that will.

You could always attempt to find one at a salvage yard, but I'll bet that would be the "needle in a haystack" story.

Another thing that went wrong on my own truck that caused similar symptoms was the Mass Air Flow Meter. There are tests here on the board somewhere to help diagnose that. I had to replace the throttle body on mine. If I had it to do over I would try to clean it first, but at the time years ago I did not know that was an option. They actually do make throttle body cleaner now.

-R


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## mgiles (May 30, 2014)

Thanks for the response guys. I did remove the MAF sensor and inspect the hot wires. They were intact and looked ok. I cleaned them according to instructions I found on the forum. I will look some more and see how to test it to see if it is ok. The guy I bought it from said he had replaced it. It is a hitachi sensor. Not sure if it is oem or not. I also used throttle body cleaner and cleaned the throttle body.


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## jp2code (Jun 2, 2011)

He said he replaced it? So, did you buy the one he replaced with a new one? You may have gotten a bad MAF sensor.

But, a bad MAF signal should cause a code to show up.


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## mgiles (May 30, 2014)

I did not buy the MAF sensor. The seller said he replaced it prior to me purchasing truck. It has never threw a MAF code when I have checked them. Only EVAP codes which I have replaced parts and no new codes. I have checked vacuum lines and can not find any leaks. Truck does have a manifold gasket leak but not sure if this can cause the problem I am having. I'm at a loss. I don't want to just replace parts trying to fix.


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## jp2code (Jun 2, 2011)

Exhaust manifold leak would make your O2 sensor read incorrect values.

An intake manifold leak would create a world of issues.

When manifold leaks happen on motorcycles, exhaust leaks can cause popping and backfires while intake leaks make the engine operation unpredictable.


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