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surges/misfires on acceleration at normal running temp


94mudrat
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Hi.

Iva 94 V6 manual Pathmaker.

it was surging/misfiring so i changed the distributor cap and rotor button and the problem seemed to be fixed but only for a couple of days, now it starts great and run perfect until it reaches normal running temperature and surges and misfires when accelerating under load (up to 2700 rpm) but it still idles perfect and starts perfect there is no engine light on. I would also like to know if the ECU diagnosis would show faults when the engine light is not coming on?

 

 

any and all help is greatly appreciated

 

cheers

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Yes it will show some faults (stored codes)

did you do new plugs and wires when you did the cap an rotor?

are the plugs gaped correctly?

Is your timing @ 15 deg?

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thanks guys, i done the plugs yeasterday and my auto shop just got my leads in (120 bones aus) so i'm hoping its it coz i'm running out bones real fast here.

 

I wonder if the catalytic converter will show up on the ecu diagnosis

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ECU only showed; code 12 = MAF

I took it off and it was rather clean so i cleaned it anyway and that hasn't helped its still the same.

now i'll try and source a second hand one.

Does anyone know if other nissans such as maxima's, navara's or 300zx's use the same MAF ?

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check your connector on top of the MAF.

 

It is a known point of failure. Could be a harness issue. Follow diagnostic proc 24 in the FSM (pg EF & EC 84)

Edited by k9sar
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defiantly check the wire going to the maf. my freinds pathy the hood would make it act kinda like yours becasue it put a short in the maf connector due to years of it hitting the hood. Where are you located? If in the US and u still want a used one from my old 93 i parted out let me know. SOmeone already has dibs on it but if they dont want it i was thinking about 30 bucks +shipping

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defiantly check the wire going to the maf. my freinds pathy the hood would make it act kinda like yours becasue it put a short in the maf connector due to years of it hitting the hood. Where are you located? If in the US and u still want a used one from my old 93 i parted out let me know. SOmeone already has dibs on it but if they dont want it i was thinking about 30 bucks +shipping

 

 

Thanks mate, I'm from Sydney in Australia, I can locate a 2nd hand maf from a few places but i'm not 100% sure the maf is the problem, If i take the maf plug off it runs even worse. i checked the wires with a muti-meter and theres definitley current running through.

 

This issue only happens when the motor is at running temp and at running temp it idles fine, if i turn it off and wait a few minutes it will start up and drive well for the first minute or so and then it occures again.

 

Thanks for your offer though you're a top bloke cheers.

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Yep got a maf off a navara works better but maybe need to give it a clean :clap:

the code 12 is gone and i'm getting 55 so :aok:

i'm about to take it for a decent drive and see how she goes.

i've only owned the old girl for 4 weeks and haven't seen even one spec of dirt yet.

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bugga it happened again today :scratchhead: i ran the ecu codes and got 55 so i'm not real sure why but after i got going again it was ok, i drove around for 1/2 an hour or so and there was no problems. i'll take it for another rap around block later. the only thing i can think of is i maybe cleared the error when i ran the ecu codes :scratchhead:

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I put a tank of premium in this weekend.. and it seemed to help. ...... the surge went away... not sure it will last.. but it sure lasted enough to get me up here! WAVEY ... .I'm thinking an injector issue..?? dirty injectors??

2932967690104806154S600x600Q85.jpg

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I still have my issue with misfiring but I think it may be because my pathy was meant to pass emissions in CA and since I added the high flow CAT and headers that the ECU might not be able to provide enough fuel to compensate for more air running through. It could also be a leaky or faulty injector but the misfire is random, not in time. Also, it doesn't do it when I first start the truck. It takes about 20 - 30 seconds before it starts. Now that I am out of warranty I may (that's a big may because I am saving for a house) get new Jim Wolf cams and have the computer upgraded. I would need new lifters too so the price goes up about $400 just for them.

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If the headers weren't balanced properly you may have problems with a random misfire perhaps, the hi-flo and headers won't do a real lot for a stock engine eccept make it louder with 3% horse power gain. I think you should get it running properly first before you spend more on performance enhancing. but for sure lumpy cams and a worked head would be nice i think you won't get much change from 4 G bangers($4000) if you do it right.

But if you go too lumpy certain 4wd tracks will give you grief but you'll be blowing the doors off any other SUV around town.

If your rig is just for off-road mud tracks and full-on hill climbs i recommend 4 cylinders everyday.

I had a Z24 Navara before this pathy and the old zed would leave this pathy for dead when comes to off-road

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bugga its happened again pathy runs rough when its at correct running temp, no codes other then 55 ive changed everything i can think of.

 

HAS ANYONE GOT ANY SUGGESTIONS AS I'M ALL OUT OF IDEAS

 

The ecu was getting code 12 but another maf has cleared that.

Plugs, leads, dizzy cap, rotor button, fuel filter, cleaned maf, sprayed ether around vacuum hoses. what am i forgetting????????????????????????????

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HI ALL

my motor doesn't mis a beat now and then, she completly misfires on all cylinders and runs crap when she's reached running temp. although she runs crap at running temp she never stalls.

does anyone know if a scan tool exist for a 94 nissan ECM?

 

any sugestions are welcome no mater how @!*%ty it may sound :aok:

 

CHEERS

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Here's what I think....

 

O2 sensors big time...It started to do it only when you were up to temp... The o2 sensor will do just that... Technically, the engine will not rely on o2 sensor readings until it is up to temp. So while it waits for it it will make the engine run with a "default" fuel/air mix. Then when the o2 sensor is up to temp, it will vary the the mixture depending on the voltage (between .2 and .8 volts) it receives... I bet you your o2 sensors (before the cat) is / are dead or sending a stupid voltage like 999 volts to your ecu... Then the poor guy tries to adjust the fuel/air mixture with the crap he receives...

 

S.

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I completely agreed with that guy. It sounds like the o2 sensor. Try unplugging your o2 sensor and drive around for a bit. This will default the computer back to open mode. If you notice a difference, then o2 sensor for sure.

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  • 2 months later...
i'll elimimate the 02 sensor next

thanks for the input

Sorry I took so long to get back but I finally got the problem fixed :whocares:

Cheers to the fellas who helped

It was the o2 sensor

 

bolts in the exhaust between the headers and the cat

CHEERS :aok:

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  • 5 weeks later...

i seem to have that same problem so im gonna try this since ive tried and checked everything else i can think of....but my only confusions is that it runs fine once i get up to a fast speed..and sometimes the problem goes away for a few months and then returns and haunts me for a few weeks and angers me...

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