1993 Nissan Hardbody Skip/misfire

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Dec 4, 2011
Location
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Any help/input would be appreciated! I don't like throwing parts @ cars too solve problems but I'm almost at my witts end! BACK STORY-------1993 Hardbody SE V6 4x4 with a handshaker gets towed in with a no start complaint. Find timing belt broken and valves crashed customer doesn't feel like fixing the truck so i Bought it. Has ALL new valves, head gaskets, Timing belt, Distributor Cap and Rotor and spark plugs and wires. Has a slight missfire when idling and a slight surge when under load and under light throttle.

I have since changed too NGK V power plugs and NGK wires, Napa Premium Dizzy Cap and Rotor New Napa premium coil. New Fuel Filter. Cleaned injectors Using a SUBAR Cleaner and B12 Carb clean Direct thru fuel injectors. STILL MISFIRING!! Smoked entire intake manifold and found 2 small vacuum leaks repaired those. Replaced injectors 2-4-6-5 with reman Injectors and new Injector pigtails as they are known too fail. Cleaned MAF

Using a test light and backprobing old plug wires i narrowed the skip too cylinders 4-5 Checked compresssion on those 2 cylinders and 110 psi. And still a rough idle when on the gas truck runs like a champ!!!! When under load and slight throttle on small incline can feel the truck surge/Skip

Snap on Verus has no data and no codes in system. My next step is too change the 02 sensor i know they dont typically cause skips but if its reading wrong and not adjusting fuel trim accordingly maybe?!?

ANY INPUT WOULD BE GREAT!! ANYONE SEEN ISSUES LIKE THIS? THANKS IN ADVANCE!!
 
If that's a VG30E, it's likely the TPS or MAF. I used to have a Maxima with that engine like 20 years ago (I'm going to go drown my sorrows after realizing how long ago that was). I chased MAF problems all over the place with that engine, and had a string of bad reman units in the process. Actually, that was my '93 SE with the VE30DE, nevermind. My other Maxima with the VG30E was something different.
Could also be a minor timing problem or distributor issue, not related to the cap/rotor.
Knowing that it's a cyl 4 or 5 misfire likely won't tell you anything, as an ECU can sometimes take a certain amount of time to try to adjust things as it goes through the firing order based on crank and cam position. I think that's likely a false positive to look at a particular cylinder. May be a sign of a position sensor problem though.
 
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a_kelley said:
Still, a compression test and hot leak down never hurt.
I have not done a check on the other cylinders as they didnt show too be skipping. Weirdly enough it is running a little better. I plan on changing the 02 sensor tomorrow too see if that helps. Maybe not switching or not adjusting fuel curves properly?
Click to expand...
 
Fabrik8 said:
If that's a VG30E, it's likely the TPS or MAF. I used to have a Maxima with that engine like 20 years ago (I'm going to go drown my sorrows after realizing how long ago that was). I chased MAF problems all over the place with that engine, and had a string of bad reman units in the process. Actually, that was my '93 SE with the VE30DE, nevermind. My other Maxima with the VG30E was something different.
Could also be a minor timing problem or distributor issue, not related to the cap/rotor.
Knowing that it's a cyl 4 or 5 misfire likely won't tell you anything, as an ECU can sometimes take a certain amount of time to try to adjust things as it goes through the firing order based on crank and cam position. I think that's likely a false positive to look at a particular cylinder. May be a sign of a position sensor problem though.
Click to expand...

I may throw a maf on it later on but doing the cheaper stuff 1st lol. I hate OBD1 stuff for this reason! Especially Japanese. @ least GM and Ford obd1 have decent data lol
 
Diagnose it and don't just throw parts at it. You can check every sensor with a meter or digital test light. I bet if you add up all the cheap parts that it's more than just the right expensive one.
 
Swapped the 02 today and it runs at least 50% better at idle. This is mindboggling too me. Normally skips get worse when applying throttle but not this one. It runs fine on the gas and the surge i feel is gone whilst driving. @a_kelley i agree 100% normally its the easiest cheapest part that fails. IN my case I'm self employed so any $ i put in the truck is a tax write off at the end of the year so its not exactly a lost cause. In my eyes parts are 20+ years old and bound fail eventually!
 
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