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High Rpm miss / engine died / old but new timing belt

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High Rpm miss / engine died / old but new timing belt

Old 05-10-2014, 12:12 AM
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High Rpm miss / engine died / old but new timing belt

Hello,
I recently bought a 93z n/a 5 speed from a friend. It's got 185,000. It had tons of normal repair work done already before he bought it. He did some things including new MAF, a few new injectors and new plugs. I added a 1 piece drive shaft (old one was toast), power steering pump, tie rod end, and a 2nd set of new plugs and 2 new coil packs. It's got a high rpm misfire that my friend was trying to fix when he replaced the MAF and the 2 injectors. Recently while driving at 60mph the car died. It then restarted when I pushed the clutch in. A few days later it died right after being started when I left for work, and would not start. Later that night I made sure the plugs were tight on the PTU (I've been reading these forums) and it re-started no problem. I didn't drive it, I ordered and installed a new PTU (old one in bad shape, and ALL plugs full of green corrosion). I cleaned everything with electronic contact cleaner, added permatex grease and turned the key. Car ran great. Still had a slight miss, but given the condition of the car and the connectors, I figured I need to clean them all. Drove it to work today no worries, tonight on the way home it died, restarted, then died again and needed towed to my mechanic. My Question? Besides the obvious checking the codes on the computer (never a check engine light) and checking for spark is there anything else I should look at? Fuel pump maybe? And according to the receipts, Nissan replaced the timing belt and water pump and tensioner at 165,000-but that was in 2006!!! Should I do it again? Any help would be appreciated.
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Old 05-10-2014, 08:50 AM
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Connections

Welcome to ZDriver forums and congratulations on getting an Older Z. Thses babies do have some issues, mostly with corrosion in the wiring connectors under the hood. A member on the site, Fricfrac has assembled a connector package to replace the EFI, MAF/MAP, TPS and a few other similar connectors under the hood, I did a conversion on my 81 280zx(oddly enough, most of the connectors remained the same for many years). You could PM him, I am pretty sure he could make up a set for a z32.
On the timing belt question, I know the VG30DE needed a new belt every 60 to 80 K, and with just 20k miles in 8 or more years, the car must have set for some extended periods possibly ? That would be my only concern, that there might be flat and round spots formed in the belt from sitting, you could remove the belt cover housings and take a look, normally at the time of the timing belt change a few other goodies are replaced, since getting to them is impossible without tearing it down again, like the water pump and some seals on the cams, new tension-er and the bolt that holds it on too, it can fail if reused. A bad belt is a ticking time bomb, since these are interference engines, the valves and pistons will make contact if the belt breaks.
Also a star grounding system is very useful for eliminating any open grounds or ground loops that have occurred from corrosion, by tying your essential electronic grounds together with the negative on the battery, not the body or frame. The easiest method is to pick a central location, firewall, fender and bring a lead from your neg battery, your ecu, your plenum/ intake (most sensors get they're ground from the plenum) and tie them all together.
By eliminating bad grounds, and cleaning up the corrosion, restoring signal to everything should be the ticket, but its a lot of mucking around and doing all the fiddly bits of tedious work, but very satisfying when the old beast runs and doesn't let you down.

Good luck with your car and keep us posted, pictures are always appreciated.

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Old 05-12-2014, 10:07 PM
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Thanks PredatorZ! It was the PTU, I had a bad connector and 2 of the pins were not contacting properly. Fix the connector, and she runs great, took care of all the miss firing. I'll post some pics when I take a few, the ones I have now are not good enough to post LOL. Last question: Clutch seems to be in good working order and not slipping/growling, but at 60mph in 5th when I floor it the rpm's rise for a couple ticks before I notice the car is accelerating. Does this sound normal to you? Again, it's only in 5th gear-all other gears respond NOW.

Thanks,
Denny
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Old 05-13-2014, 04:40 PM
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1st signs

Those are the first signs of an oily or worn clutch, as long as you are driving in a relatively flat area you should be fine for a good while. Unless you really drive it hard, it should still have plenty of service left in it. Another test is driving up a fairly steep hill, stop if you can and resume, should be pretty easy to tell if it is slipping.
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Old 05-15-2014, 12:57 PM
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Originally Posted by PredatorZ View Post
Another test is driving up a fairly steep hill, stop if you can and resume, should be pretty easy to tell if it is slipping.
Might be better to try reversing up the hill you're on so if your clutch is too far gone you just cruise down the hill as if nothing ever happened.
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