86.5/87 HB D21 surging issues before and after motor swap.

[clockworkdiamond]

Hey, I'm new to this forum (tho I have read it for a long time), but not at all new to Nissan's.This is going to be kind of long, so please bear with me.

The sad story of my 86.5' 2x4 HardBody (z24i) is as follows:Got it used and beat up, but it ran great until one day, it started surging when it accelerated passed about 2500rpm (that's a guess since I don't have a tach). I started troubleshooting it as far as I could until the thing blew white smoke, then black, then died and refused to send anything from the fuel pump at all (though the pump did work if I bypassed the pump relay).

So as it was extremely hard to find any parts for this engine around, I found a z24i on craigslist some guy was selling for another guy that he said worked fine. He said that he saw it run and the only reason the guy ditched the truck it came from was that the trans went bad. Judging by the brand new clutch attached to it, I believed him. He didn't know what year the truck was that he pulled it from before he scrapped it, but he knew it was a 4x4. I found a harness from an 87' HB that fit well (right color wires and all) and ECU and as well. Ripped the old engine out and slapped the new one in complete with harness and ECU. Everything bolted up just fine. Followed the vacuum diagrams that I found for the 87 engine and the damned thing fired right up... I was in total amazement since I guessed on so many things. But guess what? ....It surges when i get to about 2500RPM.

So I have now replaced everything in the truck... Engine, wiring (and all electronics), ECU, Fuel pump... etc. I realize that there is likely something wrong with THIS engine that may not be the same issue as the other and just has EXTREMELY similar issues, but I am so lost in troubleshooting, I think that I don't have a good perspective on it any more. I have read a few forums (including this one) that had different fixes for what sounds like this exact issue... Like one coil is not firing or the coils are swapped (not the case), or the MAF/TPS is bad (no codes at all and swapped with the old to test). The only other thing that I have found on any forum is the timing chain. Which I could believe if it were surging in all RPM's, but has anyone seen this even in a KA (which is basically setup similar), but only at 2500+ due to the chain? If so, I will rip this out this weekend! My other option is to swap to a KA (out of a 240 that a friend is upgrading) Does anyone know if the manual transmission on an 86.5/87 HB 2x4 will bolt right to a KA since they basically look like the same block? Any advice would help greatly.

Thanks for sharing my pain,~D

[Desert Rat]

How does it idle? It sounds like a either a vacuum or fuel delivery problem

Things I'd check for:

New fuel filter?Did you blow the fuel lines to ensure there's no blockage?did you reuse your distributor? Does it have vacuum advance?Look for vacuum leaks. Get a can of carb cleaner and with the truck at idel, spray around all the vacuum fittings you can find and listen for the idle to change. If it does, you've found a leak.

Is this truck new enough to have an O2 sensor?

[clockworkdiamond]

Hi Desert Rat,Yeah, that's exactly what I though too...Put in a new filter and pump. Blew the metal lines with 95psi. Replaced all of the rubber high pressure lines. No advance on the distributor, but I tried a different one (one from the new engine and one from the old). It idles perfectly (I actually replaced the wax pellet too). Replaced all the vacuum lines with new silicone. Pretty sure that I have them right, but you never know. Have not tested with carb cleaner, but I guess that it couldn't hurt. I think that I may have an extra O2 laying around somewhere I could try. I have tried 2 different ones, but I guess that doesn't really mean anything since they are both from 1987 trucks. I'll try a new distributer, O2, and the carb cleaner and post back when I get results. Thanks for the troubleshooting steps!In the mean time, if anyone has any other ideas as well, I'm totally open to suggestion.

And if anyone know if my 86.5 2x4 transmission bolts up to a KA, that would be good to know too.Thanks!

[NM50]

Try running a diagnosis of the ECCS.Take the seat out and turn the screw on the ECM clockwise till it stops then back 1/8 turn and count the red/green flashes.

[clockworkdiamond]

Thanks, but I get no codes at all...(Guess I should have put that in before)....Tried a new O2, tested for vacuum leaks, and tried a new distributer cap to no avail (though I have not actually replaced the entire distributer with a new one)...Ok, just found out something weird... I was under the impression that the motor that I put in my truck was out of an 87', so I pulled an 87's harness and ECU and put it all in. Come to find out, the guy I bought it from has NO IDEA what year it came from. To compound the issue, the block has a "refurbished" stamp on it and the heads appear to be rebuilt as well...so I can't track the year by the numbers on those... I know that my 86.5' ECU plugs in, but will not start it, and the 87' ECU starts it, but has this issue...

Any one know how many years the z24i was used? i know that it was used from at least 85 to 89... Doubt it was an 85 since he did know for a fact that it came from a Hardbody, the 86 does not start it and I am using an 87 right now... I am willing to go through more ECU's if that is what it takes!Any ideas on how to tell what year I should shoot for, or what is likely not to work at all? Does this sound to anyone else like an ECU mismatch issue?It would be seriously cool if that was all I need to make everything work!
Modified by clockworkdiamond at 4:30 PM 11/16/2007

[clockworkdiamond]

IT WORKS!!!!!!!!!!This was an 88' (or 89') motor the whole time!!! I got an 88' ECU off of craigslist, plugged it in and started it up...damn if it doesn't run perfectly now!! and with all of the troubleshooting I have done, every component on the motor is new!!!So...If anyone out there is interested, on an 88' Z24i motor, an 85' ECU does not even fit the harness, an 86.5' ECU fits, but won't turn it over, an 87' will start it, but won't run over 2500 RPM...and an 88 and 89 are supposed to be the same ECU. Thanks for all of the help and suggestions everyone!~D