ZXR_KiD Posted October 21, 2009 Share Posted October 21, 2009 OK car runs great when it runs right, but once the car warms up it fumbles off, sometimes worse than others, usually bad enough I end up sittin on the side of the road till it clears... when it fumbles real bad I can unplug the chts wires and it will temproarily clear and will run fine for another few minutes even after being pluged in. we've discovered when it fumbles you can unhook the plug wires from both #1 and #2 and it makes ZERO difference, no fall off or anything; checked the plugs wires and injectors and everything continues to function properly. I've already replaced the chts and its connectors, as well as the #1& 2 injectors (for giggles and grins really) and nothing seems to help. coil has been swapped with known good coil, as has the dizzy and MAF... after it clears up after unplugging the chts when you pull the plug wires from #1 and or 2 it stumbles as it should. I've been fighting this issue since I've got the car and haven't been able to figure anything out to get it right. anyone who has ANY ideas that I havn't thought of would be GREATLY appriciated. Oh, and just to clear it up before its sugguested I have already dropped the tank and cleaned the ever living heck out of it, as well as completly flushed the lines and fuel rail, and replaced the filters. the only thing I can think of left to try is finding another '78 ECU Quote Link to comment Share on other sites More sharing options...
blackice280zxt Posted October 23, 2009 Share Posted October 23, 2009 have you tried following the wires on the engine harness? I picked up a s130 that was acting in the same way and there were broken wires making the injectors cut out periodically. Differences aside just tryin to help. EDIT: My broken wires were inside the coating not visible Quote Link to comment Share on other sites More sharing options...
ZXR_KiD Posted October 23, 2009 Author Share Posted October 23, 2009 yea we ran a volt meter through every wire from the injectors/maf/coil/ and ecu harness today, can't find anything out of the ordinary... the injectors still fire fuel even when there's no fire, pulled the valve cover to check lifters and springs and nothing visibly wrong in any of them... next step I guess will be pulling the head and checking... sux that '78s are an oddball year on their elecrtrical Quote Link to comment Share on other sites More sharing options...
blackice280zxt Posted October 23, 2009 Share Posted October 23, 2009 off topic there is a 240z in amen I got what I wanted off it You can always make it carbed. It has everything to do it Quote Link to comment Share on other sites More sharing options...
ZXR_KiD Posted October 23, 2009 Author Share Posted October 23, 2009 is it the blue one? cause its carbs where seized up SOLID Quote Link to comment Share on other sites More sharing options...
blackice280zxt Posted October 23, 2009 Share Posted October 23, 2009 nope red the blue one was @ grade A didnt check to see if they wernt seized or not I got lucky with my 260z just cleaned the carbs and I was good to go you can aim me if you want to keep from clutering the forum datsun610t Quote Link to comment Share on other sites More sharing options...
ZXR_KiD Posted October 23, 2009 Author Share Posted October 23, 2009 musta crushed the blue one... it was ROUGH I'll have to swing out there and check it out if the weather holds out enough to warrant it Quote Link to comment Share on other sites More sharing options...
Livin9it2up1 Posted October 23, 2009 Share Posted October 23, 2009 may not sound like the problem but when i first did my motor swap, my alternator would randomly stop charging, it would do something similar to that when the voltage got too low. Something random to maybe check. Quote Link to comment Share on other sites More sharing options...
ZXR_KiD Posted October 23, 2009 Author Share Posted October 23, 2009 thats actually a good point... I wouldn't have thought of it, but its actually a possibility now that you mention it... Quote Link to comment Share on other sites More sharing options...
blackice280zxt Posted October 26, 2009 Share Posted October 26, 2009 you get the booger straightened out? I see you didnt pull any thing off that red 240z Quote Link to comment Share on other sites More sharing options...
ZXR_KiD Posted October 26, 2009 Author Share Posted October 26, 2009 never made it out there, have run the correct '78 tests now that I've found an actual '78 FSM... still no fails... got brave and pulled the injectors out WHILE it was running *during its stumbling phase* everything squirts at proper flow and pressure, found a '78 ECU cheap that I'm awaiting the arrival of. but no good news yet. Quote Link to comment Share on other sites More sharing options...
chipo280z Posted October 30, 2009 Share Posted October 30, 2009 clean all of your connections before you start replacing studd. It usually works. Quote Link to comment Share on other sites More sharing options...
ZXR_KiD Posted October 31, 2009 Author Share Posted October 31, 2009 clean all of your connections before you start replacing studd. It usually works. that was the 2nd thing that was done (dropping and cleaning the tank and fuel lines was first) and has probably been done 3 times or more now, I should be receiving a new ECM here in the next couple days, so being that's the last thing left that hasn't been quadruple checked or replaced, I'm keeping my fingers crossed this is the 7th L28 powered Z between myself and my father, and atleast the 30th L28 powered Z we've worked on, so we're well familiar with the cars and engines, being the first '78 we've come in contact with the electrical system is a little new, but everything elese has been tried... if the ECM doesn't fix it, I beleive I'll be pulling and swapping the entire wireing harness out of the '79 as it will be tri-webber powered when its done. Quote Link to comment Share on other sites More sharing options...
ZXR_KiD Posted November 4, 2009 Author Share Posted November 4, 2009 after receiving a '78 ECM I discovered during the swapping proceedure the one in the car was a '77s, after installing the new one I was able to drive the car about 4x further than its let me get it yet, returning safely to its home in the garage without so much as a sputter. I'm gonna go ahead and say the ECM solved the problem Quote Link to comment Share on other sites More sharing options...
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