Shiboh Posted March 2, 2020 Share Posted March 2, 2020 Just bought the FAST EZ-EFI kit from Z Car Depot for my 1983 280zx. Put it on my car the other day and it runs worse than it ever has. Car will idle but is very hard to start and really rough when it's running. Using any more than 1/4 throttle will stall the engine. When I am able to rev the engine it's terribly rough. Feels like or an ignition timing issue. I know that when I removed the old EFI harness I disconnected a connector going into the distributor and the new harness did not have a connection to plug back in to the dizzy. Since adding the EZ EFI, ignition timing has retarded itself about 10 degrees at idle. Advancing timing does not help the issue. I have setup the ECU with all the correct parameters listed with the info from zcardepot. ECU doesn't throw any codes, all readings seem mostly normal for not being tuned. It feels like it could be a vacuum leak or vacuum not hooked up correctly as well however my vacuum readings are perfectly normal. Has anyone else has this issue? I will add pictures of the engine in it's current state along with the connections that were left unplugged when adding the EZ EFi kit, Including the oil temp sensor. Does this stuff really get left unplugged? Quote Link to comment Share on other sites More sharing options...
madkaw Posted March 2, 2020 Share Posted March 2, 2020 How is it even firing at all with no connection at the dizzie ? Quote Link to comment Share on other sites More sharing options...
Shiboh Posted March 2, 2020 Author Share Posted March 2, 2020 (edited) @madkaw Well there is still a connector plugged in to the cap of the dizzy which I assume is part of the ignition harness or something. The plug I removed was attached only to the EFI harness. Edited March 2, 2020 by Shiboh Quote Link to comment Share on other sites More sharing options...
silverado22c Posted March 3, 2020 Share Posted March 3, 2020 I don't have the kit, but I think you disconnected more items than you are supposed to. The FAST EZ is supposed replace the fuel related side, not the ignition side. I believe you should not disconnect the oil pressure sensor, as that is tied into the ignition harness. Same goes with the connector to the dizzy. Have you or someone pulled the harness apart and swapped the routing at a previous time? Take the oil pressure and dizzy connector out of the fuel harness and run back to their locations. Also wondering if you set up the O2 sensor required in the system. Quote Link to comment Share on other sites More sharing options...
NewZed Posted March 3, 2020 Share Posted March 3, 2020 Surprising that it even started. What was wrong with the 1983 EFI computer? Why did you decide to buy the FAST EFI kit? Might be a clue. You showed a picture of your cylinder head temperature sensor, not the oil pressure sensor. And there are two connections on the ZX distributor, one for timing retard when cold and one that controls the coil. Luckily, apparently, you disconnected the one that controls retard when cold. Your coil control wires are still connected. Timing probably still advances when you rev the engine, because that is mechanical and vacuum. There is really no such thing as a plug and play engine control system. You have to know some basics of how your engine control system works, even if you don't know how to tune. You'll have to read through the instructions and the 1983 FSM and compare parts, or find somebody that knows ZX's, I think. https://www.fuelairspark.com/software-downloads 1 Quote Link to comment Share on other sites More sharing options...
Shiboh Posted March 3, 2020 Author Share Posted March 3, 2020 @silverado22c The only things I removed from the car were the ecu and everything that plugs into it, including the dizzy connection to the ecu and connection to oil sensor, which I thought this kit would have replaced. The efi harness is one piece so I don't know how I could have messed with the ignition harness. And as far as I know this engine has never had any work done to it besides normal maintenance, and the harness looked like it hadn't been touched since the factory. In order to run those connections back to their origins I would have to splice into the new harness, but the new ecu doesn't read either of those signals. I think I'll just wire up the sensor directly to my gauge if that will work. And I did add the new O2 sensor, however in the process I found a huge exhaust leak at the header, so it probably doesn't help much at the moment. Quote Link to comment Share on other sites More sharing options...
NewZed Posted March 3, 2020 Share Posted March 3, 2020 I'm going to guess that the reason it doesn't respond to throttle is because you have a MAP sensor issue. The MAP sensor tells the ECU how much air is entering the manifold. Quote Link to comment Share on other sites More sharing options...
NewZed Posted March 3, 2020 Share Posted March 3, 2020 https://zcardepot.com/products/fuel-injection-retrofit-kit-fast-efi-280z-280zx Quote Link to comment Share on other sites More sharing options...
Shiboh Posted March 3, 2020 Author Share Posted March 3, 2020 @NewZed I bought the kit with the intention of cleaning up the power band really, the engine ran great before, but would stumble and lose power under load. I narrowed it down to the ecu. Thanks for your insight on those connections. So that plug on the dizzy is only for timing retard when cold, is that needed? And my MAP sensor is actually reading more than .5 atmospheres at all times. Quote Link to comment Share on other sites More sharing options...
NewZed Posted March 3, 2020 Share Posted March 3, 2020 (edited) The MAP sensor reading should go up and down with throttle opening. It's like intake vacuum. But absolute. If it stays constant there's a problem. You can read some of the Megasquirt threads to learn concepts. I think that FAST is supposed to "self-adjust" but it will only do that if the inputs are correct. It's a good learning opportunity. Good luck. And you need the cylinder head temperature sensor. It measure engine temperature. Without it you'll run really rich or really lean. Both bad. Edited March 3, 2020 by NewZed Quote Link to comment Share on other sites More sharing options...
silverado22c Posted March 3, 2020 Share Posted March 3, 2020 Well, that kit is self tuning from the beginning, so that leak can be a major cause of your issues. I have seen other videos on YouTube about setting the base numbers to something different to have better idle and running conditions. You would be surprised how small of an exhaust leak can lead to setting codes in modern vehicles, as I removed many from Range Rovers during a major recall. They would be hairline cracks that you could barely see, but the O2 levels would be effected. So get that exhaust fixed and play with the base tune. Quote Link to comment Share on other sites More sharing options...
Shiboh Posted March 3, 2020 Author Share Posted March 3, 2020 I think I have found the issue. Engine was being flooded beyond belief. The spec zcar depot told me to input for fuel is way too high. After messing with the settings I found that 19lb/hr at 20psi for the injectors seems to be where it needs to be. I had to set AFR as high as I could. Fuel trim to -8 on every setting.Car runs much better and will rev to redline, however it's still extremely rich and backfiring still stalling if i use too much throttle. And @NewZedmy map reading does go up with throttle, it just stays high at idle. I have no way to plug the cylinder head temp sensor to my new ecu so I will probably call zcardepot tomorrow and ask them about these missing connections, if they know anything. And @silverado22c that makes sense, I'll have to fix that asap. Thanks for your replies ya'll I appreciate the help. Quote Link to comment Share on other sites More sharing options...
NewZed Posted March 3, 2020 Share Posted March 3, 2020 Without the CHTS the engine will think it's arctic cold and add lots of extra fuel. It's also called the coolant temperature sensor. If you start adjusting the wrong parameters to make up for incorrect connections you can create a big mess. You need the CHTS. Sounds like you're making progress thouigh. Quote Link to comment Share on other sites More sharing options...
Shiboh Posted March 3, 2020 Author Share Posted March 3, 2020 @NewZed Ah okay, well that's definitely what's making me run so rich i think. Although,I added a new coolant temp sensor that connects to the ecu from the front of the engine where the radiator hose connects. Wouldn't this compensate? Or must I have both of those sensors working for a proper running engine? Quote Link to comment Share on other sites More sharing options...
NewZed Posted March 3, 2020 Share Posted March 3, 2020 I don't know how zcardepot designed their system. Did they have you install a new sensor? Make sure that it has resistance that varies with temperature. That's how you would troubleshoot your Nissan system. Check at the ECU connector. Do you have an "app" to see what the ECU sees? A dashboard? If you have tuning capabilities then you should be able to check your inputs by computer/phone. Should be fun... Quote Link to comment Share on other sites More sharing options...
Shiboh Posted March 3, 2020 Author Share Posted March 3, 2020 @NewZed The kit came with a new coolant temp sensor to put in place of the old one. This sensor attaches to the radiator hose inlet on my intake manifold.I'll try to test the resistance tomorrow. The kit came with an LCD screen on which I can basically tell the ECU what engine it's running with and that's about it. Took the car for a drive and the system seems to be working good. I think I'll let the ecu work out what it wants to and if I still am running rich then I'll have to look for more about that CHTS. Quote Link to comment Share on other sites More sharing options...
silverado22c Posted March 3, 2020 Share Posted March 3, 2020 The FAST EZ system from Zcardepot only uses the 1 coolant sensor in their kit, not the 3 like factory. Newzed, your info relates more to stock set up, not the EZ set up that uses GM parts. Like I said before, repair that exhaust leak 1st, as the O2 sensor is the major component used to allow for proper self tuning by the EZ ECU. Also look up YouTube videos of the EZ system that had been installed to Datsuns and one of those videos shows the base settings they used instead of FAST initial numbers, where they had the same rich issue as you. Most of the coolant sensors are on the ignition control side, to change timing at certain temp levels, either cold start or like at the 100 degree level. The single pin is for temp gauge, large sensor under that is for cold start, smaller coolant is for warm up feed back, and the grounded coolant sensor on the side is for timing adjustment at warm up. So ignition side coolant sensors stay and fuel side goes with EZ kit install, I believe. At least this is what I see for the 1975 280Z, I don't know what the system differences are for your 1983. Quote Link to comment Share on other sites More sharing options...
Shiboh Posted March 3, 2020 Author Share Posted March 3, 2020 @silverado22c Ahhh I see. Thanks for your insight. Everything is starting to make sense slowly. Weird that this kit removes so many sensors without replacing them. I noticed that my O2 correction in the ecu is all over the place, so yeah the headers are next on my list I guess. And the EZ EFI is the same for all the 280's I believe, if it's from zcardepot. Quote Link to comment Share on other sites More sharing options...
NewZed Posted March 3, 2020 Share Posted March 3, 2020 10 hours ago, silverado22c said: not the 3 like factory. You're getting coolant switches confused with the single coolant sensor. The problem with internet advice is you can't tell if it's right. That's why I suggest learning how your system, and the factory system, works instead of just doing odds and ends. You have to know at least the basics. So that when the problem is still there after fixing the exhaust leak you'll have a path forward. Quote Link to comment Share on other sites More sharing options...
NewZed Posted March 3, 2020 Share Posted March 3, 2020 O2 correction is normally off or on. That's how it works. It swings back and forth, over the stoichiometric point. Again, this is a basic. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.