SDgoods Posted March 1, 2013 Share Posted March 1, 2013 (edited) So I recently did the z31 ECU/Maf swap on my 73 s30 with 81 l28ET.. It's a full setup from a running 87 Turbo 300zx. Car ran great despite a rich problem before the ecu swap Wired MAF except for the auto clean (for now) + coil to the pin in ECU (keep reading) CAS/degree wheel swap 02 sensor is not yet hooked up but shouldnt need it for open loop regardless. I followed all the write up's to the T sans one thing... My TRE 255 LPH fuel pump is wired through the ignition switch so I didn't wire it through the ECU as it doesnt need the ECU to turn on... Does the ECU need to see some continuity or something of this nature to send power to the injectors? It will start for a second or two and then die. Symptoms are almost identical to when a wire got ripped out of the connector in the old AFM setup, but ive checked my MAF wiring time and time again... Yes, the CAS is the right way up, with the rotor pointing at cyl 1 the big gap in the degree wheel is under the sensor... Aeromotive trick flow FPR (set at 30ish psi with vacuum connected) (disconnected sits at 40+) TRE 255lph fuel pump with surge tank Custom fuel feed line, stock feed line used as return line Front mount intercooler Some cheap BOV P/O installed MSA Downpipe with AEM Wideband uego sitting ~6 inches from the stock 02 sensor location 3" custom after the downpipe Aftermarket Coil, NGK spark plug wires. HKS EVC boost controller ** Aftermarket Throttle switch p/o wired in** Test actually had resistance with throttle depressed (bad?) . Any input would be appreciated as I cannot figure this out! On a side note...my master cylinder has been hissing which directs at the diaphragm being bad and pulling in brake fluid which is also low. Could this contribute to my problem? -Daniel Edited March 1, 2013 by SDgoods Quote Link to comment Share on other sites More sharing options...
Domzs Posted March 1, 2013 Share Posted March 1, 2013 Remove and cap off your vac hose to the brake booster and see if it runs . Quote Link to comment Share on other sites More sharing options...
SDgoods Posted March 2, 2013 Author Share Posted March 2, 2013 Remove and cap off your vac hose to the brake booster and see if it runs . It didn't fix it, it would be too small of a vacuum leak I think anyway... No one has any input on this? Im thinking it has to the be the ECU or the MAF. Ive checked the wiring over and over. Quote Link to comment Share on other sites More sharing options...
loy Posted March 2, 2013 Share Posted March 2, 2013 (edited) Does it run with the throttle slightly open? Does the pump stay on when it's running for a second or two? Edited March 2, 2013 by loy Quote Link to comment Share on other sites More sharing options...
SDgoods Posted March 2, 2013 Author Share Posted March 2, 2013 Does it run with the throttle slightly open? Does the pump stay on when it's running for a second or two? nope, throttle make it die immidiately, even faster than it dies otherwise which is within 3-5 seconds Pump is running no matter what its not run through the ecu. The symptoms are almost identical to when my afm wires were mangled, Im thinkng its the maf or ecu Quote Link to comment Share on other sites More sharing options...
loy Posted March 2, 2013 Share Posted March 2, 2013 Which wiring harness are you using? Quote Link to comment Share on other sites More sharing options...
SDgoods Posted March 2, 2013 Author Share Posted March 2, 2013 Which wiring harness are you using? 81 ET. It ran fine before the ecu swap Quote Link to comment Share on other sites More sharing options...
loy Posted March 2, 2013 Share Posted March 2, 2013 (edited) You verified/matched that it's a 87 ecu? At the bottom. http://www.xenonz31.com/ECUdifferences.html . 81 harness with 81 ecu? Just wondering if you did anything with the resistors. Are you spark plugs fouled with fuel? Edited March 2, 2013 by loy Quote Link to comment Share on other sites More sharing options...
SDgoods Posted March 2, 2013 Author Share Posted March 2, 2013 (edited) You verified/matched that it's a 87 ecu? At the bottom. http://www.xenonz31.com/ECUdifferences.html . 81 harness with 81 ecu? Just wondering if you did anything with the resistors. Are you spark plugs fouled with fuel? according to that its a CA turbo 5 speed. The car it came off I saw running not long ago. Although,one of the ECU cover bolts was stripped, possible they switched the cover with another ecu? Yes it had an 81 harness and 81 ecu. I cut off the dropping resistors and twisted/ soldered the remaining wires together as in the write up. Ill check the plugs tomorrow. Im sure theyre soaked as they were with my AFM issues. Although my wideband is reading super lean while barely idling. That wideband reading may just be a result of the not running right though and is probably not accurate. Edited March 2, 2013 by SDgoods Quote Link to comment Share on other sites More sharing options...
loy Posted March 2, 2013 Share Posted March 2, 2013 Checked timing? Quote Link to comment Share on other sites More sharing options...
SDgoods Posted March 2, 2013 Author Share Posted March 2, 2013 (edited) Checked timing? It hadn't changed since the swap. It was at 20 btdc before. It doesnt even run long enough for me to check it as of now. The adjustment hasnt moved but is it possible I need to readjust it? I can try that tomorrow Edited March 2, 2013 by SDgoods Quote Link to comment Share on other sites More sharing options...
Domzs Posted March 2, 2013 Share Posted March 2, 2013 Try to run it with carb spray , disconnect intake boot and spray it into throttle body . If it runs good then you have fuel delivery problem Quote Link to comment Share on other sites More sharing options...
SDgoods Posted March 2, 2013 Author Share Posted March 2, 2013 I pretty much already know its a fuel synchronization issue. Either the maf is bad, ecu is bad, or the ecu is not getting a correct signal. Id just like some input from some folks who have either done the z31 swap or had the same issues Quote Link to comment Share on other sites More sharing options...
Domzs Posted March 3, 2013 Share Posted March 3, 2013 Would it run with the MAF unplugged ? Quote Link to comment Share on other sites More sharing options...
SDgoods Posted March 3, 2013 Author Share Posted March 3, 2013 ^^ no if i remember correctly it didnt even start/ran worse Quote Link to comment Share on other sites More sharing options...
NewZed Posted March 3, 2013 Share Posted March 3, 2013 Have you read through the EFEC chapter of a Z31 FSM? Page EFEC - 30 looks interesting in 1988, for instance. Page 35 has a diagnostic table with some suggestions also. Quote Link to comment Share on other sites More sharing options...
Domzs Posted March 3, 2013 Share Posted March 3, 2013 Have you tried to see if ECM stored any DTC ? With an 87 ECM , you should be able to check for codes . Quote Link to comment Share on other sites More sharing options...
SDgoods Posted March 3, 2013 Author Share Posted March 3, 2013 Yes the modes are kind of confusing ill need to figure it out and see what codes are stored. Quote Link to comment Share on other sites More sharing options...
SDgoods Posted March 4, 2013 Author Share Posted March 4, 2013 I still dont understand how you get into each mode of the ecu. I recorded what mode its 'telling' me to go to but dont know what to do beyond this... The one green light flashing after the first 'both lights flashing' is throwing me off as well. Any input? Quote Link to comment Share on other sites More sharing options...
Domzs Posted March 4, 2013 Share Posted March 4, 2013 That's a little strange . Both lights are not supposed to flash at the same time . When you turned the switch , was the key on or engine running ? Quote Link to comment Share on other sites More sharing options...
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