SDgoods Posted March 25, 2013 Share Posted March 25, 2013 I'm starting a new thread as my last thread was flooded and new problems have risen. 73 240z with 81' l28et swap, z31 ECU, MAF. and degree wheel. Mods- 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* Initially the chain had skipped some teeth so it wasnt running..Replaced all timing components and Leakdown and compression checked out. I have 2 ECU's and 3 MAFS: Car will idle with my 87 turbo ECU and 86 MAF (that actually tested bad as 2 pins didn't have continuity, while one of the other MAF's tested good but wont run) The idle sounds great but the AFR's are sporadic from 13-16 and timing jumps all over the place. With ANY throttle, it hesistates badly to rev, cutting out and missing as revs climb (although they do climb) Vacuum starts to drop off. I've sprayed carb cleaner through out the Intake manifold, cant find any vacuum leaks. Sometimes if it idles long enough it will eventually lean out and die. I suspect Its a bad MAF problem but don't want to spend more money throwing parts at it. Any input would be great. Quote Link to comment Share on other sites More sharing options...
Domzs Posted March 25, 2013 Share Posted March 25, 2013 Any pic. of your setup ? The location of you MAF , intake or discharge side of the turbo ? I would use a smoke machine to check for any kind of leak on your intake side of the system , including the intercooler , hoses , pipes , BOV , everything before the throttle body . Maybe the MAF is not getting correct reading due to leaking components . Quote Link to comment Share on other sites More sharing options...
SDgoods Posted March 25, 2013 Author Share Posted March 25, 2013 Any pic. of your setup ? The location of you MAF , intake or discharge side of the turbo ? I would use a smoke machine to check for any kind of leak on your intake side of the system , including the intercooler , hoses , pipes , BOV , everything before the throttle body . Maybe the MAF is not getting correct reading due to leaking components . I dont have a smoke machine nor does my friends' shop where the car is right now. I would suspect your suspicions more, but the car ran prior to the ecu swap and the intercooler/hose setup hasn't been touched except for the throttle body hose which we've tested with carb cleaner for leaks. The maf is maybe 6 inches in front of the compressor inlet with an aluminum pipe seperating the two. I dont think its the MAF not getting the signal as much as it putting out a correct signal. Quote Link to comment Share on other sites More sharing options...
Domzs Posted March 25, 2013 Share Posted March 25, 2013 OK . How about trying to put the MAF on the discharge side of the turbo to see if it runs better . Or back probe the MAF signal to the ECM ( preffered do it with a lab scope ) to see how smooth the signal is . Quote Link to comment Share on other sites More sharing options...
SDgoods Posted March 25, 2013 Author Share Posted March 25, 2013 I attempted to read the output signal but only with a volt meter. Unfortinately dont have an o-scope. also wasnt sure which was the signal wire just guessed based on the volta but ill find out for sure and test again. Any idea wht it should be at idle? Ive heard .7 - .8 volts Quote Link to comment Share on other sites More sharing options...
Bernardd Posted March 26, 2013 Share Posted March 26, 2013 It should be 2.2vdc give or take a bit. Quote Link to comment Share on other sites More sharing options...
SDgoods Posted March 28, 2013 Author Share Posted March 28, 2013 Well im about ready to give up. I actually drove the car yesterday after finding a broken cas ground wire. It revved up smoothly but driving would hesitate bad and was running lean through out the range, 18+ pinning my wideband lean. For some reason it still likes the old maf and didnt like the remanufactured and other known good one. Oddly it also likes the ecu coil signal on the - thats supposed to be on the +. Im trading someone an 84 ecu for my 87 but am getting quite discouraged as i feel this is an unadjustable system that im throwing unnkown components at. I dont see how some guys hook it up and just like that it runs almost flawlessly. Quote Link to comment Share on other sites More sharing options...
SDgoods Posted March 28, 2013 Author Share Posted March 28, 2013 The idle was also inconsistent and had to be set high to stay alive. It would jump all over the place Quote Link to comment Share on other sites More sharing options...
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