danman Posted August 24, 2004 Share Posted August 24, 2004 What should happen if you unplug MAF while car is running? I have 83ZXT motor. Unplug the MAF and it runs the same (like crap). I just got MAF from junkyard. The one on car is supposed to be from 300ZX which year I don't know. Model number on MAF seems to be same A36-000 J13 (Is this the model number???). There is second number below which I believe is a serial number 6X06D. The one from junk yard is from 87 300zx. The one on car however looks different. The right side of connector on MAF is ground off one connection leaving six. The conector spliced into harness has seven pins, however only six wires are run to the connector. The missing one corresponding to the side that is ground off on the MAF. I guess my question is which year is used when subbing in 300ZX MAF? Computer is also out of 300ZX no year printed on computer, but number is A18-638 377. The computer has a flash from Jim Wolf Technology for 82-83ZXT, mass air flow, and 420cc injectors if that helps. Also metal circle on MAF next to connector has been drilled through to expose adjustment screw. Quote Link to comment Share on other sites More sharing options...
Bernardd Posted August 24, 2004 Share Posted August 24, 2004 The ecu # says it's a 84 turbo (california) auto ecu. You need to call JWT and ask them what the ecu is programmed for. They use either the stock (z31) maf or the mustang cobra maf (93). You also need to make sure you're getting the correct voltage between pin31 and chassis ground. If you need a known good z31 maf, I've got two of them. Bernard Quote Link to comment Share on other sites More sharing options...
danman Posted August 24, 2004 Author Share Posted August 24, 2004 Thanks for reply. Where are you located? I live in Northern California, East Bay. What should the voltage be? I don't have factory manual for engine yet, just the 74 body. When I unplug MAF nothing happens, runs the same. When I unplug the TPS car dies. Cold start unpluged nothing. I see trouble code printed on back of computer. How do you grab trouble codes from computer??? Quote Link to comment Share on other sites More sharing options...
Bernardd Posted August 24, 2004 Share Posted August 24, 2004 I'm in Canada. Check here http://z31.com/oboard/archives/view.pl?151 The stock maf will put out around 1.6vdc at key on and around 2.6 with the engine running. Quote Link to comment Share on other sites More sharing options...
danman Posted August 24, 2004 Author Share Posted August 24, 2004 You are awesome! Thanks for info, that link is great too. My buddy is coming by tommorow with Multimeter. Thanks again for help. I am complete novice, but like to fix things myself if I can. That's why I bought the car in the first place, to learn and enjoy. Still would like to know what should happen in normal car what happens when MAF is disconnected? My car runs the same. Quote Link to comment Share on other sites More sharing options...
Zhadman Posted August 24, 2004 Share Posted August 24, 2004 That MAFS was probably manufactured by Hitachi (They have been a HUGE OE supplier to Nissan for 35+ years). The second set of numbers you listed (6X06D) is a lot code for the date of manufacture. Quote Link to comment Share on other sites More sharing options...
Bernardd Posted August 24, 2004 Share Posted August 24, 2004 The car should go into limp mode when the maf is unplugged and only rev to 2500 rpm or so. It should be running real rich if the maf is faulty. Quote Link to comment Share on other sites More sharing options...
danman Posted August 26, 2004 Author Share Posted August 26, 2004 Car seems to be running in limp mode. Changed in different MAF yesterday, still running bad. How to I check to make sure the connectors are making it back to the computer. There are six wires, how do I check for continuity. The connector on the car has seven pins (only six are used). Did the 280 come with a seven pin connector to the MAF. Thanks for all the help this is getting frustrating and I don't want to have to tow to shop. That would mean admitting defeat. Quote Link to comment Share on other sites More sharing options...
Bernardd Posted August 26, 2004 Share Posted August 26, 2004 Take a paper clip or something similiar and probe the "B" terminal (Maf) with the voltmeter connected to the clip. Connect the other lead to a chassis ground or pin C. Turn the key on and you should have 1.6vdc. Start the car and you should have 2.6 or so. Revving the car a little should make the voltage increase. Start the test over by connecting the lead you had on the "B" terminal inserted into pin 31 on the ecu connector. I believe it's the smallest connector of the three plugged into the ecu. Connect the other lead to a chassis ground. You should have 1.6vdc with the key on and 2.6 or so with the car running. Another problem that could causing this is the tps connector. Only two terminals are used on the turbo model. Connect the voltmeter in ohm meter mode across the two terminals that are used. They should be closed (zero or low resistance) with the throttle body closed. They should open up when opening the throttle body. I think they are pins 26-19 at the ecu connector, not sure but you should check at the ecu as well. Hope that helps. Bernard Quote Link to comment Share on other sites More sharing options...
danman Posted August 27, 2004 Author Share Posted August 27, 2004 Thanks for the help. I'll try that as soon as I can borrow my friends multimeter. I should buy my own with the rats nest of wires I have in the car. What about the other pins on the connector, how can I test those? Thanks again Bernardd, I wish you lived in Walnut Creek, or I lived in Canada. You would probably have the problem licked in ten minutes. Quote Link to comment Share on other sites More sharing options...
danman Posted August 29, 2004 Author Share Posted August 29, 2004 VICTORY IS MINE!!! I cut off the MAF connector and rigged some wires from harness directly to MAF terminals, started the car and what do you know it runs beautifully. In fact with all the cleaning of connections I've been doing I'd venture to say it runs even better. I think the fix leaned out my mixture, no more fuel droplets out the tailpipe. I will go to junkyard tomorow and look for 280zxt connector to do a permanent fix. Thanks to everyone that replied especially Bernardd. Quote Link to comment Share on other sites More sharing options...
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