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zeenubee

Help with Throttle Position Sensor 78 280 Z

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Here's a 75 FPR for comparison. Tomohawk shows what your rail is designed for, this is what you have.

post-20342-14150826953195_thumb.jpg

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I also note in your last photo that your wiring harness is unwrapped at the bullet connectors where the thermostat housing sensors tie in. Either mice chewed the wrapping off (not likely), or a human did it. Either way, it's a place to look for issues. One possible issue is that you have a bad connection to the coolant temp sensor, which seems to be the single, most common culprit for rich running.

The best thing you can do is to go through all the EFI checks in the FSM. You perform these checks from the huge ECU connector beneath the driver kick panel. All you need is a multimeter, the FSM, and some patience.

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You can only wonder why there's a '77 FPR on there? My 1st Z I bought for dirt cheap because it would only idle. Popped the black cover off the AFM and the vane was stuck at wide open throttle from sitting I suppose. Have you taken that cover off and checked it out? Here's a Tech Tip from Atlantic Z's that shows what I'm talking about. http://atlanticz.ca/zclub/techtips/afm/index.html

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Some more clarification: the engine did NOT stop running the other day when I moved it...It just would not pull itself. Towed it the rest of the way home. Parked it and two days later it started right up and I backed it into garage. re: the bullet connectors...had asked the mechanic to clean them...said he did. The AFM was also checked but cannot verify.

So I have the wrong FPR and it is improperly attached, the BPT line needs to be plugged, and I need to do ecu checks as per FSM/EFI bible, clean all electrical connections and recheck fuel pressure and timing...sounds like no football sunday!

Thanks for your help time and info!!! I shall return.

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The FPR is the "wrong" type for your car, but that doesn't mean it will not work. The extra inlet just needs to be plugged properly. The 5/16" (or 8mm) bolt can leak and cause a fire and your car wont survive.

IMO I would start from scratch and do all the FSM/Bibble checks again. That way you know were your at, you might just find something the mechanic missed and you will have a much better understanding of how it all works.

BTW That plugged inlet is screaming for a pressure gauge so you can check your fuel pressureLOL

Chas

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I agree with Chas! A gauge on that plugged inlet would be quite elegant. As long as you've got the wrong part, why not make it look like it was substituted for a reason?

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Well after 9 years almost...I'm back on this project!...life.

Surely wish I had re-read my own post and your replies  two weeks ago as I once again took it to another mechanic ( label me stupid)  This one was supposed to be very knowledgeable on these things..go ahead be harsh!

So it seems that the problem was two-fold:  The (1) gas tank was full of rust...so was cleaned and sealed.  Car started right up (some fuel lines were replaced too).  Ran very rich...which he traced to (2) oxidized coolant temp sensor plug.  Damm...wished I had listened and not been so intimidated by this.  Any way I drove the car home 45 mi and it seemed to run fine.  Now I am going to try to sort this thing some more as I go back to the FI bible and FSM and depend on your further guidance...hopefully

my sincere thanks to all

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57 minutes ago, zeenubee said:

Well after 9 years almost...I'm back on this project!...life.

@zeenubee Six years.  Probably feels like nine though.

  • Thanks 1

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Never was good with math!   Just spent a couple of hours reading again the FI bible...what a well written and illustrated document!  Gonna go through all elec connections first, then going to replace all fuel hoses and vacuum lines.  Not sure what I'm going to do with the extra out put on the fuel press. reg...haven't looked for parts yet.  Glad you guys and gals haven't kicked me off.

 

one unrelated question:  do you all use a special motor oil with high zinc or other additive?....going to change all fluids, filters etc even though they have only <50 mi  it has been 6 yrs.  I usually use mobile 1...any concerns?

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4 hours ago, zeenubee said:

Also...want to post some pics of car and suspension....where and how do I do that?

If you're on a computer there's a "choose files" choice.  Not sure about the mobile app.  you can also use the Snip tool if you're using windows and just paste it directly in to the box.

image.png

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4 hours ago, zeenubee said:

one unrelated question:  do you all use a special motor oil with high zinc or other additive?....going to change all fluids, filters etc even though they have only <50 mi  it has been 6 yrs.  I usually use mobile 1...any concerns?

Generally, everyone uses high zinc for breaking a new engine in.  Seems mandatory to avoid destroyed cams.  But many of us have been fine with non-zinc oil on higher mileage, broken-in, engines. 

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