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rough drive home... any idea what it could be?


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I was driving my new 280z home today and when i was driving it was having trouble drive while in gear like it was stumbling.... the tps is not connected and soemthing else i cant remember what it is... it has a 280zx fuel pump it makes a loud wineing noise (i heard that was normal dont know tho) the clutch fan is always engadged so any ideas on what the problem could be? any help would be great or some where to start.. and it runs rich...

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Just kidding about the NARPs valve. That is not a real part.

 

Joking aside,

I’m assuming this is the OE EFI. With the TPS disconnected, when you open the throttle above ¾, and the EFI is tuned and running properly, it will stumble and misfire noticeably. At part throttle it should run normal. The TPS tells the ECU when the throttle is above ¾ open and also when the throttle is closed. With the throttle open past ¾, the ECU will richen the fuel mixture accordingly.

 

A whining fuel pump is not normal. The OE pump, (the 280-ZX pump is the same pump as the 280-Z), it should be almost silent from inside the car. Investigate the whining pump issue, it may be the source of the poor running, i.e. not enough fuel pressure.

Inside the inlet of the fuel pump itself there is a little cone shaped screen. Make sure it is not clogged with debris. Also, make sure the fuel lines running from the fuel pump up to the front of the car or free and not clogged with rust etc.

 

The MAF you are referring to is called the Air Flow Meter, or AFM for short. The AFM is a completely different animal than a MAF. The terms really aren’t interchangeable and when looking for parts, could you get you the wrong part.

For the most part, all 280-ZX EFI components interchange with the 280-Z, no worries there. The Turbo ZX is different animal so don’t use Turbo EFI parts on your non turbo EFI system. Things like fuel pumps, fuel injectors, AFM, dropping resistors, Air flow regulators etc, are all interchangeable between the N/A ZX and Z. The only items you need to be wary of when interchanging is the ECU and harness. The Harness MUST match the ECU for the car it came from as the pin outs changed throughout the years. Also, the early AFM, had the fuel pump switch built it, but that is easy to get around.

 

Hope that helps,

Paul

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Whew…

 

Ok.

 

 

1) The TPS is not needed for the engine to run, but without it, it wont run correctly. In short, plug it in!

 

2) The fuel pump should not be whining. Find out why it is whining. If it is whining, it most likely isn’t operating at its full potential for some reason. If it isn’t flowing the required fuel the engine needs, fuel pressure will be down and the engine will run like crap. In short, investigate why the fuel pump is whining and fix-it, cause a whining fuel pump isn’t right.

 

3) If you have the means, verify fuel pressure. Not just in the parking lot with engine running, but under load while driving. I have a long hose on my fuel pressure gauge and I place it under the windshield wiper arm so that I can see it while driving to verify fuel pressure while the engine is under load. If the fuel pressure drops off under load, then you have an issue that needs to be addressed because in short, your car will run like crap without proper fuel pressure. It is common to find clogged fuel filters, fuel pump inlet screens, bad fuel pumps etc this way.

 

 

Hope that helps,

Paul

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Whew…

 

Ok.

 

 

1) The TPS is not needed for the engine to run, but without it, it wont run correctly. In short, plug it in!

 

2) The fuel pump should not be whining. Find out why it is whining. If it is whining, it most likely isn’t operating at its full potential for some reason. If it isn’t flowing the required fuel the engine needs, fuel pressure will be down and the engine will run like crap. In short, investigate why the fuel pump is whining and fix-it, cause a whining fuel pump isn’t right.

 

3) If you have the means, verify fuel pressure. Not just in the parking lot with engine running, but under load while driving. I have a long hose on my fuel pressure gauge and I place it under the windshield wiper arm so that I can see it while driving to verify fuel pressure while the engine is under load. If the fuel pressure drops off under load, then you have an issue that needs to be addressed because in short, your car will run like crap without proper fuel pressure. It is common to find clogged fuel filters, fuel pump inlet screens, bad fuel pumps etc this way.

 

 

Hope that helps,

Paul

 

sweet thanks! i beieve the tps is messed up i beieve it was metntioned when i got it... so anyone have a spare tps?

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ok rtv sealed up i pluged in the tps to see what it actully does and the car had a hard time and cut out at 3k and when i stoped at the end of my street it was at 500 rpm spuin black smoke and i then turned the car off and unbluged the tps the idle staied the same then went to 1500 what could be the problem? it was spuin black smoke then it stoped....

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update: fuel pump is fine... its running super rich! and i cant figure out why i have 3 things in my thermistat housing i know the one with 1 wire is to my temp gadge that i got working now but the other ones i dont know.... my car stalls alot more and its freakin me out on the drive home it shot a fire ball.... need advice one how to test the temp thing im assumin...

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update: fuel pump is fine... its running super rich! and i cant figure out why i have 3 things in my thermistat housing i know the one with 1 wire is to my temp gadge that i got working now but the other ones i dont know.... my car stalls alot more and its freakin me out on the drive home it shot a fire ball.... need advice one how to test the temp thing im assumin...

 

Shot you a PM about the other sensors. Hope you are able to find it. Keep us posted.

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hey if i unscew the sencor will coolent spill out?

 

Yes. The sensor is directly exposed to the coolant and wil leak the coolant if removed. You should drain 1-2 quarts out of the radiator through the drain plug first so it doesn't dribble on the ground upsetting the community, if you know what I mean.

 

If you have an ohm meter, you can verify that the water temp sender is functioning without having to remove it from the car. To verify the ECU is getting the correct values, using that Haynes manual, you can trace the pin outs of the ECU connector, unplug the ECU and at the ECU connector, verify the same readings there as you got at the sender itself described below.

 

With the engine full warm, approx 180 degrees, resistance across the two prongs of the sensor should read in the neighborhood of 200-300 ohms. At about 60 degrees, say first thing in the morning after the engine that has at all night, it should read between 2000-3000 ohms or there a bouts. (Sorry I don’t have the manual in hand and today is going to be hectic). If my OHMs values are way wrong, someone please post the correct figures for this guy.

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man this is pissin me off...

 

That is your number one problem.

 

Step away from the vehicle, take a break, cool off, and clear your head.

 

Come back a day later. Pretend you've never seen the car before, and work your way patiently through the troubleshooting in the EFI bible I showed you.

 

I an no BRAAP, no rontyler.. I am just some 26 year old dude who was raised in S30s, and owned and operated a daily driver for five years myself.. All of my "skills" are either self-taught or Dad-taught... and the NUMBER ONE THING that I have learned about working on cars, as an amateur is this: Patience!!!! if you are frustrated, you will not figure it out.

 

Now, the Bible has troubleshooting flowcharts for just this occasion... Once you have read through the theory section a couple of times and understand how the components work together... (sensors reading information, turning that information over to the number crunching ECU, and the ECU in turn handing out a signal to the fuel injectors to fire a given amount of fuel at a given time...thats IT!)Once you have all that, THEN go to the troubleshooting section and begin testing things. Proceed in the order it dictates in the book, and you WILL find the problem. I think it was TonyD, several years ago, (on the "other forum") who wrote that he had walked up to 280Zs that had sat in a barn for eight years.. put in a battery, ran through the battery of tests, cleaned or repaired each component until they all passed muster, and then he cranked the car right up. It might not have been him, but I have heard the tale and believe it.

 

A carb can have any number of hard to diagnose issues. The only "hard to diagnose issues" with the FI are Bad ECU, or bad wiring. The wiring really isnt as difficult as it might seem, because it is easy to isolate the component that is the problem.. and once you do that, you test component function first at the component plug, then at the ECU plug to test the viability of the wiring harness.

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Fuel pump whining could be an aftermarket pump such as the Walbro. It'll whine quite loudly.

Fear not on the diagnosis. I just got my first S30 and I had to tow it home. It turned out the AFM had several TEASPOONS of water in it. I cleaned it out and tuned the AFM a bit and now it works quite well. Read the bible. It'll tell you how to get through things quite quickly as long as you can use a multimeter. Stay patient; that's going to save you a lot of grief. These cars are very simple as far as EFI goes.

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Fuel pump whining could be an aftermarket pump such as the Walbro. It'll whine quite loudly.

Fear not on the diagnosis. I just got my first S30 and I had to tow it home. It turned out the AFM had several TEASPOONS of water in it. I cleaned it out and tuned the AFM a bit and now it works quite well. Read the bible. It'll tell you how to get through things quite quickly as long as you can use a multimeter. Stay patient; that's going to save you a lot of grief. These cars are very simple as far as EFI goes.

 

 

yea but ive decided to go with carb... lol im keeping my manifold and what not might put it back on when i decide i want to do a turbo swap...

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