Getting around 11 MPG, running rich, need help

[Z Tyler Z]

Went through the whole EFI bible. Found out my TPS wasn't working correctly. It was either at the idle setting or at full throttle. We adjusted that and now its to spec. Everything else tested fine after we changed out he afm to anther one I had laying around that tested perfectly.

Now the problem is my car is gutless and slow to respond. We'll see if the gas mileage changes.

Does anyone have any info about using a 300zx ecu and MAF on a n/a 280z? I know there popular for L28et but what about n/a car? (with an 300zx n/a ecu of course)

[Zed Head]

Went through the whole EFI bible. Found out my TPS wasn't working correctly. It was either at the idle setting or at full throttle. We adjusted that and now its to spec. Everything else tested fine after we changed out he afm to anther one I had laying around that tested perfectly.

Now the problem is my car is gutless and slow to respond. We'll see if the gas mileage changes.

Does anyone have any info about using a 300zx ecu and MAF on a n/a 280z? I know there popular for L28et but what about n/a car? (with an 300zx n/a ecu of course)

I have to ask, just to satisfy my curiosity. Are you avoiding measuring the fuel pressure because the gauge is expensive? I know that I did not want to pay $45 just to measure something once or twice and then put it on the shelf. Or did you measure it and it checked out okay?

If you're not going to measure it, it would be nice to know why. You can't have good fuel injection without proper fuel pressure.

As far as the ECU swap, be careful, you could end up in this guy's boat - http://forums.hybridz.org/index.php/topic/95747-z31300zx-ecumaf-to-280zxt-problems/page__p__900526__fromsearch__1#entry900526

Plus you'll never get any help from the SU guys then...

Edited October 18, 2010 by Zed Head

[Z Tyler Z]

I have to ask, just to satisfy my curiosity. Are you avoiding measuring the fuel pressure because the gauge is expensive? I know that I did not want to pay $45 just to measure something once or twice and then put it on the shelf. Or did you measure it and it checked out okay?

If you're not going to measure it, it would be nice to know why. You can't have good fuel injection without proper fuel pressure.

As far as the ECU swap, be careful, you could end up in this guy's boat - http://forums.hybridz.org/index.php/topic/95747-z31300zx-ecumaf-to-280zxt-problems/page__p__900526__fromsearch__1#entry900526

Plus you'll never get any help from the SU guys then...

yep I'm in college and pretty cheap; only like to spend money when I have too. This might be one of those times though.

[ZCurves]

yep I'm in college and pretty cheap; only like to spend money when I have too. This might be one of those times though.

Tyler,

Buy the gauge, use it. When you are done put it on eBay or PM me and I'll buy it from you. I'll split your cost with you. (I really do not need one but it would be a nice to have in my toolbox)

[ZCurves]

yep I'm in college and pretty cheap; only like to spend money when I have too. This might be one of those times though.

You might be able to 'Rent' one from your local autoparts store - And I don't mean use it and return it, just ask if they rent the tool.

Edited October 18, 2010 by ZCurves

[Zed Head]

Or your local high school auto shop might take a measurement for you for free. Although you might be too close to having just got out to want to go back and visit.:sick:

Just a thought. Your car would be a great example of the basics of fuel injection.

[grantf]

I have a fuel pressure gauge bring you're car by.

Edited October 19, 2010 by grantf

[Z Tyler Z]

I have a fuel pressure gauge bring you're car by.

Thanks I'll send you a pm in a couple minutes.

Zed Head Or your local high school auto shop might take a measurement for you for free. Although you might be too close to having just got out to want to go back and visit.

Just a thought. Your car would be a great example of the basics of fuel injection.

For some reason most of the high schools (at least where I live) including my own didn't have an autoshop class.

[grantf]

pm sent

[HOT WHEELS]

I had the same problem with my 76 last year for months. Drove me crazy. The first thing I did was go through the EFI test. This is something you want to do instead of buying parts and guessing because I was spending $20 a day for gas. I would smell like my exhaust by the time I got to work. Z mechanic mentioned the AFM so i purchased one from him. Did not help but about a week later I went back and got a rebuilt one and it had a seal and it ran better than when I first got it.

[Z Tyler Z]

Currently my cars not running (sort of). Dave and I adjusted the TPS back to spec (or at least close to it) and it seems to run awful now. Before we adjusted it any pedal movement was considered full throttle (efi bible tps test). Maybe this was set that way on purpose?

The idle on my car currently is set at 1300 rpm but for some reason despite the idle being set that high my car wants to idle at 500-800 and not rev quickly. It's extremely hard to drive this way and I'll be lucky if I can manage to drive to Daves like this.

I'm almost positive it's fuel pressure, as I said the rebuilt afm I installed and everything else tested perfectly.

Currently I start the car and it goes to 800 then within a second dips down to 500 then back to 800 (even though the idles set at 1300). If I wait a while let the car warm up then turn it off and back on it then idles at 900-1000.

I never checked Harbor freight until a guy on Ratsun suggested it and it looks like they have a gauge for only 12 bucks (20 if you want there test kit). I'll pick one up tomorrow and see how it goes.

So I don't have to look it up what the correct PSI my fuel system should be running at?

[Zs-ondabrain]

36.3 after the fuel filter up front.

http://www.classiczcars.com/forums/showthread.php?t=34564