280Z Full Restore in 5 months, hopefully.

[Zed Head]

Check your cam lobes (a flat one will cause an intake backfire - check lubrication while you're in there), valve lash (a loose one is like a flat cam lobe), and fuel pressure (lean mixture cause backfires). Those things are always good to do in general.

[EuroDat]

If its lean mixture, you can check the AFM circuits, throttle switch and the temp sensor. They are good sources for backfiring when they go bad. The test you can do with a multimeter and are all described in the 280Z fuel injection bible. In the Test#1 section.

If it was running well before you move, good chance its a dirty contact or something along that line.

Here is a link to a method to calibrate the AFM spring. Unless someone has played with it, I don't think that is causing your problem. Springs get weaker over time which means the ECU will give more fuel. http://atlanticz.ca/zclub/techtips/afm/calibration/index.html

Chas

Edit: Dam that car looks good:love:. Impressive job in such a short time. Hats of to you.

Ford racing: shame on youLOL

Edited April 6, 2014 by EuroDat

[CG240Z]

I believe the engine is running rich, not lean. I haven't pulled a plug to confirm, but I can smell the gas while the engine is running. The car didn't run right before the move, it's been backfiring since it's first start.

It's a new cam so I shouldn't have any flat spots. But it just hit me, I'm running stock lash caps, I wonder if the cam calls for a different lash cap. I am going to call the company I bought it from this week and find out and also double check on the valve clearances with them. I still need to double check the AFM, just didn't have the energy to pull it out today.

Once I get the engine running, I need to get my clutch issues figured out. After that she's ready to hit the open road for her first test run.

[EuroDat]

Hope its not your cam.

If its running rich, it could be the spring tension in the AFM. I have seen a "performance" tip where they release a vit of the spring tension to add more fuel. If someone has tempered with it like that, it could be the cause. A lot of the ECU drift problems gennerally cause lean running, but the spring is one of the exceptions.

Chas

[CG240Z]

Working on this bad guy tonight. Going over the tech tips from Atlantic Z and EFI manual to try to figure out if this thing is calibrated or not. I'm hoping this is the key to get the engine running better.

<a href="http://s254.photobucket.com/user/taillonml/media/280z/F6065827-574E-453C-BAE5-94149AB06148.jpg.html" target="_blank"><img src="http://i254.photobucket.com/albums/hh101/taillonml/280z/F6065827-574E-453C-BAE5-94149AB06148.jpg" border="0" alt=" photo F6065827-574E-453C-BAE5-94149AB06148.jpg"/></a>

[rcb280z]

Did you install a stock cam?

[CG240Z]

Did you install a stock cam?

Nope, I still have the mild performance cam in. Hopefully that's not the root of the problems. I'd like to get the AFM cleared before I go swapping cams. I'm waiting on Lenny's new ecu to come out, I'll put that in too to help compensate for the cam.

[EuroDat]

I calibrated my AFM using the guide on the Alanticz website. It was easy to do, but my engine ran really lean afterwards. Its worth noting that my spring was adjusted to about 120gr. before I started. There was also signs that the lock screw was previously in another position on the wheel, so a PO was playing with it in the past. He may have released the tension to give him more "performance" or try to compensate for ECU drift?

I will have to lookup the weights, but from memory halfway at 135gr worked best for me. The method I used was to remove the AFM cover drive it and adjust the spring small amouts and drive, adjust, drive, adjust. I got so handy at it that I didn't stop the engine to do the adjustments.

After that I removed the AFM and checked the spring at 135gram mid position. Im not saying that 135gr is better, we are comparing systems that are approaching 40 years. I have no idea what the tension was on a new AFM.

My Z also has other variables effecting this, one being the tempurature sensor resistor pod and another the typical ECU's drift towards lean running. My calibration could be compensating for that as well.

I think I have a video of it somewhere. Ill try to upload it latter.

Chas

[TheCrazySwede]

Does your AFM have the little adjustment screws on the side? Helps to tune it a bit.

What size lash pads are you using? .175"+ is a bit too thick even for a mild cam. I assume you're at .160"?

Have you measured your fuel pressure? See what your pressure is like. You should be able to place a gauge right between the fuel filter and the rail.

[bartsscooterservice]

I calibrated my AFM using the guide on the Alanticz website. It was easy to do, but my engine ran really lean afterwards. Its worth noting that my spring was adjusted to about 120gr. before I started. There was also signs that the lock screw was previously in another position on the wheel, so a PO was playing with it in the past. He may have released the tension to give him more "performance" or try to compensate for ECU drift?

I will have to lookup the weights, but from memory halfway at 135gr worked best for me. The method I used was to remove the AFM cover drive it and adjust the spring small amouts and drive, adjust, drive, adjust. I got so handy at it that I didn't stop the engine to do the adjustments.

After that I removed the AFM and checked the spring at 135gram mid position. Im not saying that 135gr is better, we are comparing systems that are approaching 40 years. I have no idea what the tension was on a new AFM.

My Z also has other variables effecting this, one being the tempurature sensor resistor pod and another the typical ECU's drift towards lean running. My calibration could be compensating for that as well.

I think I have a video of it somewhere. Ill try to upload it latter.

Chas

I'm no electrical guy. But my common sense say don't mess with the factory set up from the AFM. I would replace the AFM if it was faulty.

[rcb280z]

Could be timing especially if you are running a performance cam.

As far as the AFM goes, I still have my original one and have adjusted it numerous times. Just study all the thread on this site regarding it and it should make you feel more comfortable with it.

Edited April 19, 2014 by rcb280z

[CG240Z]

Does your AFM have the little adjustment screws on the side? Helps to tune it a bit.

What size lash pads are you using? .175"+ is a bit too thick even for a mild cam. I assume you're at .160"?

Have you measured your fuel pressure? See what your pressure is like. You should be able to place a gauge right between the fuel filter and the rail.

I did check the lash pads, thinking maybe that was it. I called Web Cam where I bought it from and asked about it. They said as long as I can get .008 and .010 my lash pads are fine. Tight tolerances, but that's what it calls for.

Good idea on fuel pressure, I'll need to pick up a gauge.