FPR project - cheaper, more available (for a while anyway)

[HusseinHolland]

On 4/14/2023 at 9:40 PM, Zed Head said:

The print on the actual part says 0 - 5.   But the eBay text does say 3 - 5.  Who knows.

I have that one in use on my Volvo 740 (first pic). I don't recall being able to drop it below 3bar. I'll have to try it at some point to verify.

Edited April 16, 2023 by HusseinHolland

[HusseinHolland]

22 hours ago, kickstand80 said:

Nissan Stanza FPR has very close specs to the 280zx

280ZX is also 2.5bar? Volvo also used 2.5bar on most NA applications, but those regulators are not bolt on replacements (refer to Zed Heads earlier posts)

[HusseinHolland]

Coming back to this for a minute - since 2.5bar FPR are not easy to come by, what about using a 3bar regulator & going with newer (lower rated) injectors that don't require the ballast?

As far as I can determine stock 280Z injectors are 188c/min or 17.9lb/hr @ 2.5bar - most if not all injectors are sold rated at 3bar values. Can't find a calc right now that will provide a calculation to determine what value injector will run 17.9lb/hr @ 3bar.... 

[Captain Obvious]

There are a lot of web sites that proclaim to have flow rate calculators to predict the change in flow with respect to a change in fuel pressure. I haven't dug deep into any of them, but for example....   >> https://injector-rehab.com/knowledge-base/flow-rates/

And related to the topic, I recently tested a batch of injectors and got about 160-190 cc/min (using a stock FPR). So assuming the injectors I was checking were close to "as designed", then I can corroborate the 188 cc/min belief.

[HusseinHolland]

Since I need to pull the rail to replace seeping fuel hose, I'm thinking I'll just switch to the 3bar FPR (Volvo/VAG style) and keep the current injectors. It's "only" a 2psi difference, assuming mine are even flowing the spec 17.9lb/188cc. I need to revise the delivery to the rail in prep for the V6 conversion anyway.

If I recall, the AFM can be tweaked to increase/decrease fuel volume. I recall on the Fiat (which had the same system) that was a thing. I'll have to research that on here, I'm sure someone has played with it. I'll start will just the mixture adj., since that may be enough. I'll have the WBO2 on there, so I can monitor actual AFR's.

 

Edited September 3, 2023 by HusseinHolland

[Zed Head]

There is a ton, across many different web sites and on this forum about adjusting the AFM spring.  Good luck with that.

 

[HusseinHolland]

11 hours ago, Zed Head said:

There is a ton, across many different web sites and on this forum about adjusting the AFM spring.  Good luck with that.

 

I'll start with just the standard mixture adjustment, don't want to mess with the clock spring unnecessarily. I read that long thread on the pro & cons of messing with that... 

Edited September 4, 2023 by HusseinHolland

[Zed Head]

One possibility that I haven't seen discussed is to find a coolant temperature sensor that has a shifted curve, shifted to the lean side compared to the Nissan curve.  If you could start lean, you could use the 3 bar FPR, then you could use the "sensor tweak" to bring the curve up.

I'd guess that a common thermistor material was used by many manufacturers.  Who knows, maybe somebody started in a different spot on the resistance scale but the shape is the same.  The Nissan curve has been derived on the forum by CO, from the FSM numbers and I think he did some tests.  @Captain Obvious

Maybe GM or Volvo or BMW has one  with possibilities.  Probably hard to find their curves on the internet but it might be fun to test a few.

 

[HusseinHolland]

On 9/3/2023 at 9:35 PM, Zed Head said:

One possibility that I haven't seen discussed is to find a coolant temperature sensor that has a shifted curve, shifted to the lean side compared to the Nissan curve.  If you could start lean, you could use the 3 bar FPR, then you could use the "sensor tweak" to bring the curve up.

I'd guess that a common thermistor material was used by many manufacturers.  Who knows, maybe somebody started in a different spot on the resistance scale but the shape is the same.  The Nissan curve has been derived on the forum by CO, from the FSM numbers and I think he did some tests.  @Captain Obvious

Maybe GM or Volvo or BMW has one  with possibilities.  Probably hard to find their curves on the internet but it might be fun to test a few.

 

On this note - I have to search through my old Volvo "greenbooks" - the FSM's typically display resistance curves for the various sensors used with the changing EMS's from K-Jetronic in the 70's thru the various permutations of LH-Jetronic that run into the early 90's. There would be at least 4 different ECT's, and the values of them are definitely not even close. 

The two I have at hand are

0 280 130 028: 

8500-11500 @ 68ºF 

770-1320 @ 176ºF

and 0 280 130 023 (or 026):

2100-2900 @ 68ºF

270-390 @ 176ºF

substantially different values.

 

[Captain Obvious]

Here's an excerpt from an old Bosch catalog that indicates that the 280ZX (which is the same as the 280Z) uses the 0 280 130 023:

 

And here's a chart I derived from the resistance points found in the Z service manuals:

Edited September 6, 2023 by Captain Obvious

[HusseinHolland]

31 minutes ago, Captain Obvious said:

Here's an excerpt from an old Bosch catalog that indicates that the 280ZX (which is the same as the 280Z) uses the 0 280 130 023:

And here's a chart I derived from the resistance points found in the Z service manuals:
 

Thank you, CaptO :)

Any chance you can overlay the 028 values? I have no idea if the curve is similar, even though the values greatly differ.

Those two I listed are basically it for all Volvo K-Jet, Fiat L-Jet & Volvo LH2 (either white or blue contact housing). LH2.4 & newer use a 2-path sensor with the same form factor, but black contact housing. I don't know about other marque applications.

[Zed Head]

If you click Images here a bunch comes up.  It's a hot topic!

https://www.google.com/search?q=coolant+temperature+sensors+curves