That gauge may be wrong and out of calibration.
At idle spec is 30-32PSI and the gauge shows 37PSI

Pump on engine off should be 36-38PSI but you show 40PSI

I suggest you get another gauge and verify. Because if you really are running higher pressure than spec you will run rich.

The plugs are wrong type and should not be used in the 3.2 engine. I suggest you use these plugs instead:

NGK 6637 BPR6EIX Single Iridium Spark Plug, but these are 5K Ohm resistance and best used with non resistance wires.
SKU: #BPR6EIX
ITEM: # NGK6637
BRAND: NGK

Stock plug gap is 0.7-0.8mm

The plug type you currently have can not be properly gap-ed.
But I can already tell that you likely have injector over fueling issues in 5 and 6 cyls.
And those plugs are to cold, I can see this on the color of the ground strap.

as Sal said those plugs are for 930 not for you...In Europa we use wr4CC plugs for non CAT ..Or i could recommend this Euro company in Czech, Brisk..they are world wide known manufacturer and they have an excellent reputation among racing peeps.I just got myself a set, to be installed..
here
https://www.brisk.cz/katalogy/zapalovaci-svicky/filter/auto/12567,12568,12569

they make the best quality with silver tips-pricey but perfect

Just an idea...
Ivan

I really like these plugs in the 3.2L

NGK 6637 BPR6EIX Single Iridium Spark Plug, but these are 5K Ohm resistance and best used with non resistance wires.
SKU: #BPR6EIX
ITEM: # NGK6637
BRAND: NGK

Stock plug gap is 0.7-0.8mm

spark
 

i hear you...honestly i use WR4CC for several years here in Europe and no issue what so ever..But i`ll give it try to this NGK 6637 BPR6EIX..after i do the silver Briks..
Then again i have no problems with what i have,100 octane fuel plus toluene-ABOUT 2q per tank.. 420 miles trip (last weekend) plus 1/4 of a tank of fuel left in it;-) oh ya i did drove the hell out of it too;-)

Thank you Sal and Ivan for the input.

Fuel pressure reading being high... will look back to pressures when Radium gauge was newly installed. I recall pressures being very close to spec back then. Post those pics when I find them.

On the menu:

Arduino wide band system is making progress. Will bench single side set up before buying into parts for second side (for SSIs.) Benching should happen within a few days.
Will test fuel pressure at rail, swap injectors side-to-side (and later pull plugs for another look,) and compression test cylinders. Looking to accomplish this within a week.
.

Karl ..just do not use those plugs...that should help you a lot

Ivan

Am all over it Ivan -- TY. One step at a time and this puzzle is being solved. I just copied into my reference file the factory fuel pressure page you posted 4 years ago.
.

The WR4CC plugs are also a good choice.

Comparing fuel pressure from 2020 to now, 2024. Gauge = Radium, fixed into system after fuel filter and before Y hub leading to rails. Pressures displayed nearly spot on in 2020. Since then... gain of about 6 lbs from something...

Gauge?
New fuel pump?
Pressure regulator?
Combo?

http://forums.pelicanparts.com/uploa...1721387671.jpg

http://forums.pelicanparts.com/uploa...1721387671.jpg

http://forums.pelicanparts.com/uploa...1721388567.jpg
Factory ref courtesy Ivan.


Testing pressure at rail tomorrow.
.

The gauge could have gone out of calibration from sitting in the hot engine bay with tons of vibration? I'd get a 2nd test gauge and install it on the fuel rail test port and compare the 2 gauge readings to verify the existing gauge.

At idle the FP should be 30-32PSI if not the regulator needs to be replaced.

One more fuel test that should be done is fuel delivery rate. As follows:

- Remove the test port 22mm Nut on the driver's side fuel rail
- Get a clean clear plastic 1 gallon milk container
- Put a length of hose over the test port with a clamp securing it
- Put other end of hose in milk jug
- Jumper 12vdc to the fuel pump fuse to run the pump for exactly 1 min
- You must get at least 1/2 gallon of fuel in the jug in 1 min

A healthy 3.2L fuel system typically delivers 3/4 to 1 gallon of fuel in 1 min but the minimum allowable amount is 1/2 gallon.

This test should also be done after you test fuel pressure.

Given the amount of diagnostic required to fix your current problem, maybe simplicity? :D

Good luck with it though!

Or is it power and performance? A somewhat richer mixture would give a few extra hp at higher rpm when compared to a mixture that is optimized for mpg with the O2 sensor and closed loop mode.

I have a Euro engine with no cat no O2 no nothing and car runs pretty well, but my mpg has never been excellent. Reason why I am following this thread and thinking about investing in this AEM wide band gauge. I may run on the too rich side, at least at part throttle.

Yup John..;-) i`d start with the correct spark plugs....but Karl knows by now..also little turn on AFM (to make it leaner)would help too;-)

Wazz..same here, euro no cat no oxy and mileage is perfect.i by-passed the oxy circuit in my comp..with a switch, when i used to go for smog i just flipped it back....

Ivan

Ivan, thanks for the response. Can I mail you pics of my plugs (WR4CC) so you tell me what you think.
Don't want to hijack this thread.

you got my mail ,right?

Attending that today Sal.


On menu.


Thanks Jonny. Wideband O2 program is in the making. Arduino-based. (Nothing simple about this MPG sort out but puzzle will be figured out.)


Good idea with the mixture screw Ivan. Do that later today. Plugs are ordered. Am going with Iridium given the discussion I had with Sal before seeing your post.


Had discussion with Charles of CJ Motorsports concerning fuel pressure gauge. Unit I have is 1 1/2" barrel, 1 3/4" face. He and I discussed the manufacturer of these units---they're made in China with the ability to custom design/brand the face given a minimum order of 100 or so. Main topics... durability and the lens. Lens is made of acrylic. I told him I was wanting glass. He's going to look into it. Concerning durability, he said many buyers of these gauges use them temporarily in conjunction with his adjustable pressure regulator. For those that mount them permanently, it's a given that heat will eventually take them down. Perhaps we're seeing that here.
.

Pressures measured at stock rail port:

http://forums.pelicanparts.com/uploa...1721585251.JPG

Pump ON, engine OFF. Air is bled. Calling this 38.5 psi. Spec = 36.26 psi +/- 2.9 psi Within spec. "Spec book" am referring to here is page provided by Ivan --- TY.


http://forums.pelicanparts.com/uploa...1721585251.JPG

Engine now at idle. See this as 34 psi. Spec = 29 psi. Over spec by 5 psi.

Assuming test gauge just used at rail is correct, installed Radium gauge in fuel line is off (high) 3 psi.


http://forums.pelicanparts.com/uploa...1721585251.JPG

http://forums.pelicanparts.com/uploa...1721585251.JPG

Flow test. Hose is connected to rail port. Pump ON for 60 seconds. From spec book, 60 second flow is 1,700 cc / 1.79 quarts. Being at at 3.5+ quarts, flow is measurably over spec.

I have original Bosch injectors that were removed from engine in 2020. Given uneven look of plugs and down pipe temps, am leaning towards Lucas injectors being questionable. Monday, am sending Bosch injectors to Mr. Bill to test & refurb. Provided they come back in good form, idea is to have them on hand to eventually test them against Lucas (from FiveO) that are currently installed and now suspect (without proven guilty as it stands. I know better that to think one thing is wrong here. Could be a combo and so testing this & that to rule things in or out.) Sal suggested swapping injectors side-to-side... running engine... then having a look at plugs again.

Still have to sort out opening mixture screw as Ivan suggested. 3mm Allen has temporarily escaped me.
.

If you look at the manual it actually specifies to disconnect the return hose hose and to connect the hose to you r catch bucket on the return side. this will test the flow rate at the 36psi load not at open rail (0psi). your pump will likely still pas sthe test as you are seeing higher than specified pressures when running, so it doesn't seem like it is a pump supply issue.

http://forums.pelicanparts.com/uploa...1721590752.jpg