Contour Enthusiasts Group Archives Forums Modifications Forced Induction fuel pressure, again...

I think you are missing the point.

1. He was told by other people his fuel psi was too low.
Why was he told this? Did he just up and check his fuel psi for no reason or was it because he had a problem that he was trying to track down?

2. He says he has a lean misfire. He's changed everything to include the pump, screen, filter, to include reflashing his code back to stock. He doesn't know it is a lean misfire, he just has a misfire.

The result of these facts means he should reevaluate what his problem originally was, if it is still the same, or if it has now changed. Then come up with a plan of attack.
Now if he does this and everything (after ruling out the common issues) points back to fuel psi, then by all means pursue a fuel psi issue.

Dumb question : have you changed the fuel filter?

He did.

I want to start by thanking everyone for their continued help up to this point. So, Thank you all.

Here is a brief re-cap to bring everyone up to speed and save from re-reading the whole post.

Installed T-28 turbo kit...using a base tune from Keith at ADC...began tripping CEL...using xcal2 found out they are lean codes, both banks.

Sent some data logs to Keith at ADC and based on those he was concerned about adding as much fuel as the data logs would suggest. And at that point he inquired about my fuel pressure and also stated that it should be around 40psi.

From their I searched (yeah, searched hahaha) and confirmed I should be right around 40psi. Took some pressure readings with my gauge, 30psi, had a guy a local garage also take a reading, 30psi.

After some suggestions to upgrade to the FSVT fuel pump anyway, I replaced the stocker with that and changed the fuel filter at the same time. I completely removed that screen from the bottom of the tank as well.

Took some more readings, still at 30psi, still throws lean codes.

As far as the misfire, I am assuming that it is a lean misfire as the AFR goes high at idle. However, under decent acceleration the AFR looks good in the mid 14s.

Per Todd's suggestion I will be replacing the plugs as they are cheap and hopefully the misfire is gone. But I assume that I will still have lean codes. I will be sending some new data to Keith at ADC with the focus pump and new fuel filter installed and see if he is still "concerned" about the amount of fuel the data would suggest adding.

Hopefully, it is just the ecu adjusting for the larger injectors and that some quality tuning will fix it up. I mean, I really like the fact that AFR goes to a good spot upon acceleration. Sorry for the monster post, I hope this gives the experts all they need to know. Again, I appreciate all of your help.

Okay, little more info...replaced the plugs today and changed the gap. It was previously set at .035 and I increased it to .045 per a thread by Warmonger I believe. Still have a misfire I think, need to take it for a drive...but the wires are still stockers, only 38k on them though.

Link to thread about plug gap

Plug gap

Wires are on a short list of items to replace. What do you think about the plug gap War? Do you still agree with .045? It seems to hesitate more when lightly accelerating with this gap vs .035 on the old plugs.

On OEM turbo vehicles, it seems the platinum plugs are gapped over .044ish. I've seen most tuners gap copper plugs .035 to .028 I had good success with .032 when running coppers.

If the wires are in good shape then there should be nothing wrong with that gap.

On platinum plugs and autozone plug wires that 0.045" gap worked to 12psi for sure that I know of and nary a misfire.

I Never ran less than 0.040" with either my NGK TR6 and with my autolite double plats. The latter were in the car when I sold it.

You should search for a spark plug threads and ignition system threads from last year in this forum. I explained how you can't really take the plug/wire combo by themselves in your assessment.

Essentially you have the plug, wire, coil, coildriver (in pcm), and atmosphere in the cylinder that all affect the firing of the plug. THe atmosphere being fuel and air under anywhere from 10:1 to 16:1 compression.
The more boost you run the more that the air/fuel mix begins to act more like a solid insulator in between the plug electrodes (anode/cathode).

So two things can be done at that point: 1. raise the voltage or 2. decrease the resistance.
Raising the voltage is the best because the spark gets more energy this way. However it is less practical and costs lots of $ because everything from the coil drivers out has to be replaced.
Decrease resistance is as simple as changing plug wires, or sparkplug with different core, or shortening the plug gap. Remember, the plug gap is an insultor by itself and the wider the gap the more voltage required to push the gap. Therefore the wider the gap the more spark energy you get.
You would only reduce the gap if you are getting a misfire and stop as soon as the misfire goes away. You don't adjust the gap till you know your plugs and wires are good to go as this is the last and only user-adjustible portion of this after you choose your plugs and wires.
If you experienced misfiring at that tight of a gap already then you either have a plug wire/coil/plug problem, or a lean/rich misfire as you pointed out. Change the wires and if nothing changes then proceed back on course with fuel delivery.

Now, I'm not sure why your fuel psi is low. But fuel trims should tell the tale as long as you didn't turn off the pcms ability to learn.
If you have fuel trims showing that you are running lean, as in negative values on the long-term trims, then possibly the commanded A/F is too lean and the pcm is pulling fuel and thinks it is rich. Then it can misfire.
If you have fuel trims showing you are adding fuel or trying to run rich, then you need to add fuel.

You have the commanded A/F values that should have been left alone for the most part.
Then you have the fuel psi table, I'm not sure on this one.
Then there is the MAF function; this part must be right for the other two to work at all correctly.
Then you have timing which wouldn not likely affect the A/F but maybe the misfiring.
And injectors.
Of all these things the MAF function is most likely the culprit in my opinion.
I would think it is possible the pcm has altered the fuel psi down as low as it can to compensate for your car running too rich...or thinking that it is.

You must have a valid MAF for these things to work.
If you don't know if the MAF function is entered correctly, then you can put your stock MAF on and not run any boost past 3-4psi until you get the problems worked out.

Just FYI, I was able to leave the turbo in place but not hooked up in the garage while I installed the factory intake laying on top and ran factory injectors with the stock code.

For testing purposes it validates everything else in the system for engine operation like fuel, vacuum leaks, oil leaks, etc and takes the turbo out of the equation. I was able to cruise around the block too...sounded kind of weird with the air woosh though.

Anyway, sorry for the long post.