Resolved HELP: P0174 2004 Mach 1

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alwayshi

Active Member
Feb 22, 2019
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Hawaii
Hello everyone,

I'm currently battling an issue with my vortech supercharged, 2004 Mach 1 with 15,xxx miles.
It also has long tubes, cams, and custom tuned. That's the gist of it pretty much.

Anywho, I'm currently trying to figure out why it randomly deciding to throw a P0174. I was idling and warming up the car, and the SES was triggered.
Idle is a little lumpy - but still decent (prolly from 750-900 rpm). AFR gauge sits from 14.6-15.3 at idle. Vacuum gauge shows 13mm/hg.

So far I have:
- Cleaned the MAF/filter
- Cleaned IAC (figured may help the idle idk, plus its free might as well)
- Cleaned the EGR
- Tightened up exhaust flanges thinking there was an exhaust leak
- Changed Bank 2 Sensor 1 O2 sensor
- Checked for vacuum leaks (replaced a few brittle ones)
- Replaced PCV hoses and cleaned out PCV valves
- checked out bank 2 spark plugs gapped at 0.032 **THIS is where its a little interesting to me** (pics attached)
Cylinder 5,6,7 all looked like the plug on the left - Cylinder 8 is the dark plug on the right

I then replaced the spark plugs in bank 2, drove around, filled up some premium, put some seafoam in the tank and went to check them again.
So far cylinder 8 is looking more like the rest of the plugs in the bank. SES light remains.

Here's the values I was able to gather (car came with an SCT Xcal2 - unfortunately its unable to communicate with my laptop so no nice datalogs


P0174
Abslt TPS 20%
Engine speed 763 rpm
Calc Load 24.3%
MAF 0.83 lb/m
Coolant 196 degrees
IAT 75 degress
IGN adv 33.5
ST FTRM 1 32.8%
ST FTRM 2 16.4%
LT FTRM 1 21.9%
LT FTRM 2 25%
Vehicle Speed 0 mph
Rel FRP 39.77 psi
O2S11 0.255v
O2S21 0.435v


Any help would be much appreciated!!
 

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I would look at the fuel pump, fuel regulator, and injectors. Do you have a way to watch your fuel pressure as you're driving?

I would also look around for vacuum leaks.
 
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I would look at the fuel pump, fuel regulator, and injectors. Do you have a way to watch your fuel pressure as you're driving?

I would also look around for vacuum leaks.
After changing some hoses my vacuum at idle is 15. So I must’ve found a small one. Still no changes with the SES tho.


I no longer have the capability to log live. I sold my SCT with my GT 3 years ago…kicking myself for that right now

I did pull the injectors on bank2. Taking them in tomorrow to get flowed and cleaned.

After I pulled the fuel pump fuse, cranked till it no longer ran and relieved the schrader valve - I lifted the fuel rail with injectors. When I went to remove cylinder 5 injector it was still loaded with pressure! Wasn’t expecting the gush of air/fuel…I don’t think that’s normal is it?
 
Got the injectors back today - the shop said it flowed fine..
Put new o-rings on and installed them. I also changed the fuel filter since it looked like it was the original from 2004.
Fired it up and took it on a few runs. So far so good
 
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@Noobz347

It came back on today…

Freeze frame was
St ftrm1 7%
Lt ftrm 1 12.5%

St ftrm2 12.5%
Lt ftrm 2 22.7%

This is driving me nuts. Could a bad COP cause this?
I plan to smoke test it sometime next week vs the propane
 
@Noobz347

It came back on today…

Freeze frame was
St ftrm1 7%
Lt ftrm 1 12.5%

St ftrm2 12.5%
Lt ftrm 2 22.7%

This is driving me nuts. Could a bad COP cause this?
I plan to smoke test it sometime next week vs the propane
I'm not sure what this means but it appears that the bottom line is that you have a lean condition. From what you've said, you still have a lean condition in cylinder 8, is this correct?
 
I'm not sure what this means but it appears that the bottom line is that you have a lean condition. From what you've said, you still have a lean condition in cylinder 8, is this correct?

I pulled bank 2 plugs today and it doesn’t look lean..but also haven’t logged a ton of miles on them to show a solid difference from a new plug
Tomorrow I’m going to smoke test the exhaust
I did the intake side today and it looked good

Only reason why I asked about a bad coil on plug is due to the first time I pulled the bank 2 plugs - during that time all had the same color except one. The picture is at the beginning of the thread. Looked like it wasn’t fully firing compared to cylinders 5,6,7
 
For anyone who's still following along...Something wasn't sitting right with me and since I had the intake side off the blower, I smoked it again to make sure everything was good (I bought my own smoke test off amazon) including the connections for the bypass that I couldn't see under the intake.

Well, I found a leak at the throttle body (tightened it down and that's good), and a small leak that comes from under the vents of the EGR. Now, the EGR ties right into bank2, so I think I found the true culprit along with many other things.

Does the EGR have to be motorcraft? Pics attached for @Noobz347 lol

Sorry the pics suck. But if I could post the Live Photos from phone you definitely can!
IMG_2737 2.jpg IMG_2739.PNG tempImagecBPodd.png
 
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Tested for exhaust leak with pressure instead of smoke. Found a post (about 12” away from o2 sensor) and a pre! Hopefully this is it!
Hopefully tomorrow, if not, Monday I’ll have time to get under it
IMG_2795.jpeg
IMG_2794.jpeg
IMG_2792.jpeg
 
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Shop called me today -

Stated that they’re unable to communicate to the PCM and make the changes. He also requested the stock tune (idk where the heck I’m gonna get one right now) cause the Xcal that came with the car, is so old, the screen is unreadable.

I looked back in the binder that came with the car - and seen the PO took it to the dealer for a PATS issue and got work done. Is it possible, they update the PCM strategy? So whatever tune was written for the old is no longer “true” to the revision?

Idk jack about this stuff, just thinking why he would need the stock tune, and why he was able to read it but not make any changes

Edit: I have a feeling he was using hptuner mpvi3, which doesn’t support our PCM. From what I’ve read it has to be either 1, or 2. I’ll verify tomorrow
 
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