New here and looking for fuel trim expert help with P0172 and p0175 - Ford Mustang Forum
Like Tree7Likes
  • 3 Post By wmburns
  • 2 Post By wmburns
  • 2 Post By laubachs
 
LinkBack Thread Tools
post #1 of 8 (permalink) Old 06-25-2019 Thread Starter
Rookie
 
laubachs's Avatar
 
Joined: Feb 2018
Posts: 10
 
Question New here and looking for fuel trim expert help with P0172 and p0175

My son's 1996 mustang GT is unable to smog due to check engine codes p0172 and p0175 running rich in both banks. I have screenshots of short and long fuel term fuel trims that I would like to post but do not see how I can attach them to this post. I was hoping that someone could help me make a diagnosis based on the data.

845 rpm (idle)
-25% LTFT Bank 2
-6.3% STFT Bank 2
-25% LTFT Bank 1
-4.7% STFT Bank 1

2030 rpm
-7.8% LTFT Bank 2
-20.3% STFT Bank 2
-7.8% LTFT Bank 1
-20.3% STFT Bank 1

These codes showed up about a year and a half ago after replacing the (H2O leaking) intake manifold, but his car has been running fine. 2 of the fuel injectors were not working (clicking when attached to 9 volt battery) when I cleaned them so I ordered some aftermarket injectors on ebay to replace all 8 injectors (not sure if above data supports the new injectors to be the problem). I had to disconnect everything in the fuel system in replacing the manifold, so it could be anything related to that.

Most of the diagnosis material on youtube is related to lean conditions. I am just hoping that some of you experts in fuel trim might be able to help me out. I have been frustrated with this problem for long time and don't want my 17 yr. old son to get pulled over for not being registered. I would really appreciate it if some of you were able to better diagnosis and pinpoint the problem. I can do other readings on my scanner and post them if they are more relevant.

I would appreciate any expert help and direction you could give me.

laubachs is offline  
Sponsored Links
Advertisement
 
post #2 of 8 (permalink) Old 06-25-2019
BOSS Member
 
Beechkid's Avatar
 
Joined: Apr 2013
Location: SoCal
Posts: 4,447
           
Hopefully a "Tech" will jump on and provide more detailed info...but my swag would be defective or improperly operating injectors....did you get oem units or....


just as an fyi- Bosch just seems to have QA issues in the past couple of years (that I have avoided their products since) that I haven't seen before and is under an international criminal investigation relating to business practices....again, just an fyi


:hello:
Member: Never trust a person over 40 who drives a Chevy club
Flatheads ain't so bad!
Certified backyard mechanic I & II
Beechkid is offline  
post #3 of 8 (permalink) Old 06-25-2019
SHELBY GT 350 Member
 
wmburns's Avatar
 
Joined: Sep 2010
Location: Houston
Posts: 6,830
         
One of the FIRST things I would rule out is MAF contamination. One of the "give aways" are LTFT that change from idle to load. Clean the MAF using only a product designed for the job. The MAF is easily damaged. Don't trade one problem for another.

The next thing I would DOUBLE check is that the fuel pressure regulator intake vacuum reference line is connected and leak free. The symptom of a disconnected intake vacuum reference line is LTFT that are rich at idle and tend less rich at higher RPM's.

How to test if it's working? Measure the fuel pressure with an external gauge at idle. It should be around 32 PSI. Disconnect the intake vacuum reference line and the fuel pressure should jump to 40 PSI. If it does, then the system is working.

I personally have had great luck with injector cleaning and flow test service such as InjectorRX.com. Once cleaned and tested they are as good as new. Cheaper than new.

+1 it's important that the replacement fuel injectors have the same specifications that the PCM is expecting.
Beechkid, MustangLife and imps like this.

2003 GT Convertible (sold & missed)
2000 GT coupe (Craigslist project. Fixed. Now my DD). Windsor to Romeo swap.
wmburns is offline  
 
post #4 of 8 (permalink) Old 06-26-2019 Thread Starter
Rookie
 
laubachs's Avatar
 
Joined: Feb 2018
Posts: 10
 
Well the only thing I changed were the 8 aftermarket ebay injectors after installing the new manifold and the check engine light came on a day later. I think you are right about the injectors, I just ordered a set of 8 accel 19 lb. (oem replacements) fuel injectors from American muscle for $305. These injectors have a 100% five star rating from a very reputable company that specializes in Fords. I am hoping this solves the problem. It makes sense that this is cause of the check engine light.
laubachs is offline  
post #5 of 8 (permalink) Old 06-26-2019 Thread Starter
Rookie
 
laubachs's Avatar
 
Joined: Feb 2018
Posts: 10
 
wmburns: I have cleaned the maf appropriately multiple times and even pulled and installed another maf from the local pick-n-pull w/ no changes to check engine. I have not checked the fuel pressure regulator, but it is connected to good vacuum. I'll pick up a fuel pressure gauge tomorrow and check it out (thanks for the psi #'s). Thanks for the recommendation for the injector cleaning, I just bookmarked them for future use. Unfortunately, I did not see your post until after ordering the new fuel injectors from american muscle. I know that two of my original oem injectors were not firing (clicking) when connected to a 9 volt battery, that is why I ordered the ebay set. Do you think those injectors' could have been brought back to life by InjectorRX.com? I am pretty sure these 8 new accel injectors will solve my problem. A little pricey (though cheaper than oem), but the 100% 5-star reviews on the 19 lb. injectors sold me on them.
laubachs is offline  
post #6 of 8 (permalink) Old 06-26-2019
SHELBY GT 350 Member
 
wmburns's Avatar
 
Joined: Sep 2010
Location: Houston
Posts: 6,830
         
IF the LTFT's change by a large amount between idle and load that is a sign there's something going on. If the MAF is clean and the fuel pressure is correct then the other usual causes are intake vacuum leak or exhaust leak.

The specific direction and the amount of the change can give clues as to what is going on. Further comparing the LTFT's bank 1 to bank 2 can also give clues.

Regarding your question about IF InjectorRX.com could revive you old injectors, that would depend upon why. I suspect the answer is no if the reason is electrical (shorted winding). On the the other hand if they are mechanically stuck then it might be possible to restore function by cleaning. Regardless you get a report of the flow and spray pattern before and after cleaning as well as knowing for certain the repair state of each injector.

But it's a little late for that now as you have already purchased new units.
Beechkid and MustangLife like this.

2003 GT Convertible (sold & missed)
2000 GT coupe (Craigslist project. Fixed. Now my DD). Windsor to Romeo swap.
wmburns is offline  
post #7 of 8 (permalink) Old 06-27-2019 Thread Starter
Rookie
 
laubachs's Avatar
 
Joined: Feb 2018
Posts: 10
 
Just checked fuel pressure readings

It was 31 psi with vacuum connected FPR and 39 psi with vacuum removed from FPR. This seems to be about what you said the specs should be "32/40".
laubachs is offline  
post #8 of 8 (permalink) Old 4 Weeks Ago Thread Starter
Rookie
 
laubachs's Avatar
 
Joined: Feb 2018
Posts: 10
 
FYI. . .American Muscle Fuel Injectors fixed the problem immediately. Moral of the story: Don't buy cheap parts on Ebay.
Beechkid and Jeremy Weigel like this.
laubachs is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Ford Mustang Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a VALID email address for yourself, otherwise you will not receive the necessary confirmation email needed to confirm, validate and activate your new AFM member account.

Failure to provide a VALID email address, will result in the cancellation of your new AFM member account registration.

Email Address:
OR

Log-in













Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome
 


Search Engine Friendly URLs by vBSEO 3.6.1