help me diagnose

[mustangvsix]

Alright car has been acting a little funny recently.

Starts up just fine no problems there.
Drives fine when cold, no problems here

When warm from 1800-2100rpm's or so its like its running on empty.
You touch the gas and it struggles to rev whether it be 1st gear or 5th gear. Problem seems to get worse the longer it is driven at temperature.

I cleaned the MAF and unplugged the battery for 10-15mins while doing so, hoping this would solve the issue. It has not.

Mods of of some significance....

JLT RAI
1/2" intake spacer
Bassani O/R X
SLP Catback with Mac mufflers

all mods have been installed for 1-2 years.

Also when installing O/R x pipe I put splice in MIL eliminators in but they didn't work I still have the light on. Left them in and been driving like that for 2 years or so. Gas mileage so far seems to be spot on for mixed city/highway/screwing around for recently 18-19mpg+. On straight highway it does 24mpg+.

I think tomorrow I am going to pull all the plugs and check them. I did them about a year or two ago but maybe something is going on with that. I pulled one today and it looked perfectly fine, normal wear and tear but maybe one or two else where are no good.

Any ideas??

I have heard maybe EGR issues could cause this?
What about one of the COP's? I am leaning toward this or plugs...but the plugs likely would fail because of one of these going so yes I think.
Dirty Fuel Filter?
I doubt it is...but maybe fuel pump?? IDK...

Help, pleas, thanks!
:beer:

 

[Bad99SVT]

Maybe the coil on plugs...if it is getting hot and it has a crack in it the plastic on the coil may be expanding and letting it loos spark possibly...i would check all the plugs and coils in my opinion.

 

[ijt351]

Did you run a diagnosis test, what codes did you get. Don't assume the light is on because of the cats, you probably have a code that will tell youwhats going on. You can waste a bunch of money just guessing.

 

[mustangvsix]

alright pulled all the plugs this AM and they were all good looking so no problem there.
Ran over to autozone to get the codes pulled...and there were a lot of them. 11 to be exact.
P0443,, P1451, P0155, P0141, P0135 and P0161 I believe I solved these ones, my #8 fuse was blown under the dash and it is correlated to all these codes. These are O2 heater codes and EVAP system solenoid circuit malfunction as well as purge vent solenoid circuit condition codes.
Someone on another forum said this:
"Ok what I see here is circuit faults on 4 different components. I think it's extremely unlikely that all those parts went bad at once. I looked at the wirring diagram and I found a few things in common

both of the 02 sensor heater circuits and the purge and vent valve share fuse #8 in the centeral juntion box ( the box under the dash NOT UNDER THE HOOD) this fuse is a 20a fuse" p0443/p1451/p0135/p0155 - Mustang Forums at StangNet


Next up I had P0153, 1130, 0175, 1152, and 1409.
I think 0153 is a result of the previous as it is a circuit condition for bank 2 sensor 1. also P1130 is a result as it says fuel trim at its limit lean or rich. As is P0175 being bank 2 fuel trim condition.
P1152 is lack of O2 switches which is O2 at its rich limit probable cause high fuel pressure, EGR stuck open or engine mechanical condition...I think it is tied to the rest.

Then P1409 is EGR vacuum regulator circuit fault...not sure on this one, maybe failed EGR valve or EGR regulator (I think this is that little black thing bolted next to it to the left with a plug and two small vacuum lines going to it? )

ideas? Logic sounding good? I am going to go get the codes re-read tomorrow to see what pops up again but as of now the CEL is off since I reset the computer once replacing the fuse.

Definitely running better, it isn't trying to die on me between 1800 and 2000 rpms seems much better but still has a slight hesitation/stumble through there.

 

[mustangvsix]

Well between changing out that #8 fuse and now having replaced the EGR Valve Pressure Sensor along with cleaning the MAF it has significantly helped with the stumbling and hesitating. But it is still surging a little at highway speeds. Say 65-70mph in 5th gear with cruise control set at some speed in between there it feels like someone is constantly varying on and off the throttle. Not like WOT on/off but just tap it, let off, tap it, let off. Going to try replacing the EGR Vacuum solenoid and see if that solves it. So far little fixes lets hope nothing costly comes up.


edit: Changed the Vacuum Solenoid still surging...gah! Guess I will try cleaning the EGR valve itself tomorrow see if that resolves any issues.

 

[ijt351]

To see if it is egr related at all just pull the vacuum hose off of the egr valve and drive it. If it still surges it ain't the egr system. pulling the hose off will only code an insufficient egr flow. sounds like it could be fuel problem. get a fuel pressure gauge see what pressure is and then snap throttle, if it dips even a little sounds like fuel pump. and if you got the egr sensor at a parts store hang on to your old one cause it will fail.

 

[mustangvsix]

Well just took it out for a test drive after cleaning the EGR valve and I also re-installed a factory gasket on it rather then an EGR restrictor gasket I had put on along with an IAC gasket to help with hanging idle issues. Runs perfect. Ran it up and down the highway, got on it a few times, cruised it, did normal and hard acceleration through the "problem" zone of RPMS and it didn't miss a beat. So I think cleaning and a proper gasket fixed it. No CEL lights either. Will remain suspect for a while and will probably look into changing the fuel filter for the heck of it soonish as well. 42k miles and she is running like a champ again.