pulled some codes need some help?

[MY 85 GT]

Ok i pulled these codes 34 and 81 both seem to have nothing to do with why my car is bogging and popping in the intake...sometimes it does this and sometimes it runs great any help would be awesome thanks..

[JACook]

You don't think evaporative purge could have something to do with it? Actually they both
could. If your TAD solenoid circuit is malfuntioning, the air injection can be causing the
oxygen sensors to read improperly.

[MY 85 GT]

You don't think evaporative purge could have something to do with it? Actually they both
could. If your TAD solenoid circuit is malfuntioning, the air injection can be causing the
oxygen sensors to read improperly.

Well i dont have an air pump anymore and all emissions stuff is gone EGR valve is still there .and hooked up..Air pump gone,off road H-pipe...So now what how can i fix this problem?

[JACook]

Have you checked your fuel pressure with and without the vacuum hose connected? Have
you inspected/cleaned the salt and pepper connectors? Are ALL of your engine grounds
clean and tight?

Probably wasn't that great an idea to yank the evaporative emissions stuff, but I don't
think that's what's causing the engine to sneeze. I'd be leaning toward a fuel pressure
problem.

[MY 85 GT]

Have you checked your fuel pressure with and without the vacuum hose connected? Have
you inspected/cleaned the salt and pepper connectors? Are ALL of your engine grounds
clean and tight?

Probably wasn't that great an idea to yank the evaporative emissions stuff, but I don't
think that's what's causing the engine to sneeze. I'd be leaning toward a fuel pressure
problem.

Havent checked it yet...But the fuel tank is brand new..new walbro 155 lph pump,new areomotive adjustable Fuel pressure regulator,New eveything..lol...the only thing old are the injectors...didnt check the salt and pepper connections yet i will and clean them up the whole top of the motor was apart and put back together by a very good mustang shop i even have brand new PIP.ign module,coil,wires everything...lol im lost...this car is still Speed density with a 70mm TB and spacer i was told thats the problem i dont think it is tho...

[Mustang-junky]

Have you checked the EGR valve to see if it is hanging open? Your car will run like poo if it is. Take it off and check it out. Mine is on the shelf after it caused me problems.

Jess

[MY 85 GT]

Have you checked the EGR valve to see if it is hanging open? Your car will run like poo if it is. Take it off and check it out. Mine is on the shelf after it caused me problems.

Jess

didnt check it,,,but would that make the car pop in the intake and make the car run rough at idle? it doesnt run like crap all the time just sometimes...it does this then clears up runs fine then out of the blue idles poor and pops in the intake when you try to take off...

[eeprete]

have you checked fuel pressure at the valve and also pulled plugs to inspect? Also have you checked plug wire resistance? Have you also checked the distributor and TFI?

[MY 85 GT]

have you checked fuel pressure at the valve and also pulled plugs to inspect? Also have you checked plug wire resistance? Have you also checked the distributor and TFI?

Ed everything when i say everything is new on this car i mean everything...LOL fuel tank,fuel,pump walbro 155 lph,fuel lines,aeromotive AFPR,Plugs are perfect autolite 25 i have in there,MSD cap,rotor,MSD wires,New PIP from Ford new Ign Module From ford..MSD coil.New intake mainfold gaskets,Mac headers,off road H-pipe Flowmaster Cat back,70mm TB BBK 70mm spacer,Police hoses,180 t-stat,I even found the stock Speed density Air filter assy.I do have underdrive pullies,3 row Radiator,air pump delete,those check valves going to the heads are gone...This car when running good runs like a raped ape..It has a awesome AOD with shift kit,i think 3.27's this car moves..But somedays it just bogs,pops in the intake...I checked timing it was fine...did not check fuel pressure yet what is it supossed to be set at idle with hose on? Or do i check it with it off?...any help would be great this is driving me nuts..I wish i had the 90 Back that runs just fine....lol

[Mustang-junky]

Pull vacuum hose off and set to 39 to 40 pounds. With stock cam the fuel pressure should drop down to the low 30s with vacuum hose in place.

Jess

[MY 85 GT]

Pull vacuum hose off and set to 39 to 40 pounds. With stock cam the fuel pressure should drop down to the low 30s with vacuum hose in place.

Jess

Fuel pressure is perfect vac hose on around 32 psi and with vac hose off it like 40-41 psi...so there no fuel problem...Has to be a weak or bad injector i think?..i have to do the CBT to see if i tells me i hae a bad injector...

[MY 85 GT]

ok i also just noticed i dont have any Vac going to the EGR valve i dont have any thing going to the PFPE thing on the fender by the shock tower looks like my EGR valve is along for the ride can that be causing this problem?...Can you just disconnected the EGR valve like that?..i dont have an air pump anymore i think he took all my emissions out....

[MY 85 GT]

Ok still having this problem popping in the intake not all the time but does it...ok checked fuel pressure...32 vac on 41 vac off...
codes i got where 34-and now 42

Cylinder balance test was 9 flashes so no injector problem...


I really need some advice here car runs great sometimes and then sometimes it idles rough at a light take off pop..pop in the intake...what can this be??????

[FoxChassis]

It is VERY important that you state during which "Self Test" (Key On-Engine Off, Continuous Memory, or Engine Running) you are getting the codes, and that they are listed in the order that they were presented (don't rearrange them in numerical order).

34 = EVP (EGR Valve Position sensor) circuit above the closed limit of 0.67 volts (KOEO and ER); OR
34 = EVP circuit has intermittently failed above the closed limit of 0.67 volts (CM)


42 = right side HEGO sensor circuit indicates system rich (CM); OR
42 = right side no HEGO switching detected always rich (ER)

81 = TAD (Thermactor Air Diverter) circuit failure (KOEO); OR
81 = MAP sensor vacuum was not greater than 2 in-Hg (7 kPa) during normal vehicle operation (CM)

[MY 85 GT]

It is VERY important that you state during which "Self Test" (Key On-Engine Off, Continuous Memory, or Engine Running) you are getting the codes, and that they are listed in the order that they were presented (don't rearrange them in numerical order).

34 = EVP (EGR Valve Position sensor) circuit above the closed limit of 0.67 volts (KOEO and ER); OR
34 = EVP circuit has intermittently failed above the closed limit of 0.67 volts (CM)


42 = right side HEGO sensor circuit indicates system rich (CM); OR
42 = right side no HEGO switching detected always rich (ER)

81 = TAD (Thermactor Air Diverter) circuit failure (KOEO); OR
81 = MAP sensor vacuum was not greater than 2 in-Hg (7 kPa) during normal vehicle operation (CM)

Ok i got code 34-42 with the engine running i was doing a cylinder balance test thats the codes i got while the motor was running...so can that be whats causing my popping in the intake> Bad Map i have no EGR valve hooked up and the PFPE is also disconnected too...

[FoxChassis]

No sense in trying to fix fault code 34 if your EGR system isn't installed properly, i.e. no vacuum.

The 5.0L engine does not use a PFE (Pressure Feedback EGR) sensor.

Fault code 42 could be caused by a few things. Number one is the mileage on the right EGO sensor. If it has over 50K miles on it, replace it.

[MY 85 GT]

No sense in trying to fix fault code 34 if your EGR system isn't installed properly, i.e. no vacuum.

The 5.0L engine does not use a PFE (Pressure Feedback EGR) sensor.

Fault code 42 could be caused by a few things. Number one is the mileage on the right EGO sensor. If it has over 50K miles on it, replace it.

Both o2's are new....unless one is defective?...will that cause this problem tho popping in the intake/bogging but not all the time?

[FoxChassis]

Are they grounded properly?

[MY 85 GT]

Are they grounded properly?

How would i check that? where do they ground to? im not sure i didnt install them ..all the work done on this car was done by a shop...

[embler]

Still using the stock intake? Check the ground wire for the injectors. Its orange if I remember correctly and should be grounded at the back of the intake area.

[MY 85 GT]

Still using the stock intake? Check the ground wire for the injectors. Its orange if I remember correctly and should be grounded at the back of the intake area.

Yes still stock intake i'll take a look and see if its grounded..thanks..

[embler]

Yes still stock intake i'll take a look and see if its grounded..thanks..

That's a big throttle body and spacer for a stock intake. I would pull them and check where the spacer sits against the intake. With it being as big as it is, the egr passage may not line up right with those in the intake and the gasket may not seal up right. If you still have the stock tb and spacer, try bolting them back on and see if it helps. The 70 won't affect the speed density, fyi. I ran a bbk 70 tb and spacer on a trick flow intake on one of my 86s with speed density with no problems.

[MY 85 GT]

That's a big throttle body and spacer for a stock intake. I would pull them and check where the spacer sits against the intake. With it being as big as it is, the egr passage may not line up right with those in the intake and the gasket may not seal up right. If you still have the stock tb and spacer, try bolting them back on and see if it helps. The 70 won't affect the speed density, fyi. I ran a bbk 70 tb and spacer on a trick flow intake on one of my 86s with speed density with no problems.

I dont have the stock Tb or spacer...do you really think that is the problem..i mean there are days i start the car runs fin then other days i start the car runs great for a minute or so then starts running rough give it gas doesnt take it all to well pops in the intake then clears up...its really Weird if it was a bad o2 or bad ground or TB being to big i would think it would do it all the time no?