[Brandon]

I love the engine but I just started having a strange problem. It hesitates and then kicks in, and occasionaly lets out a HUGE backfire from the intake (pre-fire?). No check engine light but I haven't ran the codes. Any guesses? I'm gonna stop drivin it to work till I figure it out

 

[rockcrawl]

If it is backfiring it sounds like a timing thing to me. Might check that out. It will also cause hesitation problems.

Travis

 

[Brandon]

it is not a constant thing, just lags lags then boom it kicks it to power, doesn't seem to be all the time either. I will check the timing though - honestly never have!

 

[TR]

Sounds liek the TFI module is gonna take a crap on you.

 

[CrazyHorse]

either ignition, or fuel delivery, mine has done it for both.

 

[Brandon]

so basically it could be anything :flipoff2:

fuel pump is a stock 5.0 mustang, ignition all stock as well. I have wanted to get a spare TFI anyway - are the aftermarket ones any better (I think there is an edelbrock or something or other in summit)

Ignition - as in coil or distributor or ? I gotta get my butt out there and plug in my el cheapo code reader to see if it grabs anything off of it still

 

[CrazyHorse]

ignition as in probably TFI module failing...

 

[1SAWB]

PERSONALY I WOULD LOOK AT THE TPS SENSOR AND GET A VOLT READING THRU THE WHOLE OPENING PHASE...AND YES THE AFTER MARKET TFI MODULES ARE BETTER THEY OFFER LONGER DWELL TIME OR MORE SATERATION TIME IE HOTTER SPARK

 

[BEAR]

Cauz its a furd:flipoff2:
J/K whats up Brandon, just thought id say hi and tell ya congrats on FINALLY gettin your rig done (even though Im still working on mine)haha.
C-ya on the trail!!
Ryan

 

[H8monday]

I would check the TPS also.
The TFI usually will cause backfires a few times then go dead. I would recommend the stock Ford TFI for reliability, and just go to an MSD ignition if you are looking for more power through lengthend spark saturation.

 

[Brandon]

I found that my egr vacuum is not hooked up - but can't figure out where it goes


removed parts

this is where one vacuum from the upper intake is going on mine - to that thing below the egr

and the other one splits, one going to the egr solenoid and then t's to two of the other solenoids

with nothing going to the egr itself, been too long since I looked at the car

I'd really like to get this fixed asap, and the vacuum issue is a start - HEEEELLLLP

 

[mrs. camo]

sounds exactly the way my 4.3 is running. i have had a wiz bang tech trouble shooting it for about 6 hours already and he can't figure it out.


arrrggg.

i will let ya know when he solves my issue

 

[Brandon]

thanks

I got 2 codes, 67 and 33. 67 is related to the tranny (it had an auto now it has a manual so screw those codes) 33 is related to EGR like I knew is fishy..

 

[Nobody]

I highly suspect plugs/wires.

 

[camo]

I highly suspect plugs/wires.

i did to. changed mine. didn't fix it

 

[ToiletDuck]

id check see what kinda pressure your gettin from the fuel pump

 

[CrazyHorse]

I found that my egr vacuum is not hooked up - but can't figure out where it goes
with nothing going to the egr itself, been too long since I looked at the car

I'd really like to get this fixed asap, and the vacuum issue is a start - HEEEELLLLP

-you should have one line that goes from the vacuum tree on the bottom of the intake to the fuel pressure regulator (the little silver thing under the EGR)

-you should then have one line that goes from the same tree and tees off to the EGR solenoid, the TAB (Thermactor Air Bypass) solenoid, and the TAD (Thermactor Air Diverter) solenoid, if you arent running a smog bomp you should have this line connect only to the EGR solenoid, and leave the TAB and TAD plugged into the wiring with no vacuum to them

-the other side of the EGR solenoid should have a line connected to the EGR valve's vacuum connection

-off the large connection on the same vacuum tree you would connect to your power brakes, or to the external vacuum tree (the plastic thing with two bolt holes and a big vacuum line in your pic of parts removed) if you need vacuum for more accesories

-your PCV connects to the large port on the bottom rear of the upper intake, and down to the valve in the rear of the lower intake

-If you have a vapor recovery system it connects through the solenoid valve to the port opposite the PCV connection

Without running out to my truck to double check that should be everything vacuum wise on the motor

Hope it helps.

 

[zags]

Yup, check the fuel pressure. It should be 30-35 psi. at idle,40-45 psi. off idle. Also, check for vacuum leaks between the manifold and the MAP if it is a speed-density setup. Something is making it go lean I think. The EGR routing is pretty simple on those. Stock, there is a red hose that goes from the manifold to the EVR.(The gizmo bolted to the firewall below your sleeve in the picture). Then a green hose from the EVR to the EGR valve. Look carefully for cracks in the plastic line as these lines get older. The code 33 is pretty common as the EGR position sensor (the white plastic sensor on the end of the EGR) goes bad when they get older.

 

[H8monday]

Did you even check your TPS voltage.
Misadjusted TPS voltage is hands down the number one cause of exceleration problems of every kind. Any 5.0 performance guru that knows his ass, from his mass air meter, will tell you to correctly adjust the TPS before you check anywhere else. It affects everything from timing to fuel delivery, especialy at the bottom the rpm range.
At leats check it and tell us what the voltage is before you go crazy chasing gremilns. It should be at .99 volts at idle(if I remember correctly ).

 

[Brandon]

I never checked or touched my TPS...

Ford Motorsports wires, although that doesn't mean anything I guess. I do know the vacuum is fishy as you can see so I wanna dial that one in first, thanks for the in depth description there - I'll print that out and run out to my truck..