1994 mustang gt misfire

Tnelson-sn95

New Member
Oct 23, 2019
14
0
1
25
Washington
Developed a misfire the other day, pulled my plugs and found a wet plug in cylinder 3 and smelled like gas not oil. Replaced all my plugs and tested spark. Had a strong blue spark on my plugs that I gapped to factory specs, what else could be causing this? I'm leaning towards a failed injector but would like some input if anybody else has run into this. Already replaced my fuel filter and tested rail pressure everything checks out and compression is 165 across all holes
 
  • Sponsors(?)


General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
17,333
5,599
193
polk county florida
Pull codes
Read through it to make sure you understand and have the tools handy. 94-5 specific stuff is highlighted.
Let us know what you find and welcome to stangnet.
 

jozsefsz

5 Year Member
Aug 11, 2013
1,148
272
114
49
Cleveland OH Area
A failed injector is a good guess, though if one were stuck open you'd notice a rapidly falling pressure at the fuel rail. Might just be a leaking injector. You could try running the cylinder balance test to see if it points out #3. If it's the only impacted cylinder, and you have good compression, that eliminates a lot of things. Do other plugs on the same bank look ok? You can swap the injector to see if the problem moves with it, or pull the fuel rail and pressurize it to see if that one is leaking.
 

Tnelson-sn95

New Member
Oct 23, 2019
14
0
1
25
Washington
After pulling injectors I found debris in the nozzle of cylinder 3, replaced with new injector and found no change in idle. I'm getting really burned out on this pile
 

General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
17,333
5,599
193
polk county florida
Ok lets play 20 questions
does it misfire all the time like it is running on seven cylinders
is it random hummmmm ta da da da hummm (no I don't have tourettes)
has there been any recent work done
what size left shoe do you wear
ok that's only four but there will be more later
 

Tnelson-sn95

New Member
Oct 23, 2019
14
0
1
25
Washington
Its nonstop full rev range, and to my knowledge no there hasn't been. Only thing different is I added a new cap and rotor a month ago trying to chase down the rough idle and the contacts were cooked anyway. Checked last night and I'm only pulling 15-16 inches of vacuum at idle but the needles steady not bouncing around. My fuel trims are maxed out rich in bank 1. And size 11.5 but that's both feet so I don't know if that'll help much
 

Tnelson-sn95

New Member
Oct 23, 2019
14
0
1
25
Washington
Plug wires are good, ohm checked them and they pass and they're not in bad shape. My vac gauge was indicating my timing was too far retarded on the dial but I have my doubts as I just set base time with the spout disconnected and the distributer hold down is tight not moving around. I have a picture of the cylinder 3 injector here
20191103_131204.jpg
 

jozsefsz

5 Year Member
Aug 11, 2013
1,148
272
114
49
Cleveland OH Area
That injector looks like it wasn't flowing much, probably for quite some time. So it definitely needed replaced, even if it wasn't the immediate cause of the problem. If the left bank is being enriched, the O2's think it's not getting enough fuel (too much air). That could be caused by another dead cylinder (O2 sensors don't detect raw fuel, only the air which hasn't been used up in the combustion reaction), and it could still indicate you might have a leaking injector that wasn't #3. Did you check how they all flowed / held pressure when you had the rail disconnected?

Run the cylinder balance test, see which problem cylinder it points you to. If they're all good, then an O2 sensor might be in order since it's just one bank mis-reading.
 

Tnelson-sn95

New Member
Oct 23, 2019
14
0
1
25
Washington
I pulled plugs and found only 1 wet plug which was cylinder three and at this point I'm not convinced it's missing on more than one cylinder. I'll try pulling codes again today to see if anything new has come about. This cars like a woman, if it would just tell me what's wrong I'd fix it but that'd be too easy
 

jozsefsz

5 Year Member
Aug 11, 2013
1,148
272
114
49
Cleveland OH Area
I hear ya, the EEC-IV isn't the easiest thing to diagnose. The cylinder balance test is very helpful. Have you run that? It's basically part 2 of the KOER test, can be run with a paper-clip if needed (if you don't have an OBD-I scantool). Will definitively tell you if it's missing on more than one cylinder, for any reason, and which one(s).
 

jozsefsz

5 Year Member
Aug 11, 2013
1,148
272
114
49
Cleveland OH Area
Bearings are a gold-ish color underneath the silver coating. Could be cam, rod, or main bearings. Not sure if your cloudy oil was a lot of shavings, or coolant in the oil. A blown head gasket might explain your driveability issue, as well as the wet plug (that injector probably wasn't pumping any gas). If it was getting coolant in the oil, it'd chew up the bearings pretty quickly. Or it could be some other mechanical failure or low oil pressure.

Sorry man, brighter side used 5.0's can be found relatively cheap (in the $500 range in my part of the world).
 
Thread starter Similar threads Forum Replies Date
T Engine 1994 mustang gt Rough idle, misfire under acceleration 1994 - 1995 Specific Tech 2
K 1994 Mustang 3.8l Misfire And Jerking SN95 V6 Mustang Tech 0
T 1994 Mustang GT Floor Pan Replacement 1996 - 2004 SN95 Mustang -General/Talk- 0
G Code 172 Mustang 1994. Can it be the egr ? 1994 - 1995 Specific Tech 2
M 1994 - 1998 SN95 Mustang Paint/Color Guide - Production #'s too! 1996 - 2004 SN95 Mustang -General/Talk- 0
B 1994 mustang cooling fan wiring? PLEASE HELP!! 1994 - 1995 Specific Tech 0
D 1994 Mustang Gt erratic idle 1994 - 1995 Specific Tech 1
M 1994 Mustang COBRA - speedometer not working 1994 - 1995 Specific Tech 11
G 1994 GT Mustang The Welcome Wagon 1
G 1994 GT Mustang The Welcome Wagon 3
beyondEOD SN95 94-95 Microsquirt Pinouts Digital Self-tuning Forum 8
beyondEOD 94-95 Mustang 5.0 AODE MS3 Gold Box w/ Microsquirt Digital Self-tuning Forum 62
T 1995 Explorer intake on 1994 Mustang GT 1994 - 1995 Specific Tech 4
N Please Help I'm Having Trouble with my 1994 Mustang GT 5.0 1994 - 1995 Specific Tech 6
9 For Sale 1994 cobra coupe, 150k mi, 5spd, 5.0L, $5k obo, Ewing, NJ SN95 Mustangs For Sale (1994-04) 0
N Electrical 94 Mustang Wiring to fuel pump and cooling fan 1994 - 1995 Specific Tech 0
wolfheads Fuse keeps blowing 1994 Mustang GT 1994 - 1995 Specific Tech 3
wolfheads 1994 Mustang gt convertible fuse box 1996 - 2004 SN95 Mustang -General/Talk- 0
N SN95 Need wiring diagram for 3.8l 1994 Mustang GT Please! 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- 9
R 1994 mustang ecm running rich 1994 - 1995 Specific Tech 21
K 1994 Ranger 2.3l into a 1993 Mustang LX 2.3l? 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- 4
J For Sale 1994 Mustang GT Autocross/HPDE setup, very clean, California. SN95 Mustangs For Sale (1994-04) 1
W 1994 mustang gt convertable 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- 2
W 1994 Mustang 5.0 running pig rich, black smoke at idle. 50 miles a tank of fuel 1994 - 1995 Specific Tech 4
M 1994 Ford Mustang GT 5.0 idle issues Fox 5.0 Mustang Tech 1
M 1994 Ford Mustang GT 5.0L The Welcome Wagon 9
N Mating a 1994 Mustang 5.0L to a 1988 2.3L body harness, HELP! Fox 5.0 Mustang Tech 5
D Engine 1994 Mustang GT 5.0 popping 1994 - 1995 Specific Tech 2
no_fox_given For Sale 1994 GT 5L Trickflow h/c/i Tremec TR3550 Saleen copy - $7000 (Ann Arbor, MI) SN95 Mustangs For Sale (1994-04) 3
I 1994 Mustang Gt Mach 460 1994 - 1995 Specific Tech 2
J My 1st Mustang. 1994 GT, 5 Speed The Welcome Wagon 0
D 1994 Mustang Convertible top cables 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- 1
P 1994 Mustang GT Convertible - Side Exhaust 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- 1
M 1994 Mustang gt. cranks and tries to start 1994 - 1995 Specific Tech 2
B Engine 1994 Ford Mustang Gt 5.0 No crank, no start 1994 - 1995 Specific Tech 3
J Non Mustang question.. Which 1994 - 1997 F-150 Truck did the 351 W Come in? like which trim? 1996 - 2004 SN95 Mustang -General/Talk- 3
wolfheads 1994 mustang gt speedometer not working 1994 - 1995 Specific Tech 5
G 1994 Mustang Air Bag Flashing Code 12 1994 - 1995 Specific Tech 3
94chirps Exhaust for 1994 Mustang GT 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- 1
M 1994 Mustang GT 5.0HO - Idle issue - Seeking advice Fox 5.0 Mustang Tech 6
N 1994 Mustang 5.0 - rpms drop when pressing gas while stopped. 1994 - 1995 Specific Tech 11
W 1994 Steeda Mustang GT woes and pains! in need of help! 1994 - 1995 Specific Tech 7
S HELP! Tried Everything. Mustang Cobra 1994 Cranks but won't start... Fox 5.0 Mustang Tech 12
M 1994 3.8L Mustang Dies intermittently 1994 - 1995 Specific Tech 7
Yumagoat Engine 1994 Mustang 3.9 144k miles SN95 V6 Mustang Tech 4
Justin Fetalvero Progress Thread 1994 Free Mustang Budget Build - Project Maui Cruiser 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- 3
Justin Fetalvero Just Got A Free 1994 Mustang V6! The Welcome Wagon 3
Chythar Expired Cervinis 1994-1998 Mustang Fiberglass Stalker Front Bumper, Painted Dark Forest Green (dfg) Interior Exterior Parts 0
Chythar SOLD 1994-1998 Ford Mustang GT Seats, Front and Rear, Black Fabric Interior Exterior Parts 4
C Mustang 2003-04 Oem Subframe Connectors 1996 - 2004 SN95 Mustang -General/Talk- 3
Similar threads