• Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • Fox 5.0 Mustang Tech

Engine Need help diagnosing 2 dead cylinders

  • Thread starter Thread starter lvgnmz
  • Start date Start date Feb 13, 2025
L

lvgnmz

New Member
Feb 13, 2025
2
0
1
New Mexico
Feb 13, 2025
#1
  • Feb 13, 2025
  • #1
I’ve got an 89 hatch with hci, vortech v1, intercooler, and all supporting mods including ford performance 47lb injectors. I just finished doing intake gaskets and a catch can after the car sat for a few months. It fired up right away but has a terrible misfire, after checking header temps the number 2 and 3 cylinders are cold. Pulled the plugs and there’s no fuel at all.

I know I have fuel at the rail because the number 1 and 4 cylinders are firing correctly. Some things i’ve tried so far are testing the injector plug for 12 volts which they passed, jumped the injectors with alligator clips to make sure they’re clicking open, cleaned the injectors, switched the injectors around to see if the problem moved which it didn’t, closed the contacts on the salt and pepper shakers, and switched computers.

This really has me stumped and I don’t know what else to try. Any suggestions would be appreciated.

Update: I forgot to add that i had done intake gaskets a couple months ago do to them leaking because i hadn’t properly vented my crankcase yet. Anyway i replaced them and took the car half a mile down the road before it started overheating. Turns out the gaskets they gave me at yearwood were missing a water port right underneath the 2 cylinders that are missing.
I’ve done some more troubleshooting and this is what i’ve come up with. I put a noid light on the injectors and both have pulse. I pulled the rail with the injectors and cranked the motor, both injectors sprayed fuel. i tested spark at the plugs and both have spark. i put 2 of the old plugs in which made no difference. I pulled the valve cover and cranked the motor, both rockers are opening and closing as they should. The last thing i have to test is compression. If it fails the compression test i believe its either going to be burned valves or a blown head gasket from when the car overheated.

Thanks for all the help and i’ll update again after i test compression.
 
Last edited: Feb 14, 2025

AeroCoupe

lube between the nut and the face. I know my lubes
Founding Member
Oct 28, 2001
5,804
3,938
183
Claremore, OK
Feb 13, 2025
#2
  • Feb 13, 2025
  • #2
Have you tested the plug wires and checked the spark plugs for cracks?
 
L

lvgnmz

New Member
Feb 13, 2025
2
0
1
New Mexico
Feb 13, 2025
#3
  • Feb 13, 2025
  • #3
AeroCoupe said:
Have you tested the plug wires and checked the spark plugs for cracks?
Click to expand...
the spark plugs are brand new i replaced them along with the intake gaskets, and the wires are getting good spark at the distributor.
 

Mustang5L5

That is…until I whipped out my Bissell
Mod Dude
Feb 18, 2001
43,191
17,889
224
Massachusetts
Feb 13, 2025
#4
  • Feb 13, 2025
  • #4
Fuel, spark, air, compression.


We can assume you didn’t leave a rag stuffed down in the ports, so if fuel and air check out, only thing left to do is check compression.

I’d also assume nothing about the sprark pkugs and wires and try swapping them to a different cylinder as well. Just because they are new doesn’t mean they can’t be faulty.
 
Reactions: nickyb
You must log in or register to reply here.

Similar threads

M
Misfire
  • Mike3
  • May 30, 2026
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Replies
1
Views
64
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- May 30, 2026
Mike3
M
A
1987 5.0 speed density Foxbody crank no start
  • Alan2204
  • May 23, 2026
  • Fox 5.0 Mustang Tech
Replies
10
Views
164
Fox 5.0 Mustang Tech May 30, 2026
Mcmahst
Electrical 88 EEC Injectors batch firing ?
  • Dustin 86GT
  • Dec 8, 2025
  • Fox 5.0 Mustang Tech
Replies
10
Views
392
Fox 5.0 Mustang Tech Jan 8, 2026
gkomo
J
'04 3.8L V6 mineral deposits and oil on #3 cylinder. Does it need a rebuild or something simpler?
  • joeybuddy96
  • Mar 18, 2026
  • SN95 V6 Mustang Tech
Replies
5
Views
210
SN95 V6 Mustang Tech Jun 9, 2026
joeybuddy96
J
C
Engine Cylinder 5,,7, & 8 run significantly cooler than the other cylinders
  • Crisfixes
  • Sep 27, 2025
  • Fox 5.0 Mustang Tech
Replies
1
Views
218
Fox 5.0 Mustang Tech Sep 27, 2025
Noobz347
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • Fox 5.0 Mustang Tech
Menu
Log in

Register

  • Forums
  • What's new
  • Media
  • Resources
  • Contact
  • Sponsor
X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?

X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?