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

Totally Stumped!

  • Thread starter Thread starter De-Marko
  • Start date Start date Oct 8, 2014

De-Marko

New Member
Oct 6, 2014
12
0
1
Oct 8, 2014
#1
  • Oct 8, 2014
  • #1
Hello,

I have an issue that I'm really hoping someone will be able to shed some light on; i'll keep it as short as possible

1st. The car I'm working on is an '87 Cougar XR-7. This car has been my Dad's since '96 and it has gone through many engine/tranny transplants each one becoming more aggressive. The car was given the HO 5.0 guts, wiring and mass air from a '89 GT about 9 years ago or so. Cams, heads, intakes, fuel pumps etc. have come and gone and the car has always ran really well. About two months ago we installed a 347 from Coast with Pro comp 2.02 heads, 10.88 CR, Comp XE282 Cam, Trick Flow intake, 75 TB etc.

2nd. The issue is that the car is running rough and also having a major lean condition which in turn is causing some pre-ignition pinging. I'm not talking like at 4k or higher, it's been happening with very little throttle just to start rolling say past 30 mph. If you give the car more then about a 1/3 throttle it pings...bad!! We have an AEM wide band on the car and the A/R is off the scale lean wise. The plugs are porcelain white, no slight tan color here. The car has a big problem staying running and dies as soon as you put in in gear, of course it sputters and no power. Now mind you that the warmed over 5.0 with b-cam and 1.94 aeroheads etc. ran perfect so I doubted it was wiring but have checked it anyway.

3rd. I have researched and researched and have tried this or that!!! Ok, so this is what has been installed recently or tried on the car.

~All wiring and grounds have been combed over and tested. block, chassis, computer, firewall etc.
~New 3G alternator with an additional 4 gauge wire from block to negative battery pigtail on fender.
~No vacuum leaks, car holds about 14 hg at idle and even tried a pressure gauge on the crank case and got 1-2 psi at idle indicated no internal vacuum leak like under the intake. New vacuum hose everywhere anyway.
~Ran engine with no vacuum hoses and everything capped to eliminate any vacuum variables HVAC, booster etc.
~New TPS set at .98v
~New IAC, EGR and EVR, PCV, ACT, o2 sensors
~Have tried 3 different sets of injectors and 3 mass air meters. 2 Pro-M 75 MAF for 24s and even tried a stock MAF with 19s to see if the idle would smooth out but to no avail.
~New Walbro 400 lph pump and fuel filter
FPR set at 40psi with hose off and for fun tried 50 but no change
~checked for crushed fuel lines
~I've tested the mass air wiring and had steady 1 volt at idle and smooth numbers up and down while revving.
~Tried 2 different A9P computers.
~Two different distributors, one a new stock style with a new TFI module and the other a MSD.
~Two MSD blaster coils
~New MSD cap, rotor and ACCEL 300+ wires
~The timing is set at 7 initial with spout off for setting and also has a new Romac balancer. Have tried all different settings and if you go up to 14 BTDC it kills the engine.
~Drove the car with a fuel pressure gauge to monitor and it held steady
~Pulled codes and got a secondary fuel pump circuit fault code, but have read that if the pump runs to disregard the code. Don't know about that one.
~Tank has 5 gallons of 100 fuel
~ cleaned the salt and pepper shakers.
~no check engine light
~New autolite 3294 plugs and have tried NGK TR6's
~All cylinder pressure is in the 160-165 range

May have forgotten something but the car runs really crappy and way lean and I am totally out on what to do next.

I've never been so stumped on one of these cars and I've worked on many of my own and others.

Any and all help or suggestions are greatly appreciated!!!! Thanks for reading!
 

jrichker

StangNet's favorite TOOL
In Remembrance. Thank you for your contributions
Mar 10, 2000
27,512
2,811
234
Dublin GA
Oct 9, 2014
#2
  • Oct 9, 2014
  • #2
The vacuum should run 16"-18 " at idle. However your cam choice may alter that figure.

Exactly what code did you get? Did you also check the engine running codes?
 

De-Marko

New Member
Oct 6, 2014
12
0
1
Oct 12, 2014
#3
  • Oct 12, 2014
  • #3
Hey!

Haven't been able to mess with the car till yesterday. Ok, the code I got was 95 with the KOEO phase and a 95 for the CM. I read the thread on how to go about checking that. http://www.stangnet.com/mustang-forums/threads/code-95.836408/ The car was converted to mass air and didn't have the extra monitoring wire spliced into the relay so I think that's the issue there.

The KOER test came up with the thermactor fault which was no surprise since that equipment is long gone, but curiously I did get a code 18. I checked it out and read on here on diagnosing the issue.
http://www.stangnet.com/mustang-forums/threads/code-18-help-1990-lx.820644/ I did everything listed and unfortunately didn't find anything. Wires checked out fine, 22k resistor wasn't blown and no resistance in pin 36 wiring. The TFI module is new . It's interesting to me that when you remove the spout the idle speeds up, plug it back in and it slows down, you'd think it would be thee other way around. Not sure what to look for next, but will keep looking and checking. What do you guys think?

Thanks for looking!
 

De-Marko

New Member
Oct 6, 2014
12
0
1
Oct 15, 2014
#4
  • Oct 15, 2014
  • #4
Ok........ridiculously unbelievable!!!

I was able to find what was up with the car after much, thought, prayer, checking, shaking bones in a bag etc. lol.

Super long story short the Romac harmonic balancer timing marks are off... way off. I pulled the balancer off yesterday because I was at the end of my rope with this car and was checking everything I thought it wouldn't be. Set the key ways the same and they aren't even close. So, I call my Dad and ask him when he put this together what balancer he ordered, he told me for a '86-'93 5.0. He calls back a few minutes later and says, "Okay I screwed up, the receipts show that this is for a pre '80 302. Come to find out I guess the timing tab used to be on the drivers side on older V8's and that is where the differences are!! I had no idea! So the difference between "0" marks on the two balancers is seventy degrees. That means that by setting the timing at the "ahem" 14 degrees initial was actually setting it at 84 initial!! Pinging problems indeed!! The CORRECT balancer is on its way and THEN should be able to tune it......

Pics of the car and the engine, and then the balancers, the sharpie lines show "0" mark.

 

elarm1

10 Year Member
Dec 17, 2010
1,428
652
154
N.Va
Oct 15, 2014
#5
  • Oct 15, 2014
  • #5
My guess would have been timing all along! Glad you got it fixed
 
You must log in or register to reply here.

Similar threads

1
Engine 91 mustang 302 Low acceleration car backfires pops and acts like it doesn’t want to take fuel
  • 1991Fox5.0
  • Oct 4, 2025
  • Fox 5.0 Mustang Tech
Replies
16
Views
937
Fox 5.0 Mustang Tech Oct 6, 2025
1991Fox5.0
1
I
1994 Cobra - Fuel Pressure Drops Revving at Idle
  • IconicSilverGT500
  • Apr 11, 2026
  • 1994 - 1995 Specific Tech
Replies
16
Views
362
1994 - 1995 Specific Tech Apr 24, 2026
Mcmahst
S
Fox '87 GT can't get to stay running
  • spilly
  • Mar 29, 2026
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • 2
Replies
26
Views
567
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Apr 25, 2026
CAMTWO1070
S
Electrical Stumped No Start...
  • sydhawk
  • Oct 28, 2025
  • Fox 5.0 Mustang Tech
Replies
8
Views
257
Fox 5.0 Mustang Tech Oct 29, 2025
sydhawk
S
T
  • Locked
Digital Tuning A9l issue or something else
  • Tufgriz
  • Sep 11, 2025
  • Fox 5.0 Mustang Tech
Replies
2
Views
262
Fox 5.0 Mustang Tech Sep 11, 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?