1989 fox misses until it's warm - Mustang Evolution

Go Back   Mustang Evolution > 1979-2015 Mustang GT || Tech and Talk > 1979-1995 Mustang GT



Reply
 
Thread Tools Search this Thread
Please support our sponsors and let them know you heard about them here!
Old 11-06-2015, 01:37 AM   #1
Registered Member
Regular
 
WhiteCali5oh's Avatar
 
Join Date: Jun 2014
Location: Beckley
Region: West Virgina
Posts: 1,396
1989 fox misses until it's warm

Hey guys. Weird thing happening with my 302 fox. It runs like crap when it's cold. It pops and backfires and misses really bad until it's at full operating temp. Idk if it matter but I changed the thermostat from a 170 to a 195*


Sent from my iPhone using Mustang Evolution
WhiteCali5oh is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 11-06-2015, 09:44 PM   #2
Registered Member
Regular
 
Join Date: Jun 2015
Location: HARTWELL LAKE AREA
Region: South Carolina
Posts: 435
Quote:
Originally Posted by whitecali5oh View Post
hey guys. Weird thing happening with my 302 fox. It runs like crap when it's cold. It pops and backfires and misses really bad until it's at full operating temp. Idk if it matter but i changed the thermostat from a 170 to a 195*


sent from my iphone using mustang evolution
running lean sounds like
ALLYDRIVER1 is offline   Reply With Quote
Old 11-06-2015, 11:07 PM   #3
Registered Member
Regular
 
Tyoung68's Avatar
 
Join Date: Jun 2011
Location: concord
Region: California
Posts: 3,475
I'd let it all cool off run it for a couple min while it's cold and showing the pull the plugs and see what they look like. Also what kind of ignition do you have? Cam? Or any other work done? My car runs like crap when it's cold, but like a champ when warm.
Tyoung68 is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 11-07-2015, 02:32 AM   #4
Registered Member
Regular
 
wbrockstar's Avatar
 
Join Date: Mar 2015
Location: Nashville
Region: Tennessee
Posts: 289
I would test the ect & iat sensors.One of them could be bad and it might have been working good enough to not cause issues when you had the 170° tstat in it,but when you installed the warmer 195° tstat(25° difference) it began to cause problems.
I would also make sure the egr valve is not stuck open during idle.When the egr valve is open,timing advance is added & the fuel mixture is leaned out.The engine needs more fuel at startup and while warming up to prevent it from stalling and running rough.The egr valve should only be open during part throttle cruise,so if it opens during startup & warm up mode the ecm will advance timing & lean fuel,which is the opposite of what the engine needs at startup.The easiest way to test whether or not the egr valve is causing your problems is by removing the vacuum hose from it,plug the hose then take the car for a test drive.The ecm deletes egr function in the EEC logic,when you remove its vacuum hose.This will cause the egr valve to not open and the ecm will set timing and the fuel trim back to normal.If the problems go away by removing the vacuum hose,the egr valve is sticking open because its dirty/defective or the evr solenoid is defective.If you test the three components listed above & they all pass,use a jumper wire & your check engine light and run a koeo koer scan to see if any codes are present.Make sure the engine is at operating temp,the ac is off & the transmission is in park(auto)neutral(stick)before you run the koeo koer scan.The check engine light doesn't have to be on,in order for codes to be present.Check the fuel pressure regulator too.Let the engine idle,pull the vacuum hose off the regulator, see if there is any fuel inside of the hose or if fuel is seeping out of the regulator vacuum port.If it is,the regulator is bad.A defective fpr usually causes issues once the engine reaches operating temp,but that doesn't necessarily mean a defective regulator can't also act up during cold start/warmup mode too.A vacuum leak can also cause issues similar to yours,but I would think the engine should still show the same issues while its at operating temp too,not just during cold startup & warmup mode.
If you run the code scan & get any codes,come back here & post your results.

http://sbftech.com/index.php/topic,29608.0.html

http://sbftech.com/index.php/topic,29654.0.html
__________________
91 LX 342ci(10.5:1)
TFS 190cc(stage ll)
TFS track heat
XE276HR .544" .544"
Flowtech 1 3/4"
Prochamber w FM
wbrockstar is offline   Reply With Quote
Old 11-07-2015, 08:59 AM   #5
Registered Member
Regular
 
ALMOST STOCK's Avatar
 
Join Date: Jul 2012
Location: Prunedale
Region: California
Posts: 366
Quote:
Originally Posted by WhiteCali5oh View Post
Hey guys. Weird thing happening with my 302 fox. It runs like crap when it's cold. It pops and backfires and misses really bad until it's at full operating temp. Idk if it matter but I changed the thermostat from a 170 to a 195*
Mine did the same thing until I found the vacuum leak.
__________________
Mustang Monthly Jan 2015- Feature
5.0 Mustang & Super Fords July 2005
ALMOST STOCK is offline   Reply With Quote
Old 11-08-2015, 01:16 PM   #6
Registered Member
Regular
 
WhiteCali5oh's Avatar
 
Join Date: Jun 2014
Location: Beckley
Region: West Virgina
Posts: 1,396
Has a B cam. Also for some reason my car doesn't advance timing. Using a timing light, shouldn't the mark be moving with rpm? When we rev the engine it stays n the same place.


Sent from my iPhone using Mustang Evolution
WhiteCali5oh is offline   Reply With Quote
Old 11-08-2015, 01:18 PM   #7
Registered Member
Regular
 
WhiteCali5oh's Avatar
 
Join Date: Jun 2014
Location: Beckley
Region: West Virgina
Posts: 1,396
Quote:
Originally Posted by Tyoung68 View Post
I'd let it all cool off run it for a couple min while it's cold and showing the pull the plugs and see what they look like. Also what kind of ignition do you have? Cam? Or any other work done? My car runs like crap when it's cold, but like a champ when warm.

Yeah mine runs fantastic once it gets to where the thermostat opened up. Until then: it sucks, can barely accelerate haha it pops and backfires misses. Embarrassing really.


Sent from my iPhone using Mustang Evolution
WhiteCali5oh is offline   Reply With Quote
Old 11-08-2015, 03:53 PM   #8
Registered Member
Regular
 
wbrockstar's Avatar
 
Join Date: Mar 2015
Location: Nashville
Region: Tennessee
Posts: 289
If you do have a vacuum leak,there are a couple scenarios where I can see the vacuum leak being the direct cause for your issue.
ECM operates in two modes
(Open Loop)=cold engine
the ecm doesn't rely on sensor input.uses preset values
(Closed Loop)=warm engine
the ecm uses sensor input to adjust the air fuel mixture & timing

(1st)
If a vacuum leak occurs & the ecm is in open loop mode,the engine will have idle problems & experience driveability issues because the ecm cant compensate for the extra oxygen(vacuum leak) entering the engine due to the vacuum leak.
(2nd)
The tad solenoid sends vacuum to the tad valve during open loop mode,but shuts vacuum off during closed loop mode.The tab solenoid sends vacuum to the tab valve anytime smog pump air is being sent to the tad valve.So you need to use carb cleaner or starting fluid to test these components & their vacuum hoses for leaks when the engine is running and the ecm is in open loop.You said the problem goes away at operating temp,so the vacuum leak would have to be present in a hose or component that only sees vacuum during open loop mode.If the driveability problems were still occurring after the ecm goes into closed loop mode,then you would need to check every single hose & component thats vacuum operated.
__________________
91 LX 342ci(10.5:1)
TFS 190cc(stage ll)
TFS track heat
XE276HR .544" .544"
Flowtech 1 3/4"
Prochamber w FM
wbrockstar is offline   Reply With Quote
Old 11-08-2015, 04:14 PM   #9
Registered Member
Regular
 
wbrockstar's Avatar
 
Join Date: Mar 2015
Location: Nashville
Region: Tennessee
Posts: 289
Quote:
Originally Posted by WhiteCali5oh View Post
Has a B cam. Also for some reason my car doesn't advance timing. Using a timing light, shouldn't the mark be moving with rpm? When we rev the engine it stays n the same place.


Sent from my iPhone using Mustang Evolution
Draw a line on the harmonic balancer at the 10° & 14° mark with some witeout,to make the timing marks easier to see.Remove the spout plug (runs alongside & is part of the TFI module wiring harness)hook your timing light up,start the car & let it idle,check timing to make sure its between 10-14°,plug the spout plug back in & watch the timing marks to see if the computer advances timing once you plug the spout in.If you don't see timing advance occur,that could definitely be your problem.I believe the computer advances it up to the 22-24°+ range when you plug the spout in.The type of computer you use also determines total timing advance too.A auto A9P ecm will add more total advance than a stick A9L ecm will.This link explains that in more detail,but right now you're just trying to see if the ecm is adding advance or not.If you're missing the spout plug,the ecm won't be able to advance timing at all.Is your spout plug in place or is it missing??
http://sbftech.com/index.php/topic,4991.0.html
__________________
91 LX 342ci(10.5:1)
TFS 190cc(stage ll)
TFS track heat
XE276HR .544" .544"
Flowtech 1 3/4"
Prochamber w FM
wbrockstar is offline   Reply With Quote
Old 11-10-2015, 06:41 PM   #10
Registered Member
Regular
 
WhiteCali5oh's Avatar
 
Join Date: Jun 2014
Location: Beckley
Region: West Virgina
Posts: 1,396
Quote:
Originally Posted by wbrockstar View Post
Draw a line on the harmonic balancer at the 10° & 14° mark with some witeout,to make the timing marks easier to see.Remove the spout plug (runs alongside & is part of the TFI module wiring harness)hook your timing light up,start the car & let it idle,check timing to make sure its between 10-14°,plug the spout plug back in & watch the timing marks to see if the computer advances timing once you plug the spout in.If you don't see timing advance occur,that could definitely be your problem.I believe the computer advances it up to the 22-24°+ range when you plug the spout in.The type of computer you use also determines total timing advance too.A auto A9P ecm will add more total advance than a stick A9L ecm will.This link explains that in more detail,but right now you're just trying to see if the ecm is adding advance or not.If you're missing the spout plug,the ecm won't be able to advance timing at all.Is your spout plug in place or is it missing??
http://sbftech.com/index.php/topic,4991.0.html

Not sure man. I'll have to look tomorrow when I go back down to my garage. This spout plug, do you have a picture of that for reference?


Sent from my iPhone using Mustang Evolution
WhiteCali5oh is offline   Reply With Quote
Old 11-10-2015, 06:46 PM   #11
Registered Member
Regular
 
dave73's Avatar
 
Join Date: Nov 2014
Location: Mechanicsville
Region: Maryland
Posts: 1,058
Not to say this will help and I'm not sure if it's the same on Mustangs as the truck 5.0...but I bought a F150 years ago with the 5.0 and it was doing similar ****. I found that the routing of the spark plugs wires is crucial and someone had changed the wires to aftermarket and did not route them correctly and that was the problem.


Sent from my iPhone using Mustang Evolution
dave73 is offline   Reply With Quote
Old 11-10-2015, 06:56 PM   #12
Registered Member
Regular
 
WhiteCali5oh's Avatar
 
Join Date: Jun 2014
Location: Beckley
Region: West Virgina
Posts: 1,396
Quote:
Originally Posted by dave73 View Post
Not to say this will help and I'm not sure if it's the same on Mustangs as the truck 5.0...but I bought a F150 years ago with the 5.0 and it was doing similar ****. I found that the routing of the spark plugs wires is crucial and someone had changed the wires to aftermarket and did not route them correctly and that was the problem.


Sent from my iPhone using Mustang Evolution

Mine are in correct order. Also tried changing to new plugs. I may actually buy new wires. They're aftermarket ones.


Sent from my iPhone using Mustang Evolution
WhiteCali5oh is offline   Reply With Quote
Old 11-10-2015, 07:02 PM   #13
Registered Member
Regular
 
dave73's Avatar
 
Join Date: Nov 2014
Location: Mechanicsville
Region: Maryland
Posts: 1,058
Quote:
Originally Posted by WhiteCali5oh View Post
Mine are in correct order. Also tried changing to new plugs. I may actually buy new wires. They're aftermarket ones.


Sent from my iPhone using Mustang Evolution

It's not just being in the right order they have to be routed very specifically or they will crossfire. Click image for larger version

Name:	ImageUploadedByMustang Evolution1447203755.161219.jpg
Views:	162
Size:	250.7 KB
ID:	193464


Sent from my iPhone using Mustang Evolution
dave73 is offline   Reply With Quote
Old 11-10-2015, 07:06 PM   #14
Registered Member
Regular
 
WhiteCali5oh's Avatar
 
Join Date: Jun 2014
Location: Beckley
Region: West Virgina
Posts: 1,396
Quote:
Originally Posted by dave73 View Post
It's not just being in the right order they have to be routed very specifically or they will crossfire. Attachment 193464


Sent from my iPhone using Mustang Evolution

That very well could be a problem then. Because I know mine isn't like that.


Sent from my iPhone using Mustang Evolution
WhiteCali5oh is offline   Reply With Quote
Old 11-10-2015, 07:09 PM   #15
Registered Member
Regular
 
dave73's Avatar
 
Join Date: Nov 2014
Location: Mechanicsville
Region: Maryland
Posts: 1,058
Quote:
Originally Posted by WhiteCali5oh View Post
That very well could be a problem then. Because I know mine isn't like that.


Sent from my iPhone using Mustang Evolution

Worth a shot anyway it was definitely a problem for me once


Sent from my iPhone using Mustang Evolution
dave73 is offline   Reply With Quote
Old 11-10-2015, 09:21 PM   #16
Registered Member
Regular
 
Join Date: Jun 2015
Location: HARTWELL LAKE AREA
Region: South Carolina
Posts: 435
Just last week fixed a 3.9 misfire by putting oem wires on and reinstaling all the wire holders
ALLYDRIVER1 is offline   Reply With Quote
Old 11-15-2015, 06:31 PM   #17
Registered Member
Regular
 
wbrockstar's Avatar
 
Join Date: Mar 2015
Location: Nashville
Region: Tennessee
Posts: 289
Quote:
Originally Posted by WhiteCali5oh View Post
Not sure man. I'll have to look tomorrow when I go back down to my garage. This spout plug, do you have a picture of that for reference?


Sent from my iPhone using Mustang Evolution
See the black plug sitting on top of the TFI module wiring harness connecter(in the picture below) it plugs in to the wiring harness shown to the right of the TFI module harness. Your plug might be GREY in color instead of black because my 91 LX has a GREY spout plug.This plug has to be removed before you set initial timing then plugged back in afterwards.The computer won't advance timing until the spout plug is plugged in.

The spark plug wires have to be routed correctly on the cap because the injectors fire in a specific order.If the wires are ran incorrectly, the plugs will be firing out of sequence with the injectors.There's a clip on each side of the distributer that holds the cap on.Find the clip on the left side(standing in front of the car looking at the engine) of the distributer cap, now count two posts from that clip in a clockwise direction,this is the number one spark plug position on the cap.Snap the #1 plug wire onto this post.Now start snapping the remaining plug wires onto the posts moving in a counter clockwise position from the #1 plug wire.The firing order is 1 3 7 2 6 5 4 8,so you should have the wires placed on the cap just like they are placed in the picture below.See how the #1 plug wire is located on the 2nd post past the left hand side clip then the #3 wire is next in line,moving in a counter clockwise position??
Attached Thumbnails
Click image for larger version

Name:	SPOUT_off.jpg
Views:	324
Size:	62.4 KB
ID:	193638   Click image for larger version

Name:	Dizzy_Diagram_FO_CAP.jpg
Views:	374
Size:	81.6 KB
ID:	193639  

__________________
91 LX 342ci(10.5:1)
TFS 190cc(stage ll)
TFS track heat
XE276HR .544" .544"
Flowtech 1 3/4"
Prochamber w FM
wbrockstar is offline   Reply With Quote
Old 11-21-2015, 05:15 PM   #18
Registered Member
Regular
 
WhiteCali5oh's Avatar
 
Join Date: Jun 2014
Location: Beckley
Region: West Virgina
Posts: 1,396
Those pics won't show up


Sent from my iPhone using Mustang Evolution
WhiteCali5oh is offline   Reply With Quote
Old 11-22-2015, 10:24 PM   #19
Registered Member
Regular
 
wbrockstar's Avatar
 
Join Date: Mar 2015
Location: Nashville
Region: Tennessee
Posts: 289
Here are the pics in link form.
http://351winsor.com/joel/Ignition_Systems/SPOUT_on.jpg

http://sbftech.com/index.php?action=...ach=3116;image

http://cdn.mustangevolution.com/foru...1&d=1447633609
__________________
91 LX 342ci(10.5:1)
TFS 190cc(stage ll)
TFS track heat
XE276HR .544" .544"
Flowtech 1 3/4"
Prochamber w FM
wbrockstar is offline   Reply With Quote
Reply

Lower Navigation
Go Back   Mustang Evolution > 1979-2015 Mustang GT || Tech and Talk > 1979-1995 Mustang GT

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Mustang misses, smoking and, getting horrible mpg tdye369 Pre-2005 V6 Mustang 19 06-28-2014 09:39 PM
misses once warm foxneedswork 1979-1995 Mustang GT 15 08-20-2012 01:15 PM
What is the difference between a 1989 Mustang LX 5.0 and 1989 Mustang GT? kele74 General Mustang Discussion 8 03-21-2010 11:03 PM
What parts would i need to convert a convertible 1989 5.0 LX mustang to a 1989 Mustang GT? diwali General Mustang Discussion 1 03-17-2010 10:40 PM
What is the difference between a regular 1989 mustang gt and a 1989 mustang gt foxbody? collin General Mustang Discussion 9 03-17-2010 10:42 AM

» Like Us On Facebook



01:24 PM


Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Content Relevant URLs by vBSEO 3.6.0

MustangEvolution.com is in no way associated with or endorsed by Ford Motor Company.