T5 Issues After Efi Swap

MustangMando

Member

Jul 16, 2011

107

0

17

Mar 3, 2014

#1

• Mar 3, 2014

• #1

Hi guys, just installed and rebuilt a foxbody 302 efi from a 1990 mustang and dropped it in a 68 mustang. I left the motor stock except for for an e303 cam. I added a new stock flywheel and clutch. I had the t5 and had been using it before. I started up the car and noticed vibration in or on the t5 at idle. So i added some fluid(atf), since it had lost fluid when i droped the trans. I drove it around the block and motor seems not to accelerate even though rpms seem alittle high. At fifth gear the car begins to have alot of vibration. At idle and at fifth the t5 has vibration. I pulled the transmission out during the build and tilted over, dont know if this matters but like for people to have all info. It is a v8 t5, was working properly before i pulled it off motor. All is new, pilot bearing, flywheel, clutch, pressure plate, throwout bearing and even bolts.

Thanks any info helps

 

horse sence

15 Year Member

Nov 29, 1999

12,305

8,161

233

Wile Coyote's stunt double

Mar 3, 2014

#2

• Mar 3, 2014

• #2

check the firing order on the motor you may not be wired correct .is the motor an HO? the firing order is different for an HO and a standard 5.0. Check your cam specs to see what the correct fire order is for the cam that you are running.

 

no1hedberg

Member

Aug 5, 2013

33

1

9

Mar 3, 2014

#3

• Mar 3, 2014

• #3

The E303 cam uses the 5.0 HO/351W firing order 1-3-7-2-6-5-4-8. Which is different than the standard 302/289. Also you mentioned you added a stock flywheel and clutch. The 5.0 HO uses a 50 oz balance instead of a 28 oz balance of the standard 302/289. The harmonic balancer and flywheel both need to be specific to the 5.0 HO. If not you will get a serious vibration. I know from experience.

 

MustangMando

Member

Jul 16, 2011

107

0

17

Mar 3, 2014

#4

• Mar 3, 2014

• #4

Just ran the casting number and the motor seems to be from a 91 thunderbird 302 HO, does that change anything? The flywheel is from orillys and is a 50oz balanced

 

horse sence

15 Year Member

Nov 29, 1999

12,305

8,161

233

Wile Coyote's stunt double

Mar 3, 2014

#5

• Mar 3, 2014

• #5

I am still thinking may be a couple of wires crossed . A misfire will cause a vibration. Also are the injectors new or used ? When i did a HO swap in my 78 F150 the motor had low miles but it had set for almost a year and the injectors were plugged from old gas. It ran very rough until i ran cleaner through the injectors.

 

MustangMando

Member

Jul 16, 2011

107

0

17

Mar 3, 2014

#6

• Mar 3, 2014

• #6

The injectors are used, they are the ones it came with motor. Im running a f150 fuel pump. I only get vibration in idle and in fifth though???

 

MustangMando

Member

Jul 16, 2011

107

0

17

Mar 3, 2014

#7

• Mar 3, 2014

• #7

I'll double check all wires tomorrow Horse Sence

 

horse sence

15 Year Member

Nov 29, 1999

12,305

8,161

233

Wile Coyote's stunt double

Mar 3, 2014

#8

• Mar 3, 2014

• #8

If you hold the idle up with the trany in neutral does it still vibrate ?

 

MustangMando

Member

Jul 16, 2011

107

0

17

Mar 3, 2014

#9

• Mar 3, 2014

• #9

Vibration goes away with a little gas on idle, but at fifth gear lots of vibration when driving

 

no1hedberg

Member

Aug 5, 2013

33

1

9

Mar 4, 2014

#10

• Mar 4, 2014

• #10

If the engine is from a 91 T-Bird, where did the intake, wire harness, and ECM come from? I am definitely not as familiar with the T-Bird as I am with the Fox, but the Tbird ECM would be for an automatic. I don't know why, but if your ECM isn't from a manual transmission it can cause problems. Also the injectors can be cross wired just like a distributor which would cause a misfire and vibration like you are describing.

 

horse sence

15 Year Member

Nov 29, 1999

12,305

8,161

233

Wile Coyote's stunt double

Mar 4, 2014

#11

• Mar 4, 2014

• #11

When i did the swap in my 78 F150 i used a frame mounted fuel pump from a 87
F150 ,it was not enough and i had to add a Holley injection pump in front of it .
it would lay flat at about 55 mph.
What puleys and balancer are you using ?

 

MustangMando

Member

Jul 16, 2011

107

0

17

Mar 17, 2014

#12

• Mar 17, 2014

• #12

Thanks guys, after a couple of grueling weeks of putting my motor together and not being able to make it work correct. Today i went out with a clear head, i noticed that #5 and #6 where swapped. Took it for a ride and rode smooth. Thanks again for the great info.