Engine 351w Swap Idle Problems...help Please!

[Gftd91]

Hello, This is my first post ob this website. So bear with me please. Haha
So i undertook a 351w swap into my 1995 GT. I kept the stock fuel injection and computer system. Everything went smoothly untill first start up.

I was having problems with stabbing the dist. (Distributor) we finally got the engine to run decently enough to break in the cam. But it will not idle what so ever. If you hold the throttle a tiny bit. It will run at about 900 rpms. Around 700 to 800 the idle will surge. And any lower it will just die out.. Im sure you will need more info about parts. But this is a start.. Any help at all will be greatly appreciated!!!

Thank you
Garrett

 

[General karthief]

Give us an idea of what you have, stock cam (flat tappet), intake, throadel body, stick or auto, also a pic of the engine/compartment.
Did you attach all the grounds back? Timing?
The people here will try to help.

 

[Gftd91]

It is a stock (marine) block and heads. I have an edelbrock performer rpm 2 intake on it. With a comp cams exteme energy 35-246-3 XE274H flat tappet camshaft. BBK shorty 351 swap headers, and a CAI. Everything else on the vehicle is from the stock 302
The car is a 5 speed transmission. I have it timed at 12 degrees.
I had found a ground terminal on the frame but no ground wire near it. I took a jumper cable and grounded engine to frame remotely and it did not effect it in any way.

 

[Gftd91]

 

[Gftd91]

Sorry. I also have an MSD Distributor, coil pack, and MSD 8.5mm super conductor plug wires.

 

[Gftd91]

Sorry. I also have an MSD Distributor, coil pack, and MSD 8.5mm super conductor plug wires.

 

[General karthief]

On the subject grounds, there are several that are important to the computer and related stuff reading correctly. The battery ground to the block, there is a small wire that gos from the battery neg to a small bolt between the battery and the solenoid, that same bolt will have another small wire that gos down to a cylindrical connector then into the harness below.
One from the back of the head on the drivers side to the firewall and another on the passenger side on top of the intake, it comes out of the injector harness and bolts to the intake or back of the block, also one by the computer in the passenger kick panel. Very important that these grounds at there and have good contact.

 

[Gftd91]

All of the grounds near the battery look in order. I will attach photo. By solenoid do you mean the starter solenoid? The ground that runs from block to firewall (drivers side) is non exsistant and i cannot find any ground coming out of injector harness on the passenger side.. And i will attach a photo of a wire terminal on the bottom of the drivers frame rail. There is no broke wire near the terminal..

 

[Gftd91]

 

[General karthief]

Look for a ground wire at the ccrm, I believe it will be on the passenger side between the shock tower and radiator support, that should be the one for the injector harness, put a ground wire from drivers side head to firewall as well.

 

[revhead347]

Check your throttle position sensor voltage. The greenish wire on the TPS, should be around 1 volt.

Kurt

 

[Gftd91]

The

Look for a ground wire at the ccrm, I believe it will be on the passenger side between the shock tower and radiator support, that should be the one for the injector harness, put a ground wire from drivers side head to firewall as well.

My ccrm is mounted on a bracket between the radiator and the engine. I do not see any ground wires running off of it. I will run the ground from cyl. head to firewall.

 

[Gftd91]

Check your throttle position sensor voltage. The greenish wire on the TPS, should be around 1 volt.

Kurt

There are three wires, none greenish in color. There is a gray-red, grey-white, brown-white

 

[revhead347]

There are three wires, none greenish in color. There is a gray-red, grey-white, brown-white

Well Sh#t. I keep forgetting these cars are older than dirt, and old wires fade. Check them all, and see which one is closest to 1V.

Kurt

 

[Gftd91]

Well Sh#t. I keep forgetting these cars are older than dirt, and old wires fade. Check them all, and see which one is closest to 1V.

Kurt

Should i check the voltage while it is ru ning? They are not faded, wires are in a sheath.

 

[Gftd91]

Well Sh#t. I keep forgetting these cars are older than dirt, and old wires fade. Check them all, and see which one is closest to 1V.

Kurt

Should i check the voltage while it is ru ning? They are not faded, wires are in a sheath.

 

[General karthief]

Black(brown)/white & gray/white wires for the 95's

On a 94-95 Mustang, probe the black/white and grey/white wires to measure the TPS voltage.
It should be .5-.1.0 volts with the key on, engine not running. Note that if the black/white wire (signal ground) has a bad connection, you will get some strange readings. Make a second measurement using the battery post as the ground to eliminate any ground problems. If the readings are different by more than 5%, you may have a high resistance condition in the black/white signal ground circuit.
This is from the cranks but no start checklist that jrichker and others compiled

 

[Gftd91]

So i ran a voltage check on the TPS. The brown and white wire i got 1.00 volt, and for both grey/white and grey/red wires i got .026 volts. I ran the ground from the drivers side cyl. head to the firewall.

 

[Gftd91]

She will run and idle nicely if i put two quarters under the idle scew on the hrottle body. And now i found out she bogs out and loses all power at 3000 rpms when accelerating. But doesnt die just wont gain rpms

 

[General karthief]

Might I suggest checking for a vacuum leak and going back over the fuel system. And check for codes. It may also pay to go through the surging idle checklist in the tech/how to thread.
Really, with the mods and the year you have my advice is limited without hands on it.