94 Mustang GT Timing Issue ???? TPS?

94sleeperstang · Sep 6, 2012

1994 Mustan GT Factory Aode Car. Just did a t5 swap out of a foxbody. Also put in a 94 Mustang GT T5 computer. Cold Air Intake/Hpipe with no cats, ac/smog pump has been removed and all lines have been pluged. No issues with the T5 swap.

Problme: At WOT the car bucks/hesisates almost sounds like its bouncing off the ref limiter at 1500-2500 rpms. But runs great at 3000 and above.
New plugs,wires,cap and rotor. New Fuel filter. Noticed the issue after putting on the cold air intake

I have tried to tune the timing. At stock timing 12-14 degrees the problem is bad.
16-17 Degrees, it gets better but the car falls on its face and spark knocks bad.

I pulled the spout when i did the timing. The check engine light is out on the car, and when i hook up and scanner the computer will to talk with the scanner. I am thinking either the tps or fuel?

Also the car idles fine no surging or anything.
But the idle hanges in between shifts. Any help would be great thank you

ttocs · Sep 6, 2012

tps is easy to test with a volt meter.

rz5.0 · Sep 6, 2012

Did you use the 5 speed Trans harness..

ram360 · Sep 6, 2012

Did you set your TPS voltage? That can cause your idle to hang. You sure you have the right firing order? Sounds like it's wrong. You pull the dizzy out lately?

94sleeperstang · Sep 6, 2012

I havent checked the distributer but the timing seems right. It feels and sounds like ita bouncing of the limiter. I cant tell if the computee is shuting down the timing or the fuel. The timing seems dead on minus this problem at low rpms at wot. I am going to check the vvoltage on the tps. I am guessing the voltage is off and telling the computer the motor is pinned becauae as soon as i lightly let off the cae comea around and does fine. Or the maf.

ram360 · Sep 6, 2012

What do you mean timing seems right? You did use a timing light right?

94sleeperstang · Sep 6, 2012

Yeah i used a timing light. Like i said, at 12-14 its bad. 16-18 degreaa the low rpm hesitation is really not noticeable. But the call falls on its face and spark knocks bad. It has to do with the advancement of the timing at wot so i wild think its the tps voltage? Maybe the fuel pimp i am lost

ram360 · Sep 6, 2012

did you have the dizzy out recently and put it back in?

94sleeperstang · Sep 6, 2012

No bur it seemed to always have h
This issue since i bought it. But it got worse after the cold air intake. I thought it might the iac but i dont know

94sleeperstang · Sep 6, 2012

No but its always had this issue. I oringally thought it was the iac. Its got worse since the cold air intake. I wouldnt thinkbot was the dizzy since it seems to be in time with the timing light???

rz5.0 · Sep 6, 2012

So it did it before the 5 speed swap.. Check for vac leaks.. Egr removed?? Have you tried putting the stock air box back see if anything.changes..

94sleeperstang · Sep 6, 2012

Yeah it did it before the swap i just couldnt tell becuasw the auto tranny was slipping so bad. No i got rid of the stock airbox. The gr has been removed. Al the lines have been pluged

ram360 · Sep 6, 2012

It's not normal that the car runs better with the timing at 16 or 17*. Check your balancer and make sure it didn't spin. That could be giving you the wrong indication of timing. I'd verify I had the correct firing order. You still have a stock cam in the car right? I'd pull the dizzy and restab it in the car just to make sure it's not a few teeth off. While it's out I'd replace the dist pickup as well (not very expensive and once it'd done your good for awhile). Once you verify that's all good then you can go from there.

toyman · Sep 6, 2012

Checking the TPS is easy. Key on engine off (KOEO). You want to see that the voltage at rest is about 1v and then move smoothly from that position to WOT at about 4.6 v. There should be no dead or flat spots as the throttle is opened.

94sleeperstang · Sep 7, 2012

Thanks for all the help. I am going to check the firing order again. I will check the voltage on the tps. Oh i forgot to tell mention I put a new Harmonic balancer on it because I thought the same thing at first. But know I am at loss.

94sleeperstang · Sep 7, 2012

Well i checked the tps. Stares at 1 volt and wot its at 5 volts. What i got off the internet thats right??? I am going to pull the distributor today. I am always afraid i am going to make iy worse and get 180.

ram360 · Sep 7, 2012

94sleeperstang said:
Well i checked the tps. Stares at 1 volt and wot its at 5 volts. What i got off the internet thats right??? I am going to pull the distributor today. I am always afraid i am going to make iy worse and get 180.

Here's a way to get it right. Pull your #1 plug out. Have someone stick there finger in the spark plug hole. Turn the motor over by hand and watch the balancer (Make a mark at 10* btdc) turn the motor over until you feel air being forced out of the #1 plug hole. That means you are on the compression stroke and it won't be 180 out and just stop when the balancer 10* mark is lined up w/ the timimg pointer. Then all you do is when you stab the dizzy in make sure you have the rotor pointing on the #1 plug. Once you did that put in the hold down bolt and leave it just loose enough so you can twist it when you dial in your timimg w/ the light. With that done we at least know that your dizzy is installled right. Like I said while it's out i'd just replace the distributor pickup.

94sleeperstang · Sep 7, 2012

Well, I hand cranked the motor over a couple times with one finger in the #1 Cylinder. It always lined up with the #1 spark plug. I never pulled the dizzy out because it looked right.

Soooo............................. I went to Autozone and bought a can of MAF cleaner

I started the car and it was tapping like crazy (got me a little worried at first but it came out of it)????

Ran like straight crap for a little too, once the tapping went away and it got warm................... The car ran great with no issues!!!!!!!!!!!!!!!!!!!! So i think it was a dirty MAF the whole time!!!

We shall see, i parked the car and reset the timming becuase it was still spark knocking. I will take it out later and see what it does. Dont want to jinx myself yet but it might have been a dirty MAF?????

Thanks everyone

ChadH95GTS · Sep 7, 2012

Very possible. I had a similar problem except mine would act like it was hitting the rev limiter at anything over 3k rpms.. cleaned the MAF and it ran like a champ. Was there a lot of carbon build up on it?

94sleeperstang · Sep 7, 2012

No not really. Looked kind of dirty but man she runs like a banshee now. Well atleast compared to what it was
Thanks everyone. And hopefully this will help someone in the future.