New member. Need suggestions

Bendthebar

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Hello,

I know this has been discussed many times before. I’ve searched for weeks and couldn’t find anything semi related to my issue.
1995 Mustang GT
97 explorer engine
Anderson n-41 cam
75mm throttle body
New fuel tank, sending unit, new fuel tank harness
Aeromotive 340 pump
New dizzy, 3 of them actually
New iac
New tps

My issue is the car just decides not to start, 38lbs at rail. I unplug the tps and it will start then dies. Plug TPS back in and starts.

I thought I fixed this issue when I replaced the TPS and the car actually cold started great and open loop would act dumb with idle then back to doing well.

I had an exhaust leak. Fixed that and now it’s back to not starting again.

Done base idle reset with it idling around 750ish iac unplugged.
Turn car off let it sit for two minutes, plugged iac in. Went to start with accessories on for 2 minutes. Same outcome doesn’t fire just cranks. Unplug TPS and it will fire off.

I’m totally confused at this point as I’ve tested tps signal and so on.

I guess my question is where should I go? Bad computer? Bad ccrm?
Any test I can do to see if I can isolate what the issue is?

At some point I will go standalone ECU, however my thought is if it’s something in the wiring the new ecu will not help. Maybe I’m in left field or have no idea what I’m talking about.

I would really like to get this sorted out so I can actually drive the car some without the fear of it not starting somewhere. Take my kids for a ride in it. It needs to be safe before I can do that.

Please feel free to chime in with suggestions positive or negative lol. I have tough skin.

Thank you everyone in advance for the responses.
 

96blak54

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Is the TFI module new? A failed or nearly failing TFI module(high fail rate ford part) will do a continuous crank and almost start. Itll also play games with you about starting just as you described. The TFI module is either located on the distributor or off line somewhere on the fender on a big aluminium heat sink.

And then their is failing wire harness issues such as corrosion inside connectors, cut or exposed wires. At this point it becomes a game of chasing the issue.
 

96blak54

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It look like this somewhere on your fender. Sorry im not versed with the 94 95 sn95 mustangs locations but i do know about ford 5.0l problems

s-l640.jpg
 

duh09

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Check the TPS plug itself. Next time it doesn't start, give it a wiggle wiggle and see if it changes.
 
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Bendthebar

Bendthebar

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Is the TFI module new? A failed or nearly failing TFI module(high fail rate ford part) will do a continuous crank and almost start. Itll also play games with you about starting just as you described. The TFI module is either located on the distributor or off line somewhere on the fender on a big aluminium heat sink.

And then their is failing wire harness issues such as corrosion inside connectors, cut or exposed wires. At this point it becomes a game of chasing the issue.
Thanks for the reply. Yes it’s new. I’m starting to wonder if it’s the throttle body itself. After I posted I went and it fired up. Idle is off.
I can’t get the idle below 1k without it dying with iac unplugged.
Makes it difficult to get a base idle. If I hadn’t messed up the stock tb I would try it and see.
 
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Bendthebar

Bendthebar

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Check the TPS plug itself. Next time it doesn't start, give it a wiggle wiggle and see if it changes.
Thanks, I hope it’s good. I replaced the pigtail and repinned it when I replaced the TPS. Adjusted the TPS with the slots on the TB to .99
 

96blak54

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Ok...you have yourself a headscratcher! And troubleshooting a gremlin like yours becomes a terrible game that you can not win.

An aftermarket efi system is a terrific idea! We have a handful of members here that have swapped to the Holley efi stuff and they couldn't be happier. So that said youll have great support here with the Holley stuff.

If you are trying to keep cost low and dont know where to go next, im going to suggest a new wiring harness and then replace the ecu. Totalling roughly $900

Or you could bite the bullet on a system that comes with the harness and give you an infinite tune abilities like the Holley system does for $1300

We got alot of smart guys here and someone might chime in knowing your exact problem, which i really hope they do cause you sound like me, i want answers to a problem and i wont stop untill i figure it out. But given the age of the car and its components youll be miles ahead to just throw more money at it with a new system. And this is where im at with my car. I can leave the engine alone. Anything i change requires a tune. Ive already invested over $1200 in dyno tuning and like your car, its age is creaping on it and i feel i will be chacing down a gremlin soon too. Thats why im moving towards carburated. Ive got some old knowledgable carb friends, hoping they can school me.

Lets see if we cant get some 5.0l gurus in here
 

oz95gt

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Thanks for the reply. Yes it’s new. I’m starting to wonder if it’s the throttle body itself. After I posted I went and it fired up. Idle is off.
I can’t get the idle below 1k without it dying with iac unplugged.
Makes it difficult to get a base idle. If I hadn’t messed up the stock tb I would try it and see.
BBK throttle body ? If so , known to be problematic
 

Daryl

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Hello! I’m certainly NOT one of the Guru’s here, but have been in a similar situation. I also have the BBK 75mm TB. I replaced the MAF (?) or whatever the initials are for the sensor just forward of the TB mouth, coil, and simple adjustment to the Dizzy. These simple things set the idle rock solid (so no continuous rev or dying out coming to a stop) AND starts up every time like it should and idles (no surging) steady.

Now, I don’t know if this will help or not, but it seems like you’ve gotten WAY deep in a short time (and $$$, too) when sometimes we jump ahead too quickly and forget the “Rules of Elimination” if you will when diagnosing problems/fixes: start with the simple, obvious stuff first then go through and get deeper with each iteration.

Again, I am not a Guru here by any means. The aforementioned is, however, #1 thing that I have learned from the Members here and this thread is getting feedback from some of the very best here.

Going back to square One and regrouping (to refocus)with a clear head may be a good idea?

Cheers and best of luck to ya!
Daryl
 

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