Having Problems With Daily Driver

[Fuzion]

I have an 87 302 and this last week it’s been acting up. Car is dead stock except for ford racing headers and removal of the air silencer. Plugs, wires, rotor and cap all were changed in June.
In the last month I have been having a hard time starting the car. Especially when it’s warm. When I bought the car in May, when I turned the key the car would give that very powerful vroom mustangs sound but now it cranks a lot longer and just starts without a vroom. Hesitating to start but eventually does.
First thing I did to find out what was wrong was to run the computer codes with my friend’s reader and we received code number 23. Throttle position sensor. So with a voltmeter we set it to .97 by turning the screws on the sensor.
That didn’t help my starting problem but it made my car feel a bit quicker for about 20 minutes. Now the car feels and drives terrible. I have a huge loss of power and sputtering sounds from the engine bay. At first it only sputtered and putted when I was releasing the clutch at a dead stop to get the car going. But now it does it in first second and third. The car is just bogging down the road. Oil pressure seems to be a bit low as well. When I first installed my oil pressure gauge, fully warm at 2000 rpm my oil pressure sat at around 50psi. Now it’s below that, my fuel pump was changed about 3 months ago and I run 93 octane.
I am planning a 306 rebuild and have a 302 block ready to get sent to the machine shop. But I need this car because it’s my daily driver and down time has to be minimal.
Thanks a lot in advance
Fuzion

 

[ss93cobra]

Regardless of the status of the fuel pump, you need to do a fuel pressure test to eliminate the fuel system, then move on the to the ignition system as well as the eec system.

 

[Fuzion]

Regardless of the status of the fuel pump, you need to do a fuel pressure test to eliminate the fuel system, then move on the to the ignition system as well as the eec system.

Got to get my hands on a TPI fuel pressure test kit, or is there another way to check the fuel pressure, and to see if the fuel pressure regulator is regulating?

I should see around 40.5 to 47 PSI after it primes right?

 

[ss93cobra]

There is really no other accurate way to test it. With key on engine off after you cycle the key a few times you should see 40-45 with vacuum on.

 

[CoupedUp]

To me it sounds like the computer is receiving bad info and is making the engine stumble and run like ds.

I wouldn't be so sure your tps is in good working order ...
I'd re-pull the codes before spending a chunk of money on diagnostic equipment.

 

[HISSIN50]

As CU said, I would want to check the wiring (ref, ground and return) to the TPS and note values with an analog VOM as you slowly open the throttle. Look for voltage dips or spikes.

Fuel pressure spec on a stock FPR is 30+ PSI. Most folks see 32 PSI at operating idle. With the vac line off (simulating WOT), pressure is around 38-39 PSI. If you have an aftermarket FPR, this will be skewed.

Good luck.

 

[Fuzion]

As CU said, I would want to check the wiring (ref, ground and return) to the TPS and note values with an analog VOM as you slowly open the throttle. Look for voltage dips or spikes.

Fuel pressure spec on a stock FPR is 30+ PSI. Most folks see 32 PSI at operating idle. With the vac line off (simulating WOT), pressure is around 38-39 PSI. If you have an aftermarket FPR, this will be skewed.

Good luck.

Well it results that my PCV valve popped off, that was causing my issues. I also found that one of the two vacuum lines that go from the air pump to the h-pipe and the pipe that connects both heads was so brittle that it cracked. And then while I was trying to fix the white one I cracked the black one too. I taped those off so I don’t get a vacuum leak and deleted my dealer installed cruise control (that didn’t work, and is going to be in the way when I convert to MAS air). I also installed a high flow catted h-pipe and new header gaskets.
It basically feels like I rebuilt the engine.
Thanks for all the help
This weekend I’m going to try to test the TPS sensor to see if it’s faulty or if it still in good shape.

 

[Paul Perreca]

good to hear positive results!

 

[Fuzion]

Well this last weekend I found that my pcv valve was popped out. I cleaned around the area and cleaned the screen in there and put it all back together. I also installed a catted hiflow h pipe and started her up.
Felt awesome.
It felt like a brand new car.
The starting issues were still the same but while driving the car it never felt this good.
Well today I get out of school all excited to driver her home. She starts doing it again (sputtering). I checked to see if the pcv valve was out again but it was perfect just as I left it. Now I really don't know what to do. She sounds like a Subaru wrx.
It's all bad.
I'm going to buy a new starter soon and test both the distributor module and tps sensor.
I was wondering if my starting problems could be caused by a bad Fuel pressure regulator.
So I’m going to check the fuel pressure and run a compression check


Thanks a lot
Fuzion

 

[HISSIN50]

The thing is that since you are SD, the vacuum signal is CRITICAL. The vac leak you had before would have probably raised the idle, and the puter was fighting to lower the idle. And with the leak, the puter thought you had the gas pressed down when you didnt. On a healthy car, if you try to start it with the gas half-pressed down it will start like poo.

Pulling codes is key, esp if you have not already (again). Your SD car does not come with a functional CEL, so you dont know when a code pops up.

I am not sure if this applies so do at your discretion: I would also make sure the EGR is clean and functioning properly, even if you dont get a code. if it is leaking at idle, it will cause a crappy idle and hard start (I dont know if that is a symptom you have. Disregard if not). You can also simply apply 5" hg of vac to the valve and see if your car stalls. It should.

FWIW, a stockish SD motor should pull nearly 20" hg of consistant vacuum at idle.

My random (really random) thoughts.
Good luck.