Here we go again.....more TPI woes

[mobileortho]

Nope, still working on trying to figure it out. Looking at the regulator next.

[TX58]

I have a 92 Trans Am with TPI and I had a problem like that (low power,no more than 20 mph) it happened while driving on the freeway. Total loss of power, had to limp it back home. I heard from another TA owner that the stock injectors fail right about 90-100k miles and that's where my car was about. Ordered new reconditioned injectors and installed them. Test drove The car and it scared the crap out of me, it never ran that fast the whole time I owned it. TPI can be a pain but man it looks cool under the hood of any vehicle. I have a 96 Vortec engine that I'm topping off with TPI. Have the Edlebrock TPI/Vortec intake with SLP Siamese runners. Would love to find another TF truck and drop in in.
Good luck and let us know the outcome
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[Coupeguy2001]

Did you drive it with the fuel pressure gauge hooked up? that will tell you if the regulator is at fault.
Check the injectors one at a time cold. Disconnect the injector connector, and put a meter on the two little contacts on the injector. You should see around 14-15 ohms.
If they are all good, plug them all back in and then start it and get it warmed up to where the thermostat opens. Then ohm them all over again. the ohms shouldn't change more than an ohm or two. The ohms should go down with heat.
If any of them show 9 ohms or less, it would indicate that you could either change each bad one, or get another set.

TPI is called batch fire, in that half of the fuel is injected at each revolution of the engine. Remember the engine has to go two revolutions to get all four parts of the internal combustion engine cycle.
Intake, Compression, on one revolution,
power and exhaust on the second.
So the computer puts out two pulses for each revolution of the engine, the left injectors and the right injectors. These pulses are from the injector drivers in the computer. If you are not getting both pulses on both revolutions, it might sound like what you are describing.
Is it possible that you know someone that might lend you a computer? you would have to switch the chips, then drive it, then switch the chips back. I have a couple of those as spares for another project. If you can't get anybody to loan you one, let me know.

I have an 86 corvette with TPI, so I feel your pain.

[Coupeguy2001]

the Map sensor tells the computer that the engine is either accelerating or coasting, cruising or idling.
If the engine is under acceleration, there are three things that confirm it to the computer. low vacuum (MAP), vehicle speed sensor indicates increasing speed, and throttle position sensor is off idle.
The Oxygen sensor is a feedback that the three things add up and a lookup table in the computer chip for the MAP system is the source for fuel amount and timing and the knock sensor chimes in that the timing is correct.
In cruise, the map vacuum is higher, the vehicle speed sensor indicates no speed change, and the throttle position sensor is not at wide open throttle.

Deceleration has the same three things, but this time, the throttle position sensor is at idle, the vehicle speed sensor indicates the vehicle slowing, and the vacuum is high. The computer may elect not to cycle the injectors because of the anticipated deceleration tables.

Add into all this that the fuel pressure has to be right, and the injectors have to flow correctly, and the ignition system is correct and working, and the temperature is within the proper limits. and the engine is in closed loop.
And the Oxygen sensor indicates that there is enough fuel and not too much of it.
ENGINE SPEED IS OBTAINED FROM THE DISTRIBUTOR 4 PIN PLUG.

[1project2many]

So the computer puts out two pulses for each revolution of the engine, the left injectors and the right injectors. These pulses are from the injector drivers in the computer. If you are not getting both pulses on both revolutions, it might sound like what you are describing.

Although the wiring diagram seems to show left and right are separate, inside the ecm they are connected together. All eight injectors are pulsed at the same time.

[mobileortho]

I examined the regulator and found some corrosion and some weak spots in the diaphram so I replaced it. Still runs like crap though so I'm going through the process of elimination. Since the FPR & distributor check out, I'm going to check the injuctors. I found an interesting youtube video on how to clean them yourself.

DYI fuel injector cleaning

. Someone also suggested that I double check the lines to make sure it's not sucking air. If they check out the only thing left that I can think of is the ECU.

[LuckyJoe]

Did you ever get the problem resolved? If so, what ultimately did you find. I have the same problem now with my RamJet. Would appreciate your guidance. Thanks,

Joe,

[mobileortho]

Funny you should ask. I got frustrated with the TPI & found a great deal on a Edelbrock Air Gap intake with Endurashine finish topped off with a Demon 650 carb. Also had always wanted to swap out the existing frame mounted tank I had for a mustang setup & electric electric fuel pump. Sold the TPI & installed the intake & carb......same problem! Tonite I dropped the tank an low & behold I find my issue.... the darned sock had come off the pickup tube and trash had all but stopped up the line!!! I wished I'd started there to begin with but I'd ruled that out because all the lines from the tank forward were new! I could've saved myself a lot of time money and frustration!!!!!!!