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I'm running a TPI setup on my truck, noticed that at stop signs or lights the engine surges. It gets so bad at times I have to struggle to keep the brakes depressed to keep it from launching into on coming traffic. Any ideas what's going on?

Is there a diagnostic link you can hook a scanner or code reader so you can see if any trouble codes are stored?

Check for a bad vacuum hose to the map sensor. Could be a throttle body that is sludged up causing the idle speed motor to try and compensate.

A good scanner hooked up the computer would let you see a data stream of all the sensors and what they are doing.

Might check other vacuum hoses to see if one is cracked.

Robert,
Nice Truck by the way!!
and this is not a complete answer, just a few comments to keep you scratching your head.

I asked my son last night what would cause an issue with a TPI engine surges. A little fuel to get a heavy thinker thinking, His answer came with more questions: How much Cam we talking? Stall converter range? is the timing set correct with the computer wire-off? Fuel pressure checked, regulated ? clean injectors? and when he got to> IAC? Idle Air Control adjustment? <something about key-on set-up computer to know wide open position? & then idle-set screw. I thought wow, it can be a list of many things. the code or scanner idea mentioned is a good way to get there.. I had a bad water temp sending unit telling My Rv computer it was 35 degrees all the time. (that was a surge then stall) the Scanner picked up on it.

anyway it's not as easy to trouble shoot from an arm chair, but it's less greasy.

Mobileortho:
I think I remember some of your earlier posts, but I could be wrong. anyhow, as I recall, you had one of the earlier TPI units specifically a late 80's / early 90's OBD I fuel injection unit, just like I have on my '62. If I'm right then you have lights that give you the diagnostics on your trouble codes. I have a list of the codes that correspond to the lights. I can send them to you. In any case all of the other posts are correct in that you have to use a scanner (if it is a later OBD II unit) or you have to observe the lights as they pass through the various scanning phases for the earlier fuel injection. If it is the early unit. let me make a guess and say you have an Idle Air Control valve problem.

Getting the codes is easy enough by counting the flashes of the check engine light on the earlier TPI units. You can used the ADL link and jumper two connections to get the light to flash the codes and certainly better than nothing. But if you can actually see what each sensor is telling the computer then you can make a better choice on what to replace. You can see if that coolant temp sensor is telling the ECM it's 35 degrees when it's actually running 195 degrees.

You will also see if the IAC or idle speed motor is getting the correct signal.

"You will also see if the IAC or idle speed motor is getting the correct signal."

The Idle Air Control valve was bad on mine, yet the blinking lights showed no problem, and it was getting a signal. I found the best first look is to switch on the key and see if the thing moves. It should, and if it doesn't take it off and see if it's seized.

Opps ! I meant to say take the valve off, switch the key on while the lead is still plugged in, and see if the piston moves. If it doesn't, check to see if it is seized. Sorry 'bout that.

Yes, the IAC may not set a code, but you can see if it is being told to open or close with a good scanner. You can likely here the difference in the sound the throttle body makes when the IAC opens and closes.

Could be as simple as the vacuum line from the intake to the booster cracked. IMPOSSIBLE to even make an educated guess with out anymore more info. Let us in on what your running, what mods it has, when it does it(hot or cold or both), ect.....

No offense, but I presume that you have your speed sensor on the trans hooked up to the ECM. Its a purple and yellow twisted wires. On older retro fits, a lot of people like me have tried to by pass this, and tht will cause problems at stop signs if it is not hooked in.

Adjusted the IAC, problem solved.