need help with my tbi van

[jamesmonty]

First, 88 caravan 2.5 tbi 520 5-speed. It started with a slight miss when cold but would run fine after a few minutes. Now it won't run at all. It will start, run 2-3 seconds and stop. When it shuts off I can hear the fuel pump shut off a few seconds after. It had codes 12, 22, 14, 34, and 55. I don't have cruise control (34), I did check the timing (22), and I did unplug the map while it was running (14). I replaced the map with a new unit to be safe. Changed the coil with a known good one. Newer wires, and the plugs are toasty brown. I also replaced most of the vac lines to make sure I had no leaks. What should I be looking at as the problem? I have a fsm but it hasn't been much help yet. Could it be the asd?

[turbovanman]

Bad HEP?

[jamesmonty]

Bad HEP?

Don't know? But if you think I should try changing it I will. I ordered a asd relay today to try.

[black86glhs]

They are really easy to change.

[turbovanman]

Don't know? But if you think I should try changing it I will. I ordered a asd relay today to try.

That would be first on my list to change out. I've had customer vehicles do the same as yours and set NO codes, :(

[Vigo]

bad hep is my first guess too. funny enough, you usually dont get code 11 unless the thing is cold dead kaput, but if it works sometimes you dont get it. :(

[jamesmonty]

That would be first on my list to change out. I've had customer vehicles do the same as yours and set NO codes, :(

I got one on order today, thanks rockauto! It was a few bucks cheaper shipped to my door from them than at the local parts store. We will see how it works.

[turbo84voyager]

If the fuel pump runs a few seconds longer ASD is probabily fine. I agree with the HEP being bad. My 89 turbo mini had a bad HEP when I got it. No codes but it would not always start for the previous owner. He was told it needed a computer so he was going to junk the van. I bought it, replaced the HEP and it started every time since. Is there spark? Is the injector spraying? You can try spraying carb cleaner in the throttle body and see if it fires. If it does for a second or two it is fuel. But ta bad HEP affects both spark and fuel.

Justin

[jamesmonty]

New hep, no help. Let go over again what it is doing. 1 it will start and run fine for about 4 seconds and then just shut off. It has spark at all cylinders, fuel injector is spraying, fuel pump is running fine. New asd, new hep, and new map. Plugs, cap, rotor button, wires, plugs are all newer and good. No codes. Could it be the computer? Since it a 5 speed do I need a 5 speed computer or will an auto computer work? The reason I ask that is I know I can go to the pick a part and get a auto computer. Don't think they have any 5 speed stuff. Thanks again.

[turbovanman]

How are you monitoring the fuel and spark when it dies?

Yes, you can use an auto computer but it could idle a bit funny.

[jamesmonty]

How are you monitoring the fuel and spark when it dies?

Yes, you can use an auto computer but it could idle a bit funny.

I looked down the tb while my assistant cranked it over. I checked for spark with a spare plug one cyl at a time while my assistant cranked. My 6yr old makes a good assistant!

[Vigo]

i just had to replace the computer on an 87 3.0 van for the same symptom. ended up replacing the whole harness because it had all sorts of voltage leakage into the wrong circuits that fragged the computer.

i happen to know that this can happen by running the engine with crappy or insufficient grounds, causing it to make its own in inconvenient places.. but dont ask how i know.

[turbovanman]

I looked down the tb while my assistant cranked it over. I checked for spark with a spare plug one cyl at a time while my assistant cranked. My 6yr old makes a good assistant!

I would get one of those inline spark flashers so you can see it when it dies. The way it dies, its spark or computer related, fuel pumps don't cause it to suddenly quit then restart.

Maybe check the reistance of the injector cold then hot and when it dies, it could be out of spec and overloading the computer.

[Vigo]

if the asd relay turns off AFTER the engine dies, its not dieing because the coil, injectors, or fuel pump lost power.. its dieing because it either cut signal to the coil or injectors. or injector in this case.

[jamesmonty]

Eureka! It runs! My friend was picking up his shelby z from his mechanic and he got me 2 complete tb units for $10. We started by changing the injector and fuel pressure reg. Nothing. Next we changed the tps with what looked like a brand new one and bam! It started and ran perfect! So bad tps. At least I have some new parts and some spares for the future. Thanks for all the help, and special thanks to my buddy mark for picking up the cheap parts for me.

[Vigo]

oh yeh, that reminds me!!

lol.

easiest way to diagnose sensors other than the HEP is to unplug them! if a car wont start because a sensor is bad, unplug it and a default value will be substituted, and the car will run (badly). You can half---- diagnose a tps, map sensor or cts this way, all of which will keep the car from starting if the values are way off.

[Aries_Turbo]

i was gonna say if you didnt get it soon, swap in a turbo motor, pump and harness. :) might be easier and alot more fun hehe.

Brian

[jamesmonty]

i was gonna say if you didnt get it soon, swap in a turbo motor, pump and harness. :) might be easier and alot more fun hehe.

Brian

I have been tempted! It is a common block, and I have a turbo 2.5 under my back porch. Also have a t2 wireing harness, turbo, intake, computer, ect to do the swap. But the thing drives so good, and until that problem has been very reliable.