1990 Toyota Pickup Cold Engine Problems...

Hi all,

I need some help from those who know 1990 Toyota Pickups...

I brought my pickup into a Toyota shop because I was noticing a "low miss" at idle. They assessed it as bad piston rings and recommended an engine overhaul. (It really was a case of bad rings--verified after teardown) Long story short--we went with a remanufactured block (crankcase and heads) and the shop installed the rest of the engine with my original parts...

Here's the problem...

Now when I start the engine (cold) it starts and runs fine. If I give a sudden tap on the accelerator, the engine hesitates and coughs and the finally accelerates. Once the engine warms up, the problem goes away. It is apparent every time the engine is cold. The main thing is that the the engine never did this prior to my taking it into the shop.

I've taken the truck back to the shop and they cannot figure out what is wrong. They are also saying that it wasn't something they did so I'm going to have to pay them to diagnose the problem.

Does anyone have any suggestions about what might be wrong with the engine?

Any help would be appreciated because I'm into this engine for some major bucks already...

Thanks in advance...

is this unit fuel injected or carbed. Either way it could be a vacuum line on wrong, or a mild vacuum leak. Or, if carbed, it could be something stuck in the carb. good luck

Thanks for the reply...

The truck has electronic fuel injection. I thought of the vacuum line problem, but I don't have a proper diagram to ensure that the lines are connected correctly. Do you know where I could get a good diagram?

Hello again,

Apparently, the hesitation has escalated in it's severity...it also hesitates even when warm now although it is not as often as when cold.

I've rechecked all my vacuum line connections and they are fine so I'm pretty sure that the problem is not there.

Any other suggestions? Thanks in advance...

if it's the v6, it could be your cold start valve, the valve is located on the right side of the engine(from drivers seat) directly across the intake manifold from the throttle body, when you are cold starting, (get a helper to start the truck)and listen in the engine compartment for a ticking sound, this signifies that the csv is operating, ...make sense?

I'm sorry, I should have specified...it is a V6 3.0 liter. Engine 3VZE.
4x4 pickup.

I will look into the cold start injector and post the results...thanks!!!

My father's 91 4x4 is having the same problem.Toyota rebuilt his motor new block etc..etc...along with the cold start injector, also check/change the cold start time switch. We were also told to look into (I believe) the fast idle (switch?)also, it has something to do w/ the electronic choke.Trying to find a price on the csi as I type this.

If you are still needing any diagrams of the vaccuum lines just let me know.
And for drkgypsy above if you are still working on the cold start injector and switch, there are easy tests you can do to see if it is your problem or not. If you are still working on it let me know and I will get the info for you.

Cold start injector was the problem.1 jet was clogged, the other semi-clogged. $147 new from the dealership. Took a whole whopping 10 min to remove and install.

Good, stuff, glad to see you got it straightend out, and thanks for the follow up reply, you are helping someone else out in the future!

Nate