Don't mess with texas - 3400 swap project

[1988GTU]

So I have switched back to the oem style knock sensor, the computer now has no codes.

New problem, the car won't idle when driving at any speed.

Push the clutch car seems to die no code no anything

If the car is at idle and stationary seems fine

I used the 3400 map sensor setup, should
I be using the 3.1 setup ? really at a loss as to why this is happening now

Use the correct chip meant for the trans you have.

Put the 3.1 MAP back in place not 3x00.

[Rettax3]

Use the correct chip meant for the trans you have.

^^^This, yes.^^^

Put the 3.1 MAP back in place not 3x00.

^^^This, huh?^^^ Same sensor, same part, zero difference: 2.8, 3.1, 3100, 3400, 5.7 TBI, etc. Until they went to the smaller-style sensor, they were all the same (except for the force-induction engines, of course ).

[1988GTU]

The 3x00 one could be bad. His 3.1 sensor seemed to be fine before all the swapping took place.

[themixer]

Well that sucks I was really hoping this was going to solve the problem.

I will try it anyways but all the sensors on the 3400 worked fine no codes on the van I removed it from.

[themixer]

I switched to the original map and it had no difference

I have looked all over the motor for any ground that I have not reconnected does anybody have a listing of all the grounds on the specific vehicle ? In some more troubleshooting I wanted to see if the oxygen sensor was reporting a signal, so I unplugged it. The oxygen sensor is still reading and no check engine light on the tech 1 scan tool. I feel like this is not normal behavior for the oxygen sensor, I will be testing the wire from the ECM to the sensor


When the car is not stalling it seems to be driving just fine with plenty of power and very smooth.

Here's a YouTube video of the car stalling

http://www.youtube.com/watch?v=aYFtULcyQ0A

[1988GTU]

Is the IAC active? Blocked? What TB do you have? Post up a few pictures of the TB that you are using showing the front and back side of its mating surface.

[themixer]

It seems the IAC is active, it opens up and sounds like the car is sucking though a straw before it stalls out. I can get pictures of my TB setup, its just the original that was on the venture van motor. Was I suppose to switch to a 3.1 throttle body?

[1988GTU]

Toss up pics of the TB like asked and the UIM with the TB detached, I'd like to see something.

[themixer]

I didnt have time this morning to remove the TB before work, but i will tonight

Just as a test I did check the fuel pressure of the brand new pump I installed, 48psi constant.

Here are some quick pics i snapped this morning of the throttle body area, what exactly are you looking for I was unaware of any changes to this area for a 3400 swap, but would not be surprised if i missed something.

[1988GTU]

Those pics do nothing for me.
If you can and should be able to post of the pictures of it not attached exposing the back side of the TB and the face of the UIM mating surface I can better explain anything should I see something.

[themixer]

I will get these tonight!

[3X00-Modified]

First off, the fuel pressure regulator nipple should go to a vacuum source... its NOT supposed to be 48PSI constant, it should drop at idle. Second that solenoid you have just sitting on the back of the intake is a newer purge solenoid... you need to re-run the line that's there to where ever you have your current purge solenoid, (if it's a stock MPFI car I believe those were on top of the canister)

It's a possibility the extra fuel pressure is causing it to stall... Have you done an idle relearn process yet?

And you can read codes but can you see data from the ECU such as sensor readouts? That data will help us tons rather than just shooting in the dark.

Pics to illustrate what 1988GTU is looking for...
Pre 2000 Intake


2000+ intake


TB choices... TB on right is NEEDED for the pre 2000 Intake... The right version was made for the 2000+ intakes....


SO basically you can't have a 2000+ TB on a 99 3400 upper intake otherwise the IAC wont get air into the intake.

[1988GTU]

Boy do I ever wish people were more forum helpful like you Jon!
I couldnt find my pics for that configuration and setup differences.
Thanks Jon for doin his homework.

[themixer]

Yes thank you for having pictures of this problem. But I fear that my entire motor was working in a van, it is a 2001 all the parts are original. There's no way that I would have an older or newer part on the motor as I have the complete service history.

As for the vacuum line it is actually running a small vacuum line from the fuel pressure regulator back to the Map sensor. This was original to the way the venture van was set up. I will try hooking it up directly, and see if the fuel pressure drops.

I will make a video of the sensor readouts as I have the original tech 1 GM tool. I did try an idle relearn but sometimes have not been able to do it as it stalls

[themixer]

So after playing around with the fuel pressure regulator and vacuum lines it seems that like the pump is running at a constant 48-50 psi when the car is at Keyturn and idling. With the vacuum line unplugged to the fuel pressure regulator I get 60 PSI.

I'm no gynecologist but this seems like too much fuel pressure.

I am currently checking over the lines to make sure my return doesn't have a pinch in any of the rubber connections.

Before doing the engine swap I did all the brake, gas lines and installed a new pump. Is it possible that this new pump is pumping out this much pressure? Thankfully the pump was cheap from rock auto so I could easily go get another one.