hesitation and stalling on my 87

[justice]

When my 87 is cold, it will bog down and hesitate when starting from a stand still. You know, it starts to go, bogs down and then recovers. once its warmed up it does not do this. Today, (also when cold) it would die when I put it in gear. it took me several tries to be able to get moving. once moving, i had the hesitations and bogging until it warmed up a bit.

It also through a SES light today.

Another thing I have noticed is that when driving at crusising speed (around 50mph) it seems like the transmission is shifting in and out of OD. I can hear the engine revs get higher and if I accellerate a little, it will shift back into OD and the RPMs will drop.

Could the problems be related? Torque converter maybe?

[rlsllc]

Pull the codes first, that should point you in the right direction. It could be any number of sensors, TPS comes to mind with what you describe, as does the MAP. Although not as likely, it could be a coolant temp sensor, stuck EGR, or a vacuum leak (unlikely).

Does the idle seem to adjust itself normally? That would clear the IAC motor or whatever it's called on a GMs.

The SES is a good thing, it will help find the problem.

[kings-x59]

So curious, what code was set?

[justice]

just checked the codes.

got a 44, which according to http://www.troublecodes.net/GM/86-90_43Z_tbi.shtml

is

44 Oxygen sensor voltage was under 0.25 volts for 50 seconds of closed loop operation.

[rlsllc]

I guess it could be the O2 sensor, but I'm more inclined to wonder what is causing the lean condition. Running it on a scanner is the best bet unless you want to throw ideas and parts at it. I still think it is one of the possibilities I posted before, but could be wrong. It's happened before, lol.

[justice]

as an update, it looks like its the transmission/torque converter

time for a new one...

[6spd_monte]

How did you come to that conclusion?

[Kidhauler]

If your o2 sensor fails or is cold in the morning it will run the car rich to warm it up and stop you from burning up a valve or piston.

This is called open loop mode because the sensor is not feeding any info back to the computer yet thus the loop is open. The early vans had a bad time with O2 sensors being slightly too far back in the exhaust and running a little on the cold side and would cause them to fail on a regular basis. If you swap it out for a heated sensor it is a easy mod you simply have to hook the positive wire to a 12v source that is hooked to the ignition and then find a good ground for the negitive side. The other wire should just plug in to your old sensor port. If you do the mod your computer will go into closed loop mode faster in the morning and you should get slightly better mileage as the van will not run rich for as long. Plus you will not have to put a sensor in every year like I used to do so I could pass AIRCARE.

[justice]

How did you come to that conclusion?

I have known there was an issue with the trans for a while. I have my transmission guy come check it out and according to him, the bogging and stuff is a combination of the torque converter trying to lock up when its not supposed to, and the trans not completly shifting down to 1st gear when i come to a stop.

Its also shifting much later than it should be.

[kings-x59]

well..if it's the original trans I'd say you got your money's worth.

[justice]

yea, i guess so. Seeing as I only paid $400 for the van. But now since i'm investing almost $1300 (complete trans rebuild, new muffler and new shocks) I guess i'll have to break down and start doing some body work on it.

I wonder how hard it would be to pull the windows out and weld steel fillers in their place so I can have more of a cargo look....

[justice]

annnnnd lets add a rear main seal and a new transmission mount...yay

[kings-x59]

Well if the tranny is going to be yanked, best time to do the rear main anyway.

edit: oh, a thought on the rear main. Lockdoc posted here quite some time back about a rear main seal with a different part number than the original that has an L shaped lip to it. The rear main seal wears a slight groove in the shaft and even when a new seal is installed it will still leak. I guess the L shape to the lip puts the seal on part of the shaft that is not grooved.
..anyway, I suggest you search for the post. I think he posted the part number.

[justice]

got it back today, taking it for a new muffler in the morning.

all the hesitation is gone, and a good amount of the (vans) vibration has goes as well. My trasmission guy said that when he rebuilt it, that he built it as if it was going behind a 5.7 engine and not a 4.3. So it should be pretty durable.

[1Gary]

Sounds like you got it close to being done short of the muffler. =D> =D>