Loss of power and stalling

Hi,

When I hear of power loss, I always thing of a plugged catalytic converter. Have you checked that? Next, is there any black smoke from the exhaust when this happens?

Let me know.
Joe

The catalytic converter is eliminated. Also i have like grey smoke coming out when this happens i noticed my transmission fluid was low so i topped off and smoke got worse and hesitating and stalling got worse. Could it be a bad radiator causing the problem?

Hi,

Have you noticed any loss of engine coolant? Also, with the cat eliminated, it is hard to know what the computer is doing with fuel trims (air/fuel mixture).

Do me a favor, I'm not sure why topping off the ATF would have caused this, but the idea that you have the white/gray smoke is a concern. That could be related to coolant getting burned in the combustion chamber via a bad head gasket. Take a look through this link and check as much as you can following it. Let me know what you find.

https://www.2carpros.com/articles/head-gasket-blown-test

Let me know.

Joe

I'm not leaking coolant. the smoke smells like oil burning. i checked all plugs i'm getting good readings on all of them. Checked the combustion chamber it stayed blue. no oil leaking. after replacing radiator topped off transmission fluid again and it has not gone down. checked fuel flow to the carburetor that's okay. checked timing that's all okay. i don't have a clue unless the re-manufactured carburetor is bad. any other suggestions would be greatly appreciated.

The only thing I can think of related to the ATF causing it to get worse is the old vacuum modulator on the trans. However, if this is the original transmission, I don't believe it had one. Was the transmission changed (different model)? The ones that had the modulator valve would allow ATF to be sucked into the engine via the vacuum hose when they failed.

It's the original transmission no vacuum pump on it.the car is all original but sat for a while and did not run at all when i purchased it. I did change the radiator and i'm not losing transmission fluid anymore, but the car still wont run under load.

Hi,

Do you know what model the transmission is? Is it a turbo 350? It could also be a 200. Are there any vacuum hoses going to the transmission? My manual shows several different possibilities. One is a turbo 350 that does have a vacuum modulator. It is a valve that simple identifies engine load (via vacuum) to determine line pressure and shift points. In it is a diaphragm which can go bad and allow ATF to enter the combustion chamber and create odd shift patterns.

Joe

I will check tomorrow to see if i see any vacuum lines going to the transmission and try to determine what transmission i have and get back to you. thank you

Sounds good. That is the only thing I can think of that would cause the engine to smoke when you added ATF.

I will watch for your reply.

Take care,
Joe

I do have a vacuum modulator on my transmission i ordered a new one and waiting for it to come in and see if that helps with the problem. thank you ill get back as soon as i know something.

Not a problem. If you disconnect the vacuum hose at the transmission modulator valve, is there any ATF in it?

Joe

Yes, there was a lot of ATF that came out. That's why i ended up ordering a new one hopefully this is the all end cure.

That's the cause of the smoke and likely the cause of the driveability issues. When you said adding ATF made it smoke more, that is the first thing that came to mind.

If you have the chance, let me know if it takes care of the issue for you.

Take care,
Joe

I changed the vacuum modulator and ran the car no more smoke car runs good except if you just step on. The gas the car bogs down and stalls or it kicks back up. if you lightly step on the gas you here a vacuum noise from the air filter area but the runs fine was able to drive it for about 15 plus miles and ran good except for that bogging down when not lightly stepping on the gas.

When you press the throttle and hear the vacuum sound, is that only when driving or can you hear it if the vehicle is parked and you hit the throttle? Have you checked for other vacuum related issues?

Here is a link that explains how to check:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Joe

The car is running perfect except for you have to lightly feather the gas to go or its stalls from to luch vacuum can't find any vacuum leak at all its like the air filter is taking too much air and its original air filter housing.

If there are no vacuum leaks and the carburetor and fuel pump are new, the only other thing I can think of is ignition timing. When you installed the new distributor, how was timing set?

Here are the (sad) directions from the manual:

___________________________

1981 Pontiac Grand Prix V6-231 3.8L
Ignition Timing Adjustment
Vehicle Powertrain Management Ignition System Ignition Timing Adjustments Ignition Timing Adjustment
IGNITION TIMING ADJUSTMENT
Set timing at slow idle and Before Top Dead Center, unless otherwise specified.

Disconnect and plug distributor vacuum hose at distributor.

On 4.3L (265), 4.9L (301) engines, ground distributor bypass pigtail (blue connector).


On others, carburetted, disconnect 4-wire connector at distributor.

Timing must be set to specifications on emission label. If "Check Engine" light comes on during procedure, remove ECM fuse to clear.

________________

Let me know.
Joe

I replaced the EGR valve because that was failing checked all vacuum lines found a couple are crushing with vacuum. i had not had time to replace them yet. I will get back to you soon.

Hi,

What you mentioned can certainly be the problem. If you have a chance, let me know how it turns out for you.

Take care,
Joe

I replaced the vacuum lines and it still is bogging down and stalling. when you do give it throttle it sounds like carburetor is sucking in too much air causing it to bog down and stall. what could be the cause of that? how do i fix it? i have put 3 gaskets on for the carburetor still no change.

Hi,

Have you ever trued adjusting the float level in the carburetor? The engine could be starved for fuel if not enough is available. Also, is it possible for you to record what it is doing and uploading it for me to see and hear?

_____________________

As far as the float, here are directions. There are two carburetor options. I'll provide directions for both. The attached pics will correlate with the directions.

____________________

1981 Pontiac Grand Prix V6-231 3.8L
Rochester Dual-Jet M2M Series
Vehicle Powertrain Management Fuel Delivery and Air Induction Carburetor Carburetor Float Adjustments Rochester Dual-Jet M2M Series
ROCHESTER DUAL-JET M2M SERIES
Float Level Adjustment

Pic 1

1. Remove air horn, gasket, power piston, and metering rod assembly, and float bowl insert.
2. Attach J-34187-1 or BT-8227A-1 to float bowl.
3. Place J-34187A in base with contact pin resting on outer edge of float lever.
4. Measure distance from top of casting to top of float, at point 3/16" from large end of float. Use J-9789-90 or BT-8037.
5. If more than +/- 2/32" from specification, use J-34817-25 or BT-8427 to bend lever up or down. Remove bending tool and measure, repeating until within specification.
6. Check float alignment.
7. Reassemble carburetor.

__________________________________

1981 Pontiac Grand Prix V6-231 3.8L
Rochester Dual-Jet E2M Series
Vehicle Powertrain Management Fuel Delivery and Air Induction Carburetor Carburetor Float Adjustments Rochester Dual-Jet E2M Series
ROCHESTER DUAL-JET E2M SERIES
Fig. 5 Float level adjustment. E2M units

See pic 2 for figure 5

Refer to Fig 5 for float adjustment procedure. Adjust as directed to dimension listed under Specifications, Adjustment Specifications.

____________________________________

If you could, record it with your phone and upload it. Hopefully, if I hear and see how it's reacting, I'll be better able to help.

Take care,
Joe

I checked the float and readjusted that. i also went up a little on the idle air screws. the car ran better at idle but still bogged down and stalled when applying gas. Just for haha i unplugged the o2 sensor and i was able to drive it down the street with little bogging down, but i give it gas and it does i still have a little stalling, but i can go down the road. i'm assuming that with the o2 sensor unplugged the ECU is going sporadic not knowing what to do, either go lean or rich. i have ordered a new sensor waiting to get it in. I will keep you posted if the o2 sensor works. thanks again.

Sounds good. Let me know if it helps.

Joe