1995 Astro V6 engine shakes

My 1995 Astro V6 CMFI shakes violently when partial throttle is applied.
I have installed all the standard maintenance components.

In addition I have repaired an EGR problem and that unit is now 100% operational

The static/dynamic fuel pressure is between 58 and 60 psi on my gauge.
With this shaking there is a losss of power. I can maintain 80+ mph in overdrive when the road is flat but with a steady up incline the van will start to bogg down (vacuum gage reading is slowly decreasing) and may even down shift to normal drive.

It is hard to explain at 45 mph and just a touch of throttle the engine will shake violently. Add more or less throttle and the shaking stops. In different gears the shaking occurs at different speeds so I have concluded that it is RPM dependent and is between 1000 and 2000 rpm.

I hope this is enough info. Thanks for your help!

If this ONLY occurs at part throttle load, and not at idle, heavy load, or light cruise, it may be a fuel delivery problem. If it occurs at idle and all RPM ranges, I'd suggest a cylinder leakage test, or at least a cranking compression test to determine if a cylinder is weak.

This will be hard to believe but this is what happened.

I gave my 1995 Astro v6 a drink of water. I remembered many years ago we used to allow the vacuum line to suck in some water while running at a high RPM.

This engine has a vacuum line just behind the distributor that controls the vacuum switches for the heater and AC. I removed this hose and replaced it with a hose that had a needle used to blow up a football or basketball.

I warmed the engine, went on the freeway and cruised at 65mph.

I then took the needle and placed it in a 16 oz bottle of drinking water. It look a few minutes to suck up this amount of water.

Engine still not running correct, so I returned home. let it sit for a few hours and then restarted it. Wow the idle was perfect so smooth I did not think it was running. Went out on the road and it had great throttle response just like when it was new.

I don't know what to say but this saved me a trip to the dealer and boo koo bucks!

Carbon blasting with water wouldn't be necessary if you use good gas with engine detergents at least occasionally. My wife had a similar problem with her 89, two tanks of chevron gas with techron fixed the problem. You can buy techron as an additive but I just stick to name brand gasoline with detergents. It really does make a difference.

I read somewhere that the EPA is planning on making detergent additives mandatory in all brands of gas.

It seems that gasoline has had detergents added since 1995 See following link:

http://www.epa.gov/otaq/regs/fuels/additive/fact7gda.htm

In any case I also use gasoline that contains detergents. This keeps the fuel components free from deposits that cause erratic fuel distribution.

The addition a water spray into the air mix tends to steam clean valves, piston rings and the throttle body. Keep in mind that this has nothing to do with the fuel injection system. This is a procedure that provides very moist hot air to the cumbustion process.

I am sure if I had this van in Seattle (in stead of the desert) where the air is moist all the time this procedure may not be needed.

Bottom line is that it took a van that was almost unuseable and returned it to near new condition. A simple and no cost procedure that may just cure your 4.3L V6 ratty performance. (see my earlier post) Remember the K.i.s.s principle.

I also have a 2005 Safari van and it does not idle as smooth as the 1995 Astro.

Maybe its time to give the Safari the water treatment.

...The addition a water spray into the air mix tends to steam clean valves, piston rings and the throttle body. Keep in mind that this has nothing to do with the fuel injection system. This is a procedure that provides very moist hot air to the cumbustion process.

I am sure if I had this van in Seattle (in stead of the desert) where the air is moist all the time this procedure may not be needed.

Seattle can't be much more humid than the Atlantic shores, and I know of one engine in New Jersey which had a completely different personality after a water decarbonization procedure. I was writing ECM programs for an owner who conatantly complained of detonation, and the timing tables were backed down to something more suitable to an air cooled lawnmower than a V-8. after a recommended water/methanol decarbonization, I was able to take the peak timing back to 54º BTDC in the table with no knock events, insteal of limiting it to 29º. That engine had only 60,000 miles of use on premium fuel.

Wow, I'm impressed.
When you were cruising down the freeway at 65, were you using a long hose from behind the distributor to the cab so you could do this proceedure by yourself? Not like you had some buddy sitting on top of your engine with the hood up while you were driving, or vice-versa. I'm serious, I need a little more detail if I am to attemp it. Please and thanks.

At the time that I did the water injection, I had the engine cover removed!
This allowed me to have direct access to the vacuum port located just behind the distributor,

To do the same proceedure without removing the engine cover, you will need to locate the vacuum line that goes from the carbon canister to the vacuum connector behing the didtributor. (under hood passenger side just to the left of the fan).

Remove the vacuum line from the carbon canister and connect it to a long hose that goes into the passenger front window. Tape in place! Now you can connect that line to the before mentioned valve and stick it in the water bottle after the engine is warm and you are at hi-way speeds.

Just for evey ones information, I did this ONCE and have been running for months without any problems, my repair station wanted to clean my injector to the tune of $900, this fix cost 50 cents for the water!!

After the water treatment let the van sit for a few hours, then restart and you will see a drastic difference. Remember if there are true mechanical problems this fix will not work!!

Thanks, I'm going to do it to my 94 Astro.