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Hi. I have a 1986 Chevy astro with the 4.3 liter v6 TBI engine. I am having some problems during acceleration. Van does not want to go when stepping on the gas, but seems to do fine when it gets up to speed. At idle it seems like its struggling to stay running, but if I step on the gas the engine will hesitate, but Rpms will increase and everything will seem to be fine. As long as I am stepping on the gas, it seems fine, but when I let off the gas, it seems like it wants to die. Where should I start?
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How many miles on the van? And when was the last time you replace the spark plugs? Also sounds like you either have massive intake air leak or clogged throttle body. Start by inspecting the intake system for major cracks. If everything looks good, remove intake boot and see the condition of throttle body. Clean it up with shop towel & intake cleaner if required. Take out one spark plug and check the condition and type of the spark plug.
I have about 127k miles or so. Spark plugs were changed about about 40 to 50 thousand miles ago. Spark plugs and wires look pretty good.
I would take close look at throttle body – at 127K miles, it is highly likely that throttle body may need cleaning.
seeing the vehicle seems to be starving for fuel at idle.
change your fuel filter and check your fuel pressure.O.k. I will clean the throttle body and change the fuel filter. I did notice the crank case tube leading to the throttle body area was damaged and I replaced that. I noticed a tube going from the exhaust manifold to the air duct intake system. It was disconnected. It looks like it fits in there. Is that normal (a tube going from exhaust manifold area to air duct intake system)?
[quote=”mckrishes” post=32544]O.k. I will clean the throttle body and change the fuel filter. I did notice the crank case tube leading to the throttle body area was damaged and I replaced that. I noticed a tube going from the exhaust manifold to the air duct intake system. It was disconnected. It looks like it fits in there. Is that normal (a tube going from exhaust manifold area to air duct intake system)?[/quote]
You may be looking at some EGR/emissions setup.
I would also be checking for vacuum and voltage leaks also.
Keep us posted!
Hi. I changed the fuel filter, air filter. Cleaned the throttle body. Inspected the plugs, wires, caps and they all appear good and in working condition. I checked the vacuum connections and they appear tight and secure. I checked the pcv valve and it’s working properly.
No luck. When you step on the gas, it doesn’t want to go, but then it will get up to speed and start driving fine as long as you are stepping on the gas. But if you let off the gas and coast for a few seconds, then step on gas again to speed up, same problems.
What direction do I need to go now?
Something else I’ll throw out here is to check the transmission fluid level and condition. It may not be an engine performance issue but rather a transmission issue so don’t forget to look there as well.
Update. I removed the idle air control valve. There was sludge on the tip and in the chamber. Got it all cleaned up and now works fine. No more issues.
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