sporadic surging at idle, check engine lite on , sometimes stalls at stoplite New distributer cap, wires, plugs, MAP sensor IAC, 02sensor air filter,oil coolant
No mileage listed, no engine type listed, “Chevy van” not specific enough.
Please tell us this info and explain how you decided to replace what you did.
Possibly bad Throttle Position Sensor, but nothing is concrete without more information
Under the dash below the steering column, locate ALDL connector and jump between pins A & B.
Turn the ignition switch on, and the Check Engine light will flash any stored codes.
Here’s the code definitions.
5.7 Litre engine, automatic/w overdrive, 125 "wheelbase conversion van, fuel injection
Flash the codes out as Testers post shows and post them.
leaking intake manifold gasket repaired by mechanic thensurging at idle stalling at stoplite 1st mechanic changes distributer cap coil plugs wire air filter EGR valve1st mechanic gave up . 2nd mechanic replaced IAC valve still not driving properly stumbing when accelerating surging at idle returned to 2nd mechanic replaced MAP sensor drives better but still surges at idle trans shifting abnormal.
1988 G20 van 5.7 litre 125’ wheelbase conversion van
1988 chev G20 van codes 33 and 44
You have a vacuum leak. 33 is a bad map sensor signal indicatong low vacuum and 44 is a lean fuel condition. To me, that says vacuum leak.
Sounds exactly like a vacuum leak to me as well.
1988 chev G20 van codes cleared then aldl code 13 came on when engine heated up which is O2 sensor which had already been replaced. Check engine light goes off occasionally while driving in traffic. Map sensor and IAC replaced by mechanic. Any way to test O2 sensor in vehicle?
A 13 is an open circuit or no signal. Considering the sensor is new, I would look for a broken wire.
The signal from the O2 sensor can be probed from the ecu from the right pin… don’t have a wire diagram or at the sensor to see if it is putting out about 0.7 volts… on average… it should be changing a lot.
Not that I know of unless you have a scanner.
But you can bench test it with a torch.
Set a meter to the 2 VDC scale.
Connect the red lead to the senor signal wire and the black lead to the sensor body
Take a torch and start heating the sensor tip. This removes the oxygen.
The voltage on the meter should rise smoothly to about .9 volts.
When the flame is removed, the voltage should drop smoothly back to zero.
If the voltage reading is erratic when rising or dropping, the sensor is bad.
Many thanks , I shall check it.
Check entire path to thtottle body for leaks then check entire vacuum system then the idle air control system. Post findings here for more ideas.
Thank you I am still trying to find out why I am showing an open circuit in the new O2 sensor