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1997 Chevy Express 1500 Mark III LE. 5.7 liter 350 V8.
Purchased the van knowing it needed transmission repairs. 144000 miles. Transmission was rebuilt by a reputable shop. New intake manifold gasket installed, complete tune up at the same time. Plugs, wires, distributor module (cap). Also had a new fuel injection module (8 legged spider). I installed a new IAC valve. Also threw a code for one of the oxygen sensors (O2).
The van runs great. However once it warms up to normal temperatures, never overheats. It will start to sputter and stumble at a stop when in drive. Like it wants to cut off. If I shift it to neutral or even park it seems to idle just fine. Once I leave a light of a stop sign the van will run just fine. I can dive it 200 miles without an issue unless I come to a stop. The check engine light is no on, and this problem throws no codes.
I have read thread after thread in this forum. One post where someone had a similar issue. The poster stated that after he replaced the engine temperatures sensor the problem was solved.
This is the point I am at. I've ordered an AC Delco engine temp. sensor. My next step is to replace it. I thought I would start from here with the least expensive things I can do to try to solve th issue. My questions ti the forum are: Are there two engine temp. sensors on the model year? I also read that some have two. One for the gauge on the dash, and one for the signal to to EMC (computer). Which is the one I want to replace. Temp gauge on the dash is reading fine. I can see the thermostat open and close. Does anyone know the exact location of this sensor?
Lastly any other information or serious suggestions on this issue anyone may have, I would appreciate hearing. I think I have all the pertinent information I have in this post. Thanks
1997 is OBDII so you should have some good sensor data available. You said no codes. Do you have a scanner? You can get cheap ones and use the Torque app on your phone for less than a temp. sensor and see what all the sensors are reading...aka freeze frame data to see if what computer sees from the sensor and if that makes sense.
No problem. I'm not a fan of doing much swapping without diagnosis... I do. But I don't like it. Part store sensors are often of worse quality than old OEM from a junkyard so I buy OEM and it's expensive. If you already paid the shop to diagnose it go ahead and swap the part.
Don't use Teflon tape on it because it won't ground well. Use liquid thread sealer.
This is the one I have. It works ok for the cost. I got a short OBDII extension so it will tuck up behind the dash.
No problem. I'm not a fan of doing much swapping without diagnosis... I do. But I don't like it. Part store sensors are often of worse quality than old OEM from a junkyard so I buy OEM and it's expensive. If you already paid the shop to diagnose it go ahead and swap the part.
Don't use Teflon tape on it because it won't ground well. Use liquid thread sealer.
I ordered an ACDelco sensor, I thought that was OEM. I agree, most things I refuse to use anything but OEM. Depends on the part and cost I guess. I had the transmission beefed up some. I hope it lasts.
And that's the exact ODB 2 I just bought.
I had similar stalling symptoms in a 2000 3500 with 5.7 and 4L80E. When I would come to a stop with the transmission in Drive or at low throttle when in reverse, RPMs would drop significantly and sometimes the engine would stall. I learned that one cause can be a faulty brake switch - my switch was OK and not the cause. I also had no codes and all sensors were working normally. I installed a Sonnax 34200-14K valve in the transmission (easy job) which eliminated the stalling problem and 20K miles later my 4L80E is still performing great.
So I got this scanner. No problems found on the diagnostic. I don't know how the fuel trims can help me. I'm not a certified mechanic, I just work on my own stuff. I'm gonna try to attach some screen shots of the live data Idle in drive Idle in drive Idle in park Idle in park
August 2nd, 2023, 1:21 PM
Engine stumbles at a stop
