Problem with 1994 Chevy Lumina Van

Hi everyone,
While I'm driving down the road, the engine suddenly speeds up and then bogs down. Sometimes it quits running. When it speeds up, I notice the
speedometer increase about 10 mph, but don't notice the vehicle actually increase in speed. I have found some vacuum leaks, but the vacuum line going to the transmission doesn't leak.
Thanks in advance for any help with this problem,
Ken
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Only a guess but it sounds like the lockup torque converter.

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Check the engine grounds. Also have the battery checked. They can go bad and allow a lot of engine noise which drives the computers crazy. Make sure connections are clean and as I said all ground connections.

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I replaced the battery and went for a drive to test the lockup torque converter. I drove the van at 55 mph and depressed the brake just enough to turn on the brake lights and felt and heard the downshift (engine rpm went up a bit). When I let go of the brake I felt the up shift, but it was more subtle. It was hard to concentrate because of the road noise and wind noise. The engine did not bog down or mess up while I was doing this. Later last night I was driving in the city and had just made a turn and was accelerating and the engine bogged down and stalled. I had the transmission selector in "D" instead of the "D" with the circle around it. This problem is really intermittent.
Thanks,
Ken
see below

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The exercise you did at 55 mph demonstrates that the torque converter lock up is working - at highway speeds. You're right - it's a fairly subtle thing, but you should have been able to notice it on the tachometer (if your van has a tach).
As for why it bogged and stalled in town, it's anybody's guess. Could be a lot of things. The van really needs to be scanned as a starting point. Anything else is just guessing and that will get costly in a hurry.
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I got it scanned today and there were two codes. I don't remember the numbers but one was EST (Electronic Spark Control) which the mechanic is replacing my crankshaft sensor to repair. The other was Quad something which refers to a circuit board under the dash. The mechanic said the quad something controlled my transmission. He also said the crankshaft sensor is probably causing the quad board to mess up. I hope he is right.
Ken

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Great Ken. It's always good when there is a code to go by. Keep us posted how you ultimately make out.
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Does that mean I have to replace the torque converter?
Ken

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With the description of your problem that you posted Ken, nobody can tell you that. It does sound torque converter related, but I sure would not jump into replacing it at this point. Get the car scanned and see if there are any codes. Step through from that point forward.
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Picked the van up tonight and it is not fixed. $140 down the drain. Tomorrow I will remove the coil packs to test them and see if I can get into the ignition module underneath to test it. I knew I couldn't trust a mechanic to fix it.
This reminds me of the time my ex-wife had a problem with her car. It ran bad when it was raining or damp. She took it to the same place and each time they replaced something different. She ended up spending $340 on parts that were not bad. When she told me about it I took a squirt bottle on a nice day when the engine was running okay and started squirting different components. When I squirted her coil her car ran bad because there was a crack in it.
Ken

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I hope you're planning on a visit back to this mechanic to allow him to refund your money. $140 should never just go down the drain on repairs that don't repair.
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wrote:

Interesting point..... ( I've been burned there too )
The mechanic's done the work, installed the parts... and the problem's not fixed.
What do you owe the shop ? Do they owe you a refund ?
In the medical field, even if the patient dies the surgeon and the hospital still send a bill....
<rj>
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I don't owe the shop anything. I think he should definitely give me a refund if he can't fix it. He told me he would look at the books to see what else could cause the problems that I am having.
Ken

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You are a more tolerant man than me Ken. I would have insisted on a labor refund at the very least. I know that mechanics get away with this all of the time, but that does not make it right. I can see covering the cost of the part and he's got profit in that part, but he should have refunded the labor for this. I'm not faulting his diagnosis, but when the problem is clearly not repaired, it's not repaird.

I can troubleshoot to the component too Ken and it's frustrating today because there are not schematics and so many things today are inputs to a computer or triggered by one. Very complex and one would need logic flow charts to troubleshoot it.
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