I have a '94 3.8 Lumina APV.... at highway speeds (45 -75) it will sometimes, very intermitantly miss, or sort of surge. You'll be driving, and it will feel like a little water was in the gas... the hesitaions periods are very breif, say 1/2 second, but if they occur, say 3 in a row, it will be very noticable.
I know there is a PROM update for a torque converter "chuggle" issue where the computer activates the torque converter at 45mph rather than 55mph... I am having the PROM flashed soon, but I don't think that is the issue.
To note: I have replaced, plugs, plug wires, all 3 coil packs, fuel filter, air filter (what the hey..), drained the gas tank.

Thanks in advance, for any help with this devilish issue!

I had similar problem as posted elsewhere in the forum on my 95 APV with a 3.1, they only get worse, and did all things you mentioned as regular maintenance with no effect. I then changed the thermostat since temp fluctuated and the 02 sensor at the same time. Problem seems solved. I used a good thermostat and OE style Bosch o2. Cost $28 plus $10 for socket or borrow at Autozone for free.

Thanks for the input, I never thought about the o2 sensor.... everybody wants US $50 for them around here tho.... :(

If it fixes it I'll post a followup.

I am sorry about the price, I have a 3.1 which does not have a heated sensor. Yours having the 3.8 has a 50 dollar sensor as you have found.

I am sorry about the price, I have a 3.1 which does not have a heated sensor. Yours having the 3.8 has a 50 dollar sensor as you have found.

No prob, I'm glad you replied as I was wondering if there had been a price spike on o2 sensors recently! :0

At any rate, my mechanic is very skeptical the o2 sensor will fix it, but he is open minded and said "you know it could be the left front tire is 2 lbs low of air..." being sarcastic. He is a ASE master tech, and a good guy to boot.
What we are doing is upgrading the PROM Monday with an update to correct a torque converter "chuggle" and if that does not fix it, on goes the o2 sensor. (Crossed fingers...) and then we'll see where we are.

I will definitly update this thread with my progress for the benefit of others...
Peace!

Yes not the eprom but the torque converter and since that is at least a $500 job on a $2000 van we might just trade it.. couldn't sell it! I might fix it... not sure.

so you got the PROM flashed and it didn't fix the chuggle? I'm getting a chuggle shifting into and out of overdrive. Trans was rebuilt at 140,000 and I have 188,000 on it now.

so you got the PROM flashed and it didn't fix the chuggle? I'm getting a chuggle shifting into and out of overdrive. Trans was rebuilt at 140,000 and I have 188,000 on it now.

In the course of discovering this... I replaced everything ignition related, etc. All you have to do if you want proof.... drive your vehicle around in 2nd gear (not fast!! ;) ) and it will NEVER "miss"..... but put it on D or O/D and here we go again.

I've had a similar problem for about 2 yrs, that kept getting worse. I have a 1992 Lumina APV, 3.8L, 4T60E Auto Trans. 132K miles.

It would start up fine when cold. After it warmed up, it would die on the road. I found that if I waited at the side if the road, it would start again. I flashed the check engine light and found no trouble codes. I suspected spark or fuel, but always had it when I checked it at home. Also, when I got on the freeway in 3rd or 4th gear, the engine/trans would buck and hickup and randomly stall for a split second when the torque converter would lockup (TCC solenoid). I thought I may have more than 1 problem going on.

I removed the ignition module thinking that may be causing the stalling problem and had it tested several times at a local Autozone parts store. It passed every time. No progress on the stalling.

So I switched problems and focused on the bucking. Having read before that sometimes the TCC solenoid goes bad, I inquired at the AutoZone about a TCC for this car. The counter salesman said he did not sell this part and the only part he sold was a vehicle speed switch. He then said "sometimes the motor will stop if this sensor goes bad". I bought it, $45, and installed it. It goes in the tail shaft of the trans. I noticed, when I pulled the old one out, it had a build up of band/clutch debris on the face of the sensor pickup. I installed the new one anyway but the clutch debris accumulated on the pickup face could have been the whole problem with the VSS sensor.

Now the van does not buck and has not stalled for a couple weeks. I would have never guessed this one.

I've had a similar problem for about 2 yrs, that kept getting worse. I have a 1992 Lumina APV, 3.8L, 4T60E Auto Trans. 132K miles.

It would start up fine when cold. After it warmed up, it would die on the road. I found that if I waited at the side if the road, it would start again. I flashed the check engine light and found no trouble codes. I suspected spark or fuel, but always had it when I checked it at home. Also, when I got on the freeway in 3rd or 4th gear, the engine/trans would buck and hickup and randomly stall for a split second when the torque converter would lockup (TCC solenoid). I thought I may have more than 1 problem going on.

I removed the ignition module thinking that may be causing the stalling problem and had it tested several times at a local Autozone parts store. It passed every time. No progress on the stalling.

So I switched problems and focused on the bucking. Having read before that sometimes the TCC solenoid goes bad, I inquired at the AutoZone about a TCC for this car. The counter salesman said he did not sell this part and the only part he sold was a vehicle speed switch. He then said "sometimes the motor will stop if this sensor goes bad". I bought it, $45, and installed it. It goes in the tail shaft of the trans. I noticed, when I pulled the old one out, it had a build up of band/clutch debris on the face of the sensor pickup. I installed the new one anyway but the clutch debris accumulated on the pickup face could have been the whole problem with the VSS sensor.

Now the van does not buck and has not stalled for a couple weeks. I would have never guessed this one.

Thanks for your reply. My van fixed itself... it hasn't had this issue for 5 k miles now (knock on wood.) (knock, knock)
That TCC solenoid sounds like a very likely suspect.


This is a good thread, I will update if I find the answer or confirm yours....

i have had the same problem but i do not know where the tail shaft of the transmition is. please help me i really need my van back.

[QUOTE=patrich9999]i have had the same problem but i do not know where the tail shaft of the transmition is. please help me i really need my van back.[/QUOTE

As I recall, I laid down a piece of cardboard and slid underneath were the backside of the transaxle meets the firewall. I recall the steering rack up in this area also, running parallel with the axle shafts. Anyway the tailshaft is a nose piece looking thing at the end of the transaxle before it changes to a drive shaft. It typically has a speedometer cable running to it, as this is were the speedo gear is located. As I recall, the tailshaft that goes to the passenger side drive shaft/axle was the one with the VSS sensor in it. The sensor is not pointing down were you can get at it or see it easily (idiots). You'll see the wire harness going to it. It's up in the topside of the tail. It has a bolt and clamp device holding it in. You can only feel it. There isn't much room to manuever a ratchet either. I recall using a stubby box end wrench and taking lots of time turning the bolt out. Or you might use a ratchet with a flex handle. Once you slide the sensor out of the hole, taking care not to knock dirt in the hole, you could try cleaning it off first before you spend $45. I recall using an inspection mirror and flashlight to see inside the hole. I noticed some debris on the gear teeth, but did not clean it off. You could go a step further and wash the teeth with something but this step would be time consuming depending on what you have to spray thru a tube. Maybe shooting air on it might work, but in order to turn the gear the wheels would have to be up and out of park.

Be patient sliding the sensor back in. You can't see the hole and it takes time to line it up. Machined fit.

[QUOTE=patrich9999]i have had the same problem but i do not know where the tail shaft of the transmition is. please help me i really need my van back.[/QUOTE

As I recall, I laid down a piece of cardboard and slid underneath were the backside of the transaxle meets the firewall. I recall the steering rack up in this area also, running parallel with the axle shafts. Anyway the tailshaft is a nose piece looking thing at the end of the transaxle before it changes to a drive shaft. It typically has a speedometer cable running to it, as this is were the speedo gear is located. As I recall, the tailshaft that goes to the passenger side drive shaft/axle was the one with the VSS sensor in it. The sensor is not pointing down were you can get at it or see it easily (idiots). You'll see the wire harness going to it. It's up in the topside of the tail. It has a bolt and clamp device holding it in. You can only feel it. There isn't much room to manuever a ratchet either. I recall using a stubby box end wrench and taking lots of time turning the bolt out. Or you might use a ratchet with a flex handle. Once you slide the sensor out of the hole, taking care not to knock dirt in the hole, you could try cleaning it off first before you spend $45. I recall using an inspection mirror and flashlight to see inside the hole. I noticed some debris on the gear teeth, but did not clean it off. You could go a step further and wash the teeth with something but this step would be time consuming depending on what you have to spray thru a tube. Maybe shooting air on it might work, but in order to turn the gear the wheels would have to be up and out of park.

Be patient sliding the sensor back in. You can't see the hole and it takes time to line it up. Machined fit.

I am trying the same thing on a '94 APV w/140k & the random bucking, plus the dying.. typically at a red light. Will update with more info Tuesday

I had A freind of mine who owns an auto repair shop scan my car and the last thing that came up was the throttle positioning senson. It was not as hard to get to as the other sensors. It is behind the thermostat housing. You can not get to it when the van is hot though. Any way it cost 49.99 at Pep boys (auto zone did not have it). But in the end I am happy to have my van back!!!!!

I had A freind of mine who owns an auto repair shop scan my car and the last thing that came up was the throttle positioning senson. It was not as hard to get to as the other sensors. It is behind the thermostat housing. You can not get to it when the van is hot though. Any way it cost 49.99 at Pep boys (auto zone did not have it). But in the end I am happy to have my van back!!!!!

ATTENTION ALL:
The following did not fix the bucking so well descrobed here:
1. Throttle Pos Senor
2. TCC Solenoid
3. Coil Packs
4. Wire, et al
5. Vehicle Speed Sensor

We traded the bitch for a Toyota and we ain't looking back. Personally I think it was a grounding issue that finding could take 10's of hours.
Sell it.

I had the same problems and did all of the items listed. But that wasn't it. First, most/all scans won,t detect a code unless the sevice engine light is on. Second, check the breake booster vacuum to see if its working correctly, parts with no wires attached can't be scanned, with the vehicle started and in neutral press the break peddal, if the engine idles down more than a hair this could be your problem. To test remove the booster hose from the pcv valuve and place your hand across it (the pcv valuve), this requires 2 people, repeat the previous test if the engine idle stays constant this very well could be the problem *This was my problem*. Third but not final, check the the transmission modular valuve($15 GM universal easy change), be sure to get the pin head out, and no dirt in. Finally, and although last most important *make sure that all the hoses are solidly attached and that none are cracked*
By the way she has 217,000 miles on her and is running like a dreamship.