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It sounds like you have your hands full so let’s look at your surging RPM. Normally, RPM surges can be caused by several things. Its possible that the torque converter has one or more broken vanes in its impeller. This would cause a weird loading pattern for your transmission fluid and could result in surging. Another possibility is that the clutches are slipping in a major way, causing the engine to overrev as the transmission hunts for the right gear. And, it is always possible that the input shaft is damaged and slightly out of round so the input it is delivering to the transmission is oddly loaded, causing the surging.

As you can see, there’s a whole range of problems that might be possible and which exhibit surging and overreving.

Here’s what you absolutely have to do to find the cause: get to a good transmission shop — or even the dealer — and have the facility put an OBD-II scanner on the diagnostic connector under the dash. Watch the readout and get a hard-copy of the results. I think the chances are good that you will see error codes for a failing transmission control module or the module and sensors. It is also possible that the solenoids are shot and contributing to the problem.

Honestly, I think you are facing the need for a transmission replacement. That will cost you about $3,300 — more or less, depending on the location. There are so many potential problems in your transmission that it’s the only way to handle things, even with the diagnostic printout.

As to the other problems, it sounds like you have some metal-on-metal issues in the engine itself. If that is the case, then, you could be facing some really expensive problems as it will cost you thousands to replace the engine.

Frankly, maybe it is time to consider a new conveyance. After all, your car is 13 years old and it is likely paid to the ground. I’d take whatever equity I could get for it and buy a relatively recent used model. The reason I suggest used is that the former owner has already rung the engine and transmission out so you will likely gain some years of pain-free driving. And, yes, your bills will go up monthly, unless you pay in cash. However, with leases today averaging much less than $200 it only makes sense to get some more modern wheels. Let me know your decision.

There are lots of things to check but your first move should be to a shop with a good OBD-II diagnostic scanner with the right software for your Nissan. Have the shop run a complete scan of the transmission and get a printout of the results. I am willing to bet you a dozen donuts — any variety — that you will likely find the problem is in the control module.

Since the problem occurs after you shutdown and restart, it sounds like the control module or TCM does a hard reset to the transmissions electronics so that it works correctly for a time. As the time goes on, though, your TCM begins its failure routine all over again and you end up with the situation you are in.

I’d try having the shop replace the TCM, for starters. It is a lot less expensive than replacing the transmission with a rebuilt (maybe $2,500 less expensive as a new TCM will cost about $700 and change to replace). Once it’s replaced, I think you will find your Nissan’s problems clear up. If not, it may be that one or two of the sensor arrays relating to the tranny have also been knocked out by the bad TCM and have to be replaced. Again, it’s a relatively straightforward fix, although it will cost about $400 per sensor. Still it is lots less expensive than a rebuilt.

The TCM, by the way, is also known as the computer that controls your car’s transmission.

Please let me know what happens.

When you had the big oops, I believe that you damaged the gear train that allows you to set the gears. If the gear train is damaged — bent or knocked out of line — then you will likely lose at least one gear or maybe more. In your Neon’s case, it is a bit more serious because you cannot get the vehicle to go into Park. The result being that the engine and transmission will remain engaged and the potential for a crash and injuries increases.

With that said, I think it is time to turn to the professionals for help. From my vantage point on the other side of your screen, I cannot tell whether the train is damaged beyond use or whether a little judicious tinkering with a hammer on the gear train will put things back in order.

Like as not, you are looking at about a $1,200 investment added on to the work you have already done. I wish I could have had better news for you.

First, your problem isn’t in the transmission at all, it’s likely in the half-shafts. Let me ask you a question: when they pulled the CVs, did they replace all of the bearings? Sometimes, it is easy for a technician to miss the inner bearings because they are rather hard to get to. Indeed, some techs make the assumption that since the outside devices carry most of the load and since they tend to load up the most heavily in any turns that they are the ones that should be replaced.

The result is that you can get uneven wear and a vibration or wobble can set up and happen.

Even more troubling, though, is the fact that the half-shafts may not have been replaced correctly so that there’s a mismatch occurring that could be causing some rather significant damage to your car’s front end.

Here’s my recommendation: get your car back to the shop where the work was completed (or rather incompleted, in this case) and have them take the front CVs apart again, making sure they replace all of the components, not just some of them. Have them go over the service manual to make sure they follow each step of the factory-outlined procedures. Because of the complexities involved, many times techs will either skip a step or two, assuming that parts on the inside are still good or not completely replace all components outlined in the service manual.

Be sure that they do and that they recheck the work. And, oh yes, make sure that the comp this work because it should be warrantied because they have already completed job one time and you have already paid for something they obviously haven’t completed correctly.

I hope this helps. Let me know what happens and what the shop says. I’d be interested to hear.

I notice you said there were “codes” generated by the problem. Can you give me a list of those codes?

There are many reasons a car can go into limp-home mode. As your scanner told you, one or more of the solenoids could be bad — did you replace both solenoids; there’s one on outside of the valve body and one on the inside. Usually, the solenoid on the interior of the valve body handles gears 1 and 3, for instance, while the one on the outside handles gears 2 and 4. I won’t say that it is a universal template for the industry, but, by and large that is the way things happen.

With that said, it is quite likely that the other solenoid, the one that apparently wasn’t replaced, may have been the one that failed so the Solara will remain in limp-home mode until the device is replaced.

The solenoids aren’t the only reasons for a vehicle to go into and remain in limp-home. Indeed, it is possible that one or more gears has or is failing. That is a condition that would generate a limp-home command from the engine control module (computer). Another condition that could generate a limp-home command is a failing clutch pack or packs, or a failing band or bands.

In addition, the problem could be one of the many sensor packs or control modules that work with or in your Solara’s engine bay. Among the sensors that could be failing are the throttle positioning sensor, the mass air flow sensor, the mass air pressure sensor, a temperature sensor and others. There are at least a dozen sensors that work with either the engine control module or the transmission control module (it could even by the TCM) and there may be as many as 8 or more control modules and which may be at fault.

For my money, I would have the other solenoid replaced asap as I think you will find that once the second one is changed out that the code will go away.

Please let me know the outcome.

It sounds as if one of the major components of your Buick’s drivetrain has blown. Let’s rule out the parts that don’t fit you car’s problem. If the universal had failed, it would still try to go into gear as you shifted because the transmission would have been working. It would not have moved, though, because there was no power getting to the wheels. The power was being derailed at the universal joint.The important thing to look for here is the fact that the car would still go into gear and try to move, but would not.

Moving to another component, if either of the half-shafts on the front-drive LeSabre had failed then you would have had at least one of the front wheels trying to move at some point. It would have been pointless because ultimately the broken half-shaft would have compromised the other side and the universal joint.

Still, if the LeSabre is trying to go into gear and one of the front wheels moves, you can rule out the tranny and universal as the problem and have the technician focus on repairing the half-shafts.

Since, there was a loud bang and the Buick stopped moving and still refuses to move, though the engine is turning over, then, it is more than likely a problem with the transmission. Indeed, I would be surprised if the problem was not right at the start of the power transfer chain in the transmission, either the input shaft or the torque converter. Each could fail separately, though the torque converter is the item that would go bang before it stopped functioning. The reason for the noisy failure is that the converter is an energy transmission device as it starts the transmission fluid on its way through the engine. If it fails and there is a build up of inertial energy on the converter vanes, then it is likely it would go bang and then stop.

Since I suspect that the culprit in your problem is the torque converter, I think you can stop your hunt there. It will mean that you will have to drop in a rebuilt transmission into your car’s case because it is just not economic to try to repair the converter. You don’t know the downstream damage its failure might have caused so repairing the individual systems costs just too much. Indeed, if you fix the converter and then find the gearing is gone, you will have to replace the planetary gearing and other packages relating to it. Almost immediately, this puts the cost of your repairs into the astronomic zone.

Yes, $3,200 is a lot to pay to replace the transmission with a rebuilt unit, but it isn’t when you realize that replacing individual systems within the transmission case can quickly raise toe cost to, at a minimum double the cost I mentioned.

I hope I’ve helped a bit. Please let me know what else I can do for you and do tell me the results. I am always excited to hear from readers.

You did a great job of preseving the mechanicals in your 300, no doubt of it. The only problem was that the transmission fell through the cracks. Most people assume, when they are laying their vehicles up for a time, that when you add the stablizers and other items, pull off the wheels and stack them flat and remove the battery that they have done all that is needed.

That’s not the case as you have found. Over time, it is possible for your transmission fluid to go bad, if the vehicle hasn’t been driven — which yours hadn’t been. You see, the transmission fluid is an organic that can develop all kinds of issues, especially if you left your 300 in a warm, humid area. Not only are laqs and gums built up, but things like seals can become porous, allowing the transmission fluid to leak out. When that happens, especially if your car is not moved, the fluid continues to leak every time your car is turned over.

At some point, your transmission is going to be nearly dry and that’s when damage occurs. You took the right precautions with your vehicle, except for a big one, it should have been driven, at least weekly, and brought up to operating temperature and then run for some miles. This would have kept the seals in good shape. It would have also kept the filter working properly as well.

Instead, however, you let the car sit and rev which is not good because it not only builds up all kinds of nasty stuff that has no place to go but back into the engine oil and transmission fluid, but, the various systems never have a chance to keep turning correctly.

I concur with the technician, you’ll need a rebuilt (it will cost too much to replace individual units).

Wow, that is a bummer and here’s my thinking: there are several key hoses and lines that either come off the transmission itself or are internal to it that act as not only cooling lines but also as return lines for the device itself.

I would be willing to wager a Box of Coffee (if you know Dunkin’s you will know what I mean) that if you look at your transmission’s housing and the input and output shafts that you will find some sort of rather large wet patch where either a clamp failed or where one was forgotten on the rebuild.

Unfortunately, it can happen, especially if it is at the end of the day when a tech may be tired. I know that’s of little solace to you, but, now they have to make things right for you. I will grant that you are likely to have kind feelings toward the shop, but, give them a chance to make things right.

There’s a bit but that comes with the chance to make things right. It is just this, since they have caused this (it could be a bunch of check valves in the valve body itself that may not have been reset correctly as well as the lines or instead of the lines or it may be that somehow something was reinstalled incorrectly and inhibited tthe flow across the valve body) they should offer you at least a rebuilt transmission for your troubles.

Yes, it is a huge investment for them to make, but, think of this, you have already spent the better part of $2,250 to repair the valve body and related parts so it is of little moment, really, that the extra $900 or so that the rebuilt transmission costs should be rejected by the shop. It’s just good business. If they refuse that deal, let me know what they offer and let’s see what we can do — I’ll be happy to help as I can.

If it was an issue with the fuel line and sender unit, I suspect your Montero would be doing other strange things like bucking at times, seeming to lack power, say on hills, or when you are trying to pass another vehicle on the highway.

That you are burning extra gasoline does tell me something and it also leads me to a question. First, it tells me that your SUV is likely over-revving and using lots of gas because you are running in gears that are well over a 1:1 gear ratio. In other words, your engine is running too fast for the speed you are traveling. For example, if you look at the RPMs when your SUV is in first, the chances are good that you are running well above 4,000 rpm — likely higher — to maintain a speed. And, just maintaining that speed is likely straining things pretty well.

With that said, it leads me to this question: does your Montero seem to be straining with every shift? In other words, is it overrevving all the time? If it is, then I am sure I have your answer. Could you let me know, when you have a moment?

Wow, it is possible that the gearing is bad, but, there’s a whole list of things that can cause the sound you are hearing. Let’s see, there’s the torque converter, possibly a slipping input shaft, maybe slipping bands and clutches and possibly the output shaft. And, that’s just for starters! It could also be an ailing valve body or simply a very low transmission fluid condition.

My first inclination is to have you take your car to a shop and have them look at the transmission fluid. I suspect the tranny fluid is quite low. In fact, if it is down by as little as a pint or two then your transmission can make the sounds you are hearing and give you the performance, too.

If that isn’t the case, then I would look at the torque converter and other parts of the input chain, including the impeller. That sets up the flow of transmission fluid through the case. If there isn’t enough transmission fluid in the housing, then you can get an overpressure situation where the transmission is trying to build up pressure to normal levels but it is failing. Your torque converter and immpeller are telltales that you have low transmission fluid.

Let me know if this helps. I don’t suspect it is anything major because transmissions usually fail over time and exhibit other things that tell you there are problems.

If the transmission fluid works out, by the way, we’ll have to find out where the problem is. It may be something as small as a check valve that is stuck closed and not allowing the transmission fluid to flow.

It sounds as if your reverse gearing may be slipping, though, it is slipping under lots of stress. Reverse is normally a high-stress business as the tranny drops down, uses a pretty much direct 1:1 linkage so that when it pulls, it pulls at your engine’s full capacity. So, when you put the truck into gear on a hill not only are you asking the transmission to pull strongly and directly to the rear, but you are also adding the inertia caused by the incline. The transmission has to overcome that inertia first before it even begins pulling.

With that said, if your transmission’s reverse is beginning to wear out, the it will shift in sharply and try to slip out but it will not succeed. Therefore, you have juddering. The problem may lie in the gearing itself, though, I do not think that is the primary issue.

I think your transmission’s primary issue is in either the clutches or the bands and clutches. As I just said, when your transmission goes into reverse, it is pretty much a 1:1 lockup between the rear wheels and the engine. In order to handle this, you are asking the clutches to handle a full torque load when they may not be willing to do so. If they are worn, then the clutches will allow the slippage. This situation is compounded by the bands contributing to the problem.

What this means is that you will have to have the bands and clutches replaced. In order to do this, your transmission will have to be stripped down to just about the last nut and bolt. So, here’s what I would suggest you do, ask your transmission shop to find a replacement transmission. You may be lucky and they may be able to find a transmission replacement from a partially junked vehicle. The body and/or the engine may be shot, but the transmission may be in good shape and may last for many miles.

Indeed, this is the less expensive option of the three available to you as it is likely you will only have to pay the cartage from the scrapyard, a small fee for the transmission and the fee for having it pulled out. The other options, a rebuilt transmission and replacing the bands/clutches/gears, are far more expensive. I honestly don’t know what the pricing may be in the U.K., where you are obviously writing from, but I suspect it may be similar to the pricing in the states so that the more expensive options are still more expensive.

Whatever the expense, though, your transmission needs work. I would have it done as soon as possible.

Please let me know what your shop finds as I honestly like to know what happens.