86 camaro iroc z Drops Into Neutral Instead of 4th

Let’s see, it’s possible, if there’s too much transmission fluid in the case, that there could be an overpressure situation going on in the transmission. When that happens — not many people look for it as it is easier to look elsewhere — it can cause all kinds of problems, including what you describe. Believe it or not, transmission fluid, because of its composition, acts not only as a fluid, but also as a solid, if conditions are right. At that time, anything in the general area of the “solid” will not work correctly as it is starved for fluid.

My suggestion here would be to look at the transmission fluid level quickly — with your engine properly warmed — to make sure your transmission is not seriously overfilled. In this situation, it can cause as much damage as an underfilled transmission.

Remember, though, this is only one suggestion. Here are some others:

The fourth gear solenoid could be acting up and not firing correctly. There are usually two solenoids in the valve body that control the gearing choice. Their firing sequence controls the actual gear. If one of the solenoids fails to fire in proper sequence, then you will have lost a gear. This is one of the easier fixes in a transmission as the part usually costs about $150 and labor another $140 to diagnose and replace the solenoid.

The clutch for fourth gear may have burned up. If it has then your transmission will react as you describe it. If this happens, by the way, the band is usually shot, as well. This is a major repair as the transmission has to be pulled apart to access the particular band and clutch. Any way you look at it you are likely going to spend the better part of $2,000 to fix this problem.

It is possible that your transmission could be failing in a major way and this is just the first sign. In many ways, the problem you are describing is “limp-home” mode or a form of it. In this mode, a transmission that is experiencing trouble will lose a gear or more, leaving only a forward gear or two and, possibly, reverse, so that you can either get home and have your car towed in from there or so that you can get to a service area. If this is the case, you are likely looking at the replacement of the transmission with a rebuilt that will cost you about $2,400.

It is possible that the culprit, though, could just a sensor such as the MAF (mass airflow) or the TPI (throttle position indicator). To find out if it is just a sensor, have your technician plug in a diagnostic tester and run a check of the engine control module (ECM) to see if there are any transmission codes. If there are, you can have the tech begin the hunt for the problem there.

I hope this helps you out. Let me know what you find as I always interested to hear what happens.