93 Suburban K2500 questions

dogdays · May 11, 2005

Vehicle: 1993 Sub K2500 5.7 4L80E

1. My transmission sometimes will not shift into 3rd or OD. I am planning to change fluid/filter but have read the screens to the solenoids sometimes get plugged with debris, causing these problems. Before I yank the transmission and get it overhauled I would like to try to clean out these screens which are in the valve body. The FSM describes the operation with transmission upside down. Is there a decent chance of success in taking off the outer part of the valve body and setting the checkballs with Vaseline to keep them where they belong when I reassemble? Any gaskets to buy?

2. As soon as I turn the ignition on or off I get a clapping sound from the HVAC unit. It is the recirculate door which flaps back and forth for more than 15 seconds every time I turn ignition on or off. Where do I start looking for the problem?

3. On startup the injectors go wild and spray tons of fuel for about 20 seconds. I have replaced MAP, TPS, Temp sensor, O2 sensor, knock sensor, checked operation of the IAC, and looked in the FSM. Not all of these replacements were to try to fix this problem. In addition no codes are set during these episodes. I have to hold the throttle open to keep the engine running and the exhaust stinks like gas. After a length of time it will idle and run fine. I have followed the troubleshooting keys in the FSM and have no idea what's the problem. Left to my own devices I would look for a rebuilt ECM next. Do you have any suggestions?

Thanks,

Rich

Lakewood, CO

GM-Tech · May 11, 2005

1. I'll have to talk to our tranny tech tomorrow. I'm not a tranny guy even though I know enough to be dangerous. Still, don't see many 1993's around a dealership anymore, so I don't know what sorts of problems they used to have.

Dropping the valve body is not difficult... The spacer plate gaskets will probably be molecularly bonded to the spacer plate by now. That'll be real fun. If the plate comes down with the valve body, the check balls will be in the right place as long as you bring it straight down and don't jiggle it at all. We hold 'em in with "trans goo" but vaseline will work.

On the other hand, the solenoids can be removed without removing the valve body, so I'm not sure why you want to drop the valve body. I wouldn't unless absolutely necessary. As for crud in the solenoids... I doubt it.

2. I recall something like this problem. I just don't recall what caused it or what fixed it. When I go in tomorrow, I'll ask one of the other guys that's done AC for quite some time if he remembers.

3. Does sound like a possible PCM, but try removing any and all connections from the distributor and see if it still sprays with you turn the key on. Seems like something about the distributor comes to mind, but I could be thinking of something else.

#2 and #3 sound familiar, but jeez, a '93! I have a hard time remember last week these days.

dogdays · May 12, 2005

Thanks for any and all information. Yes, I know it's a 93 but that's what I can afford at the moment.

R.

dogdays · May 16, 2005

Just putting it near the top again. This weekend I replaced rear brake shoes. After 206,000 miles the original drums were barely worn, the original shoes were more than half-there. I hope the new shoes will aid in stoppiong the Sub.

But my other 3 questions remain.

R.