I have a 4L60E in my Silverado that might be having problems. Sometimes from take off it feels like I have all power to the rear wheels until I stop again and sometimes it resumes, Othertimes it feels like a dog on take off like in a higher gear than 1st. I've had it in at the dealer and they said I have no problems to diagnose but they did notice a slight power loss. They wanted me to have the trans flushed and my intake manifold and all 8 injectors cleaned for the tune of over $400. I've tried all the engine cleaning/performance chemicals that I know work and no difference. Cleaned the MAF with a special spray specificly for it and nothing although it was dirty. This power loss is random and hard to manually replicate on demand. Although, If I drive it, floor it, let off and get back on it even if it is a dog on take off, I have power. Local trans shops want around $100 for a simple computer diagnostic on it. Lot of money to be told nothing.

What do ya'll think?

NOTE: When I have power, Throttle and sometimes the brake pedal is firmer, When I have power loss, Pedals are softer.

 

Get Autozone to pull your codes. For that money, buy the scanner yourself and charge your friends $10 to do it for them. Electronic controls are a bear to diagnose without talking with them (the controls) first.

Don't know how many miles you have on it. 4L60E's are electronically controlled TH700R4's, and the 700's weren't known for going much further than 100K or so before needing a rebuild.

50/50 chance that you'll finish out the "toast" job if you flush the transmission.

Rebuild kits should be fairly cheap since they made so many of them.

-blaine

 

Already had it at the dealer and had multiple parts houses attempt to pull codes. All came back with none. There is no way I could re-build this tranny myself.

 

Rebuilding my TH700 cost me $1200 out the door.

You might have better luck perusing recycle yards...

-blaine

 

The 4L60E is NOT a 700R4 with electronic controls any more than an E4OD is a C-6 with an extra gear and electronics. They both were, for better or worse, new designs. Were do these myths start? Maybe because the 4L60 (without the E) may have been a renamed 700R4, which may have been based on the TH-350, itself based on the aluminum Powerglide.

If you believe it is starting in 2nd, have an independent trans shop, not the dealer or AAMCO, look at it. It may be a just a sticking solenoid in the valve body or corroded contact. My E4OD suffered, among other problems, bad solenoids and corroded connections next to the trans. No stored codes were found. The mechanic had to drive around with a special laptop connected to capture the problem. You can watch the tach and count the shifts to determine if it is really starting in 2nd.

I suspect from what you say about the pedals, that the problem is the engine and not the trans. Is it a cable, or "throttle by wire" system? GM diesels had it in the 90's, dont know about the gas ones.

Jim

 

GM has a lot of problems with the electronics in their transmissions. I have a 4T65E here right now that runs great for about ten minutes, then starts slamming in every gear. It was really puzzling me because it had no debris in the pan, and did not stall at idle like a locked up TCC would. It turns out the Pressure Control Solenoid sticks when it's warm, maxing out the line pressure.
Your issue might be a vacuum leak.

 

Its cable controled throttle. I plan on getting it to cottman soon for them to check it out. They have a free 21 point inspection so it can't hurt. But they're way out in the woodlands about an hour from me. 4L60E had 4 gears correct?

 

Yes, its a four speed with lockup torque converter, so the lockup will move the tach needle a small amount itself. Gear changes are more noticeable.

If you put the selector in '2' it will start in second rather than first. That should help you compare the feel from a dead stop.

Jared,

The E4OD did the same thing to me, but randomly. Shifts were so hard I first thought I was rear-ended.

Jim

 

I will try the gear selector. It shifts fine but does still act random. I can't feel when the TC locks up. It may start in first but a bad TC. I don't know. Still doing trial and error. It's been pouring down here in Houston. Not a good time to drive long distances.

 

It's not the torque converter. When the converter locks up you can't feel it but can may notice the tach move a little when hitting highway speeds. Sounds to me like your starting in second some of the times. Cheapest thing you can do yourself is drop the pan and replace the filter and 5 quarts of ATF. It's run you about $35 and an hour and a half of your time. Careful not to strip out those pan bolts. If it's a high mileage vehicle (100K+) DO NOT have the trans flushed. I hear more bad stories about that than good. My Silverado has the 4L60E, 178,000 miles and had the trans rebuilt once. Around here a rebuild will cost you about $800. About the pedals.... the gas pedal is cable operated so it should not ever get soft and hard. The brake pedal runs off of intake vaccum so check out the thick hose that goes from the brake booster to the intake see if its cracked or worn through, if it's leaking that could also cause a power loss but should also set a trouble code for O2 sensors lean.

 

When I get some money together after this divorce I'll try to replace the filter and fluid. This truck has almost 154,XXX miles so a flush would be really bad. I did check the vaccum booster line and there is no crack in it. To my knoledge this trans has never had a flush or filter replacement.