performance issue

[Jethro]

I have the TB at the stealers and have been trying to get my issue resolved. I have no error codes and my problem is when i am pulling the boat there are times when the tb will slow to 55 and if I try to accelerate, the motor revsbut no go. I also find it doing this when I trying to merge into interstate accelerating from (50 to 70mph) traffic not towing anything. They suspect maybe a catylitic (sp) might be clogged. I have 120k miles with half of them as a tow vehicle. Would this sound right? They will sleep on it tonight and try diagnosing tomorrow. Ant insight might help me help them in what chebby can do to fix this.
fuel filter has been replaced along with tranny fluid and filter

[maxwedge]

If the engine revs and the car is no go then the trans is in too low a gear or is slipping no? The cat or any performance issue would stop the engine from revving, no?

[Jethro]

i dont know. I guess I'll get an answer today I hope.

[jdmccright]

How heavy a boat? Do you know the equipment setup for your TB? Tow package? 2wd/4wd? Axle gear ratio? Model year? Engine size?

All these affect how much you can tow. If you have the 4.2L I-6 engine with a single cat, it might affect high-rpm power at highway speeds as you describe. BUT look carefully at your tachometer when you try to accelerate.

At highway speeds, your transmission should be in OD and in full lock-up mode where there is no engine to transmission slippage at the torque converter (TC...Google this to learn how this marvel works). When you apply throttle to accelerate (but not hammer down), the TC will unlock and the engine RPM will increase some without increasing speed. Then, it should feel like it is going faster and the tach and speedo should more or less climb in tandem.

If the RPMs change alot or fluctuate as speed increases, then you may have problems inside the tranny. Either a slip band is worn, or a servo piston or valve inside the valve body is leaking. If it were a malfunctioning valve solenoid it would illuminate the CEL, but a sticky one might not. If the tach and speedo stay the same and you're simply not accelerating then I might suspect the cat or something else preventing good flow. Live in a rural area? I've found acorns in my truck's intake snorkel where squirrels stored them!

This 4L60/65 tranny is common for having weak servo piston. If tranny work needs to be done, ask them to install the "Corvette" servo which is much stronger and seals better. There are other mods that can be done to harden your tranny for trailering, but get a diagnosis first. Hopefully, they won't have to drop the tranny to fix it.

Please let us know what they find...good luck!

[Jethro]

I was pulling a 5800 to 6200# boat/trailer I forgot my gear ratio but was told it was rated to tow 6200# but I would get the sway at 60 and ended up getting the dully in my signature. I tow a 1600# boat now with the tb. It is the I-6 4.2 4x4 and I it actually has 131k miles on it.
Diagnosis from chebby is......
#402 1.2 test fuel pressure 55psi check fuel filter. ok scan
system foor code none in system. check exaust system back pressure 3 lbs. at 2500 rpm act. converter partially restricted. may or may not help but needs repaired to see if drivability concern is fixed

$800 for converter and was warned some aftermarkets can set off codes and damage parts.
any suggestions before I pull the trigger

[jdmccright]

Aftermarket cats are federally required to meet the same OEM emissions requirements, but you are better off buying one from a reputable manufacturer in the event of warranty issues (this is especially true in California). Here is the EPA bulletin link:

http://www.epa.gov/otaq/cert/factshts/catcvrts.pdf

The dealer will say this because, of course, they want to sell you their expensive part and service. The only part that could be damaged by a bad cat is the downstream O2 sensor. Will an aftermarket cat last as long? Unknown, but again the more reputable mfrs will offer a better warranty and follow-up assistance.

Good luck!

[Jethro]

Thanx for your help I will do some looking and till then drive like granny lol

[Jethro]

It was definately the problem. Now it runs like I thought it should