no acceleration in overdrive

[gwisdalla640]

I have a "87 suburban that has me puzzled! Once the transmission (770r4) shifts into overdrive I lose my acceleration. What ever the rpm is when it shifts into overdrive it drops with the shift. Now wherever i move the pedal nothing changes except if I floor it it kicks down and accelerates. No trouble codes have come. TPS is fuctioning properly according to scanner. PLEASE HELP. I don't have any more hair to pull out!!!!!!!!!

[hrcslam]

Check your fuel filter. Sounds like your engine is starved of fuel. It should be located on the frame between the gas tank and engine. But I could be wrong about the location. If your filter is cloged it will still run but you'll loose alot of power.

[2000CAYukon]

Have you check the TV Cable adjustment? If you tap the brake pedal before you hit the gas, does that help?

See this for instructions on adjusting the TV Cable http://www.tciauto.com/Products/Inst...ble_adjust.htm

//2000CAYukon

[gwisdalla640]

It doesnt help. All my shift points are good. Just changed fuel filter did not help either. My fuel pressure is reading good. Is is possible that the pump just fails in fourth gear under the heavier load!!

[hrcslam]

Well it sounds like your drivetrain is working correctly. You have a problem with your engine, it isn't producing enough power. If all your filters are good(fuel, air, engine,ect) then I'd check the timing. Check your spark plugs. If you can remove them clean all the stuff off of them so they are kinda shinny and regap them (I think it should be at 0.060" but I could be wrong) you can find the spark plug gap on the sticker under the hood that has the fan belt route on it, then see if it fixes your problem. If that doesn't work the check the timing. Your distributor could be loose. If it is loose you should be able to turn it by hand, with the engine off just grab the distrubutor cap and turn it. If it turns by hand the get the timing reset back to stock and see if this fixes it. If it doesn't work or your distributor isn't loose then check the contacts inside of your distributor. It is held on by ( I think) 4 quick-release screws. Pull it of (you shouldn't have to disconnect any wires) and look inside, if it's dirty or corroded clean it of and see if this fixes your problem (personaly I'd replace the distributor if it were corroded). If all is good with your ingnition & timing system then you need to check your compression ratio. You'll need a pressure guage for this. Before you do this though I recommend checking your oil to see if it looks like chocolate milk and the radiator fluid for oil (just pull of your radiator cap and if there is any oil in the radiator system you'll see it, oil floats on water). If your oil is good and your radiator fluid is good then check the compression ratio. If your compression ratio is low ( your compression ratio should be no lower the 8.5:1) then you probably need an engine rebuild. I'd go to the local auto parts store and see if they recommend anything for a quick fix (something to hold you over til you can get the rebuild done) if your tight on cash, like me. These are all possible problems, I could be completly off. Good luck.

[gwisdalla640]

Thanks to all who responded to my question!!! I finally figured it out it was a problem in the cruise control system. I disconnected the cruise control system at the brake switch and the control modular and the problem went away. Thank goodness. I figured it out because if I put pressure on the brake pedal my accerator came back! How crazy is that!!!! I hope if anyone else has this problem this fix can help you out as well!!!! Thanks again to all who responed!!!!!!!