Hey guys just signed up to the forum today because i have a problem with my chevy blazer and figured someone on here can help me. I just bought the suv about a week ago. It's a 1999 4dr 2wd LT with an auto transmission and 133k miles. SO far i have been doing some preventave maintenece on the truck so things won't go wrong. I have done some simple things like checking tire pressure, the fluid levels, changing oil and filters, air filters. ect... The only problem that seemed to be big was a rattly catalytic converter. I stomped on it the other day and the truck responded great, with very impressive acceleration. No problems then. I then checked the transmission fluid the other day and even though the level was ok, the fluid looked horrible, almost like used motor oil and by rubbing my thumb and forefinger against the stick very minute metal shavings from the tranny were visible on my fingers. I dropped the tranmission pan and it was the most filty pan i have ever witnessed. I took of the magnet in the pan and there was at least a half inch or more sludge from the gears on the magnet. I put in a new filter, gave the pan a very methodical cleaning along with a new gasket, and put new fluid in the tranny which the guy said at autozone was dextron3 which is what they recomend in the manual. Ever since the truck feels as if it is surging/slipping out of 1st gear. On the way home from work the truck is kind of jumping in place in overdrive at about 55-60ish mph. I put some stop shake stuff in the transmission with no help from it. I recently noticed the slipping/ hesitant acceleration problem seems to be more pronounced but not progressivley worse. It starts at about 10mph and the trucks rpms go up slightly from 1200 to maybe 1500 and then hover at about 1500. the truck then seems to catch up after a second or two and shift into second. It then is fine up until overdrive where it shakes slightly. I'm not sure what is causing this because the tranny changes so smooth you can't even feel it. Maybe the catalytic converter could by stopped up but in second and third the acceleration is still great even at full throttle. Any suggestions?

 

Mine does the same. It seems to be something to do with the secondary air (obd 2 code po410). Above and below 42-55 mph it runs smooth. In the 42-55 mph range it "lunges." Started this after I had the tranny rebuilt. Although, this may or may not help in your case.

 

thank you for your help, i wish a check engine light would come on so i could diagnose it but oh well. I intended to use it for towing my bass boat at speeds of 35-40 so the overdrive problem dose'nt bother me that much but the problems in first gear make me so frustrated i want to cry. I'm probably gonna drive it to the transmission shop tommomrow to see if they can give me some ideas.

 

I have heard of people having the fluid changed (professionally mind you) and cleaned good and it fixin their minor slips, but if you have a good bit of metal shavings in the pan then more than likely the gears are ground down a little.

 

Yeah i figured that by changing the filter, fluid and giving it a good cleansing i could prevent these problems from happening, but i talked to a guy today and he told me that i could've gotten it to clean and that the gears could've only been griping good because of the dust that was priorly in the pan. I just wanted to save some money but would've probably been better off with just a flush and 5 qts of fluid. Then again the gears could be good and the slipping feeling could have been caused by something else that just happened to go bad when i changed the fluid. I know when i shifted into reverse to back out of the drive way it felt as if it shifted fine but slipped under a little throttle. Idk. I hope you get your blazer fixed btw.

 

I'm going to go out on a limb and guess that the pump is worn from the metal filings. So you're getting a loss in pressure which could be causing it to slip. You're well on your way to a rebuild IMO. If you take it to a shop they may/may not run a line-pressure test on it. That would give the definate answer though as far as the pump. Besides that all I can say is good luck.

 

thank you. I'm starting to think more and more that somethings gone bad with my o2 sensor though. At the start of overdrive 42-55 i get exactly what 6lbsledge is getting. Out of the hole at full throttle the car feels less as it is slipping but more of a bucking feeling, same at overdrive. in second at full throttle the car seems normal but the tachometer dose'nt rev up as the engine is reving. Idk these modern cars are confusing..

 

I concur with TFZBird. Metal filings in the transmission pan came from the clutches, bands, drums, & steels in the transmission. These metal filings can actually aid in creating friction between the clutch & steel or band & drum. Put in new fluid and the clutches/bands can now slip or slip/grab as in your case.

A problem with a sensor shouldn't be gear dependent, rather it should be RPM, engine load, throttle angle (etc) dependent.

 

i was just thinking that because it feels rather like it is bucking than slipping and my tach is not shooting up smoothly with the engine. Could it be a torque converter?

 

The torque converter is unlocked in 1st gear. The torque converter will lock up while cruising along in OD at ~45mph, but that wouldn't occur that that speed under WOT.

Is it more RPM based than gear based? Everything you have stated so far leads us to believe that it is based on the gear the transmission is in.