3.1grandprix Posted June 12, 2007 Report Share Posted June 12, 2007 Hi im new to this site and fairly new to gm w bodies i love my 1990 grand prix LE it isnt much but but i love the way they drive i have 304,000 Kms on it and ive owned it for about a year but it seems to have a problem, sometimes when im in low RPMs of second gear i will step on the gas and the engine will rev about 200 RPM and then get back into gear and also when im driving at about 90 KM/h and have my foot on the gas just enough to stay at that speed my car jerks and there is no spike or drop in RPMs i would really like to know what this is ive been tolled it may be a lock-up solenoid but i want some w-body die hards to give me some insight oh and it has a 3.1 L, 4 speed automatic or maybe its a 3 speed with overdrive i think its that anyway please help thanks a lot Quote Link to comment Share on other sites More sharing options...
1990lumina Posted June 12, 2007 Report Share Posted June 12, 2007 Not sure about the lower second gear problem. But the jerk when in overdrive is probably the torque converter. My Lumina does it as well. You could try and unplug the torque converter solenoid from the transmission (TC will not lock then, and see if you still have problems)..the plug is below the air cleaner box (you will have to remove it to see the plug if I recall). It's on the top of the transmission. How is your fluid level and fluid color? Doesn't hurt to check that out before you go ahead and unplug the TCC soleniod. Quote Link to comment Share on other sites More sharing options...
3.1grandprix Posted June 12, 2007 Author Report Share Posted June 12, 2007 ok i was goin to try that and my fluid is fine both in color and yes a little above the full line ill try unplugging the solenoid and see what happens Quote Link to comment Share on other sites More sharing options...
ns87 Posted June 12, 2007 Report Share Posted June 12, 2007 The drop out of second gear thing is somewhat common for our transmission (mine has done it for 3 years and counting) Try adding a bit more fluid than "level". That helped me out. The second problem sounds almost engine related to me. Check your plugs and wires. Every time I thought I had a transmission problem, it turned out to be more engine related like injectors, plugs, wires, coil pack! Good luck Quote Link to comment Share on other sites More sharing options...
3.1grandprix Posted June 13, 2007 Author Report Share Posted June 13, 2007 ok i unplugged it and it doesnt jerk anymore going down the highway it still revs in second and theres a rough idle that used to be there even before i unplugged the solenoid and theres always been a high pitched sound almost like a vaccuum leak somwhere it follows the cars speed and it makes a different sound when i slow down or the car shifts Quote Link to comment Share on other sites More sharing options...
Q-Ball Posted June 13, 2007 Report Share Posted June 13, 2007 whats your car idle at for rpm's? Quote Link to comment Share on other sites More sharing options...
3.1grandprix Posted June 14, 2007 Author Report Share Posted June 14, 2007 it will rev at 1500 for about 2 minutes when its cold (like all cars) then it may decide to rev at a normal 900 or it may be stubborn and idle at about 500-600 Quote Link to comment Share on other sites More sharing options...
ns87 Posted June 15, 2007 Report Share Posted June 15, 2007 If you need tips with the vacuum leak lemme know. I just found several of mine a couple weeks ago and took some pics Quote Link to comment Share on other sites More sharing options...
3.1grandprix Posted June 15, 2007 Author Report Share Posted June 15, 2007 hey ya let me know that could cause the idle problem. my dads a mechanic and im only 18 and still in highschool but my dad wont really help he knows what it is he just wants me to figure it out on my own Quote Link to comment Share on other sites More sharing options...
ns87 Posted June 15, 2007 Report Share Posted June 15, 2007 Fixing a Vacuum Leak on the MPFI You're going to use rubber lines instead of brittle plastic. You need to save a bit of the hard plastic lines. They're used as connectors between engine/sensors and the new vacuum line. Unplug the middle vacuum line and the bigger line on the right. Break off a chunk from each. Bring those chunks to any auto parts store. Tell them you need replacement vacuum line for these two sizes. I would get about 6 feet or ~2m of the small one, and half a foot or about .2m of the big one. So you got your parts! Start with the line to the left. This runs to the Fuel Pressure Regulator under the plenum. It has a T fitting, which then branches to a random connector to change direction in back of engine, and then to the MAP sensor on the back of the engine. This was cracked for me. Instead of taking off my plenum to replace a vacuum line, I ran new line around the side of the engine. Just remember you need a tiny chunk of old hard line to connector the new line to the MAP sensor. Map sensor is on the back of the engine left side. Don't forget to pull out old line under plenum. Now the middle line! This one controls your HVAC/cruise control. I didn't run it exactly stock, but it gets the job done. Use some zip ties to make it look nice. It runs from the engine to the right side of the engine compartment. It hits a "check valve". This picture borrowed from Discostudd sums it up nicely! (Borrowed from Discostudd) The Vac ball is at the bottom driver side of the front bumper. It removes with two bolts. Take it off and check for cracks. A replacement is cheap at the JY or something. The last line is the bigger one. It runs to the EGR? (someone correct me on this). Just do the same thing you did with the other two. This is a hand drawn vacuum line map from Bossman429. Ignore the bottom turbo part (Borrowed from Bossman429) Good luck dude. Quote Link to comment Share on other sites More sharing options...
3.1grandprix Posted June 15, 2007 Author Report Share Posted June 15, 2007 thanks i will try this and let you you know Quote Link to comment Share on other sites More sharing options...
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