Myotis1134 Posted March 9, 2009 Report Share Posted March 9, 2009 Hey people, I'm having a hard time solving this one. 1991 Lumina Euro 3.1, 4T60 tranny. I failed an emissions test a few weeks back, with the results being: hydrocarbons - pass CO2 - fail (big time) I did some research and found that bad/failing injectors could be the problem due to reduced atomization of the fuel. I bought some new 15 lbs/hr injectors from summitracing and installed them, cleaned out my plenum as much as I could with a dremel, assorted wire brushes and lots of throttle-body cleaner, took apart my throttle body and cleaned it (had to replace the IAC gasket in the process), broke a couple of vacuum hoses and decided to replace all of them too. To replace the vacuum hoses, I used rubber tubing that was approximately the same size (the original hard plastic tubing would just fit inside the rubber tubing), but the length of the replacement vacuum hose might be longer than what was there originally. While I was dicking around with my vacuum hoses I broke my TV cable, and had to order a new one from rockbottom. The new cable I got looked slightly different from my original, but I figured it was because the old one was made in '91, and it fit perfectly. I put everything back together and now the car has a pretty rough idle in park, but smooths out after a while, and the tranny doesn't shift where it ought to- it seems to be shifting a couple thousand RPM higher than it should, and the shift occurs after several seconds at high RPM. Then when slowing down, it stays in second until around 5 MPH and kind of lurches into first gear. Other than that the car runs pretty good, but I'm getting a code 33 which is MAP sensor - High voltage, Low vacuum indicated. Just in case the code was old, I unplugged the battery for a few minutes after I replaced the vacuum hosing, but got the code again. I'm wondering if the rubber tubing I used is too large, and not enough vacuum is being produced for the transmission to shift at the appropriate RPM, which would explain the high RPM shift. My other concern is that the new TV cable is not adjusted properly, but I didn't see anyplace on the throttle body to do that. I'm getting desperate enough to start thinking about taking it in to a mechanic, but would rather not as I am not confident in anybody else's throughness when it comes to working on my car. I figure if anybody can give me some suggestions as where to look to solve this, it's you guys. p.s. bad EGR possibly? Quote Link to comment Share on other sites More sharing options...
AL Posted March 9, 2009 Report Share Posted March 9, 2009 Possibly a bad MAP sensor too. Quote Link to comment Share on other sites More sharing options...
Night Fury Posted March 9, 2009 Report Share Posted March 9, 2009 Yea supposedly if you hit them when working near them they can go bad? Or am I going crazy? Quote Link to comment Share on other sites More sharing options...
slick Posted March 9, 2009 Report Share Posted March 9, 2009 You can run too large of hosing for vacuum, which could be part of the problem. Do as suggested above, hit the MAP sensor while running, and listen for any changes. Quote Link to comment Share on other sites More sharing options...
Myotis1134 Posted March 9, 2009 Author Report Share Posted March 9, 2009 I did bang the MAP sensor around a bit when I took off the plenum, but could it be the source of the shifting problem? The new rubber hose I used to replace the old vacuum tubing has the same id as the original tubing's od. Would that kind of size difference be enough to cause the symptoms I'm having with my car? I left a little extra tubing on when I replaced them because I plan on replacing the "T" in the fuel/MAP line with a better one than what I have on now. Would a couple of extra inches of line reduce the vacuum enough to notice? And if so, is there a resource that would tell me approximately how long the line should be? Just for clarification, should I beat the hell out of the MAP sensor, or start with soft thumps and progressively smack it harder? Quote Link to comment Share on other sites More sharing options...
slick Posted March 9, 2009 Report Share Posted March 9, 2009 Just tap it. You could have a vacuum leak somewhere. Have you checked that out yet? Quote Link to comment Share on other sites More sharing options...
Myotis1134 Posted March 10, 2009 Author Report Share Posted March 10, 2009 I'm an idiot! Figured it out. Thought it might be the "T" I made with parts from Lowes plumbing section, but I went and took another look at the damn hose I used. Think this might be the problem? Quote Link to comment Share on other sites More sharing options...
Myotis1134 Posted March 10, 2009 Author Report Share Posted March 10, 2009 Guess I either have to get a vacuum hose kit from a auto shop, or go to a specialty rubber hose store and get some tubing that is actually the right size. Quote Link to comment Share on other sites More sharing options...
carkhz316 Posted March 10, 2009 Report Share Posted March 10, 2009 Also, if that doesn't fix it, check the line that goes from the the plenum to the trans for the vacuum modulator. This can cause both symptoms Quote Link to comment Share on other sites More sharing options...
Myotis1134 Posted March 10, 2009 Author Report Share Posted March 10, 2009 I'll check it out. I'm off to match hose size. Thanks guys. Quote Link to comment Share on other sites More sharing options...
Lumineer Posted March 10, 2009 Report Share Posted March 10, 2009 Huh, interesting. My Bonneville shifts higher than it should and shifts pretty hard too. It drives normal, but if REDLINE shifted, it shifts around 6,000 RPM, when it should shift around 5,500ish. It shifts so hard that it feels like someone shifting a manual car hard (from the outside, it looks like a manual car shifting). In fact, I did a WOT test run with the car (testing its acceleration due to the miles) and it shifted into 2nd at 45 mph, then it held 2nd until 85 (it was JUST about to shift at close to 90...probably 87ish.....and it's a 4-speed). I let off because the engine was revving high enough that it wasn't pushing enough power to really get to shifting point very quickly (it was accelerating like a snail at that point). By letting off the gas and giving it maybe 3/4ths to 4/5ths throttle, I was able to continue accelerating again, but decided to just stop anyway since this car has to last me *smart move*. Quote Link to comment Share on other sites More sharing options...
Myotis1134 Posted March 11, 2009 Author Report Share Posted March 11, 2009 Reduced my fuel pressure regulator/MAP vacuum lines and it idles like a champ now. However I'm still shifting at high RPMs. Looks like I screwed up my vacuum modulator somehow. Sucks, but the one in there now is probably OEM, and needs to be changed out anyways. $26 at NAPA, and $16-71 at CSK- I love living in Alaska. Quote Link to comment Share on other sites More sharing options...
Myotis1134 Posted March 11, 2009 Author Report Share Posted March 11, 2009 By the way, is the plenum/vacuum modulator line supposed to be metal? The line stops about an inch from where the hub screws into the plenum, and there is a major size difference between what's coming out of the plenum, and what's leading up to it. I had it bridged with some hose, and reduced the connection to what I used on the MAP line, but that didn't stop the crappy shifting. Anyways I'm wondering if the line from the vacuum modulator needs to be metal, or if it is that way because it is so close to the exhaust? Possible to reroute? Or possible to use rubber and heat-shielding? Quote Link to comment Share on other sites More sharing options...
carkhz316 Posted March 11, 2009 Report Share Posted March 11, 2009 Not sure about the necessity of metal. OEM it is, but not sure if it is specifically needed. Others will chime in on this. As far as the line and modulator; double check them. Pull the line off both ends and blow through it to make sure it's not plugged. Also, look at it closely to make sure it doesn't have any leaks. Also, if when you pull it off of the modulator, if there is ANY trans fluid in the line, or on the end on the modulator, then the modulator is shot. The service manual way is to vacuum check it with a vacuum gauge, but that's up to you. Don't forget about the Throttle/ TV Cable as it controls shift timing. If you want to eliminate the possibilty, just unhook the cable and drive it. If it is the problem (I.E. too tight/ binding cable), then it should quickly shift through the gears as if you were just "grannying" it around. Quote Link to comment Share on other sites More sharing options...
Myotis1134 Posted March 14, 2009 Author Report Share Posted March 14, 2009 Fixed it! The high RPM shifting turned out to be the TV cable. I adjusted it and now have a much more normal shift vs RPM. I found a TV cable adjustment post and followed those instructions - press the button, relieve all the pressure on the line, floor the gas pedal. I think it's still shifting slightly high, but I'll monkey around with the cable settings until I get it where I want. Also replaced the vacuum modulator, as the old one was pretty ugly looking, and have a nice tight shift (2 clockwise rotations). Thanks for all the help everyone. To think this all started because of a failed I.M. Quote Link to comment Share on other sites More sharing options...
Addicted To Boost Posted March 14, 2009 Report Share Posted March 14, 2009 If you want to get the TV cable tighter, push down on the button with a long screwdriver, then look on the right side (driver's side) where the cable is connnected to the throttle body.. follow it to where the TV cable is mounted into the bracket. On the right side (pointing toward the throttle body), there is a cone-shaped piece of plastic, push the cone in, toward the passenger side of the car while holding the button down. The cone should go in a bit. Then go inside the car and slowly give it WOT. That should tighten your TV cable a bit. Both of my GPs I've gotten to shift at about 5,100-5,200 RPM on the 1-2 shift with a tight cable. Quote Link to comment Share on other sites More sharing options...
Myotis1134 Posted March 15, 2009 Author Report Share Posted March 15, 2009 Thanks, I'll give that a try. Been driving it around a bit, and it could stand to shift a little sooner. I used some fuel line for the vacuum modulator to plenum connection, and covered it with some shielding. I re-routed it a little, and zip-tied it to the coolant line so it didn't run right next to the exhaust. Hopefully having rubber hose that close to the exhaust won't fuck it up, but I'll look at it every now and then. Quote Link to comment Share on other sites More sharing options...
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