VSS question

[COPTZR]

I was reading a code 24 before my car started acting up. I have two questions....

1. What does the vehicle do when the VSS atually goes out(my speedo liked to stay buried and also jump back and forth from time to time....)?....it was acting like the MAF sensor was out right before it decided not to crank anymore...

2. Could it have been set by me stalling up the convertor? Something like 1400-4000rpm below 4mph will set it I think....but is it the same when stalling up and how long does it have to occur to be set?

Thanks

 

[COPTZR]

I guess I should of asked if the setting of the code below 4 mph includes 0 mph....if it really is 4mph anyway. If not, please correct me so no one gets the wrong idea.

Oh yeah.....what are you guys using for VSS's??? I bought the last two Delco units I could find here in FL...just in case.

 

[Stephen Soulsby]

To answer one of the questions, the VSS is there mostly for tourque converter lock-up. For me that is a very important thing. Keeps the transmission cooler, extends tourque converter life, and gives you better fuel economy. Stalling up the motor really shouldn't set the code because when you're staling, you're loading up the motor. The code will set during a light engine load and must remain that way for at least twenty seconds. Best thing you could do is disconnect the battery for ten seconds and then drive the car in a NORMAL manner. Take it on the highway for some driving. If a code 24 sets (without another code at the same time) then it is likely to be a defective VSS. I have replaced them a few times before. Seems like almost every G-body I get has a bad one when I get it. It's good to replace it though if it's defective. If you're speedometer likes to jump around (mine did at bout 15-25MPH) then that is likely to be a sticking speedometer cable. It would be a good idea to replace that too. When a VSS goes bad, usually all that happens is the TCC doesn't function and the check-engine light glares at you.

 

[COPTZR]

THANKS for the tip Steve! I would try driving around to see if it resets....only my car won't start now. Yeah, I kinda figured it was having an effect on the convertor...it was locking up and not unlocking...had to put it in Neutral...rev the engine a bit(not much really) and then put it in first or second to get it to unlock. Then manually shift through the gears. As soon as I got into 3rd and teh convertor locked up, it was stuck. Happened on and off for a bit. Then the car decided to start acting like my IC'd cars have when the MAF sensor goes out or the pipe blows off the TB...kinda like it's getting more or less air than it's reading. the car has run a little rich since I got it about 5months ago. Not real bad though. then it started wanting to cut one day and was building no boost. Then it started cutting regularly and I thought it was the MAF sensor. I got it home and replaced the sensor....no difference. It's possible the sensor I used is also bad though, as I've yet to have it on a running car since I got it. Guess I'll test em all right away from here on out. I'm kinda thinking it might actually be the sensor, but I'm not real sure. Is there a way to test a MAF without using the "tap test". My car wouldn't stay cranked for more than about 2-3 seconds is at all. I ended up pulling the turbo cause I thought that might be it. I decided to change out a few things while I have it off and have put it off long enough. I really want to get it done and move on to the next project...or rather, the first project that's been delayed for almost a second year so far

Let me know if I can test a MAF sensor without having it on a car...I know, I know...

 

[COPTZR]

Will a car crank with a bad coil? I've actually never had a bad coil in the entire time I've owned TR's....don't know what it's like. This car does have the 86/87 coil installed...he said he didn't install the module, but I think he may have been talking abou the ECM and not the ignition module as the car was running okay for about 3k mi's since I bought it.

 

[Stephen Soulsby]

A few things to note here. First, if you're car was stalling when coming to a stop unless you have it in neutral (like stopping with a manual transmission and forgetting to push in the clutch) then that is a bad TCC solenoid. They get stuck, more often when hot, but can get stuck anytime. It is a $35 part available at NAPA. However that has no affect on the VSS, but it obviously is a problem. Second, there really is no way to test a MAF sensor. If there is no code for it (I think it's 34) then I'd leave it alone. You could swap one from another hotair TR just to see if it makes a change, but don't waste your money on a new one if you're unsure. Third, a car will crank with a bad coil. It just won't start or run. It is common to have an '87 coil on an '84 module. My car had that setup when I bought it. they're 100% interchangable when you have the small plastic adapter between the coil and module. It converts it from 6.5" to 5.75" so the smaller '87 coil will fit. If you have that setup, make sure the firing order is set as printed on the emissions sticker under the hood. If it's an '87 coil and module (look at the base of the module for an adapter that is usually shiny aluminum) then follow the firing order as printed on the coil itself. There should also be an adapter wiring harnedd going into the module if it's an '87 module, it's very easy to see. Sounds like the next thing you need to check for is spark. To test the coil take an ohmeter to each pair of towers (1-4, 5-2, 3-6) and check for resistance. You should see no more than 13.5 ohms when the coil is cool. If you see any more, replace the coil. Let us know what you find and we can go from there.

 

[COPTZR]

Firing order appears correct and I got(from PS to DS) 11.65, 11.92, 11.25 as far as resistance on the coils....I see the little wires on the DS of the coil...nothing hanging out like it's unplugged or anything. The car drove fine until it decided to act up the day I cranked it up.....maybe I'm wasting my time and I have sugar in the gas tank or something

Anyway, I'll double check the plug wires to make sure the firing order is right, but I think it's all right on. Something interesting is that my car has sat since January and the battery still has a full charge

 

[Stephen Soulsby]

The coil is appearently in excellent shap. You still need to check for spark. If there is a bad module, cam sensor, or crank sensor then it will show up by having no spark. I assume that when you are cranking the motor it still sounds normal. No abnormal skips and bumps. I chased a problem like that in my Cutlass last summer. I had spark, fuel, and air. The porblem was the timing chain jumped a gear and thrww the cam timing off so the motor wouldn't run. The symptom I overlooked was the unstable sound when cranking the motor.

 

[COPTZR]

Ah....I see. Well, it was suggested in an earlier post I left a few months back that the chain may have jumped. It's a 92k mi car, so I guess it's possible. Need a double roller in there anyway
No odd sounds as far as I remember...maybe I should just change the timing chain anyway. Do that, the fuel system(well, at least the regulator(got a 237 to go on), inj's, fuel pump, sock, clean the tank out while I'm at it....already replaced the filter about a month before it decided to quit running), valve springs, and a few sensors as needed. Just kinda freshen things up before the turbo goes back on... I'll check for spark and then if it's getting good spark...I guess I have to decide whether or not to start replacing stuff or just put it back and try again. At this point, it's easier to just replace a bunch of stuff and maybe fix the problem. I do have an 85engine on the stand though....it's got a double rolled filet crank, two-dot rods, new pistons, rebuilt heads, new cam, etc etc etc....basically everything but the block, heads, turbo, and intake were replaced and all those were redone to either improve them(heads and turbo rebuilt, rotating assembly balanced) or just make em look nice. I was hlding out for when this one quit, but I'd like to keep the original engine in it. I'd hate to drop in the other engine to find that something wasn't right in it and I only needed a timing chain or something little like that for the original... I got it when I got my 85T-Type I'm parting. The car is rusty, but the engine....well, he went a wee bit overboard for a hotair engine. He put over 2k in it and it's beautiful. Painted up black with polished: valve covers, accessory bracket, alternator, compressor housing on turbo(I did sell the turbo though....kinda regret it, but I needed cash and he needed a good turbo), and throttle body. Looks great, but I have no idea what the clearances are at and I'm hesitant to put it in and fire it up without first going in and at least plasti-gauging the rods and mains. Anyway, I'll try checking for spark and let you know how that goes. THANKYOU for your help!!!!!