Hi,
After some time with fairly high fuel consumption (and the inspection date being very close) i did the key dance on my Van with 318 TBi.
I got the numbers 15 - 21 - 52 which, according to the OBD1 codes (found elsewhere on this forum, https://dodgeforum.com/forum/1st-gen...d-1-codes.html ) means the following;
15: No signal from speedsensor
21: O2 sensor problem
52: Fuel system rich

It runs very rich, i can see black smoke and smell unburned gasoline from the exhaust. Furthermore, the temperature sensor goes no more than 1 step up from Cold, also after more than 15 min.s driving in city / highway traffic, though i've changed the thermostat to a new item today. There's warm air coming out of the heater, but can it be enough to tell?
Can it be the water temp. sensor that has a failure, and if, shouldn't it read out on the key dance with code 17 or 22?

The O2 sensor looks like it's been sitting in the mainfold since the car came off plant 6 at Pilette...so it may be time for replacement.

OK, this was the description...now it's time to bring on the big Q's...

1: Is the OBD1 numbers for use on B250's as well as Dakota's (hence the forum thread the codes is in, is a Dakota forum)?

2: What's the best way to remove the O2-sensor from the manifold - it looks like it's pretty seized (which is NOT pretty at all!). Can it be done without ruining the thread?

3: Speed sensor? What's the use of it for the ECU, where is it located, and what will typically be wrong with it, since the OBD1 says so?

4: Temperature is below the middle, in fact just above cold, despite long times driving at approx. 55 mph and normal city speeds. Is it the 2-pin water temp. sensor on the intake that's faulty? Is there any more temp. sensors than this one?

5: Is the temp. gauge, as well as the other items listed above, prone to failure on these TBi-models?

I look forward to the experts' words... so li'l Dodgey can get her "digestion" all right, and pass the inspection.

 

The last O2 sensor I removed, while hot, I put parrafin wax on it, did that for about a week and it came out without incident. PB blaster also works. But I think a plugged catalytic converter will also give a bad O2 sensor code. Or if a wire is broken on it. Or if the tube going to the catalytic converter rusted off.
The temp thing sounds like a bad heater core.

 

The Vehicle Speed sensor is responsible for telling the ECM to tell the transmission when to engage overdrive, and /or lock up the torque converter. It is located either on the transmission, where the speedo cable comes out, or under the power brake booster, inline with the speedo cable. There are 2 wires going to it. The ECM sends out 5 volts to the VSS. The speedo cable turns a magnet which then in turn opens and closes contacts within the VSS. The ECM determines the vehicle speed by the rapidity of the pulses. I'm guessing the contacts open and close about 10 to 15 times per revolution of the cable.

The VSS can collect rain water. The contacts for the 2 wires can become corroded. The h20 can get inside as well, and corrode the contacts within. On my VSS, the 2 contacts which are opened and closed by the spinning magnet get stuck on occasion, and I have to flick the VSS with my finger a number of times to free them up.

I have always had difficulty getting a tool onto the oxygen sensor, and wind up removing the old ones by crushing the body with a pair of Vice grips. They are rated to last 60 k miles. If the engine is running poorly, the o2 sensor can get fouled, causing the engine to run even poorer. Using penetrating oil is a good idea a few days before hand, and removing while warm too. But do check to make sure the wires are good first. They do see a lot of heat.

There is a 2 wire coolant temp sensor for the ECM. There is a one wire CTS sensor for the gauge on the dashboard. They are both located on the intake manifold. On my '89 the 2 wire is next to the thermostat housing. The one wire CTS on the opposite side.

AFAIK the OBD 1 codes are the same for a Dakota as a B-Van.

The CTS's can be tested for resistance. I know my dash gauge is inaccurate. It barely registers up to the first notch, but I also know it is running slightly cool despite having a newish 195 degree thermostat.

Installing a 185 degree thermostat will cause it to run rich.

If you havn't already, replace the spark plug wires, dist cap and rotor, and sparkplugs to eliminate electrically induced misfire as the cause of running rich.
Make sure the SP wires do not touch each other, or anything grounded. Use Zip ties to hold them in place when the doghouse is re installed.

The distributor caps with the brass contacts last significantly longer than the aluminum contacts.

If it has never been done, you TB might really benefit from a removal and cleaning. When I did mine at 175k miles there was a huge amount of carbon buildup. Afterward it ran noticeably better and smoother.

If you don't want to remove it to clean it, and before you replace the O2 sensor, get a can of TB cleaner, and run it through the intake with the engine running. Doing this can foul an O2 sensor, but can help clean off deposits from the intake valves.

Seafoam is a good product. Don't know if it available in Denmark.

 

@ Fepowerguy & Landyacht318: There's no catalyst on this car, it's probably been removed due to Denmark's emission/catalyst law, which only demands catalyst-equipped cars from 1989 onwards. The air pump is also removed, and the air line to the catalyst is plugged. As i can see, this has been done some years ago.

The engine runs smooth and evenly, without misfires. The cap & rotor is newish, so is the plugs. The wires is not new, but free from cracks etc.
I put in a 195 degree thermostat yesterday, so it's the correct item.

My schedule on making this thing work, is to go through all the wiring related to the O2 sensor, VSS and the two coolant sensors, and most likely i'll replace the O2 sensor.

I'll be back with a "status update" when i'm done.

 

I've located the VSS under the brake booster. The speedo cable runs trough it and into the cruise control. Both the cruise control and speedometer works normally.
The speedometer gets an impulse from the VSS, that means that the VSS is OK - or?
Perhaps there's a wire fault from the VSS to the ECM?

 

Yee ha! Dodgey's doin' allright again.
The O2-sensor came off without vise grips, and a measurement with a Voltmeter showed it was long gone. I discarded it and installed a new sensor - a 3-wire "universal" sensor from Standard, and the engine runs great again.

When i drove to my garage to fix the car, it turned out that the cruise control, which has functioned properly 'till then, didn't work. The VSS was unscrewed from it's position under the booster and tested for induction. Didn't show nothing, but after a good squirt of WD-40, the cruise control worked again.

The temperature sensors were both replaced, after that the temp gauge showed properly values again.

To sum it all up, it runs superb now, and passed inspection today with thumbs up from the car inspector (he's an american-car-enthusiast). Now's just the time to drive into the summer of cruises and meets...and throw some rubber on the asphalt (Dodgey has a limited slip diff).

The only thing that worries me now is, i did the key dance again today. It still shows a code 15 (no signal from VSS). The speedometer & cruise control works perfect.
Can a code 15 mean something else, or is it the lock-up TC that's playing around?

 

The VSS has nothing to do with the operation of the cruise control, or the speedometer. It is to inform the ECM when to operate overdrive or lock/up.

Without it working, You probably do not have the lock/up. Count the gear shifts, lock up is pretty obvious if you are looking for it. Without it, you are wasting fuel at higher speeds.

You can check to see if the VSS itself is the problem. It is easy to remove. If you put an OHM meter across the two contacts, and then spin the speedo cable recepticle, the OHM meter will read 0 then 1 then 0 then 1 as you spin it. About 10 to 15 times per full revolution

If it does not change, then the spinning magnet is not opening and closing the contacts within.

I would first clean the 2 pins and receptacles in the connector. It collects water in there. The water bridges the contacts, and the ECM sees this as no variation in signal.

Sometimes the barrels and pins do not contact strongly. Rolling up a very small piece of aluminum foil, and inserting it into the barrell can make a better contact.

When re installing, pay close attention to get the square drives to line up with the receptacles.
Here's a photo of the interior of mine:

http://i557.photobucket.com/albums/s...g?t=1268952852

 

How to dismantle the VSS without ruining it? Looks like it's put together with a metal belt, no screws.

Furthermore, the engine RPM goes up and down repeatedly when i start it for like 10 seconds. I did the key dance again and got a code 13 "No change in MAP from start to run".
What's the typical failure, when such a code comes up, and where's to look?

 

The map sensor reads vaccuum from the throttle body. There is a vaccuum line from the back of the TB to the map sensor, about 10 inches long.
Check the integrity of that hose.
Try blowing air into it and see if there is much resistance, could be carbon build up in the TB blocking the vaccuum.
Try sucking on the map sensor vaccuum receptacle. There is a diaphram in there that could have ruptured. If it does not stick to you lip or tongue,replace.

Also check the condition of the wires leading to the MAP, and connections there.

My VSS had been previously opened by a Tranny Shop who then charged me for a new VSS. They put it back together with blue RTV silicone. I reopened it by just prying it apart along the seam, didn't see any metal belt.

 

Back from the garage for today.

I dismantled the VSS, and, just as expected, it was filled with cakes of rust and WD40 as shown here:


After thoroughly cleansing, i put it together again, using instant gasket.

The "metal belt" i wrote about is in fact a frame thats bended around the VSS casing. I molested it completely when dismantling the VSS. It's not that necessary, the instant gasket and a couple of cable ties does the trick. The frame or what's left of it is visible on the picture above.

The MAP sensor was tested as you described. It all seems to be OK, hence there's no plugging in the hose / inlet on the TB, and the diaphragm is intact.


Still getting codes 13 (MAP failure), 15 (VSS failure), 52 (fuel system rich), though.

The idle is still going up & down in RPM. When i press the accelerator pedal quickly to the floor, the engine hesitates a little. When the pedal´s pressed slowly, it's not hesitating. I wonder what's making it do like it does?
I have a video on youtube with the symptoms right here:
http://www.youtube.com/watch?v=nA6TgyI7-6E


Can the computer show these codes, and have another internal failure instead?