Stutter...Zoom!...Stutter... What gives?

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Pat Dodge Dakota JOIN HERE 4/22/2004 04:34:30	Subject: Stutter...Zoom!...Stutter... What gives? IP: Logged Message: My '89 recently started overheating. Had a good rad shop look at it. The original rad had finally given up, after 140K, and they fixed it fast, good, and cheaper than the other shops (anyone wants to know a great rad shop in L.A., ask). HOWEVER, starting a couple of days later, I noticed that she ran real rough cold. At first, it was just the first few minutes. Later, I'd have to run her all the way warm, before I could drive normally. Now, it does it all the time. I call it the "Sputter/Lurch Boogie". The engine just barely stays lit, and when I try to accelerate - slowly, since it'd die if I gunned it - it sputters, sputters, sputters, then - ZOOM! It takes off like a bat out of hell! Then, keeping the throttle in the same position, it starts sputtering again. It does this constantly now. Have to drive the automatic by shifting gears manually, and that's a bit dangerous, when I have to shift to "N" at every light, even at low speed, just to keep it lit (only one little notch away from "R", which stands for Rebuild the tranny again). Since it started after the rad job, I first looked for a vacuum hose the rad mechanics might've left off. Or a loose coil wire or something. But, since it started off as a temperature-related problem, I suspect something like a temperature sensor at fault. New Distrib. Cap and Rotor, new TBI's, Fuel Filter, checked EGR and PCV valve. About to change wires, but before I throw a lot of $ at new parts - like MAP sensors, O2 sensors, TPS's and such, I'd like to know what might be wrong. This thing is so instantaneous, it's almost like somebody flipping a switch back and forth, which makes me think it might be an electrical prob. But since everything in this beast is electrically operated anyway, I suppose it could be any of these things. Any ideas?
bump Dodge Dakota JOIN HERE 4/22/2004 08:18:14	RE: Stutter...Zoom!...Stutter... What gives? IP: Logged Message: " check engine light " is it on ? What codes from computer ? Sounds like probable O2 sensor ! Code would tell..
Pat Dodge Dakota JOIN HERE 4/22/2004 16:52:01	RE: Stutter...Zoom!...Stutter... What gives? IP: Logged Message: No light, code 55. At least the COMPUTER thinks everything is fine! Bump, if it is the O2 sensor, why would it run OK when it was warmed up, like it did for the first week of this problem?
Pat Dodge Dakota JOIN HERE 4/22/2004 16:55:39	RE: Stutter...Zoom!...Stutter... What gives? IP: Logged Message: One other thing - could a faulty Coolant Temperature Sensor cause all this? I just got my Haynes, and noticed that it's right next to the Tstat that these guys replaced. Maybe they whacked it with a wrench or something.
oh Dodge Dakota JOIN HERE 4/22/2004 18:25:05	RE: Stutter...Zoom!...Stutter... What gives? IP: Logged Message: loose wire?
L Dodge Dakota JOIN HERE 4/23/2004 09:38:47	RE: Stutter...Zoom!...Stutter... What gives? IP: Logged Message: Soot contamination - The two primary sources are oil and fuel. Oil soot is a result of a mechanical engine condition such as worn rings or valve guides. Fuel soot is either the result of a rich-running engine or a misfire. Either form of soot impedes the operation of the oxygen sensor. The output voltage remains constant at around 0.5 volts. Testing the sensor: Most Rams: left sensor - black/darkgreen wire right sensor - tan/white wire ground - black/light blue 1996 models with pre cat and post-cat sensors: Pre-cat sensor - tan/white wire Post-cat sensor - orange/black First, try this simple test of the oxygen sensor. With the oxygen sensor connected, start the engine and allow it to run at 2,000 rpm for two minutes. Connect a digital voltmeter between the signal wire and ground. With the engine idling, watch the voltage reading on the voltmeter. You should observe the voltage toggling above and below 0.450 volts. If the voltage is stuck high, or in the middle, create a vacuum leak and look for a response. If the voltage is stuck low, or in the middle, goose the throttle and look for a response. If there is no response in the voltage, replace the oxygen sensor.
? Dodge Dakota JOIN HERE 4/23/2004 10:37:38	RE: Stutter...Zoom!...Stutter... What gives? IP: Logged Message: O2 may work when fully warmed up , partially at least. But when cooler , the contamination as stated above will STOP proper operation , resulting in what sounds like your problem..
L Dodge Dakota JOIN HERE 4/23/2004 13:22:12	RE: Stutter...Zoom!...Stutter... What gives? IP: Logged Message: Bet that is it !
Pat Dodge Dakota JOIN HERE 4/24/2004 02:00:20	RE: Stutter...Zoom!...Stutter... What gives? IP: Logged Message: Thanks for the feedback! Reckin I'll take a gander at it this weekend, drag out my digital v-o-m and see what she reads. Do I just pull apart the connector enough to get a probe in there, and leave it still connected? Or do I unplug it completely and test it?
Bob Lincoln Dodge Dakota JOIN HERE 4/24/2004 08:57:56	RE: Stutter...Zoom!...Stutter... What gives? IP: Logged Message: You need to stab through the insulation with needle leads, or run narrow bare wire out and re-mate the connector. It needs the ground and power connections intact for you to get the reference voltage.
Pat Dodge Dakota JOIN HERE 4/26/2004 18:34:24	RE: Stutter...Zoom!...Stutter... What gives? IP: Logged Message: Well, Thanks L and thanks, Bob - I gave it a shot! But as it turns out, there is only ONE sensor, located on the "downpipe", right after the 2 exhausts come together. It has a 4-wire connector, and I puzzled over the Haynes wiring diagram (page 12-27) and it does not show what, if anything, is ground or power or signal. I tested with a V-O-M and none of the 4 show continuity to ground, and with the ignition ON, none shows 12V, which would be the power lead. The only voltage present, in fact, is .37 volts from the smaller (18 ga.) black/dk.green wire, to any of the other 3 wires. And it's the same when I start it, although now it only stays lit for a minute or so, and won't restart. During that minute, (after I made my measurements) I unplugged the sensor, and the engine sounded just the same. So, of course, now I suspect wire damage, since there's neither hot nor ground there at the sensor. I am now getting a little black smoke at startup, but it quickly disappears. The patient is looking weak. Is there a Mechanic in the House?
Bob Lincoln Dodge Dakota JOIN HERE 4/26/2004 19:26:20	RE: Stutter...Zoom!...Stutter... What gives? IP: Logged Message: Unfortunately, I left my Dakota manual at work. But my Daytona manual shows the 4-wire sensor, which may have the same wire colors. At the sensor, of course, you typically have 3 white and 1 black wire. At the next upstream plug, I'm showing dark green/orange stripe, black/lt blue stripe, black/dark green stripe, and black/tan stripe. Ground is the black/tan stripe. Black/lt blue is also a ground - one is heating element ground, one is signal ground. Black/dark green stripe is the O2 signal, and dark green/orange stripe is 12V. The reason you didn't measure anything is that the 12 volts comes off the ASD relay, so with engine off, there will be no voltage to the O2 sensor. Wiring is probably OK. You were reading the correct wire, however. Check from there to ground with engine running, if you can reach without burning yourself or getting caught in moving parts. I'm wondering about that temp sensor, since you mention that they did replace the thermostat. Does your gauge read normally, cold and reaching the normal mark in a few miles? It's easy to hit that sensor or the wire when digging down in that space to get the thermostat out. If there were an issue with that, it would feed more fuel, thinking the engine was colder than it is.
Pat Dodge Dakota JOIN HERE 4/27/2004 01:13:08	RE: Stutter...Zoom!...Stutter... What gives? IP: Logged Message: Yes, indeed. That's what I've suspected all along. Since the O2 doesn't even read until it's warmed up pretty good, what sensor(s) does the computer read UNTIL the O2 has heated up? Could it be that prime suspect, the Temp. Sensor? See, it doesn't just run rough, it's really hard to START, in Open-Loop mode, and that's before the O2 is a factor. Guess I'll have to test that Temp. Sensor. Haynes shows both a Coolant Temperature Sensor and also a Coolant Temperature Sending Unit. This is probably an Aggie question, but... are those two separate items? Haynes tells how to test the Sender, but not the Sensor. How do I do that? Stick it in a pan of boiling water and see if the resistance changes? What should it read?
99dak Dodge Dakota JOIN HERE 4/27/2004 03:58:14	RE: Stutter...Zoom!...Stutter... What gives? IP: Logged Message: My 99dak ran like that for 2 days. Just out of the blue it wouldn't start. Jump started it and ran fine. Had to keep the engine reved up at stop lights or else it would die. But at higher RPMs it seemed fine. Ended up being bad battery and positive connector.
Pat Dodge Dakota JOIN HERE 4/27/2004 04:07:42	RE: Stutter...Zoom!...Stutter... What gives? IP: Logged Message: It's definitely not a prob with that stuff. She turns over like a banshee, has good juice to lights and everything else. It's that rich/lean diet she's been on. Gives her indigestion.
Bob Lincoln Dodge Dakota JOIN HERE 4/27/2004 08:36:27	RE: Stutter...Zoom!...Stutter... What gives? IP: Logged Message: "See, it doesn't just run rough, it's really hard to START, in Open-Loop mode, and that's before the O2 is a factor." OK, I didn't see that in any previous posts. So check your MAP sensor, which is right behind the thermostat on the throttle body (at least on most V-6s). There is a vacuum hose and an electrical plug. MAP sensor is used during cranking and all running operation. O2 sensor is ignored for about 2 minutes while it heats, and SBEC runs a default program in the meantime. Could be MAP sensor, even without fault code. They don't last all that long in MoPars. The fault codes look for vacuum present (code 13) and look for voltage over 0.4V and under 4.96V (code 14), but if it's off in the mid-range, you get no code. MAP is about $30-$40, easy to change.
L Dodge Dakota JOIN HERE 4/27/2004 08:38:50	RE: Stutter...Zoom!...Stutter... What gives? IP: Logged Message: Don't discount that O2 sensor yet . It don't need more than a minute or so to be " active " .. But your temp sensor and temp sender are near front of manifold , one on each side of it. However , if bad = should send a Code.. O2 may not send a code as long as it is still in one piece , which has nothing to do with how it operates..
Bob Lincoln Dodge Dakota JOIN HERE 4/27/2004 09:58:30	RE: Stutter...Zoom!...Stutter... What gives? IP: Logged Message: It may be an issue, also, but if he's having hard starting, the O2 sensor has NOTHING to do with that. It's ignored for about 2 minutes, then cuts in.
Pat Dodge Dakota JOIN HERE 4/27/2004 23:23:23	RE: Stutter...Zoom!...Stutter... What gives? IP: Logged Message: You're right, Bob. I didn't mention that "hard to start" business earlier. 3 weeks ago, when all this trouble started, my dakota started all right in warm weather, just a little rough in cold. But this got worse and worse, and now it's hard to start at all. Plus, being only a novice, in the "Bush-League" of Shade-Tree Mechanics, I just last night got privy to what all you other cats already know - that these perfect, computerized engines have those 2 modes: open-loop and closed loop, and that the O2 doesn't factor in until it's warmed up. Also found out the different types of O2's and that mine is apparently the "heated" type so that those extra wires are for the heater circuit. So now I know that being hard to START (open-loop mode) has a potentially different diagnoses than just being hard to RUN (closed-loop mode). Quite possible that the O2 is shot also, but I can't even test for that until I can start the damned thing. I'll get a new MAP this week and see what it does. Thanks very much for your input!
L Dodge Dakota JOIN HERE 4/29/2004 08:03:42	RE: Stutter...Zoom!...Stutter... What gives? IP: Logged Message: Thing is , Computer remembers ' determined ' " optimum " values to use next time in open loop . Could try a { reset ) -disconnect neg. of battery turn key on for a few seconds then to start , then off reconnect battery See how starts , and runs for first few minutes at least now.. Map should be throwing code , especially when engine does not want to start.. As previously O2 may not.........
Pat Dodge Dakota JOIN HERE 4/29/2004 15:51:44	RE: Stutter...Zoom!...Stutter... What gives? IP: Logged Message: L - Damn, you're good! Ran the codes right after reset, and you can guess what I got: 12 and 14! "12 Battery or computer recently disconnected" "14* MAP sensor voltage below .16V or over 4.96V" Parts House - here I come!
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