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Possible TPS/MAP/o2 sensor out? HELP!

I have a 93 Dodge Grand Caravan (3.3L V6 AWD). I was on road trip and first time it happened, I stopped at a store, got in my car, pulled out, went about 100 feet and it was acting like it was running out of gas so I pulled over. Would start up fine, but when I accelerated to pull back out, it bogged down and then would die (repeatedly). Also got a sense it was running pretty rich from the smell. No smoke, no check engine light, happened out of the blue.

Prior to this, it’s been getting horrible gas mileage, no power whatsoever up minor hills, exhaust smells strong, runs rough on idle and occasionally would “hiccup” at various speeds. I’ve run out of gas in my van before and it was acting like it was out of gas, which it wasn’t.

Had to leave on side of freeway to tow the next day. When I got it home, I started it up and initially it chugged for 2 pushes on accelerator, but after that it seemed fine. Minor gray smoke (from running rich) from tailpipe (very little) and it smelled bad from exhaust. From my research, I’m assuming it could be the TPS, MAP sensor,o2 sensor or something like that. Checked everything else and it doesn’t appear or sound like it has a vacuum leak, etc. Please someone give me direction…it’s our only family car; we have no money to put in shop and we have 5 kids to haul around and this car left us stranded in 100 degree heat. HELP!!

Well It’s A Marvelous Night For A Key Dance.

Seriously though, You may be able to help diagnose your own problem, here.

Do you have the little numbers that roll over on the odometer (as opposed to digital read-out) ?

Has the “Check Engine Light” come on or is it on now ?

Let’s See If There Are Any Trouble Codes Stored By the Caravan’s ECM (Engine Control Module) That Will Help Us. Shall We Begin ?

Being a 1993, you don’t have an OBD 2 data socket (it’s OBD 1), but with the engine off, try turning the ignition key :

from “off” to the “on” position (not start),
then to “off”,
then to “on”,
then to "off,
and then to “on” (the third “on”) and leave it there.

Do this “key dance” all within 5 seconds and get ready to count how many times the “Check engine” light blinks. It will send out a code or codes if it’s got any stored. The codes are 2 digit numbers.

blink, pause, blink, blink, pause . . . blink, blink, blink, pause, blink, blink, blink, would be two codes - code 12 and code 33. The codes may repeat after the first time through. You may have to try this over again to catch it. It takes a little practice. You will probably get a code 12 at the beginning and should get a code 55 “End of Message” at the end of the other codes.

See if you can do that and post the 2-digit codes here and we’ll see if it helps with anything.
Is the “check engine” light on at this time?


One thing I have seen on Chrysler products is that the manifold vacuum line to the MAP sensor breaks. When it does, it will give you the exact symptoms you are experiencing. At that time they were using a hard plastic tube connected to the manifold and MAP sensor with rubber hose. The hard plastic tube cracks (leaks) and then completely fractures.

An easy test is to pull the rubber hose off the MAP sensor; put your thumb over the hose end; and crank the engine. If there is no vacuum pull, look for the break in the line. Alternately, do as common sense answer suggested and read the codes. If you get a 51 and a 12, suspect the vacuum line or a bad MAP sensor.

It is unlikely to be the O2 sensor as that operates in closed loop which you are not in when this problem happens. The TPS is pretty easy to check using an ohmmeter – reply if you need details.

Good luck on this. Post back when you find the source of this problem.

Based on the temperature gauge on the dash, does the van look to be running at normal temperature?

How old are your spark plugs, wires & air filter?

Oops, I forgot to post the codes…I did this last night (my mechanic dad taught me this trick luckily…helped me many times :slight_smile: The codes I got were 12, 33, 55 which seems odd because what I read is ‘12’ will always come up because it means the computer is engaged, but the engine is not running and of course ‘55’ is end of test. The results on the ‘33’ from much research is the a/c clutch switch or something like that. For 4 years my a/c hasn’t been working-doesn’t seem to engage (maybe the switch/relay is the prob), but these codes seem unrelated to the symptoms. The check engine light was not on at anytime. Hope that answers your question because I’m all out of ideas. I was thinking MAP sensor??

After researching this issue,I was thinking it was the MAP sensor or a couple other ones related to that. I did not know it was a common problem however. The codes I got were 12, 33, 55, which are totally unrelated to these symptoms but the 33 code may explain why I haven’t had my a/c kick on in 4 years. my husband thought compressor, but it may be something as simple as a switch/relay, etc. The check engine light never came on at any time, which I’ve read that with a bad MAP sensor or problems with the sensor, the check engine light doesn’t always come on. Here’s the kicker: today I started it and drove it around the block and even though it runs pretty rich and there’s some very slight gray exhaust and smell from tailpipe, it ran normal. Weird…the only thing that happened from it breaking down and today was I had it towed. Maybe he jarred something “back” into place or whatever…who knows? I’m going to try to check the MAP sensor info you gave me, but if you wouldn’t mind, could you briefly explain how to test the TSP? From my Chilton’s, it appears to be easy and everything’s basically on top of engine so that’s a good thing. Thanks for your reply; I really appreciate it!


Well because the fan switch is out and I can’t find where it is in the engine compartment to replace it (I have part), it did overheat twice yesterday a few hours before this break down (broke down twice in one day for 2 different problems!). Actually because we have 5 kids and my husband is the only one working, the maintenance on the van is never on front burner because of other bigger priorities (food, house, etc) so unfortunately it hasn’t been tuned up in a while and we’ve owned it for 4 years and never really done any preventative maintenance to it. It’s also got 180k miles on it. Luckily I’m getting a large check next month which I will use to get it back in great shape :slight_smile: But to answer your question, at the time it broke down, the temp was fine, running right in the middle normal temp. And the air filter is filthy. Could that be maybe causing the problem?