I have a early 93 viper that has been running rough. It starts pretty good on the second try hardly ever on the first. The car idles great revs up faily good when no load is on the car.
BUTTTTT then I get going down the road and get a load on it and it runs like hell. Almost as soon as I hit 4000 rpm it starts to sputter and back fire. You put the cluch in it goes back to normal. Normal as long as you keep the revs between 2700 and 4000 rpm.
Now I did install a new battery to try and solve this problem. I did the trick touching the + wire to ground then reseting the WOT. I also installed new plugs and one new plug wire that was cracked. I have the the other 9 just have not had a chance yet to install them.
The car has a full header pipe type exauhst. Looks to be a Corsa. Not real sure about what else. The guy I bought the car off of did not know a whole lot about it.
Oh and the car was running like crap before the battery and plugs so I don't think those are the problems. Is there a TPS on these cars? Both throttle cables look to be the same postion.
1 - Check your plug wires once more. Make sure they are pressed in good in the back as well as on the spark plugs. I'm assuming they are all plugged in the right plug and nothing is swapped, since the car has a good idle..... or does the car idle really bad too?
2 - It is more than likely your MAP sensor. At least that's the most logical, easiest part to attack next. The "Manifold Absolute Pressure Sensor" (MAP) is located at the top most part of the intake manifold at the farthest part, next to the driver. It's a small black box with 3 wires at a connector on the end.
The "Power Control Module" (PCM - Computer) supplies 5 Volts to the MAP sensor. The MAP sensor converts intake manifold pressure into voltage and the PCM monitors this voltage. As vacuum increases, the voltage proportionately decreases and vice versa.
During "Key On" before cranking the engine, The PCM determines Atmospheric Pressure from the MAP sensor voltage. When the engine is "on" and operating, the PCM determines intake manifold pressure in relation to atmospheric pressure
AT WIDE OPEN THROTTLE - THE ATMOSPHERIC PRESSURE IS UPDATED BASED ON MAP SENSOR VOLTAGE AND INPUTS FROM OTHER SENSORS (maybe the TPS sensor?). AT THIS TIME THE "IGNITION CONTROL MODULE" (ICM) ADJUST SPARK ADVANCEMENT AND THE PCM ADJUSTS AIR/FUEL MIXTURE.
The Throttle Positioning sensor may be the actual problem (or adding to your problem as well) as it may be one of the "other sensors" mentioned in the statement above. It's located on your left / drivers side throttle body. When the throttle butterfly changes position, it changes voltage, sending a signal to the PCM, working in conjunction with the MAP sensor.
Check all those connectors and let me know if you make any discoveries. You should probably take the MAP sensor off and inspect it... or replace it. -FROG-
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94' RT/10
12.1 @ 115 (1.87 60ft) on worn Pilots, cone filters and Dynomax w/no cats-406HP/475TQ
obd1's are a pain in the ass, you really need to put a drb on this and check the values as the motor is running. OBD1 wont throw a code as long as the sensor is putting out a signal.
obd1's are a pain in the ass, you really need to put a drb on this and check the values as the motor is running. OBD1 wont throw a code as long as the sensor is putting out a signal.
Oh yea, good idea... get a code reader and toss it on there and see what code it throws out. I thought these cars were OBD2 but whatever the case, I have also heard the DRB is better scan tool. For what it's worth, you can rent an OBD reader from Auto Zone and other local parts shops.
Ive had a 94 and still have a 98. When my car acts like that and it's happened more than three or 4 times already. It's usually the TPS Throttle Position Sensor. Simple part, simple bolt in job done in 3 minutes.
Check wires. One small crack in a wire will totally kill your performance
When's the last time you checked your 02 sensors. You said you just did headers and exhaust? Did they put in the correct downstream 02 sims? Sensors?
Doesn't sound like anything major.
Thanks guys I'm going to order a TPS and a MAP sensor even just to have it. My buddy works at Chrysler so I 'l have him check them for me and I'll let you guys know. As far as the o2 I have not looked at them the pipes have been on since 97. Way before I bought it last fall. The only time I even drove the car was when I bought it. I drove it the 18hrs to home. Then it was winter. But the car ran really well all the way home through the mountains to the great white NORTH.
Well I did the MAP sensor no go. But the TPS should be here Wednesday. I'll keep you posted. The plug wires have not been done yet either. I'm going to do them tommorow. Thank you for every one who has posted I'll keep yah up to date.
Well I did the MAP sensor no go. But the TPS should be here Wednesday. I'll keep you posted. The plug wires have not been done yet either. I'm going to do them tommorow. Thank you for every one who has posted I'll keep yah up to date.
Thanks for keeping us updated. Hopefully you will tackle down the problem soon. Also, when you swap parts like that, remember to unplug your battery and then install the part. Then of course, plug your battery back in. Then go for a little 10 mile (easy) cruise to let your computer "learn".
Well I did the TPS and plug wires it's not that. Next is oxygen sensor and fuel filter. Sure wish my local Dodge dealer new a little bit more about these cars.
I did recheck the plug wires and everything was good except one wire may have been a little loose. I pushed it on and the car runs worse. Won't idle anymore. I did do one oxygen sensor and the other one is going in right away. The car is at the body shop getting a new gas filler door. The original owner installed a GTS gas door. I put it back to stock. So the car is getting the new oxygen sensor and then it goes to the local Chrysler dealer to get check engine light that turned on checked. I'll keep you posted and let you know what code popped up.
.... I pushed it on and the car runs worse. Won't idle anymore....
Sorry to hear that. Good luck with everything. I would deffenitely run a check on your computer if you can. Tell the dealership to run a check on the PCM.
Well I did everything I can think of sooooo. I brought it in to Chrysler cause it finally turned the check engine light on and low and behold they can't get the computer to communicate with there scan tool. What? So they are going to check to see if the plug has power on all the right pins and see if they can get it to read. I was thinking it may have a vacuum leak cant they check vac pressure with some thing to see if the intake is leaking? The car has no power across all rpms now and idles like crap. Any ideas? I might pull the intake and replace the o rings and gasket. Any buddy think this is a wise idea? Some one polished the intake before I got it so maybe that's the problem?
Well I did everything I can think of sooooo. I brought it in to Chrysler cause it finally turned the check engine light on and low and behold they can't get the computer to communicate with there scan tool. What? So they are going to check to see if the plug has power on all the right pins and see if they can get it to read. I was thinking it may have a vacuum leak cant they check vac pressure with some thing to see if the intake is leaking? The car has no power across all rpms now and idles like crap. Any ideas? I might pull the intake and replace the o rings and gasket. Any buddy think this is a wise idea? Some one polished the intake before I got it so maybe that's the problem?
hmmmm...... I just had a problem with my car not starting. I hooked up a Scan Tool to my computer and it wouldn't communicate with the computer either. It was as if... a computer was not even hooked up. I took the scan tool over to another car and it ran scans perfectly with no effort. Turns out my PCM was shot and after replacing the PCM, my car started right up.
How much was a new PCM? How do they test it? My Dodge dealer doesn't seem to know how to do anything on this car. Except maybe to charge me for trying crap that doesn't work.
I got mine from Chuck Tator at Tator's Dodge. The guy is pretty awesome and he spent some time with me on the phone. I know he's a busy guy, but he treated me like a friend and that seems to be the impression from all the other folks in the Viper world as well. It was about $470.00 for a remanufactured PCM for my 94" RT/10.
Here's his number - 914-763-3136
If I were you..... just for kicks, I would go to an Auto -Zone, Pep Boys, Oreilly, etc... and rent a OBD-II Computer scanner. I think it's about $100.00 to rent, but you get a full refund when you return it. Plug it into your connector (weird looking 5 pin or so connector, right beside the PCM in the wire bundle) and run a scan. There are 2 scan modes. 1. You can enter in the information, like "Dodge" - "Viper" - "Year", etc... and 2. you can just run a generic scan without entering in the data.
I borrowed an OBD-II scanner from a friend and it would not recognize my Viper in any mode. I unplugged it, walked 5 feet to another vehicle and ran both scans with ease. After scratching my head a bit, I walked back over to my Viper plugged it in, hit "SCAN" and still... it said something like "no data connected" or something obvious that it wasn't making contact.
I was still skeptical that it was my PCM, but all the problems I was having with my car, were directed to the PCM as the source of my problems.
Spend a little more time before buying a PCM, but keep it on the list. There is ALSO your ECU, which controls your Spark, so it could be that. That's the box below the PCM.
Just an FYI.... My bad PCM... When I turned the key I could hear a faint, high pitched squeel, like a high frequiency whine that occurs sometimes... like when a TV is on and you walk into the room and hear the high frequency sound. Turn your key to the on position and put your ear next to the PCM to see if you hear anything weird.
Thanks I'll try that. I do have an OB II scan tool doesn't show any thing. When we hooked up Chrysler's scan tool it was doing something cause the check engine light was flashing away. Then we tried the snap on scan tool. No dice there either. They were going to check my connections just to see if I had power to all the ports. Except the ground. If that's a problem then it wiring if not we'll try something different. The listing to the PCM I'll have to try that. $470.00 seems like a steal right now. I just wanna drive the car.
So the dealer had to fix that wire on the PCM and then they were able to comunicate with the computer. They ran a check and there is a sizable vac leak. So I ordered the intake gaskets. I'll let yah know on Friday how it runs.
This has to be good if he even gets a response...
