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roman_ltd
Dodge Dakota
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1/23/2007
23:51:11
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 Subject: map sensor question
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hi!
got question here !
when you supercharge you dakota!,,the supercharger comes with ignition system,that have his own map sensor....
wat to do with OEM sensor????
tap them with a tee(both)??,or just use new one ??
Thanks !!!!
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Luke
Dodge Dakota
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1/24/2007
14:01:31
|  RE: map sensor question
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Depends. What does the instructions say to do with it?
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roman_ltd
Dodge Dakota
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1/24/2007
20:54:32
| RE: map sensor question
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If we are boosting pressure in the intake manifold (bolt on supercharger installation). What is happening in all the vacumm lines attached to the TBI or intake manifold. I figure the PCV valve is a one way check valve and will close under positive presure but, what about all the other lines. Should they have check valves. and most important map sensor:when it sees positive pressure it will shut off fuel ???
Any input appreciated!!!!
Thanks!!
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J and J Auto
GenII
1/30/2007
03:10:38
| RE: map sensor question
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The super charger kits come with all nessasary
parts and very good instructions the second map
will run a boost guage and also tell the inline
pump when to come on to raise pressure under
boost so you have enough fuel
I have installed about a dozen super chargers
just follow the directions and you will be fine
we also use the boost retard control on them
performance computer on obd1's custom flash
or a superchips program with the obd2's
All the kits I have installed were true bolton's
and work very well
some we also added a GS motorsports split second
fuel controler to tune the fuel there is another
50 to 100 hp with the fine tunning dyno and a
wide band air/fuel o2 tweaking the fuel
I have 2 pulling over 500hp at the wheels
1 360 and 1 hemi truck
Man thats fun
Oh ya the map will not read brhond 0 and you can
do that on a stock motor at WOT so it will not
trip a sensor code
Larry
J&J Auto
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roman_ltd
Dodge Dakota
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2/03/2007
20:22:41
| RE: map sensor question
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Thanks Larry !
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Mike Stager
Dodge Dakota
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2/04/2007
23:37:37
| RE: map sensor question
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Well, here's a question...not supercharger related, but MAP sensor related. What exactly does the MAP tell the computer to do? Is it in charge of timing advance and fuel along with the O2 on the back side trimming the levels?
The reason I ask is because the problems I'm having with my truck remind me of troubles I ran into with a vehicle that had MAF issues, and I assume that MAP and MAF are similar in their jobs for engine management.
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Bob Lincoln
Dodge Dakota
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2/05/2007
08:44:09
| RE: map sensor question
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The MAP (Manifold Air Pressure) sensor is an air pressure sensor connected to the manifold that converts negative pressure (vacuum) to a proportional voltage. At idle the voltage is high (somewhere around 4 volts) and at wide open throttle it drops to just about 1 volt (these are not exact figures). The computer uses this voltage signal at engine start and run, to select the proper air/fuel mix. It alters the air/fuel mix by changing the pulse width of the fuel injection firing, and at idle by moving the pintle (plunger) of the AIS motor.
It has a dramatic effect on air/fuel mixture, and if defective will usually cause very rich running, rough idle or stalling, and flooded restart.
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Mike Stager
Dodge Dakota
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2/05/2007
18:03:31
| RE: map sensor question
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Bob, I thank you. Everything you just said is what my truck is doing. Poor fuel mileage, IAC trouble code set, rough idle and flooded restarts on occasion. I will see if I can secure a replacement part and find out if my troubles are cured.
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Fasstdak
Dodge Dakota
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2/05/2007
21:58:06
| RE: map sensor question
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I don't know why they're giving you an aftermarket MAP sensor when even the Viper kits we install (1000+HP) use the factory MAP - the same MAP sensor that's on your truck. You can easily alter the MAP signal to compensate under light boost conditions or use an aftermarket programmable system (FAST, AEM, etc) to give the engine an even better tune to the new found boost (HP/TQ). Some kits now even come with their own controller...however, the Kenne Bell Optimizer system is pretty much garbage on modified engines...basically anything more than stock and their supercharger.
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Fasstdak
Dodge Dakota
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2/05/2007
22:02:08
| RE: map sensor question
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The MAP doesn't control everything...there's a long formula that's involved in the fuel control. Injector pulse-width is calculated based on various sensor inputs and also includes battery voltage.
Here they are:
SBEC/JTEC PCM
(RPM/Max RPM) x (MAP Baro) x (TPS x ECT x IAT x Sensed Battery Voltage x LTFT) x (Upstream O2) x (STFT x LTFT) = PW
NGC I/II/III PCM
(RPM/Max RPM) x (T-MAP Baro x EGR*) x (TPS x ECT x IAT x Sensed Battery Voltage x LTFT) x (Upstream O2) x (STFT x LTFT x Purge Vapor Ratio) = PW
* If equipped
LTFT is also calculated via the rear O2 sensor(s).
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boomer
Dodge Dakota
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2/06/2007
07:16:24
| RE: map sensor question
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I was thinkin that I have a MAP sensor problem also. my 98 throws a "multiple cylinder misfire" code every now and then but the engine light goes off after a couple of start ups. I already got some advice, but I'm thinkin I should go through and check every sensors connection and even apply some dielectric grease to all of them. at least I have an idea of what the MAP sensor does now.
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Fasstdaj
Dodge Dakota
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2/06/2007
07:44:45
| RE: map sensor question
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A misfire is a variation in crankshaft rotation. Yes, a sensor can cause the misfire due to fuel delivery problems...but so can a leaking intake plenum gasket, cracked head, fuel pump, or slipping serpentine belt. What do the fuel adaptives look like? (That'll tell you which direction to go.)
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Mike Stager
Dodge Dakota
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2/06/2007
19:05:06
|  RE: map sensor question
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Sounds like we got a guy with some good knowledge on the subject. Will a malfunctioning MAP sensor necessarily throw a code? I started my truck up today ( -3F ) and it wouldn't idle, and boy did she run RICH...blackened smoke and carbon on the snow behind me RICH. You could smell it. My mileage has gone into the crapper lately, so there is definetely something awry. It went to hell and a handbasket after I yanked the Catalytic converter out, so I know that is part of the problem, but got worse after replacing the O2 sensor ( and I'd like to know why my 97 only has ONE sensor AFTER the catalytic converter, and NO OTHER O2 sensors on an OBD2 truck, especially when my haynes manual says that all trucks have 2 sensors except the 5.9 which has 4 )
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trev1
Dodge Dakota
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2/06/2007
19:56:13
| RE: map sensor question
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OK, I understood until the math wizzard spat that out. Fasstdaj what is the "fuel Adaptives"? simple explination is all that I require (ASK). Although the above programming garb was a change of place.
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Fasstdak
Dodge Dakota
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2/06/2007
20:15:27
| RE: map sensor question
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Fuel Adaptives: Basically the fuel "adjustment" that the PCM calculates to deliver the correct mixture (that's the simple explanation).
Yes, I do know quite a bit on the inner workings of the dodge systems (I'm a lead dealership tech - Master Tech, Viper Specialist, and Mentor). Also have extensive knowledge on building up these engines - 3.9L up to 8.3L (and everything in between).
Yes, the MAP can operate abnormally without actually tripping a code. Best bet to find out if the MAP is bad - look on a scanner for the "BARO" reading at Key On/Engine OFF. It should be somewhere in between 29-30.5" on the average. If it's above that...either you're in a storm or it's malfunctioning. Voltage readings can be misleading at times - watch the BARO and manifold readings to know what's going on.
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Fasstdak
Dodge Dakota
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2/06/2007
20:33:04
| RE: map sensor question
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Mike...have you checked the coolant temp sensor to see if it's reading properly? Reason for asking is that it acts like the old fashioned chokes - under colder temperatures, it will richen up the mixture. If it reads too cold, but not cold enough to trip the MIL, it will richen the mixture too much. Also, an IAT sensor moved into the intake in that cold of weather will also cause issues like what you mentioned. (Happened to me.)
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Mike Stager
Dodge Dakota
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2/06/2007
21:37:16
| RE: map sensor question
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IAT hasn't been moved, and I questioned the Coolant sensor too, but haven't tried replacing it or testing it. A lot of my troubles were went the temps dropped below freezing, so I did wonder whether or not I was getting screwy readings from the IAT and the Coolant temp sensors. I was getting 18 mpg hiway this last fall when I bought the truck with the check engine light on the whole time. It suprised me when the truck started really acting up badly, the light went out and stays off ( yet I get 100m down the road and it acts like the fuel gets shut off and I get backfiring through the throttle body ).
Maybe you can tell me why I would feel a noticable increase of power once I hit 3000 rpm with the truck, regardless of what gear I'm in or how badly the truck is running around idle. Literally, I hit 3000rpm and it's like someone puts on a shot of nitros until it shifts ( obviously this is under some heavy throttle as it usually shifts around 3000rpm...the power increase goes straight up to 4500rpm and then I get the next gear shift ).
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Fasstdak
Dodge Dakota
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2/06/2007
21:50:12
| RE: map sensor question
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Without actually seeing what the fuel adaptives and other sensor readings look like, it's hard to say. Can't be a plugged cat or exhaust restriction as it would be the opposite of what you described. I know on my '97 V6 (with cam and other engine work), the power band is from 2800-5500rpm and it does feel really strong in that band. However, the stock cam should be strong from about 2000-4500 but it falls off after that - no need to shift a stock V6 any higher than that anyway.
The back firing could also be a lean condition. You have to remember, the fuel is controlled via O2 sensor input. If they're reading lean, the PCM will fatten up the mixture (rich) accordingly (simple explanation - much more math but you get the point).
Did you ever get the code(s) from when the MIL was on?
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Mike Stager
Dodge Dakota
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2/06/2007
23:47:08
| RE: map sensor question
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Yup, got codes for the IAC and the O2 sensor, which is why I replaced both of them. When I had the computer reset after replacing the O2 sensor, that's when I suddenly started having the driveability problems ( backfiring, loss of power after driving a few hundred yards ). The check engine light was on the whole time, and then driving to work one morning it went off and has stayed off, which really suprised me since it ran great with the light on when I bought the truck used a few months ago, then I get the computer reset, the light is still on and it runs like crap, and then the light goes off....it's just got me baffled, and without having the computer read with a proper scanner, I really am just trying to take my best educated guess as to what is really wrong with the truck.
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Fasstdak
Dodge Dakota
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2/07/2007
07:07:56
| RE: map sensor question
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You may want to have someone scan it with a scanner. You could be spending money that's not required - especially if you just start throwing parts at it.
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Mike Stager
Dodge Dakota
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2/07/2007
22:00:51
| RE: map sensor question
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I'll get it scanned. I threw parts at my wifes car trying to figure it out only to find out that the camshaft had snapped in half on us ( after pulling the heads and having the bent valve fixed and going through all the trouble of putting it back together ), just to end up replacing the motor...what a nightmare.
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