Chrysler to continue using MAP sensors

[StevieC]

My '95 Neon is on it's second one and they were OEM replacements because my dad gets Chrysler discount for being a retiree.

Anyways... I can tell you they err on the side of lean-ness and I think adjust with the 02 sensor because I haven't seen a neon not pass the emissions test even with the EGR not working, and they seem to spend more time in the "LEAN" side on the rich/lean monitor.

 

[dishdude]

I remember being amazed when I bought my Neon in 94 that it didn't have a vacuum line going to the MAP sensor!

 

[StevieC]

Yeah it's right on the engine, a great idea from Chrysler but I think it was because they learned good and hard with the 2.5's & 2.2's and 3.0L's how bad condensation in the hose leading from the engine to the fire-wall could be as well has how bad the hose could crack over-time and create a leak.

 

[CBR.worm]

Many MAF equipped cars also have MAP sensors, one in the manifold and one in free air.

Remember the old spring loaded vane type air flow meters? Talk about restriction. And slow response.

Even better, remember the mechanical Bosch fuel injection with a fuel distributor and the spring loaded flap that regulated the fuel at the distributor?

 

[Nick R]

13 Year old cavalier with 136k miles still has original MAP sensor, no signs of trouble from it.

 

[OVERKILL]

Originally Posted By: Nick R
13 Year old cavalier with 136k miles still has original MAP sensor, no signs of trouble from it.


BAH! I have TWO 80's MAP sensors (though both were last functioning as BAP sensors, since they are the same device during the 80's and early 90's in EEC-IV Ford's)

One from 1987, the second from 1989. Both work perfectly. Both have well in excess of 300,000Km on them.

 

[StevieC]

Originally Posted By: CBR.worm
...

Even better, remember the mechanical Bosch fuel injection with a fuel distributor and the spring loaded flap that regulated the fuel at the distributor?


Yes I have one of these with the "Fuel regulator air bowl flap". It runs great and passes emission test every 2 years with flying colours and it has almost 200K KM's (120K miles) on it. It's an '89 and I wouldn't trade it for the world.

Was some ingenious technology at the time while others were still messing around with carburetors and poor quality electronic injection.

 

[VNTS]

Originally Posted By: StevieC
Maybe they would give us a calibration POT that we could turn.

I would buy a Chrysler for sure!


Let see my cars:

86 TurboZ 130K miles still original MAP, with reworked custom Cal based on Shelby GLHS Stg 2 cal for 20 PSI Boost

89 Shadow 272K miles I replaced 1 MAP, run custom Cal for +20 injectors and 20 PSI

89 SPirit Turbo, sold it but had orignal MAP at 185K, was still running to person sold it to and last I knew had over 200K miles

90 Daytona, I replaced the MAP once in 140K, still have car

00 Durango still orignal MAP only 50K

02 Jeep Still orignal MAP only 55K

03 PT GT Stage 1 computer 101K Still original MAP

06 PT GT orignal MAP only 45K miles

Thew newer Mopar you can get a Diablo Sport with custom Cals, Speed density system have some advantages. Older stuff has been hacked and you can burn your own chips and socket the LM, SMECS, SBECs etc I have a cal for a 3 BAR MAP sensor so I can run+40 injectors, bigger Turbo and 25 PSI of boost on one of my projects if I can ever get to it LOL

 

[scurvy]

Originally Posted By: StevieC
Japanese seem to have success with MAF sensors for long mileages and I have seen lots of MAP sensors go bad because of condensation, broken/cracked pressure lines.

Your thoughts?
Sounds like shoddy sensor design.

My cars have both MAP & MAF sensors, never a hiccup.

Lots of VWs have busted MAFs due to morons installing K&Ns or warm air intakes but if you leave the excellent oversized OEM filter alone they both seem to live quite long lives. I really only hear about folks replacing MAP sensors when they upgrade to a bigger turbo (going from a 2 bar MAP to a 2.5 or 3 bar sensor).

 

[dhise]

Originally Posted By: CBR.worm
Many MAF equipped cars also have MAP sensors, one in the manifold and one in free air.


My subaru has both and until I read this article it always puzzled me why they did that.

 

[StevieC]

I was kinda puzzled too that my Santa Fe has both until I read it... I had thought it was because it was more accurate and easier for the ECM to figure out if one of them was buggered because they could reference 1 versus the other. Now I know I'm right.

 

[JetStar]

Originally Posted By: mechanicx
Originally Posted By: JTK
Originally Posted By: mechanicx
.. I don't think bikes hold the A/F nearly as tightly contolled as cars.


I wonder if they err on the rich side? You'd think even a few seconds of a lean condition when those bike engines are SCREAMING would turn them into molten metal madness.

Joel


That'd be my guess. Honestly I'm not familar with FI bikes and their emissions requirements. they can't have much of any emission requirements because they still sell new carbureted bikes with no emission controls. The FI bikes don't have an o2 sensor? They don't have a CAT either so there's no need for them to cruise at at around 14.7:1. They could cruise safely leaner than that for gas mileage, if allowed, but would need to go richer like all engines at load. Without as many sensors they'd probably go rich quickly on throttle transition and load.


My FJR and FZ1 both have factory cats and O2 sensors as well as MAP, TPS, Barometric pressure, as well as IAT sensors. The Warrior has all the above minus the cats and O2 sensors (open loop). All three are speed density and are not N-Alpha. Here is some text from a car craft article on the N-Alpha system (pretty crude).
N Alpha
A relatively simple design, N Alpha systems use only engine speed and throttle angle to calculate the amount of fuel needed by the engine. This system doesn’t measure airflow directly; instead, engine load is assumed based on throttle-angle versus engine rpm. The various load-rpm points make up the computer’s lookup table, with the amount of fuel needed at each point manually programmed by the tuner. N Alpha systems work well on engines that operate primarily at wide-open throttle—such as race cars—but are much less accurate at part-throttle than more sophisticated systems because of their relatively simple fuel map. They generally do not have a closed-loop mode for air/fuel correction, resulting in part-throttle calibration that is crude at best when compared to other systems. This also makes them incompatible with modern catalytic converters. Any significant engine change requires remapping.

Additionally: The "Alpha" indicates the angle of the throttle plates and the "N" indicates RPM, no other sensors are used in this sytem.

 

[brianl703]

I think Ford vehicles go into N-Alpha mode when you unplug the MAF. They will run with the MAF unplugged.

 

[01rangerxl]

My parents had an '86 Ranger that used a MAP sensor with its EFI 2.3L Lima I4. It usually started up right away, but would often stall shortly after, and was generally cranky in the mornings, especially in the cold. Maintenance was very poor on this truck though. I think the ONLY maintenance ever done on this truck was oil changes and air filters.

My Fords have all had MAF sensors...3.0 Vulcan V6, 2.5L Lima I4, and 4.0 OHV V6. I have never replaced a MAF sensor or had any problems from one. All of my trucks have passed emissions without any trouble, and don't stall. MAF sensors have worked great for me.

 

[StevieC]

Originally Posted By: brianl703
I think Ford vehicles go into N-Alpha mode when you unplug the MAF. They will run with the MAF unplugged.
You do that on a "GM" and it goes into "I'm not your friend" mode and starts acting like a spoiled kid!

 

[JetStar]

I don't know about cars, but the Delphi produced FI systems on Harleys can go into either N-Alpha mode or Speed Density mode depending on engine parameters or conditions from what I have read. So I guess it is possible for these systems to switch mode for the best fuel control.

 

[mechanicx]

Originally Posted By: StevieC
Originally Posted By: brianl703
I think Ford vehicles go into N-Alpha mode when you unplug the MAF. They will run with the MAF unplugged.
You do that on a "GM" and it goes into "I'm not your friend" mode and starts acting like a spoiled kid!

I think the technical term is limp home mode lol. Some of the GM seem to run OK without a MAF or MAP sensor working by substituting an expected value for the sensor. Really though when you go into power mode and WOT, MAP sensor FI systems are in open loop and basically are in N-Alpha mode. I think N-Alpha can include BAP, coolant temp, IAT, but not MAP, MAF or O2 of course.

 

[StevieC]

N-Alpha mode = Fine I will take you home, but I'm not going to like it and I will complain the whole way so there!

 

[Ben99GT]

Originally Posted By: SteveSRT8
MAF is a restriction in the intake which can be an issue for some big breathers.


Slot/card style MAFs fixed that issue as they can be fitted into any diameter inlet tube you can build.

 

[brianl703]

Originally Posted By: mechanicx
Really though when you go into power mode and WOT, MAP sensor FI systems are in open loop and basically are in N-Alpha mode. I think N-Alpha can include BAP, coolant temp, IAT, but not MAP, MAF or O2 of course.


They can (and do) still apply learned fuel trim corrections at WOT by extrapolating the fuel tables.