• The site migration is complete! Hopefully everything transferred properly from the multiple decades old software we were using before. If you notice any issues please let me know, thanks! Also, I'm still working on things like chatbox, etc so hopefully those will be working in the next week or two.

bad map sensor?



haha my car wont start at all good crank no start condition. not to sure if its the map itself but just an idea...as for other symptoms maybe someone else can chime in?
 
Scan the car at idle and see what it says.

Scan the car when it's off and see what it says, and confrim it with a boost/vacuum gauge.

I don't think I've ever seen a map go bad ! !
 
thank u finally someone answered,my reason for asking is my boost indicator light on DIC is acting screwy...and i was told it could be a bad MAP.Im not getting a code as of now.I just wanna double check and make sure before i blow 50 bucks on sensor that this could be causing my boost light not to work.
 


gtpinsc, I spent a good chunk of the evening yesterday searching for symptoms and causes of a bad MAP sensor and I looked through so many articles, forum posts, etc that I thought I was going to dream about map sensors.

The think I learned in all that is that it must be one of the most mysterious sensors in the engine bay because virtually no one seems to know. In the hours I literally spent yesterday looking for something the best I could come up with is that it would cause some driveability issues and/or fueling issues which I know is probably about as vague as it can get.

Its probably why there were so few responses to your inquiry, there just doesnt seem to be a lot of info on them in relation to troubleshooting and Im just as guilty as I cant say I know much more. I will agree with Meemperor in that I do not believe I have ever seen one go bad.

I'll keep digging around when I can and see what I can come up with, Im kinda curious myself to be honest if for no other reason than Im not caught off guard when I do come across one that has actually failed.
 
Thanks man i appreciate it,i was talking with a buddy of mine whos a mechanic and he basically said the same you did.Can you think of anything else that would cause boost indicator light to not work?It lights up all the way on a start up,but under any kind of throttle it doesnt do anything.Not a big deal,but i like to have everything in working order.
 
SyntheticShield said:
Restriction in air flow, or maybe a vacuum line that isnt quite 100% connected well are my best guesses at this point.
Click to expand...

Ok so i looked around under the hood and didnt see any loose or disconnected vaccuum lines.Do you happen to have one of those nifty diagrams for vac, lines?As for air flow restriction,where should i start looking?When you say that,all i can think of is from intake to the throttle body.Thanks in advance.
 


Well i just cleaned my air filter a few months ago,cleaned MAF and throttle body a few days ago.I only found about 3 or 4 vac. lines.Do you know how many vac lines there is on a GTP?
 
Not off the top of my head. I know its not a huge number. Theres the big one from the brake booster. Theres a couple on the supercharger and then ones that go from the map around to the LIM and then to the FPR. Thats all I can think of off the top of my head.
 
yea that seems like the ones i found,im lost as to what can cause my light to not work.Im getting boost and as i said before it lights all the way up on a start up.Ive had sevral problems in the past few months as you have seen in my threads.Im starting to think its my PCM causing all of this.I havent been able to find a stock one locally.I want to go to GA and get a custom tune from TDC but not sure if it would be worth the drive if these problems arent PCM related.I sent him a PM with my symptoms for his input.Ill go ahead and post them up here to get feedback from you and other members

The past month my GTP has started acting really funny.It has thrown numerous throttle pos. sensor codes.After replacing the sensor twice it still keeps popping codes,one day i had the idea to reset PCM and see what happens.It obviously cleared the code but it killed all the other symptoms of a bad TPS also for example transmission slippage,rough idle etc etc.At speeds from around 30 mph to 60 mph the trans has some intermittent off the wall shift points.For instance it feels like it upshifts wayyyy too early.Seems like it is in 4th gear from the speeds of 30mph and up and erratically downshifts and upshifts until i get over 60 mph.Sometimes when i go WOT to pass someone it will stumble hard for a few seconds then downshift to proper gear.My boost indicator light on DIC has stopped working since all these other problems have come to light.Boost light will come on at a start,but fails to work any other time.I know everything on these cars is all pretty much electronic and a minor problem in one area can cause other problems in other areas such as TPS causing trans problems ETC.Doubt its of any significance but i got the ABS light on and trac light off also.My question is can a bad PCM cause these problems?Im not getting any SES lights except when TPS starts acting screwy.I also had EPC solenoid in trans replaced a few months ago.
 
gtpinsc said:
yea that seems like the ones i found, im lost as to what can cause my light to not work. Im getting boost and as i said before it lights all the way up on a start up.
Boost light will come on at a start,but fails to work any other time.
Click to expand...

Hello, I'm having a similar boost meter problem and can't seem to find any info. It worka fine for awhile, but if I cruise on the highway or sit too long, the meter starts to jump all over, full boost to none, like a little lightning storm on my dash. The idle usually gets rough about the same time, and if I'm on the highway it starts lurching and has died on me a half-dozen times. I recently bought and installed a Racetronix fuel pump, since everyone I asked seemed to think mine was going bad. It ran fine a couple days, but as soon as I sat at the taco bell drive-thru on a hot Saturday, it acted out again like before. I've recently replaced the fuel filter, so I'd like to rule that out. I've been advised to change to MAP next, but no one seems to know why my boost meter is acting up. Did you ever find a solution for yours?
 
gtpinsc hasn't been on since 08-25-2012. If a search hasn't turned anything up please start a new post and we'll see what we can do. Be sure to include the year and any mods of your GTP. My thought is either you have a vac. leak somewhere or the fuel pressure is dying off, or worst case a failing ECM.
 


An engine with a bad MAF sensor may be hard to start or stall after starting. It may hesitate under load, surge, idle rough or run excessively rich or lean. The engine may also hiccup when the throttle suddenly changes position. A maf problem should but not always set a code. Right now mine is hunting for idle and will eventually stall after a few surges. Mine has readings in hptuners. I unplug the maf and it's a lot better but not 100%. I have one on order and will be here on Tuesday so I will know for sure then. From what I've read, theses 3800's commonly have a maf failure problem. Here's how to test.

Part 1 -MAF Sensor Test (P0101, P0102, P0103): GM 3.8L (1996-2005).
 
Last edited:
The map sensor on the grand prix is used to show boost and for the EGR monitor.. on the normally aspirated go it's used only for the EGR monitor, readiness monitor and code setting. If your boost gauge is full all the time just unplug the map sensor and if the boost gauge drops then replace your map sensor. I know this is an old thread but figured I would respond so anyone searching for a fix can see this post even though it may not help you anymore.. the super charged 3800s have 2 map sensors. 1 is a barometer to measure outside air pressure and doesn't have a hose connected to it. The 2nd one does have a hose connected to it running to the intake manifold, a full boost gauge on idle will only be caused by a bad map sensor, shorted wires or bad pcm.. so unplug it and see what happens
 
You must log in or register to reply here.
Back
Top