LT1-LT4 Modifications 1993-97 Gen II Small Block V8

Bad MAP Sensor?

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Old 09-24-2012, 08:38 AM
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Default Bad MAP Sensor?

well today i decided to take my 95 camaro z28 for a drive to a 1 hr location from home. Drove fine for 35 minutes. i was driving around 65mph. when all of a sudden car starts to backfire and just dies. after i got it towed. i plug in my code reader. i got error Code 33- MAP sensor signal voltage high. Check vacuum hoses to MAP sensor. Check wiring and connections for any shorts or opens. To replace sensor.( has not been replaced)

I have done whats stated above. Could this cause my car to die and not wanting to start back up? when i try to start it up it turns over.
fuel pressure is 42psi. replaced stock fuel pump with a walbro 255 like 9 months ago. as well as the optispark like 8 months ago.

I know the MAP sensor is a cheap part to buy. I just dont want to go out buying parts and get no results.
Could a bad MAP Sensor cause a no start?

Please help its my DD and i dont want to keep driving my dads Suburban, lol takes a bit to get use to. lol

Last edited by davidc212k; 09-24-2012 at 08:40 AM. Reason: forgot something to type.
Old 09-24-2012, 12:41 PM
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Often when the engine dies unexpectedly, you will get a MAP code. It is because the computer is expecting the engine to be running, but it is not. MAP sensors rarely are an issue. I can't say that it is not the sensor, but I would pursue normal no start troubleshooting methods first. You say the opti is relatively new, but did you actually check spark?
Old 09-24-2012, 04:22 PM
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I will check the ICM and the Coil tonight.
Can the MAP cause a spark plig wire to foul ?

Also, when the engine tries to turn over. it kinda sputters and throws out a bit of white smooke out of the CAI.

Last edited by davidc212k; 09-24-2012 at 04:50 PM.
Old 09-24-2012, 05:04 PM
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I had an issue this past thr. car was working fine all day and then just died on me just like that..In my case it was the ICM that crapped out..I did the cooling mod and added a new ign. coil and has been working great. swap out icm's if you have one.
Old 09-24-2012, 05:25 PM
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Originally Posted by jlpz
I had an issue this past thr. car was working fine all day and then just died on me just like that..In my case it was the ICM that crapped out..I did the cooling mod and added a new ign. coil and has been working great. swap out icm's if you have one.
My car suddenly died on the highway, had no tools to check it out. Thought it was the fuel pump, changed it, went home. Died in the driveway. Did some troubleshooting. Found it to be the MSD6AL randomly shutting down. Maybe getting hot. Check the ICM.
Old 09-25-2012, 08:15 AM
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well last night, since i had an extra ICM. from the junkyards, lol .
anyways. i switched ICM and it turned on the 2nd time i tried to crank it.
So i put the previous ICM back on and it did the same thing.
Today i will install the new MAP sensor i got and see the results.
Old 09-25-2012, 09:47 PM
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i swapped the MAP Sensor with a new one. no more error code. but car keeps stalling.
when it stalls or dies it kinda picks itself back up, sometimes. 8 months ago that i changed optispark it stated Code 16- Low resolution pulse (distributor). so optispark was replaced that time.
im not getting that error code this time. my dad states that it can be the timing chain is loose. sometimes when i try to crank it, sometimes it has difficulties to crank. a couple a tries does the trick. when it turns over and doesnt die. the rpm stays around 1000-800.
sometimes i push the gas for the rpms to move and no problem but sometimes it starts to studder like it wants to stall. then i try and start it up again its a no go or just takes a couple a key turns. for it to work and then it just dies. i will try and make a video tomorrow. its kinda difficult to explain. lol
Old 09-25-2012, 10:20 PM
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Originally Posted by davidc212k
i swapped the MAP Sensor with a new one. no more error code. but car keeps stalling.
when it stalls or dies it kinda picks itself back up, sometimes. 8 months ago that i changed optispark it stated Code 16- Low resolution pulse (distributor). so optispark was replaced that time.
im not getting that error code this time. my dad states that it can be the timing chain is loose. sometimes when i try to crank it, sometimes it has difficulties to crank. a couple a tries does the trick. when it turns over and doesnt die. the rpm stays around 1000-800.
sometimes i push the gas for the rpms to move and no problem but sometimes it starts to studder like it wants to stall. then i try and start it up again its a no go or just takes a couple a key turns. for it to work and then it just dies. i will try and make a video tomorrow. its kinda difficult to explain. lol
I'm currently working on a corvette lt1 that has that same issue your having. It was taking a while to crank over..I installed new plugs and car started right up with no issue..then it would start to stall out..for some reason. What I did next was check for arcing and sure enough 3 msd wires where pulsing with light..MSD sent 4 replacement wires for free..Might want to take a look at night and check the wires.
Old 09-25-2012, 10:29 PM
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Originally Posted by jlpz
I'm currently working on a corvette lt1 that has that same issue your having. It was taking a while to crank over..I installed new plugs and car started right up with no issue..then it would start to stall out..for some reason. What I did next was check for arcing and sure enough 3 msd wires where pulsing with light..MSD sent 4 replacement wires for free..Might want to take a look at night and check the wires.
I will double check each spark plug wire for spark and maybe some should foul and be the solution.

Here is a quick video. quality is horrid and its dark. please ignore my voice, lol.
http://www.youtube.com/watch?v=vfrRs...ature=youtu.be

Last edited by davidc212k; 09-25-2012 at 10:39 PM.
Old 09-26-2012, 07:39 PM
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well, i tested around 4 spark plug wires and they all have no spark, but car still turns over and engine runs?

i do remember that last time i changed optispark. before i changed it, it was the same result. after i changed it i still had no spark and it optispark ran fine for 8 months. it weird.

Last edited by davidc212k; 09-26-2012 at 08:02 PM.



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