LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

MAP is reading 93.4 KPa at idle?

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Old Oct 29, 2006 | 12:48 PM
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From: savannah ga
MAP is reading 93.4 KPa at idle?

ive just replaced my MAP sensor and got rid of my DTC 34. now my MAP is reading 93.4 KPa at idle just the same as the BAR and throwing a DTC 33.
ive re-adjusted my valves with the same results. what are the other possible mechanical causes for such a high MAP reading? is it impossible for a vacuum leak to cause such high MAP readings?

thanks
Old Oct 29, 2006 | 01:35 PM
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i forgot to add... my IAC counts are bouncing around between 120-150 or so. the car starts up and then dies within seconds. i can keep it running by giving the car gas.
ive already went around the intake with starting fluid and the idle has stayed the same. ive taken off the brake booster hose and plugged the hole with the same results.

could i have messed something up when i took my intake mianifold off for powder-coating? i removed the valley plate at the bottom but i didnt mess with the plugs.
Old Oct 29, 2006 | 04:02 PM
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i would say you have a major vacuum leak
Old Oct 29, 2006 | 04:15 PM
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I think you have some sort of wiring problem.... first you are getting 10kPA at idle, now you are getting 93kPa at idle. Did you do anything in between that would have affected the engine?

You said in the earlier thread on the problem (you really hurt your chances of getting good info/help when you start a new thread and people can't see all the previous steps that have been taken, or advice that has been given in trying to solve the problem) that you installed a new MAP sensor pigtail. Is it possible you somehow have the wires shorting together in your splice?

At least provide a link to the previous thread so people can follow along and not backtrack into theinkgs that have already been checked:

http://64.65.63.61/forums/showthread.php?t=480313
Old Oct 29, 2006 | 06:17 PM
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you really hurt your chances of getting good info/help when you start a new thread and people can't see all the previous steps that have been taken, or advice that has been given in trying to solve the problem
thanks for the advice,...i did that only because i thought the DTC 34 was a wiring problem and i thought it was solved. i thought my real problem was the issue causing the DTC 33. thanks for adding the link.

earlier today i found that i did have a problem with my MAP pigtail. after wiggling the pigtail around i got it to read correctly.

now my MAP KPa is bouncing around between 38-65 with me giving the car gas and the BAR is 101.5. the car still does not want to idle and i am now getting both DTC 33 and 34 (im not sure how that is possible). im wondering now if the one or both of the codes are just stored and need to be cleared.
my IAC is now moving around from 30 to 160 counts.

i re-adjusted my rockers again today to be extra sure. im running stock lifters and ive tried 3/4, 1/2 and 1/4 past 0 lash. right now i have them set at 0 lash, i dont see how my valve adjustment could be causing the problem but im out of ideas as to what else it could be.

i'll clear the codes tomorrow and see if they come back.
Old Oct 30, 2006 | 11:33 AM
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Clear the ECM to get rid of the stored codes, and to reset the long term fuel corrections.
Old Nov 1, 2006 | 04:23 PM
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i reset the ECM today. i started the car up and its running very badly. im getting random backfires. my MAP codes are staying gone and my LT and SL counts are at 128. im guessing i have some kind of mechanical issue now but im at a loss. ive checked my plug wires so far and they're fine. valve lash is good.
i guess i'll take my opti cover off and make sure its on correctly and check my fuel pressure. i know my cam is installed correctly. the car was running without any misses before my intake was taken off for powdercoating, im not sure of all the malfunction possibilities that can cause a backfire so if anyone has any more suggestions.....thanks
Old Nov 1, 2006 | 09:21 PM
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i just found that my fuel pump has burnt up due to an incorrect reading on my fuel gauge. turns out i was pretty close to empty and that probably had a major part in the way the car way acting. i'll install a new pump and see where that takes me.
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