Car wont start need help erratic rpm

[justin10morrissey]

hello im new to the forum. i recently bought an 2004 grand prix gt that was supercharged from the factory i am fairly familiar with these motors as ive owned two ssei's before the other day as i was driving the car started to surge dropping from 1500 rpms to 500 then it died. it started back up and barely made it to work. the rpms were very erratic. after work the car would not start it just turned over and over. finally started with the help of keepin it going like it was carbed. couldnt find any unplugged vaccum lines. new 3" downpipe with cat installed bout a month ago it has a slight leak at the front. water pump replaced 3 days ago tensioner pulley is loose and makes a little noise. and a CAI was installed on the car before purchase. any help on this would be very much appreciated i dont want to regret purchasing my first grand prix

[Fivefingerdeathpunch]

clean your throttle body and maf sensor

does cai by chance have a oiled filter?

if so that harms maf sensors and can cause issues.

[CTKGP09]

sounds like a shotty MAF sensor, i say unplug it and see if it runs better, if so clean or replace it

[BillBoost37]

Coming from the Ei world myself..I can sarcastically say..you made a mistake...lol

It does sound MAF sensor ish.

[justin10morrissey]

okay i will give that a try today cleaning the air filter the maf and the throttle body i think what happend was when i blew those coolant elbows maybe the steam from the coolant entered the intake and dirtied up those parts will post results later today

[Hixc]

try checking the fuel pressure, It should be in a range of 48-55 psi. any check engine light?

[justin10morrissey]

okay cleaning out the throttle body no help. i unplugged the MAF sensor and nothin couldnt even get it started. will be checking fuel pressure tomorrow really need to get this baby back on the road i just bought some new purtty wheels

[justin10morrissey]

also no check engine lights. im thinkin possibly clogged fuel filter or bad fuel pump

[justin10morrissey]

clean your throttle body and maf sensor

does cai by chance have a oiled filter?

if so that harms maf sensors and can cause issues.

its a weapon R intake not sure if its oiled or not but i dont think so

[Scottydoggs]

when was your last tune up? check that the wires are not laying on the manifolds too.

could be a fuel problem as stated earlier.

[max98]

mine done the same thing i removed the relays and cleaned them and have not had a issue with it any more

[justin10morrissey]

when was your last tune up? check that the wires are not laying on the manifolds too.

could be a fuel problem as stated earlier.

have only owned the car for 2 months havnt changed plugs just two oil changes and the downpipe and water pump the wires seem fairly new as theyre performance 7mm pulled a plug and saw normal wear no bad signs there. also when trying to start puff of white smoke came out of CAI filter i think it was just a misfire. not quite sure if im getting fuel i can only here it prime to where the fuel filter is but not in the engine bay

[Cstealth]

I may have the answer to your problem, i had the same problem with my car, and after replacing everything, it was so simple to fix, the problem might be the fuel resistor... the resistor is located in the right-side Qauter panel, right behind the headlight. the resistor looks like a white horseshoe or U-shaped Magnet with a2 wires coming out of itand a connectio at the end. one bolt holds it the the right Qauter panel. this may do the trick and will only cost you around $40 Bucks... Good luck!

[justin10morrissey]

pulled p1518 code today think thats the direction of the problem

[justin10morrissey]

Coming from the Ei world myself..I can sarcastically say..you made a mistake...lol

It does sound MAF sensor ish.

ehh i do like the looks of the new grand prix much better than my older bonnies

[justin10morrissey]

p1518 is no link between the electronic throttle control and the pcm

[justin10morrissey]

anything guys i just replaced the electronic throttle body

[coolone]

Was there an issue over heating engine prior to fixing or replacing pump? Just curious... Crank positioning sensor is sensitive to high heat temps... Not as common a problem but It's something I ran into with my old GP... Just sayin. But others might be able to chime in better on this suggestion? But if it goes, you will see erratic rpm's and even the engine shutting down and not starting cause the computer doesn't know the actual rpms of crank and firing position, etc...

Hope you find solution!

[CTKGP09]

maybe its fuel related? regulator or pump? injector?

[Hixc]

sounds possible that it could be the fuel pump resistor, i had it happen on my sisters gtp. Here is a guide i found to help you locate it.

http://ww2.justanswer.com/uploads/Bl...p_resistor.pdf