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1997 grand prix engine problems

  
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1997 grand prix engine problems

 
ktolsenk06 ktolsenk06
New User | Posts: 1 | Joined: 12/13
Posted: 12/31/13
08:07 AM

I currently live in MN and the winters are very cold. in the morning when starting my vehicle the rpm jumps up to 2000 then will keep rising. I have to let it warm up for a few minutes like this till I can shut it off and restart the car and the rpm's go back to normal. can anyone help me with this problem ?

**the check engine light is on and has been before this problem has started  

wayne712222 wayne712222
Moderator | Posts: 187 | Joined: 10/13
Posted: 12/31/13
08:50 AM

first thing is to check the codes stored in the computer.. it sees a problem..


next is to examine the live data stream with the scan tool.

look at the Throttle position sensor voltage...

look at the IAC counts.. i am running thru my head and i don't recall these are always displayed..

you may end up just swapping out the idle air control motor for a new one.. its just two screws..

you will also want to look at the ECT.. Engine coolant temp sensor.. perhaps even replace it..  

what .. why.. when you turn the key off.. the computer backs the Idle air control valve to somewhere around 120 counts ... this is 120 steps from CLOSED.. this is cold start position..    so the engine goes directly to fast idle...

as soon as it starts the computer starts commanding the idle air closed.. this brings the idle speed down..

please.. if your scan tool in live data mode displays IAC...

with the engine warmed up to operating temp..  over 185F..
with the throttle closed..  TPS voltage below 1.00 volts.. usually around 0.55 to 0.75 volts..

the transmission in park or neutral..

the IAC idle air counts should be between 20 and 50.. this shows that the base idle is set properly.. the what.. the idle stop screw that changes the angle of the closed position of the throttle blade..  and that there are no extra AIR LEAKS..


you will want to clean your throttle body blade and bore also..  spraying brake or carb cleaner on a rag and wiping the throttle bore. and the blade... without spraying excessive into the throttle body.. which can damage the throttle position sensor.



during cold start up.. the

these are kinda generic for all cars.. but its a good list to explain what you are looking for..


Obd2scandatachart Zps65411833

Obd2scandatachart2 Zps6e93e7de  

shyrgfuh70 shyrgfuh70
User | Posts: 93 | Joined: 12/13
Posted: 12/31/13
03:31 PM

Hi,

In my experience it typically throws a general code like 53 or 54 etc. Either way, I would replace the oxygen sensor with oxy senser safe silicone. This fixed 80% of my lite problems and if you have over 80k on the sensor you likely need one irregardless.

After replacing it disconnect the battery for at least 10 minutes. This will reset some computers and the lite.

This will likely NOT fix your idle problem though.

You can also check the codes with a paper clip on some models. Done it dozens of times. You simply need to plug it into the correct slots. The lite will flash the code. Example, 53 will be 5 flashes followed by a few seconds of nothing then 3 flashes.  

idrivejunk idrivejunk
Addict | Posts: 5000 | Joined: 12/09
Posted: 12/31/13
06:32 PM

Yeah first thing to do is find out why the car has turned the check engine light on. The first thing I would look at is the fuel regulator vacuum harness and the super-long plastic vacuum pipe that runs over the right strut tower and along the firewall into the car. Typically at the age yours are, the lines are easily snapped in two or cracked due to deterioration. Breaks can be sleeved with the right size vacuum hose though. There is an EVAP canister behind the left rear wheel that can cause a high idle if faulty. A code reader will never tell you "theres a vacuum leak" but as Wayne explained, it will if you apply mechanic's skill and put two and two together. You pretty much have to have some level of diagnostic tool to find out what the car says is wrong. Parts stores usually have one and will hook it up to your car, they sell parts that way.  
idrivejunk