Vac Line

Where is the Vaccum line on the GT>GP i read Vac leaks can cause Mifire and i'm tryin everything to fix my misifire problem< PO 300 muitiple/Random> i erase the code and it comes back it doesnt say a specfic cylinder< it alway say Multiple < when the car is warmed up upon accleration>

There are many vacuum lines. There is an accessory line that feeds the HVAC system from the intake manifold. On the throttle body are vacuum lines that go to the fuel pressure regulator and evaporative emissions system. Good engine vacuum is a result of how healthy the engine is both electrically and mechanically. Poor engine vacuum could cause misfire or other issues.

The best way to check engine vacuum is with an automotive vacuum gauge. It is marked from 0 - 30 in hg. Good engine vacuum ranges from nothing less than 15 - 22 in hg at idle and after engine warmup. A clogged CAT convertor or restricted exhaust cause cause abnormal engine vacuum. Also, bad intake manifold gaskets (UIM/LIM) to include throttle body.

You may want to look for another reason such as bad plugs, wires or coils along with the vacuum leak. Plugs and wires are the most common cause of random misfires. If they are new you may want to look at the coils as a possible cause.

You may want to look for another reason such as bad plugs, wires or coils along with the vacuum leak. Plugs and wires are the most common cause of random misfires. If they are new you may want to look at the coils as a possible cause.


Lynn he has BTDT. He has multiple posts on the issue. Here is one and if you look easy enough there are others.

http://www.automotiveforums.com/vbulletin/showthread.php?t=573443

I have New Sensors ( IAT < no cat 02 simulator, front 02 sensor) New Spark Plugs and wires, Coils all seems to fire i made the mistake of taking them off one by one to see if the spark anf they do) Lucus fuel injector cleaner, fuel filter) i wanted to try new fuel injector but the price is too much right now 99 dollars a peiece from autoZone. ZZperformance sell them for the GTP 159 for six< well they fit a Gt without a bigger TH body, or MAF, i wanna try a new MAF sensor also. I really dont wanna take it to a dealership b/cuz i know there just going to replace everything i replaced to fix the problem and charge me for it.

I have New Sensors ( IAT < no cat 02 simulator, front 02 sensor) New Spark Plugs and wires, Coils all seems to fire i made the mistake of taking them off one by one to see if the spark anf they do) Lucus fuel injector cleaner, fuel filter) i wanted to try new fuel injector but the price is too much right now 99 dollars a peiece from autoZone. ZZperformance sell them for the GTP 159 for six< well they fit a Gt without a bigger TH body, or MAF, i wanna try a new MAF sensor also. I really dont wanna take it to a dealership b/cuz i know there just going to replace everything i replaced to fix the problem and charge me for it.

NO!!!! You cannot use L67 fuel injectors in a GT L36. GTP injectors are rated at 33# lbs. GT are only 22# lb. Plus the PCM must be re-programmed for the bigger injectors.

On the MAF sensor try this test. With ignition off, just unplug it. Let the connector dangle. Then fire her up and take it for a spin. If the cutout/misfire disappears then it is the MAF sensor, if it doesn't change then do not waste your money or time and effort at least on the MAF.

Here is some advice. Sometimes there comes a time when you need to get it to a Pro. A lot of us have been trying to help you for a while now.

Yeah i appericate the help< and i dont have the money to take it to the pros< thats why i've been trying to do the little stuff b4 i do that. ( Well It didnt even start without the MAF plugged up and i tried it with it started up already and it crunk up but when i put it into to gear it started acting crazy. so i just turned it off

I going to get my injectors Professionaly Cleaned< and if that dont work i'll just take it to a dealership< thanks for all the help> but i wont be asking for any other help in the furture>>>..>.? But thanks for everything i know ya'll getting tierd of me asking question on the same topic.