Hesitation at 1200-1600 rpm 1995 Grand Am GT 3100

[IsaacHayes]

Eh, they'd have to be worn pretty bad for the valves not to open, and why just on those lobes? I'd look into spark stuff or injectors more. Especially since junkyard injectors likely have sat for a long time and might be stuck... Swap in your original ones..

or check the CPS like I said and other stuff some more.

[JoeMechanic]

Too much work..how about if I just clean them with one of those Injector cleaning tools where you pour in GM Top Cleaner and plug it into compressed air.you know a professional tool.I saw one at harbor freight for about $120..but I won't buy that..My friend will lend me his snap on one..he has a garage 2 miles from me.

[JoeMechanic]

Hey thanks for all your help..I am thinking Injector problem..if #6 plug looks clean as if not firing..#6 injector probably isn't working..make sense to me.

[IsaacHayes]

I guess if there is no fuel burning then that's a possibility. Never seen plugs that had no fuel but were still sparking. I guess they would erode fast and get hot looking is my guess....

It's not that much work removing the injectors, just have to be careful and take your time. Take the clips off and pry up on the fuel rail with a screwdriver. They will pop out of the rail then you can remove that and pull them out by hand easily out of the intake. Make sure to vacuum the dirty out before you pull the injector it doesn't fall down into the intake.

It may take some time but it will be worth it if it fixes it and you aren't chasing your tail and wasting time anymore.

[JoeMechanic]

Thanks IH..I talked to my brother and he suggests

that I do exactally as you suggest.He has two mini vans 1 is a montana and other is a venture both with 3100 motors.He did that and said its not too bad and replace the orings while I'm at it.I just picked up a new fuel pump and thats what I am changing on Monday first.I will see if that helps any first and if not out come the injectors.About the dirt that may fall in..This engine doesn't have any..I cleaned all the grease and painted the block black when I brought it home from wrecking yard..It looks like a brand new motor..I take pride in my work.I will put rags on the intake injector holes just to be safe,Joe.

[gpse3400]

..An engine is an engine....If you have spark all around and stll not igniting that cylinder then you have bad injector. OBD2 is not a bad thing, the fact that it can tell you of a misfire save you a whole bunch of time.

[JoeMechanic]

GM's better Idea..this car has OBD 1.5 and no SES

light illuminated.If it had OBD2 I have a scanner for that and would have pulled up the code for the injector and saved me alot of time and aggravation.This vehicle Has about 39-40 Fuel Pump PSI Key On Engine OFF and slightly better with Engine ON vacuum disconnect from regulator.I am taking injector's and fuel rail out tomorrow as well as replacing fuel pump with a brand new one.Isaac Hayes gave me a great idea to pull off rail and place cardboard underneath and have someone turn key on to see injector spray pattern which should be a misty swath and even accross the cardboard all 6 cylinders should spray pretty evenly.I have 6 Injectors from old engine and manifolds,heads,block..anyone need any parts?..lol.

Fuel Pump Pressure spec is 41-47 PSI Ignition On Engine Off.

[JoeMechanic]

Oops,By No SES light illumination I mean it works fine just no codes set..which means I did a good job and didn't miss any wiring plugs .

[IsaacHayes]

With these "obd 1.5" you HAVE to use a scanner the paper clip trick does not work. If you have a laptop and ALDL cable you can get tuner pro RT and the def file for 3100' to scan though.

[94GPGTP]

With these "obd 1.5" you HAVE to use a scanner the paper clip trick does not work. If you have a laptop and ALDL cable you can get tuner pro RT and the def file for 3100' to scan though.

IsaacHayes where can i get that setup and how much will it cost me for it to work on my laptop?

[IsaacHayes]

http://tunerpro.markmansur.com/downloadApp.htm

the def:

http://tunerpro.markmansur.com/download/datastreams/1FA.ads

And you'll need a 8192 baud ALDL cable. Do a search for ALDL cable circuit to build your own or check the links section on the tunerpro website I think they list some places that sell pre-made cables.

I suggest one with the max232 chip over the 2 transistor circuit and one that has external power as it will be the most compatible with all laptops/etc.

And that's it really.

[JoeMechanic]

I downloaded tunerpro and tunerprort on my desktop

I didn't know its free..there is a $30 donation charge but its if you choose to donate.I don't see anything related to automobiles on it..I guess I have to get a laptop and cable to interface with cars ECM first right?.I've seen those cables that come with software advertised for $100..my sister in law has a laptop I want to try this..this is awesome,Joe.

[IsaacHayes]

Yes the ALDL cable interfaces with the car and laptop. Make sure you have a serial port on the laptop if not you'll need to get a USB cable and install the drivers that come with it. Or get a USB to serial adapter but I would only try those on cables that are self powered as I've heard of people not having luck with the adpaters all the time. The cables without external power steal it from the serial port and the usb adapters may not provide that power to steal from..