Engine miss help!

[Ktm858]

I have an 85 T-Type and it had a pop under load so I was told to change the plugs and wires. so far I changed and did the following

plugs
wires
coil
all vacuum hoses
cleaned EGR Valve
cleaned fuel ? ( thing on bottom of throttle body that unscrews)

So now not only do I have the poping but I have a miss, anybody have any ideas what I should do next?

 

[Ktm858]

[I forgot I also changed the oxygen sensor and sprayed the MAS with cleaner.

 

[turbojd]

Is the firing order right? when you changed the wires.

 

[Ktm858]

Is the firing order right? when you changed the wires.

Yep I checked them when I changed the wires.

 

[turbojd]

Have you checked the ign. module.

 

[Ktm858]

Have you checked the ign. module.

I havent changed it and I didnt think there was any way to check it. I have been into antique cars for years so this is new to me. Im used to the old points system without all the electronics

 

[TurboBuRick]

Pull drivers side valve cover and check #3 exhaust rocker. Get a towel and lay it across the bottom of the head to catch any oil. Start the motor and look to see if all rockers (specially #3 exhaust) are moving the same.

These cars a notorious for wiping the #3 exhaust lobe. Sound like that could be your problem.

 

[Ktm858]

If it were that would it do it all of the time because the problem went away then came back

 

[Ktm858]

I have found the problem. The injector on the drivers side rear cylinder wasnt working at all. I took off the plug cleaned everything up and it ran fine again. Thanks for all the info guys.

 

[85TurboTtype]

How did you determine that this was the problem? I have a similar issue going on, but haven't changed the O2 sensor yet. I am getting code 13, so that is where I'm going to start.

 

[Ktm858]

My car kicked no codes but it had a bad miss. So I changed the plugs because I thought one might have fouled. Then took it for a ride and that wasnt it. With the engine running I pulled off every plug wire one at a time to see if the miss got worse. It did with all except one. I pulled that plug and it was just as it was when i put it in. I figured it wasnt getting fuel so I decided to check the injector and I unplugged it then pluged it back in and moved it around a little to check the wiring and that took care of that problem. I still though have a pop when that engine is under load. I changed the EGR and next is changing all the injectors.

 

[Monte231SS]

Not sure if this year has a similar cam sensor like the 86-87's? Check that if it does. I had a bad pop under throttle and was guided check the cam sensor from a fellow buick friend. Unplug the sensor while the car is running and see if it goes away. Make sure you plug it back when your done checking before you shut the car off or it will not start back up. I def. did have a bad cam sensor. Good luck

 

[Ktm858]

Yep that was it. It was a little bit of a pain to get to with the screws and all but I changed it and so far it runs fine. Thanks again

 

[bison]

If any of the injectors were not pulsing id think it would throw a lean exhaust after a while. Id throw a fresh set of injectors in any car that still had the originals or at least have them professionally cleaned and flowed

 

[Ktm858]

Eventually when I get the $$$ up they are the next thing to be changed.

 

[85TurboTtype]

Thanks

My car kicked no codes but it had a bad miss. So I changed the plugs because I thought one might have fouled. Then took it for a ride and that wasnt it. With the engine running I pulled off every plug wire one at a time to see if the miss got worse. It did with all except one. I pulled that plug and it was just as it was when i put it in. I figured it wasnt getting fuel so I decided to check the injector and I unplugged it then pluged it back in and moved it around a little to check the wiring and that took care of that problem. I still though have a pop when that engine is under load. I changed the EGR and next is changing all the injectors.

Thanks for the information on that. Sorry it took me so long to reply. I was on vacation.