Ok Im stumped..

The Green GT · Feb 24, 2006

My car started shaking about a week ago. I thought it might be the HB so I was redy to change it. I had checked the wires loke 3 times but I decided why not one more time. It stopped shaking... Then a few days later, it started back again, but not as bad. It vibrates pretty hard around 4500 RPM and 800-1000 RPM. and shakes a good bit throughout the whole band.

I just got finished pulling all the plugs to see if any of them were fouled out cause I could swear it felt like it was running on 7 cyl. I pulled them all and not one of them were fouled out. I dont know what to look for next. Any suggestions are welcome.

The Green GT · Feb 24, 2006

Ok I just found a broken vaccum line for the smog pump. there is a something behind the alternator (dont know what to call it) and the vaccum hose on it is broken. that shouldnt be causing it should it. It was disconnected wheni got the car and I just found the hose and reconnected it yesterday and today I saw that it was broken.

bill302 · Feb 24, 2006

mine done the same as yours did i had bought a new master blaster coil it was bad and shorting at higher rpms but not all the time. have someone rev. the engine to 800-1000 RPM and watch wires and coil for a short (glowing spark) it also needs to be dark as possible.....goodluck

HISSIN50 · Feb 24, 2006

The EGR vac lines and a couple others (IIRC) run from the TB area down behind the alt, where they exit stage right (towards the pass fender) and go inside the fender liner to a vac distribution block dealie.

If the vac line to the EGR is not functional, it is possible that you could get part throttle detonation. Not sure that it could cause a miss though.

If it misses at idle, run the codes and do the CBT and let the computer tell you which cylinder(s) is/are missing.

Good luck.

The Green GT · Feb 24, 2006

bill302 said:
mine done the same as yours did i had bought a new master blaster coil it was bad and shorting at higher rpms but not all the time. have someone rev. the engine to 800-1000 RPM and watch wires and coil for a short (glowing spark) it also needs to be dark as possible.....goodluck

nothing... I have an MSD Blaster coil that is actually not even a year old btw.

The Green GT · Feb 24, 2006

HISSIN50 said:
The EGR vac lines and a couple others (IIRC) run from the TB area down behind the alt, where they exit stage right (towards the pass fender) and go inside the fender liner to a vac distribution block dealie.

If the vac line to the EGR is not functional, it is possible that you could get part throttle detonation. Not sure that it could cause a miss though.

If it misses at idle, run the codes and do the CBT and let the computer tell you which cylinder(s) is/are missing.

Good luck.

I dont have a code reader but I plan on getting one soon. Do you have any suggestions or will just any one do?

The Green GT · Feb 24, 2006

HISSIN50 said:
Not sure that it could cause a miss though.

But Im not even sure if its missing. All of the plugs look as if they had been firing.

drakesdad · Feb 24, 2006

I would agree with the above and just to make sure check your wires for any burns, if they are touching or rubbing.......My wifes car GTP ran fine and then under load it would shake really bad until I let off and I searched through all the lines and found a minor wear spot , replaced the lines and it ran fine after that......when I first read your thread I was thinking vacuum but I see you are ahead of me there....good luck.

The Green GT · Feb 24, 2006

drakesdad said:
I would agree with the above and just to make sure check your wires for any burns, if they are touching or rubbing.......My wifes car GTP ran fine and then under load it would shake really bad until I let off and I searched through all the lines and found a minor wear spot , replaced the lines and it ran fine after that......when I first read your thread I was thinking vacuum but I see you are ahead of me there....good luck.

Its not really when its under load. Its when its running. The whole car shakes at 800-1000 RPM and around 4500 RPM, and I can feel it shaking through the shifter through out the rest of the band.

bill302 · Feb 24, 2006

you dont need a code reader click on link, you need a test light,

http://www.muscularmustangs.com/test1.php

The Green GT · Feb 24, 2006

bill302 said:
you dont need a code reader click on link, you need a test light,

http://www.muscularmustangs.com/test1.php

I wish they had a smiley for :wayovermyhead:

huhu
EDIT: Test light is at a friends house anyway.

HISSIN50 · Feb 24, 2006

I think you can count the CEL flashes, so no need for a test light (the test light is needed only for SD cars which had no functional CEL, like my 88 GT vert).

Were I buying a code reader, I would get the one with the LCD display (a lot of guys get it from Midwayautosupply). It's like 35 bucks, plus shipping, plug the extension cable (optional).

I still would do the CBT (cylinder balance test). The computer will cut juice to each cylinder one at a time and note if any cylinders are not contributing as much as they should. What you are describing does sound a bit like a miss.

Good luck.

The Green GT · Feb 24, 2006

HISSIN50 said:
I think you can count the CEL flashes, so no need for a test light (the test light is needed only for SD cars which had no functional CEL, like my 88 GT vert).

Were I buying a code reader, I would get the one with the LCD display (a lot of guys get it from Midwayautosupply). It's like 35 bucks, plus shipping, plug the extension cable (optional).

I still would do the CBT (cylinder balance test). The computer will cut juice to each cylinder one at a time and note if any cylinders are not contributing as much as they should. What you are describing does sound a bit like a miss.

Good luck.

All of this self test diagnostic stuff is new to me. My last vehicle was an old truck that I couldnt do any of this on. I dont know what CEL is or where it is, or how to do a CBT, but im guesing I have to do that with the code reader.

SeventyMach1 · Feb 24, 2006

CEL = Check Engine Light (displays below/between factory speedo & tach)

As far as the CBT ..... the link that Bill gave you tells you how to do it.

The Green GT · Feb 24, 2006

SeventyMach1 said:
CEL = Check Engine Light (displays below/between factory speedo & tach)

Oh

The Green GT · Feb 25, 2006

Awesome, now its surging AND shaking. Now I have to find a vaccum leak too.

The Green GT · Feb 27, 2006

Ok I didnt get a chance to mess with it this weekend but I started it earler. Its still shaking and it burning oil now? Im thinking maybe a leaky head gasket causing me to lose compression and making it run like ****?

go-stang5.0 · Feb 27, 2006

If its burning oil, you may want to check the pcv valve and all the lines to see if any are kinked. But hey quick test of the coil would be to put the stocker back on and see if the same thing still happens. Just because its not that old does not mean that it wont fail.

The Green GT · Feb 27, 2006

go-stang5.0 said:
If its burning oil, you may want to check the pcv valve and all the lines to see if any are kinked. But hey quick test of the coil would be to put the stocker back on and see if the same thing still happens. Just because its not that old does not mean that it wont fail.

Well i dont hacve the stock one b.c I got the car a few months ago, and the friend I got it from put the MSD on it because he had to get a new coil anyways.

The Green GT · Feb 27, 2006

Ok I pulled the codes from it. Im not sure if i did it right but I think I did. on the running test I pulled a 116 (engine coolant temp higher/lower than expected), 314 (Thermactor air system/fault during engine run self-test/left side), and a 311 (Thermactor air system/fault during engine run self-test).
Then on the cylinder balance test I got a 538 (Insufficient RPM change during KOER Dynamic response test). Im guessing I did the CBT wrong.

Ok Im stumped..

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