1993 Grand Cherokee engine vibration

[gean_yus]

Please help! I have the 5.2 liter, V8. Here is want I have done:

replaced the failed fuel pump
worked fine
replaced Ignition coil worked fine(two weeks later)
worked fine
Started having 'missing'/vibration symptoms...
replaced plugs,wires,cap,rotor, engine mountschanged fuel as well as added dry gas
problem seems to be getting worse
cleaned the Throttle body
no repair

I unplugged number 5 and the vibradtion stops the same thing happens if i disconnect injector 5 but then the check engine light comes on.

I can best describe this problem as an engine vibration at idle that increses in intensity as vehicle speed increases. It is highly annoying in fourth gear. But if I turn the overdrive off the vibrations decrese in magnitude.



help!!!!

[YtseJam454]

Perform a power balance test. An easy way to do it is to run the engine at say 1200RPM. You will need to have a tach. Disable #one injector. Record engine RPM with injector disabled. Reconnect injector harness and repeat test doing it to all injectors. Let's say you record a 150RPM drop with each one except cyl #3. Then #3 is not contributing and is your problem cylinder. This will help you identify if there is a cyl misfire.

[xj31]

The power balance test is the way to go .Just make sure you unplug the IAC motor or it will try to compensate for the rpm drop

[dksob81]

ok I like this idea with the power balance test, my question is how do u get the tach to stay at 1200 RPM's without using ur foot or is there no way to do this...... the reason I ask how would u no exactly what the drop would be, u could have let off the gas a lil then that would affect the reading, or are u saying u have to be really steady... anyways please email me with your answer Joe [email protected]


question for Gean Yus, would u send me a pic of your Vacuum Harness, I have the same engine and I had a lil fire in my engine compartment and burnt my lines, and the dealer says they were discontinued, and I have looked at all the Diagrams in autozone, Haynes, and my engine Compartment. please will u send me a pic of your harness.... send it to me (Joe) [email protected]

[gean_yus]

Originally Posted by dksob81

ok I like this idea with the power balance test, my question is how do u get the tach to stay at 1200 RPM's without using ur foot or is there no way to do this...... the reason I ask how would u no exactly what the drop would be, u could have let off the gas a lil then that would affect the reading, or are u saying u have to be really steady... anyways please email me with your answer Joe [email protected]


question for Gean Yus, would u send me a pic of your Vacuum Harness, I have the same engine and I had a lil fire in my engine compartment and burnt my lines, and the dealer says they were discontinued, and I have looked at all the Diagrams in autozone, Haynes, and my engine Compartment. please will u send me a pic of your harness.... send it to me (Joe) [email protected]

TELL ME WHERE IT IS LOCATED A IT IS DONE?

[dksob81]

u will have to remove it to get a pic of it, it is connected to the Throttle Boddy, Egr Valve Transducer (Control), Purge Solenoid, Fuel Pressure Regulator, and both sides of the Intake Manifold. if u need anymore help locating it just email me or reply to this msg. further help locating, there are 2 black lines located on the driver side of the Intake Manifold (there is 3 lines, one is for the Power Brake Booster, and 2 other lines connect'd to the Purge Solenoide, and I believe Fuel Pressure Reg., then just follow the lines and disconnect from everything else, you will notice that there is a connector connecting 2 lines to 2 other lines, the other 2 lines go to the EVAP Canister, I do not need this, just the first half that connects to the Intake Manifold, Throttle Body, Egr Valve Transducer, Fuel Pressure Reg., etc..... just send me a pic of this harness

Thank You, Joe.

[gean_yus]

Originally Posted by dksob81

u will have to remove it to get a pic of it, it is connected to the Throttle Boddy, Egr Valve Transducer (Control), Purge Solenoid, Fuel Pressure Regulator, and both sides of the Intake Manifold. if u need anymore help locating it just email me or reply to this msg. further help locating, there are 2 black lines located on the driver side of the Intake Manifold (there is 3 lines, one is for the Power Brake Booster, and 2 other lines connect'd to the Purge Solenoide, and I believe Fuel Pressure Reg., then just follow the lines and disconnect from everything else, you will notice that there is a connector connecting 2 lines to 2 other lines, the other 2 lines go to the EVAP Canister, I do not need this, just the first half that connects to the Intake Manifold, Throttle Body, Egr Valve Transducer, Fuel Pressure Reg., etc..... just send me a pic of this harness

Thank You, Joe.

I have mine installed upside down I think. I hope this is what you need. I am emailing you 5 pics...

Ken

[dksob81]

are those Lines Metal cuz mine were plastic, well anyways could u disconnect them and get a pic of the whole thing, if it's not too much to ask........ I only seen the first 2 pics the other ones won't upload and it won't let me download them, my connection is too slow.

[YtseJam454]

Originally Posted by xj31

The power balance test is the way to go .Just make sure you unplug the IAC motor or it will try to compensate for the rpm drop

Yeah I forgot to mention that. You can try the test at idle speed and see what happens.