Vibration?

[Anchor]

Hello; Just deleted long winded post begging for help. After all of the hours invested in troubleshooting I have come to the conclusion that my remaining problem may well be a vibration. Can anyone tell me how to troubleshoot a possible flex plate problem or any other reciprocating vibration. Thank you.

 

[evilunclegrimace]

5 pounds of fuel presseure is not correct for a TBI engine. 9-13 is the factory spec with closer to 13 being the preferred pressure.

 

[Anchor]

5 pounds of fuel presseure is not correct for a TBI engine. 9-13 is the factory spec with closer to 13 being the preferred pressure.

I appreciate comment. What I so poorly conveyed was that when I found the 5 lb. I installed new Delphi. Thank you will correct post.

 

[Schurkey]

Can anyone tell me how to troubleshoot a possible flex plate problem or any other reciprocating vibration.

Does it change with ENGINE speed (RPM) or does it change with VEHICLE speed (MPH)?

Changes with engine speed, it's engine related, including flexplate.

Changes with vehicle speed, it's chassis related.

In either case, be sure that the "speed" isn't a matter of transmission or transfer case gear ratio affecting either the engine speed or the vehicle speed.

 

[Anchor]

Does it change with ENGINE speed (RPM) or does it change with VEHICLE speed (MPH)?

Changes with engine speed, it's engine related, including flexplate.

Changes with vehicle speed, it's chassis related.

In either case, be sure that the "speed" isn't a matter of transmission or transfer case gear ratio affecting either the engine speed or the vehicle speed.

Hi Schurkey; My brick tells me no knock counts at idle. Is this a good or bad thing? When ecm wire disconnected timing holds steady on 0. When connected the timing fluctuates 2-4 or so degrees. The truck idles sweet with no pops or stumbling. When I grab a handful of throttle while sitting shop I feel a bit of vibration as it wraps up. Truck just does not feel as crisp as I would expect. When throttle is floored from idle in neutral it accelerates smooth as silk. I will listen to the bell housing today while up on rack and see if I hear anything unusual. I have fought with this for so long I am second guessing myself and getting confused. I have found a lot of problems already, starting with bad fuel pump, bad map sensor etc. Most all of my snapon MT2500 readings are in the appropriate range but I am not a master of the scanner. I am going to do some reading up on testing knock sensor and try banging on exhaust manifold while looking at timing today. Thank you for your input.

 

[Schurkey]

My brick tells me no knock counts at idle. Is this a good or bad thing?

No knock counts at idle is entirely expected. It's a good/normal thing.

When I grab a handful of throttle while sitting shop I feel a bit of vibration as it wraps up... ...Most all of my snapon MT2500 readings are in the appropriate range but I am not a master of the scanner. I am going to do some reading up on testing knock sensor and try banging on exhaust manifold while looking at timing today.

Keep in mind that it's a KNOCK sensor, not a VIBRATION sensor; in so far as a "knock" is a higher-frequency vibration than what a human being would feel or describe as an "engine shake" or "vehicle shake".

 

[Keeper]

are motor and tranny mounts OK?

 

[Anchor]

are motor and tranny mounts OK?

Yes, seem to be. With it up in the air all looks good. Somebody installed this motor after 2019 and could never have had it running right with bad fuel pump and several sensors. Motor assembly and install appeared to have been done by someone with good sense. They installed hydraulic roller and roller tip rockers. Appeared to have spent some money on it. I just had the scanner on it and pulled a 42 code. First time I have seen that. Module? I had my wife watch timing light while I hammered on exhaust manifold Pass. side and no change in timing. Am going to examine my wiring harnesses to module also.

 

[Anchor]

No knock counts at idle is entirely expected. It's a good/normal thing.


Keep in mind that it's a KNOCK sensor, not a VIBRATION sensor; in so far as a "knock" is a higher-frequency vibration than what a human being would feel or describe as an "engine shake" or "vehicle shake".

Should hammering on front of pass. exhaust manifold while using timing light cause change in timing?

 

[Sean Buick 76]

Get it up to 65 mph and shift it into neutral. Does it still vibrate?