7.3 Idles Rough, Runs Great Otherwise

[Justin Short]

Hey Guys,

New to the forum. I have searched and searched but was not able to find anything that is like this particular case.

My truck is a 1990 (N/A) 7.3. It has since had a hypermax T4 turbo setup at some point in time. Not too long ago I replaced the IP and injectors (maybe 300 miles). At idle I get a terrible vibration that almost feels like a miss and it seems to increase with RPM as well. There is no blue smoke at anytime at any temperature. All compression checked out within 10 psi of each other as well.. I can loosen the injector cap lines and all seem to effect idle similarly. It also passed the clear line test. Would engine mounts be next to question???

Pyro: Never above 1100 degrees. And runs excellent when not at idle.. or under load.

P.S. I replaced the IP with Delphi and injectors were from Pensacola.

Thanks!

 

[jwalterus]

first guess: TIMING

 

[Justin Short]

Timing feels right on, and does not change the feel if it is changed.. Right now I get a tiny bit of black on full throttle, and no smoke otherwise.

 

[jwalterus]

no offense, but get a meter on it, if you are timing by ear, there's a specific process




oh, and welcome to the forum

 

[Justin Short]

None taken! Knew I should have gotten a meter for it but I was not sure a slight out of time would effect the vibration of the truck SO MUCH

 

[jwalterus]

None taken! Knew I should have gotten a meter for it but I was not sure a slight out of time would effect the vibration of the truck SO MUCH

These things will run when you are way out of the ballpark timing-wise............

For example, I retimed my truck 2 weeks ago (60k miles on IP/injectors), to set it right, there was none of the standard "dime thickness" nonsense, I ended up advancing my pump over 1/4" in total!

I keep meaning to take a picture of the scratch marks I started at......... but it's dark right now, and I'm lazy

 

[Justin Short]

Now that I am thinking about it.. When I put the IP in I started at static timing, but right now I think it is set at something like 1 inch advanced. Now you have me questioning my abilities. I am going to go out to take a picture.

 

[Justin Short]

Not quite an inch but pretty far..

You must be registered for see images attach

 

[jwalterus]

to advance timing you turn pump to the passenger side



looks like you went bass ackwards

 

[Justin Short]

Bass ackwards times a million! I was just looking at that! Maybe the truck wasn't the one that was too retarded

 

[jwalterus]

It's a learning experience, we are here to help

 

[Justin Short]

I am not out of the woods yet, I will advance and give results.

Is there a meter you recommend to time them 100%?

 

[FORDF250HDXLT]

Don't offset your lines that much,when you go to advance it either.Just line 'em up and call it good until you get a meter on it.
The place you went shopping at doesn't have the best of reputations.If your injectors are new,they should be ok but if remans,that may be your miss at idle.Line your marks up though and go from there.
When timed correctly,the lines nearly touch.When timing,a little goes a very,very long ways.When you offset the lines for example,so they still touch one way or the other,that's probably 2 or 3 degrees alone.

If you were to time your engine,you would probably see your around 0BTDC or even most likely - 4 or 5 BDTC.
With the lines matching,your almost guaranteed to be between the ditches (6-10BTDC) or at the very least somewhere safe,for going blind.

 

[snicklas]

I hate to say it, but don't dismiss that it could be the IP or injectors......

https://www.oilburners.net/threads/the-oilburners-hall-of-shame.19805/

Read up and make your own decision........

 

[Justin Short]

Lined up pump to marks last night and it sounded like my PSD in -40 degrees! Im at a loss. Right now I am about halfway more advanced than the picture above. I could hear the cold advance kick in this morning for about 5 mins or so it seemed then went away..