89 Jetta eng. miss at anything over idle

[dieselherb1]

89 Jetta eng. idles fine, quick rev good. Increasing rpms starts to miss. Eng. is bolted to trans sitting on floor Your thoughts?
Thanks

[Rabbit on Roids]

bad injector, or low compression in one or more cylinders..

[Dakotakid]

Or, maybe just an inadequate fuel supply for the task (air?).
Don't overlook the small stuff. It'll bite you.

[dieselherb1]

Checked compression today, 400 in all but #3 360. Is that enough difference to cause a problem?

[Baron VonZeppelin]

Nah not really enough at all, for your symptom.

Get it going again in the same range and crack an injector line open one at a time until you find which one makes least difference.
Then work backwards from there.

If you have any known good/decent injectors around, swap one into that spot. If no extras, swap a good one from one of the other cylinders and put the suspect into its replacements spot. And see if the change follows the injectors around.

Like it could be internal corrosion in the line restricting higher flow instead of the injector, gummyish delivery valve, etc...process of eliminations.

[dieselherb1]

Gummyish return valve?

[Smokey Eddy]

To get a crude idea whats going on with the injectors I like to get a long screwdriver, shove the handle into my ear (not literally but you know) and stick it firm on an injector while it's idling. Plug your other ear so you can hear the sound going through the tool.

listen to each one carefully. I know exactly which 2 of my injectors knock and which one knocks really bad. If i come into some money i'd replacement but i just don't have the freedom atm. I know that pistons are a lot more expensive than injectors though - sighhhhhhh

[dieselherb1]

Eddy you need to build a pop tester. I have all the stuff, just have not had the time to drill tap and bolt everything together. Always a problem vehicle first in line.