weird injector quantity values

dealing with a rough idle issue on my passat. checked the quantity on the injectors at idle and got this:

cyl 1: 2.42
cyl 2: 2.68
cyl 3: 2.99
cyl 4: -.21

the value on cylinder 3 stayed the same. no matter the throttle position it was frozen at 2.99. can anyone tell me what that indicates? i have not checked continuity in the wiring, have only visually inspected the wiring and tightened the connector on cyl 3.

Bad camshaft. Cylinder 3 has probably worn through the lifter.

cam is not excessively worn. lifters are brand new. less than 100 miles on the head rebuild.

It usually indicates low compression, or clogged injector return holes from grease or veggie fuel. I have also seen poorly sealing injectors and cracked head give same results. Injectors expect 18:1 compression and if it is low, it must compensate electrically to make proper timing, ie. 2.99 is max timing correction.

I would do a compression test, and if cylinder pressures are good, than it must be injector anomaly. Make sure you unplug the main injector harness and remove glowplugs to do compression test.

If fuel filter is blackened, compression is getting into fuel rail and returning soot to fuel system.

btw, did this occur after changing a tb or cam? or just slowly develop over time?

edit. Also check the tandem pump pressure, should go up to 90psi if you wack the throttle. There is a test fitting on the end of the head. http://www.youtube.com/watch?v=-FHfTOrWS88&list=UUeSQyBUwBHa24XiBAh2vc8A&index=4&feature=plcp

Jeff

aorsinger said:

cam is not excessively worn. lifters are brand new. less than 100 miles on the head rebuild.

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Did the new head come with new rockers ? or did you reuse the rockers from you old head ? was the install procedure for the injectors with stop screw setting followed ?
It sounds to me like the stop screws are set all wrong on the injectors and it is struggling to compensate.

CharlieT said:

Did the new head come with new rockers ? or did you reuse the rockers from you old head ? was the install procedure for the injectors with stop screw setting followed ?
It sounds to me like the stop screws are set all wrong on the injectors and it is struggling to compensate.

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Ahhh, Injector lash adjustors must be set properly ie. 4x @ 180deg!

i checked the return line for air already. didnt see any so i assume injector seals are good. ive run a full can of diesel purge through the injectors. didnt see any blackening in the old filter when i changed it. old rocker arms were re-used when the head was rebuilt. i am unsure whether the symptom existed prior to the head rebuild. i bought it and began the head immediately due to a improper head gasket install. injector lash setting is good. now cylinder 3 adjusts below 2.99 when throttle is applied but returns slowly to it when left to idle. the symptom is considerably better when the car is warm but is still there. compression is good(450-475 across). fuel pressure at the tandem pump is good. im beginning to reconsider the cam as the culprit. anybody have a cheap line on a cam that is readily available? along with cam bearings?(not looking for chinamade crap on either) if not i should have one on the way by the 27th(hopefully). on the bright side, when all this work is done, someone will be buying a well sorted passat with almost all the major problems sorted.(im unsure whether the bsm has ever been done)

cam replaced along with cam bearings finally. cylinder 3 still shows 2.99. while running cylinder 2 started climbing as well. went to 3.01 for a while and eventually the car sputtered and died. would not start again. pulled the vcover. nothing out of sorts. timing belt is still secure. anyone have any input?

If the cyl head had been serviced by a shop familiar with these engines, they would have spotted the bad cam for sure as well as checking injectors and properly installing them. As far as the bsm being changed, assuming that it hasn't will be 98% correct.

Have you checked cam timing? This will cause rough idle.

Double check the routing of the fuel lines. When idiots work on these, often the lines get crossed and some strange things happen.

Right now though it looks like you have a bad injector.