Max IQ Value

Hi All,
I just installed rebuilt injectors (stock nozzles). The car seems to have a lot more power but blows coal at WOT. I set injector timing to the top of the graph and when I check IQ it showed originally at 4.4. I bumped it to 5.8 figuring I would need to lower it later, but it is still blowing black smoke.
The prior inectors did not blow coal at all. I have a new OEM head and new OEM turbo on the car. I just cleaned the EGR 5k miles ago. Should I bump up the IQ even more, or should I be looking into something else? My understanding is the more I increase IQ, the less fuel and power and black smoke, but the upper part of the range is 5.
Thanks,
H.ubk

h.ubk said:

Hi All,
I just installed rebuilt injectors (stock nozzles). The car seems to have a lot more power but blows coal at WOT. I set injector timing to the top of the graph and when I check IQ it showed originally at 4.4. I bumped it to 5.8 figuring I would need to lower it later, but it is still blowing black smoke.
The prior inectors did not blow coal at all. I have a new OEM head and new OEM turbo on the car. I just cleaned the EGR 5k miles ago. Should I bump up the IQ even more, or should I be looking into something else? My understanding is the more I increase IQ, the less fuel and power and black smoke, but the upper part of the range is 5.
Thanks,
H.ubk

Click to expand...

How large of nozzles did you go? You might have to do the hammer mod to get the smoke level down...

The nozzles should be stock. If I do the hammer mod, wouldn't that just increase IQ even more? How high should I go?

H.ubk

h.ubk said:

The nozzles should be stock. If I do the hammer mod, wouldn't that just increase IQ even more? How high should I go?
H.ubk

Click to expand...

If the nozzles are stock, I suspect you have other issues going on. Boost leaks immediately come to mind. Hammer mod can reduce or increase IQ depending on which way you slide it.

I would be suspicious of the new settings of pop pressures. Try to get a printout
from whomever did the 'rebuild'. That is assuming they used all original Bosch parts.
What condition led you to get them rebuilt? Have you contacted the rebuilder?

I say forget the 'printout'. We have never provided any and really, what difference does a print out make if the injectors are blowing coal? Also, of the 'printouts' we have seen, it only guarantees pop pressures, not flow rate. WHAT GOOD ARE INJECTOR SETS THAT DON'T FLOW RATE EQUALLY??

I think maybe I spoke with you before, but the bottom line, if you have the IQ set to 'normal' settings and you are painting the road black out your tail pipe, you have very poorly set injectors. You could have very poor injector nozzles. In any case, a simple check on the VCDS Engine Module/ Block 13 will show nozzles and their compared milligrams per stroke variation. They should read lower than .2mg/str. I'm betting it's not even close...

Setting IQ could be as high as 8.0 or more, but realistically, that would be heroic efforts for poor nozzle calibration.

If it's the same place, doing the same thing, we are looking for the "Baker's Dozen" of destroyed engines from poorly set nozzles over a one year period. When your pistons melt and blow out the exhaust, your happiness fades as fast as your pistons.

One thing I have to say, as this is very typical. We get nozzles back that all that was needed is the piece of dirt removed from the nozzle tip. All lines and the tops of the injectors should be blown out with compressed air before assembly. That could take care of a lot of problems.

Hi Frank,

Thanks for the reply here. I believe I found my problem this morning. One of the pieces that connects to my intercooler is broken in two pieces. I ordered a used replacement from eBay and will install it next week when it arrives. I'll post if I'm still getting any black smoke afterwards.

h.ubk

What condition led you to get them rebuilt? Have you contacted the rebuilder?

Click to expand...

I was getting lots of white smoke upon cold starts on cold mornings. I also believe the fuel economy should have been better. The PO ran vegetable oil and I did not know when the injectors were last worked on (car has almost 400K miles).

Since I have replaced the injectors, the white startup smoke has gone away. I'll post after my intercooler leak gets fixed.

The rebuilder said it was a turbo issue or a boost leak. The turbo is brand new OEM and I installed it about 5K miles ago.

h.ubk

I got the replaced intercooler line in today and the car has substantially more power than it did before. I can hear and feel the boost. I still have a bit of an air leak in the large custom hose that goes into the turbo, but the black smoke is not an issue any more and I don't think I'm going to have any issues maintaining speed while going up hills. The car is actually kind of enjoyable to drive now.

h.ubk