Bogging down at point of turbo engagement. Why?

If the boost is there (shows on a pressure gauge correctly) and the fuel isn't then it's a fuel management problem.

 

Any easy way to test this? I'm lead to believe I'm not emptying my bowls because bike fully recovers immediately every time. Could it be leaning out? hmm so many variables. If I apply the choke during boost attempt it runs even worse, I thought this would richen the mixture a little and I'd see an improvement... not the case. Am I too rich??

 

Look at the plugs. They'll be wet and really dark if you're running too rich. I'm used to using a wideband AFR to monitor stuff like that when tuning a car turbo. Fuel smoke is black if it's blowing any. Oil is typically light grey to white.

 

I will check. If it leans out when I'm having the issue (white plugs) and running rich at idle or normal driving conditions, will the plugs turn black again? Do I need to lean it out and shut it off immediately?

 

Eagerly waiting for your response lol.

 

Easy? Not without a boost gauge and a port on the manifold for it. The MAP sensor in the manifold should be able to tell you if it's sensing boost or anything at all. That will affect the fuel ratio.

 

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replace that paper fuel filter with a sintered bronze filter

 

Yes i think? Timing needs to be retarded when on boost. Without that signal, the ECU will stick with ambient air pressure settings. Make sure the wiring is good with the sensor.

 

Sensor checked out according to service manual inspection. Any other testing procedures I could try? Voltage = 2v at ambient, voltage = ?? At 8psi.
What's out there in a way of replacement sensors?

 

Or eliminate it. The bowls will settle stuff out.

 

I appreciate all the advice. I'm noting everything as future improvement opportunities, but I'm hard pressed to believe the fuel filter, or dry vs oiled air filter is causing my current problems.

Annnyyoonnee wanna chime in with a countermeasure? Even if it doesnt work I can cross it off as the issue. Bring on the ideas!

 

Hmmm... Interesting.
Asks for advice.
Gets advice.
Ignores advice.
Asks for advice again.

 

By "noting" advice, one might assume I am making a note to myself NOT to ignore the advice. If advice was given to check tire pressure, i would note this but i wouldn't go inflate the tires than try a hard pull on a motor that is running incorrectly.

 

The tires are not part of the fueling system. The filters are.
Small things do matter in the correct function of systems.
Things that are both easy and cheap to change should not be ignored just for the sake of thinking that they do not matter.

For example: Using a replacement foam air filter (K&N or Uni) on a non-turbo XJ instead of an OEM-spec paper filter. One causes a poor running condition, and the other does not.

You've been given two potential "countermeasures".
You've stated that you're willing to try things that might not work just so you can cross them off the list.
Why not try those first?

 

Absolutely agree. I'm trying to rule out the LARGE things before the small things. Most likely first to least likely. Filters, I believe, would effect efficiency/poor performance. I am getting zero turbo performance.
Like I said,noting all suggestions to my list, no advise is wasted.

 

Fair enough.
Do you happen to know what small item causes a very noticeable mid-range bog on a non-turbo XJ?

First rule of thumb in the industrial maintenance world: eliminate the easy things first. You'll get better raises that way.

 

many little things can add up.

if your not getting fuel at boost what happens?


Problem: Under load at high RPM I lose power. My boost gauge never reads boost pressure. It's as if when it is time for the boost to kick in, the engine goes LEAN

lean by to much air or lean by to little fuel Hmmmmmmmmmmmmmmm think about it

 

No, I do not own that bike. My research is centered about the motorcycle I own.

Although our conversation is going on undesirable tangent which may draw attention from the original post intend. You have my curiosity?

 

Changing from a paper air filter to a foam one (drop-in filter with factory airbox).
Every XJ of the era was delivered running on the lean side in order to meet U.S. emissions regulations.
When combustion is already running on the edge of being too lean, every little thing in the fuel system matters.

Manbot's advice shouldn't be ignored either, because more oftten than not there are multiple issues that contribute to a single problem with any old machine.

 

Thank you for the reply. Thinking about it
.. turbo purpose to ADD air so lean by little fuel is culprit.
Okay, what havnt I already checked, tested, or replaced as part of fuel system? Suggestion for next root cause?