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91 XJ missing at 2000 +rpm only when at operating temp


NAXJA Forum User
Hello all I am sure this has been discussed more than once but I am unable to find the answers I am looking for. So here goes.

Seems to be random missing and or Fuel injectors not Firing. But Constant like a chug ONLY when Warmed UP

What has been done and tested
Full rebuild 30 over with less the 200 miles on it. has done this since day one but getting worse and un drivable.

rebuilt head 7120
Compression tested and good
Leak down tested and good
New CPS from Napa
New temp senders both
New Distributor from Napa
New quality cap rotor Plugs and Wires. Copper plugs
New O2 sensor
Cleaned TB- and IAC.

CPS tested and within spec

TPS testing completed
.6v closed
3.6v Wide open (questionable)
Smooth transition with no jumping when let off

Coil tested
Primary 1.2 ohms
Secondary 12.12 Both sides

Checked and cleaned ECU harness connection was visually good

this is a new ACCEL 140021 Ignition Coil
New Echlin Map sensor tested and working correctly.
Tested temp on Cat In 299 out 199 after 20 min run time ( I Know this is not enuff time and temps should be higher (Suspect but was not able to run to hotter temp due to poor performance Missing hick ups and at 2000+rpm and lower when warmed up and under load
Oil Clean Water Clean No cross contamination.
Fuel pressure holds steady at 31psi at idle as well as higher RPMS runs at 39PSI with Vacuum removed from regulator. Holds PSI at 31 PSI and slightly climbs to holds 34 psi when not ruining from 10 Min.
Checked all vacuum lines for leaks as well as Intake and TB for leaks None found. Vacuum is at 18 to 20

On a side note. When Connected with a spark tester from the coil to the dizzy. I noticed inconsistent spark during its failure of running poorly