Hi All,
Had my GTS25 for 12 years now, serviced every year (only does 2-3K per year if lucky). Last service as well as the usual, i had the Timing belt and water pump replaced. All had been fine up until 2 weeks ago when i was on drive. I was cruising up the motorway at a steady 70mph (yes really...lol) when all of sudden it started to sound more like a old Subaru than a Skyline and i had some power loss.
I pulled off of the motorway and had a look but i couldn't see anything obvious. Managed to get it home and hit the forums. Suspecting a normal misfire type issue and starting with the obvious, i checked and tested the coil packs, they seemed ok, tested the coil pack loom, that was ok. Looked at the spark plugs (replaced last service and NGK platinum), they seemed ok, gap was ok, no fouling. cleaned up the coil packs and connection etc, sounded a little better, but still rough.
Then as a belt and bracers measure, bought and fitted new benchmark coilpacks and new plugs. Same result.
After more digging on forums i got a USB Consult cable and ECUtalk. Managed to log the data and checked against known voltages / ranges at idle and 2500rpm. The readings for the TPS, Timing, Air Flow, O2 sensor, injector pulse and AAC all seem to be within normal.
Car does run a bit better, however, it is still lumpy / missing.
So far i've
Replaced coils
Replaced Plugs
Tested coilpack loom continuity, all ok (original loom so may get a wiring specialist harness)
Tested ignition amplifier continuity, all ok
Cleaned connections for TPS, AAC, CAS, AFM, coilpack loom
Cleaned all earthing points
Checked the obvious pipes and hoses for leaks, none visible to the eye (maybe smoke test needed)
Ran ECUtalk and checked the voltages / ranges. These seem ok, but i am not an expert.
Car is going into garage tomorrow to get a compression check and to have the injectors tested.
Anyone out there have any other thoughts on what could potentially cause this issue?
** update **
Forgot to add, no fault codes showing*
Had my GTS25 for 12 years now, serviced every year (only does 2-3K per year if lucky). Last service as well as the usual, i had the Timing belt and water pump replaced. All had been fine up until 2 weeks ago when i was on drive. I was cruising up the motorway at a steady 70mph (yes really...lol) when all of sudden it started to sound more like a old Subaru than a Skyline and i had some power loss.
I pulled off of the motorway and had a look but i couldn't see anything obvious. Managed to get it home and hit the forums. Suspecting a normal misfire type issue and starting with the obvious, i checked and tested the coil packs, they seemed ok, tested the coil pack loom, that was ok. Looked at the spark plugs (replaced last service and NGK platinum), they seemed ok, gap was ok, no fouling. cleaned up the coil packs and connection etc, sounded a little better, but still rough.
Then as a belt and bracers measure, bought and fitted new benchmark coilpacks and new plugs. Same result.
After more digging on forums i got a USB Consult cable and ECUtalk. Managed to log the data and checked against known voltages / ranges at idle and 2500rpm. The readings for the TPS, Timing, Air Flow, O2 sensor, injector pulse and AAC all seem to be within normal.
Car does run a bit better, however, it is still lumpy / missing.
So far i've
Replaced coils
Replaced Plugs
Tested coilpack loom continuity, all ok (original loom so may get a wiring specialist harness)
Tested ignition amplifier continuity, all ok
Cleaned connections for TPS, AAC, CAS, AFM, coilpack loom
Cleaned all earthing points
Checked the obvious pipes and hoses for leaks, none visible to the eye (maybe smoke test needed)
Ran ECUtalk and checked the voltages / ranges. These seem ok, but i am not an expert.
Car is going into garage tomorrow to get a compression check and to have the injectors tested.
Anyone out there have any other thoughts on what could potentially cause this issue?
** update **
Forgot to add, no fault codes showing*