1uz running problems

[Boguey]

Hi all, think it's my first post here,
I'm currently running a 1uz from a celisor in my s13 drift car, I have it manualised with a 3sgte flywheel and clutch set up, the car idles great but the revs have always been limited at 4500rpm and recently the car won't run properly at all, yesterday in particular it would drive for 500 meters and then stop again. At first I taught it was the fuel pressure regulator or the afm so I replaced both of them, I set the fuel pressure at 45 psi and it idled perfect, I also replaced the plugs with ngk twin tipped plugs but nothing has worked, yesterday it was also back firing out the air intake with makes me think it's a valve or a cam problem as i swapped the ignitors at the track yesterday. Has anyone had problems like this before? Really need some help as I'm lost with it, thanks.

 

[gloverman]

If you think it has a cam or valve issue then a compression test is the place I would start. I have seen internal issues lots. Stuck valves , shims jumping out holding valves open and broken cams. Incorrect cam timing is really common and I have found incorrect phasing of sissor gears a few times. Doing a compression test also allows full inspection of spark plugs and I inspect and meter the leads at the same time. This checks if issues are between banks, between ignition systems or the whole engine

4500rpm rev cuts I have generally found to be engines incorrectly wired. I do a wiring check of the basic's then put the scan tool over it to see what the ECU is seeing. The last one with the scan tool on I could easily see a nasty back feed giving strange readings.
Another one which didn't rev out had a tired fuel pump. I have also seen bent crank trigger wheels but these ones generally misfired on the way to a early rev cut. And these ones overheated the ignitors. One was running aftermarket ignitiors which exploded so I put some stock ones on for testing which have a safety shutdown feature then after cooling off would be fine again.

Also had a few with stuffed ECU's but these generally had other symptoms. Early AFMs have been the issue a few time and just diagnosed one late one which did the 4500rpm rev cut which had no power to the AFM. I'm surprised this one even started.