Kzj78 fuel cut at ten psi (solved) (1 Viewer)

[Lomoski]

Hello gang. 1995 kzj78 with the 1kzte. I am running 10psi on my gauge and I believe it's accurate. I've put it on the turbine side and the IM side and it's consistent. When I go WOT it stutters for the first four or five seconds then smooths out and builds boost. So I don't think it's fuel cut but it sure feels like it.

Things I have tried in no particular order: fuel filter, air filter, in tank filter, injectors rebuilt and pop tested all equal and nominal, I have some blow by but compression is within tolerance and spec, full size catch can, cleaned the map filter and hoses off manifold, new intake and throttle body seals, EGR deleted long ago and IM is clean and clear, valves are within spec, ecu is rebuilt, spill control valve is newish and adjusted to within spec, engine ecu temp sensor is new and I'm fairly certain that the other sensors are fine as the only code I sometimes get is a injection timing code but I rebuilt both of my resistors and they are tested within spec.

Do the map sensors fail regularly on these? Will be a couple hundred to get a new one to me if it's not the problem. Anyone else have this issue? I don't want to go above stock boost until I have an intercooler but I would like to be able to step on it and not go lug lug go.

I'm tempted to put a bleeder on the sensor side of the IM to see if that helps?

Thank you all in advance my wizards.

Lomo

 

[Bad Mojo]

Hello gang. 1995 kzj78 with the 1kzte. I am running 10psi on my gauge and I believe it's accurate. I've put it on the turbine side and the IM side and it's consistent. When I go WOT it stutters for the first four or five seconds then smooths out and builds boost. So I don't think it's fuel cut but it sure feels like it.

Things I have tried in no particular order: fuel filter, air filter, in tank filter, injectors rebuilt and pop tested all equal and nominal, I have some blow by but compression is within tolerance and spec, full size catch can, cleaned the map filter and hoses off manifold, new intake and throttle body seals, EGR deleted long ago and IM is clean and clear, valves are within spec, ecu is rebuilt, spill control valve is newish and adjusted to within spec, engine ecu temp sensor is new and I'm fairly certain that the other sensors are fine as the only code I sometimes get is a injection timing code but I rebuilt both of my resistors and they are tested within spec.

Do the map sensors fail regularly on these? Will be a couple hundred to get a new one to me if it's not the problem. Anyone else have this issue? I don't want to go above stock boost until I have an intercooler but I would like to be able to step on it and not go lug lug go.

I'm tempted to put a bleeder on the sensor side of the IM to see if that helps?

Thank you all in advance my wizards.

Lomo

Have you looked at the VSV and tested that sensor? Let me know if you need the test procedure out of the factory service manual.

 

[Lomoski]

Have you looked at the VSV and tested that sensor? Let me know if you need the test procedure out of the factory service manual.

I have not looked at the VSV. I don't have a butterfly valve though, so I'm curious how this would affect? Thanks!

 

[Lomoski]

Well colour me confused.

I have a manual boost controller on my rig to control waste gate creep and to compensate for high altitude (I live at 1400m and had a hard time getting to 9psi pre boost controller). Not boosting over 10 psi and somehow hitting fuel cut. So I swap out for a different boost controller, because why not, and now I am boosting at ten psi with no fuel cut and can go up to 14 psi now to hit fuel cut. Not sure why the old one was not working as it was set at ten psi and the waste gate was working. Wondering if I was getting some sort of rapid pressure spikes the boost gauge isn't picking up and some sort of oscillation from the spring and ball on my "broken" boost controller. I took it apart and tested it and it spills at 10psi. So, confused, yet happy the problem is "fixed".

Regardless. This is solved for now. Running 10 psi safely and I'm currently looking for a crate motor if anyone knows of one! Also, does anyone know if the factory intercooled motors fit in the kzj78. Have found one on eBay and it looks boss.


Thanks and take care

Lomo

 

[Combat Wombat]

If youre feeling really brave you can use the spare boost controller (without ball and spring) to bleed off the vac line that hooks up to the map sensor....
Just T it in and adjust to let a very tiny amount of boost pressure out. This will allow you to turn up the turbo pressure to higher than fuel cut limit.
Not sure how safe/reliable/endurance effective it will be, as long as you can get the cool air in, and hot exhaust out.
I had a lot of playing about in my younger years, had some epic adventures (some were to the hospital hehehe)