3uz-fe weird idle and throttle lag under 3k rev

[Jgrov2]

I’ll try and post videos of the revs and idling plus what little data I could extract from live data ecu.

I’ve put 3uz from Celsior into 96 hilux. Its usually hard to start both hot and cold and sometimes idles fine sometimes rough. Biggest issue is the throttle. Revs usually drop until it’s 30% in then they pick up and act normal it will rev out to limit. If I let them drop to idle it will act crap again and sometimes stall out in neutral.

I’ve ditched the auto and running manual gearbox with no emulator yet. I’ve put new plugs in clean maf and new Vvti sensors as I leaned on them and broke them. It’s not throwing any codes except for missing trans, fuel circuit , stop light and secondary o2 sensors.

My fuel pressure is up at 4.5bar as all I had laying around was 4.5bar Audi unit. I’m waiting on adjustable fpr. What else should I be looking at in the mean time as the car is pretty undrivable/unpredictable especially trying to use clutch and dodgy accelerator. Below is pic of engine bay and don’t worry vacuum hoses are sorted and connect just off during work and pic.

 

[Jgrov2]

 

[gloverman]

Any chance of a proper photo of the MAF? Placement is important.

 

[gloverman]

Should run fine without the auto even with emulator providing the wiring is correct however will lack bottom end power.

 

[Jgrov2]

Maf is mounted 90 degrees from upright I talked to a few blokes reckon won’t matter.

I think I may have just burned out my fuel pump it’s tone has changed a bit. It’s surpose to be walbro gss342 255lph. Thing is running normal voltage, 14.5 amps and flowing 120 lph from the regulator into a jerry can. It’s my understanding that if the regulator is open ie not connected to fuel rail, the pressure is zero and amps should be done and flow at max. When I pulled the hose of the fuel rail there was no pressure either.

 

[gloverman]

We went away from walbro years ago due to many failing when running higher pressures. I was doing lots of turbo cars and found walbro falling over around 60psi. I know plenty of other guys finding the same. Ive since moved over to a genuine nippon denso pump. I tested one of the high flow units the other day which came in on a rough test at 4litres a minute (around 40psi). I use these on all my conversions now including the vvti engines and boosted engines. On the vvti I stay with a constant 4bar pressure.

Ive also found Maf placement to be important. Length of intake affects the tune and diameter of the piping the maf fits into. We applied the same principles as toyota of smaller tube richer mixture and larger tube less mixture recently on a 2uz landcruiser. Known for being thirsty we increased tube size slightly and improved econony. End mixture is the same due to oxygen sensor trim but default mixture before trim is leaner so it gets to trimed lean faster.

 

[Jgrov2]

Yer right I think I will look for denso fuel pump then. Do you know if they are able to take a pwm signal and e85 suitable? I’m looking at boosting it later down the track and using a different ecu that can control pump speed.

That’s interesting about the maf as before all this happened I was testing it out with the maf if different orientations and the pipe on different planes and found it made no difference to idle and stuff. Only thing that did make a difference was the diameter, it’s location along the pipe and the obstructions before the maf. I’m using exact diameter of original pipe and I’ve located it in the middle of the only straight pipe of the intake. It does behave a bit different with my other intake pipe which has a smoother bend into throttle body. I’m wondering if I need to make the bend more gradual and/or add honey comb before the maf to straighten the flow out.

 

[gloverman]

The pumps i use are not suitable for e85. If using a pwm ecu output for fuel pump speed control ive only ever gone through a control unit first. Ive used the pumps fine on old fashioned resistor two speed setups though. Just did another on a supra on my youtube channel CartuneNz.

Theres definately more in intakes than just putting the maf in randomly. I had one years ago that drove nice but on the dyno at full throttle went extremely rich down in the 10:1 range and the auto transmission was never quite right. Customer wanted it sorted but didnt want to spend the money. Several owners later its back at mine and now fixed better than ever. Eventaully we worked out how to delete afm while retaining stock ecu to control trans and having all gears. No afm meant no second gear.

 

[Jgrov2]

That’s crazy. You mentioned before it will lack bottom end without the auto. Why is that? Mine constantly says 5 gear on techstream. On another note, do you know if it’s possible to run without the ethrottle and switch back to a cable? I hate the feeling of the ethrottle already plus I feel like it’s gonna be real shit offroad

 

[gloverman]

3uz on stock ecu dont work without the e-throttle. Ive had to convert several back after guys have tried to convert to manual throttle. Did testing on that years ago. One we wired the pedal to the ecu but hadnt swapped the TB yet so id move the pedal and someone else co-ordinated moving the throttle plate and we had it revving. If you plan aftermaket why not do that straight away and get one where you can adjust the dbw settings to suit. Like the 3uz i did recently and its throttle settings are super responsive.

 

[Jgrov2]

Issue is I can’t register it here in Australia with an aftermarket ecu because emission rules etc. I’m thinking about using haltech waterproof jobby which do dbw now just gotta get it going first. What were you saying about bottom end and missing auto? I’ll send you a pm about pump as well if you have them I think I’m running your engine mounts also. Still in one piece so far lol

 

[Zuffen]

Why not run the Haltech in a hidden position and have the stock ECU (apparently) wired in.

I know most Engineers wouldn't check which ECU it was running, and they will look and see the stock ECU and go "all good"!

Gotta think outside the square.

I had my supercharged engine Engineered with an aftermarket ECU and the Engineer didn't comment on it being mounted in front of the shifter, so very obvious, but we are in NSW.

 

[Jgrov2]

Yer I mentioned turbos once to the guy I sussed out for engineering and he nearly threw something at me. I figured I didn’t want to tempt fate and will just wait til after it’s all signed off. My luck they will find it and I’ll be black listed everywhere and constantly harassed by tmr.

 

[Zuffen]

You need a new Engineer.

One that uses common sense.

Think about it a dirty 3UZ is always going to be cleaner than the original lux engine. Not too many people get that.

 

[Jgrov2]

I know exactly what your talking I’m actually about to graduate as a mechanical engineer in a few weeks and this thing is kinda like a side project. I plan on sampling and compiling as much data as possible about the engine hence wanting to switch to a aftermarket ecu to make it easier to record data and install different sensors.
I can’t sign off on this myself as I’m not a certified person under tmr plus it’s kinda conflict of interest signing my own toys.
I’m running all the emissions gear even worked to get a charcoal canister working considering the 3uz one was in the fuel tank. EGR was blocked by factory so I think some people might have a hissing fit about that.
Any hints on someone else to try for engineering in Brisbane? Also what was the damage and process ie get engineers certificate or just mod plate and then head to dept main roads or what.
I’ve cracked it with this fuel system starting again from scratch. Is there any value in switching to a more generic system layout ie pump filter y block rails then fpr or keeping it dead head system with fpr running rail feed and return?

 

[Ritchie36]

Hi just found the post as I’m have a similar issue with my 3uz. Wondered if you’d found a solution to your problem. My car will stutter when pressing the throttle Fast but be okay if I do it slowly. Any help would be appreciated.

 

[Jgrov2]

Hi just found the post as I’m have a similar issue with my 3uz. Wondered if you’d found a solution to your problem. My car will stutter when pressing the throttle Fast but be okay if I do it slowly. Any help would be appreciated.

Dude from memory it was the fuel pump. it was slowly dieing and after these videos and few more runs would hardly build pressure.