Balancing throttle bodies

[Jooles81]

Hello,

I have a 4.2 cerbera that has unbalanced throttle bodies. For instance, on the driver bank, the body that is up front is displaying 7 on the balancer at idle, the other 3 are displaying 5. I don't want to increase the flow of the 3 less flowing cylinders as I don't think a hole in a screw is the solution. I would prefer to decrease the one cylinder that is flowing too much.

Do you have any idea how to do this? Make new butterflies?

Thanks in advance.

Julien

[Jooles81]

Thanks for your inputs. Definitely the most flowing has a problem. I'll try to exchange 2 butterflies. If the problem is changing cylinder, then the butterfly is faulty. If not, that's the rod or the body...

Wish me luck!

Julien

[Jooles81]

Twinkam, what do you mean by badly fitted butterfly? I'd there a specific way to install them?

Julien

[Jooles81]

YOU'RE THE BEST!

I've cleaned the 3 less flowing bodies and now they are all equal at around 6.5/7. I'm doing some little things by myself, more because no-one know Tvrs here in Bulgaria than anything else, but I'm very slowly learning and didn't knew the throat had to be cleaned when setting the car.

Thanks a lot for the tip! As I've very little available time, I'll finish the cleaning and will set the car properly and will tell you what's the final result.

For now I'm enjoying my little victory on the car

Julien

[Jooles81]

Good evening!

I've cleaned the other bank today and all cylinders went from 4-5 to 7... So a good clean was really needed.

I still have discrepancies between cylinders, though à lot better than before, and now all manifolds are heating at the same rate,which is good. What is the acceptable difference between the most and least flowing cylinder on one bank?

Thanks in advance!

Julien

[Jooles81]

OK, thanks a lot again for the answer. It's pretty close to that currently. I'll have a look at it again, then I'll set the engine, and then check it again. As all cylinders are currently around 7, I guess it'll be pretty good when it will be around 5. I'll tell you!

Julien

[Jooles81]

Hello,

I need your help again!

The car is now a lot smoother, responsive and easy to drive, but it's impossible to get tje adaptatives set properly!

Basically, both adaptatives are to the max around 30 but I can't increase anymore the value at the potentiometers.

All cylinders are sucking an equal amount of air (tested before, not after messing with the engine). Idle set at 1500 rpm for setting the adaptatives without stalling, pots are around 17/18. When I remove all stops, butterflies are closed at 14.4 and 16.9. Adaptatives at 30 at idle à d lambda at 0. When I give gas, lambdas move so apparently not shot?

My gut feeling is that my induction is leaking air. Am I right? How to test that? Spraying wd40? Where?

Thank you in advance for your help.

Julien

[Jooles81]

Hello,

Any input gents?

Julien

[Jooles81]

Hello,

Thanks for your inputs.

My problem is precisely that I can't move the throttle pot enough to increase the tpots value enough to have good adaptatives.

Said another way, my butterflies are so closed at idle that I have 1200rpm and tpots value of 17 and can't move the tpots to a higher value. I can close the butterflies a bit though.

Julien

[Jooles81]

OK, thanks.

Am I right thinking that this may also be a leak at the thermal barrier?

I've clamped the hose that goes from the catch tank to a splitter to the fuel rails without results. I also sprayed the whole induction with carb cleaner without change of rpm...

How could. I check the fuel pressure? I have doubt this would be the problem as the car is pretty nice at full throttle and high rpms...

Julien

[Jooles81]

OK, thanks a lot for the feedback, again.

I understand what happens if the pressure is low and I'll have a look at that. I'll make you a feedback.

Julien

[Jooles81]

Hello!

I'm undigging this thread a bit because it appears that no-one here has the necessary fitting to plug a fuel pressure manometer...

Can you please tell me what is the standard of the fitting on the hose feeding the fuel rail? I've read 1/2 bsp somewhere but I'd like to be sure...

Thanks in advance!

Julien

[Jooles81]

Hello,

Anyone could tell me how to check the fuel pressure on those things? I've bought some fittings, but they are apparently not the right one. Is the feeding of the rail the right place? If so, could someone tell me the standard or point à manometer kit that works?

Thanks in advanc!

Julien

[Jooles81]

Hello,

so, for the record, the standard of the fuel hose connector feeding the injection rail is 1/4 BSP.

So now, find a fuel manometer...

Julien

[Jooles81]

Hello,

I've finally had the fuel pressure checked. It comes at 3.7 bars. That's not a lot over normal, so should not generate those problems according to my mechanic. There is huge crack in one manifold. He'll weld it and check the injectors and we'll see what happen...

Julien

[Jooles81]

Hello!

I'm slowly going forward... One manifold was cracked and has been welded. Today I had the car on the dyno with wide bands on both banks because one lambda was showing constantly lean. It appears that one bank is in dead constantly lean, whatever you do. So lean the wide band do not show anything. What could be the causes? My mechanics says it can be a blocked injector, or maybe a cylinder not igniting. Any other cause?

Thanks

Julien