Rb26dett Single Throttle Body

[grippy]

I have a Power FC D-jetro running my RB26dett and at the moment I am running the stock multi throttle body setup.

I cannot get the car to run smoothly, idle or have any use below 4000rpm. The ECU has been re-tuned 4 times already and each time it comes back with different issues in regards to daily driving.

My tuner has advised me that when running the D-jetro ECU (map sensor) I will always have low rpm issues as long as I keep using the stock multi throttle body setup.

He has advised that I go to a 80 or 90mm single throttle body setup and an aftermarket inlet plenum. This is going to cost big $$$.

Has anyone experienced a similar problem with the RB26?

I see many RB26 engines running the same ECU and retaining the stock throttle bodies and runnign big HP as well, do they all have low RPM issues due to the multi throttle setup?

I really don't want to spend any more $$ on a maybe fix for this, I can replace the ECU with a haltech E11v2 for the cost of upgrading to single throttle.

Is it going to fix my problem?

If I change ECU will I still have the same problem?

Thanks for your input..

Rgds,

Grippy.

[jonn]

Short answer.... Change your tuner asap. There are plenty of cars, Australia wide, including mine, that run on D-Jetro setups using the std throttles. There must be an underlying issue with the car that needs to be attended to. Only then will you have a starting point to tune the ecu.

Out of interest, where did you install the MAP sensors?

[grippy]

My MAP sensors (2) are on top of the fuel rail and have remote sense lines coming from the inlet plenum. I'm not real happy with the way it is setup. They are just silicone vacum hose the same size that you would use for your boost gauge going to the MAP sensors, the port in the inlet plenum is used for the temp sensor.

I agree with you that there is loads of cars running the same setup as mine and have no issues at all dispite what power they run.

Shouldn't the map sensors be bolted directly onto the inlet plenum and not run remotely via vacum hose?

Cheers..

[paulr33]

the map sensor install is crucial for the djetro setup to run properly

go back and look at the apexi documentation for the djetro install kit

it has in specific detail how to install the map sensors correctly

you should read this - its on my website paulr33.skylinesaustralia.com

there is some known gotcha's with map sensors and individual throttle body setups

but its usually only an issue with a f**ked instal - ie: not correctly

[paulr33]

http://paulr33.skylinesaustralia.com/docs/...6%20djetro).pdf

pages 14 to 25

i would suggest printing them out and go from there

i dont have english translation unfortunately

[grippy]

The other issue I have with the tuner is that this is my work car and I work in Malaysia, and there is no one here that really has any clue about anything, thank goodness for Skylines AU. My Skyline in OZ runs stock ECU with eprom and has no issues at all. This is the first time I have dealt with aftermarket ECU and from what I know Power FC is pretty much idiot proof, yeah right, not here in KUL.

Thanks for your advice and I will not be upgrading to single throttle. The car has everthing it needs, just missing a good tune and a few bugs ironed out.

It is in an A31 Cefiro, I have track day tomorrow at Sepang and I will run it as it is and see how it goes but I'm sure you are right in saying that there seems to be an underlying issue that needs to be sorted before I can get the tune right.

I wish I could tune this ECU myself, all the other work I do myself but I just don't have any experience in tuning these ECU's. For now I will have to learn little bit by little bit.

Anyone tuners from OZ that want to make a killing in Malaysia? There is only 8 dyno's in the whole of Malaysia and not 1 good tuner...

[STR8E180]

im running a D jetro with the standard RB26 throttle body's and plenum and my tuner has no problem tuning my car wat so ever

Shouldn't the map sensors be bolted directly onto the inlet plenum and not run remotely via vacum hose?

there is nothing wrong with using vacuum lines and bolting the map sensors else where

most people have there map sensors mounted on the bracket which holds the throttle cable onto the plenum and run vacuum lines to the plenum

if u bolt the map sensors directly onto the plenum u run the risk of causing a air leak in the plenum when u drill and tap into the plenum so u can bolt the map sensor onto it, the only way i would recommend mounting the map sensors onto the plenum itself would be to weld on a thicker plate so u have more metal to play around with but at the end of the day ur still going to need to run vacuum lines

Edited December 7, 2008 by STR8E180

[Blue32]

My MAP sensors (2) are on top of the fuel rail and have remote sense lines coming from the inlet plenum. I'm not real happy with the way it is setup. They are just silicone vacum hose the same size that you would use for your boost gauge going to the MAP sensors, the port in the inlet plenum is used for the temp sensor.I agree with you that there is loads of cars running the same setup as mine and have no issues at all dispite what power they run.

Shouldn't the map sensors be bolted directly onto the inlet plenum and not run remotely via vacum hose?

Cheers..

See red above - here is your problem. This temp sensor is in the plenum and will not see vacuum at all. It needs the map sensors installed either in the no 3 and 4 runners as per the d=jetro instructions, or if you don't want to take the inlet manifold off to drill and tap, just tee the two lines of the map sensors from the PCV valve on top of the vacuum rail. I have had both setups on my 400+ awkw GTR and it makes ABSOLUTLEY NO DIFFERENCE to the tuning or results using either method for the map sensors. Also make sure the vacuum lines are equal length as per the instructions (150mm I think it was).

If tuner has GTR/D jetro experience he should know this.............

Edited December 7, 2008 by Blue32

[STR8E180]

See red above - here is your problem. This temp sensor is in the plenum and will not see vacuum at all. It needs the map sensors installed either in the no 3 and 4 runners as per the d=jetro instructions, or if you don't want to take the inlet manifold off to drill and tap, just tee the two lines of the map sensors from the PCV valve on top of the vacuum rail. I have had both setups on my 400+ awkw GTR and it makes ABSOLUTLEY NO DIFFERENCE to the tuning or results using either method for the map sensors. Also make sure the vacuum lines are equal length as per the instructions (150mm I think it was).

If tuner has GTR/D jetro experience he should know this.............

thats how ive got mine setup and ive got no problems at all

[Swiper the Fox]

Grippy you have your MAP's installed before the throttle plates...they need to read pressure/vaccum after them

[grippy]

This info has been fantastic, I did not install the power FC on my car and this is why I am having issues. Every point made out here is 100% spot on and even though they are only small discrepencies on the install I know it is causing me pain.

I will re-configure the map sensor setup and have the ecu re-tuned, I hope this will solve my problem.

Another issue that I have which I think is MAP sensor related is when the rpm reaches 6000 and the throttle is held constant the engine misfires badly and coughs and carries on. If I power through 6000rpm and de-cellerate through 6000rpm there is no misfire, it only happens when the throttle is held steady at 6000. Previously it was doing it at 4000rpm and I complained to the dodgy tuner here and all he could do with the re-tune was move the problem to 6000rpm. That's the way they fix things here, just fudge pucker it so you won't notice it.

Thanks for all the input, I will advise on how it runs when I sort the install myself. Give me a week and it will be done.

I will need a re-tune after I fix the map install right?

Rgds,

Grippy

(Andy)

[grippy]

I will have to confirm where the tap off for the MAP sensors is coming from but for sure my install does not look like the photo here. It may be from the PCV valve. My vaccum hoses are much longer and different length. The sensors are only zip tied to the fuel rail.

I will take some photos and post.

Thanks again for all the help with this. I would never have got this fixed without your input.

Rgds,

Grippy

[STATUS]

the port in the inlet plenum is used for the temp sensor.

there is your problem......

put the two vacuum port where they should be and it will run smooth as silk.

[grippy]

After looking at the install of my map sensor sense lines it seems that I will need to fix the position of the sense lines as advised by everyone here.

Both my sense lines are tapped off the the vacuum rail that sits above the injectors, right next to the rocker cover. One map takes the sense from the firewall end of the rail and the other from the timing belt end. The firewall end is also fitted with a tee that runs to my boost guage and the timing belt end is also fitted with a tee that runs to my fuel press reg.

This is definately not how the Apexi install manual shows how to install them. (Thanks Paulr33)

Both of my vacuum hoses are of entirely different length which may not be helping either. When I get some time this weekend I will fix it properly and see if it all runs ok.

Thanks for all the advice.

Grippy....

[rbs14kouki]

my map are plug on the balance tube and i dont have any problem !!! idle fine at 1000rpm all the way to 8000 when i drive it !!!

Edited December 9, 2008 by rbs14kouki