stuckheng

Will need some education. I just pulled out my intake manifold and fuel rail, and it looks like this underneath. The vehicle's a RHD 1988 Turbo S, could anyone tell me what component has deviated from stock?

I know for sure I do not have a cycling valve, and even the harnesses required are missing. Is there a way that I can fit the cycling valve back with this setup? Without a cycling valve, and having the charge air pressure routed to the wastegate, the boost is kept at 0.2bar (wastegate setting). So I'm looking to fix this by getting a brand new cycling valve, but I need to make sure it'll work. Can someone help me out by telling me what are the components pointed out by the arrow? Apologies for the messy engine bay, only now I realise the whole routing is a mess, someone did not take much care previously.

Nevadarain72

I'm not an expert, but I have recently done some work on my own cycling valve/vacuum line setup. The top arrow is a little tricky to figure out what it's pointing to; is that the electrical cable going to the throttle body plug? The bottom one is pointing to the Idle Stabilizer Valve (ISV).

From what I can see, in addition to removing the cycling valve, they also removed the factory metal tree and replaced it with that long rubber hose. That, combined with the lack of banjo bolt on the turbo intake pipe (big chrome one), makes me think that while it's *technically* possible to return it back to a CV, in practice it's probably far too much trouble. With those mods, I'm guessing there's a boost controller of some kind? Black **** manual control or electronic one?

Here's a picture of what my car looked like before I put the intake back on. You can see the CV with the hoses going to the metal tree and wastegate, among other things.

Sam Lin

Lower green arrow is ICV (idle control valve).

Dan Martinic

Your top green arrow appears to be pointing to a vacuum line that runs from a little temperature-activated switch. This switch warms up and allows vacuum to pass to a little nipple under the throttle body. It's part of the fuel vapour control system.

You also appear to have the boost control line going straight from the chrome pipe to the wastegate and therefore no boost control. Given that you don't have the bracket, wiring, or metal vacuum "tree" for the CV, I suggest that you simply install a manual boost control in this boost control line. Very simple operation: cut this line and install an inline control kn*b (diaphragm-type control). Your only consideration is where to put the actual control kn*b. Since you don't appear to have cruise control, you can mount it passenger-side just in front of the firewall like I did. There are already some studs there to use:




To mimic the factory CV a bit, you can also install a second ball & spring type boost control into this line upstream of the kn*b diaphragm-type control (ie. closer to the chrome pipe). Set the ball & spring to delay opening until about 10psi (use a bike pump and rig up fittings + hose). Then, adjust the diaphragm kn*b control so that it limits total psi to whatever you want (15psi is pretty safe and fun).

The diaphragm kn*b type control always allows a bit of air through. The ball & spring does not but is said to be tricky or unreliable as a "total psi" device. Hence, the two work well in combination.

EDIT: Just realized yours is RHD so the above mounting area for a control kn*b may not apply

stuckheng

Thank you all for the informative replies. I was trying to fix boost control issues on the car, only to realise there's no boost control as correctly diagnosed by you all. I figured the vacuum lines can be plumbed back to original cycling valve configuration, but the electrical signal line from the KLR can be abit more problematic.

The top green arrow, I realise I was intending to point to the Air-Oil-Separator. I suspect mine is needing maintenance since there is considerable traces black of engine oil in the intake. Thanks for helping to diagnose the bottom line.

Thanks to Dan and Nevadarain, I am now considering a manual boost controller, even though it detracts from stock, it may simplify things where I have now, furthermore it sounds almost guaranteed to work. I will make the decision within next few days.

Dan I do have a bit of space there as suggested. I don't quite understand the second ball and spring type boost control suggested though. Are you suggesting to put 2 types of boost control in series? I may have to get educated on how the KLR controls boost via cycling valve. If I don't remember wrongly, it has a lower max boost setting at lower RPM and will raise max boost settings at higher RPM?

Dan Martinic

There will always be some oil residue in the intake; this may not be an issue. However, it is always a good idea to change the air/oil separator seals if original or unknown.

This site gives a good explanation of the three types of boost control: https://www.enginebasics.com/Advance...ntrollers.html

Yes, I put a ball & spring type in series with a diaphragm or bleed type.

The factory cycling valve is an electronic boost control, controlled by the KLR computer. It takes inputs like engine load, knock, airflow psi, etc., and keeps the air to the wastegate closed until a certain point then opens to maintain a maximum psi (I think the setting is 10 or 12psi). The KLR sends the CV electric signals. The CV then "cycles" between no air, full air, something in between. To change all this behaviour including total boost psi requires re-coding the KLR computer. I don't think there is much action on KLR chips.

You can somewhat imitate the CV by running a ball & spring boost control, without all the electronic sensor-based action of course. You set it to not let any air through until a certain point then hope it will react properly to limit overall boost. You lose the sophisticated load and other input control from the KLR, but you have a much simpler system that works well plus you can set max psi to higher than stock. The KLR will still be able to cut timing and spark in extreme events such as knock, so there is some safety left.

However, over-boosting, even for short periods, can blow a headgasket real easy. As suggested by the linked article above, there are some issues with ball & spring "spiking" or possibility of overshooting total boost psi. For this reason, as a safety, I have a bleed type in series after the ball & spring. The bleed type is easy to set for total psi and very reliable. It's basically the same control found on air compressors... very cheap. But, if you buy the bleed type from Lindsey Racing, you get a nice bracket and fittings. It can also be used with a dual-port wastegate, though I have no experience with that.

Why not just use the bleed type control? It is always bleeding, that's why. You will get better low-rpm action with a ball & spring type. The Lindsey Boost Enhancer is a ball & spring type control.

On my car, I have a ball & spring set to open around 10psi and a bleed type kn*b set to limit boost around 15psi. Setting the B&S is real easy: use a bike pump. Setting the bleed type is a bit tricky as temperature, load, the gear you are in, and more can result in different reactions. I have a psi gauge in the car--plumped into the vacuum line leading to the KLR computer--and every now and then I observe total psi to make sure I'm within 15psi or so.

In LHD cars without cruise control, there remains a nice spot to mount the bleed type control kn*b assembly (with a bracket as supplied by LR) where the cruise control would mount. That's what I did.

The ball & spring is installed without a bracket: it just gets fit into the vacuum line, close to that chrome pipe you've got there

Dan Martinic

I should add that I replaced the stock DME/ECU chip with the Rogue Tuning A-Tune chip (currently sold by LR) which uses a MAP psi sensor to see boost level and make adjustments accordingly. If you are increasing total boost over stock levels, I am not sure if the stock chip will work at its best

stuckheng

Great! I read up on both, and now I understand. I'm leaning towards getting a ball and spring type MBC, but setting it at a lower pressure to test it out, 0.5-0.6bar of boost, so even if there's a boost spike, hopefully it doesn't exceed stock limit. LR somehow doesn't have the MBC now, are these the same? https://www.paragon-products.com/Var.../lr-mbc-25.htm

Also, while cleaning the components underneath the intake, i've found this harness, around the area of where the cycling valve used to be, and it's routed back to the brake booster area for some reason. Could this be the Cycling Valve electrical signal connection? It is connected to something though, so bummer. I can't find out where it leads to unless I cut off all the harness covers.





Also, what's this terminal here? Could it be an aftermarket terminal? I'm thinking the car's not as stock as I think it is. If it's far from stock, I may have to give up the cycling valve setup... Thanks to all the constructive feedback, well appreciated!

Breakaway944

You need that connection. The CV connector is a "T" shaped connector. The thing circled in yellow is the factory connector to connect things such as engine temp etc to the inside harness.
You should have posted that last picture first - now we know you are running a Vitesse MAF kit. Remember if you would give as much info up front it will be easier to help you. I am not that familiar with this kit. Some have boost control ability, I believe, and that is why the CV is missing.

Dan Martinic

Contact John at Vitesse.. here on Rennlist, he is fast951. I found this email: john@vitesseracing.com . He also has a website http://www.vitesseracing.com/. He may offer to help you solve your issue. You obviously have his MAF.. and most likely chip. What happened to the boost controller is anyone's guess or we are missing something. Good luck!

stuckheng

Thank you both for your kind help so far. Apologies that the intake wasn't shown at the start. In fact, I did have a previous post diagnosing boost a few months back, and that topic has now shifted there. While it's true I don't understand enough of Vitesse systems, the wastegate in the car is permanently connected to the line before the intercooler and after turbo, meaning no boost controller. Would really like to check if the MBC posted previously would work in this scenario.