Experience With SVX Throttle Body Intake Box From VanCafe?

[BCgee]

Slowly improving components of my SVX swap in terms of electrical and acceleration and came across Van Cafe's 'Throttle Body Intake Box." Anyone use one and if so, could you please share your experience?

https://www.vancafe.com/SVX-VANAGON-INTAKE-BOX-p/svx-intbox.htm

Looks like the limited production run is still in stock but won't be reproduced again; if VC's aftermarket piece could help smooth out throttle and acceleration patterns/prevent known weak links in the SVX swap I might need to pick one up.

Thanks in advance for any feedback.
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1987 SVX Syncro Hightop

[flomulgator]

I think if anything it will increase turbulence through the throttle body, as it is a reduction in volume of the large stock throttle body intake box. Probably not an issue though as someone would've reported this as an issue by now if it existed (this part was produced for years as a whole intake system).

The bigger benefit is durability. Most DIY jobs (mine included) are cut and weld jobs to make the plastic box shorter, and it still takes up more space then this does which makes intake manifold service work very difficult. All those pipe nubs are plastic too and will only get weaker over time. This small aluminum box addresses both of those.

Do you have throttle/acceleration issues?
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She's built like a steakhouse, but she handles like a bistro!

[Howesight]

"Slowly improving components of my SVX swap in terms of electrical and acceleration and came across Van Cafe's 'Throttle Body Intake Box." Anyone use one and if so, could you please share your experience?

https://www.vancafe.com/SVX-VANAGON-INTAKE-BOX-p/svx-intbox.htm

Looks like the limited production run is still in stock but won't be reproduced again; if VC's aftermarket piece could help smooth out throttle and acceleration patterns/prevent known weak links in the SVX swap I might need to pick one up.

Thanks in advance for any feedback."




Like Flomulgator, I modified my own factory SVX air box. So long as the modified factory air box has no air leaks, it will not be contributing to the "throttle and acceleration patterns" that you describe above. In that case, the problem is likely elsewhere. I have had my own difficulties sorting those issues. Based on my own experiences, and assuming that you have already gone over all the vacuum hose connections on, under and around the intake manifold, then here are my thoughts:

1. The most likely source of poor throttle response, especially if you notice that the problem is much worse with a cold engine, is a failing Throttle Position Sensor. The factory manual has a testing protocol for them.

2. But a very simple test is also available. If you notice that your engine bogs when driven right after a cold start, but improves once the engine warms up, then this is a strong sign that the TPS is faulty. Test the theory the next time you are about to do a cold start by flooring the accelerator and releasing it fully say, 20 or 25 times before cranking the starter. Then start as usual. If the bogging disappears or improves noticeably on this start, then you can be 99% certain that the failing TPS was the main factor. My theory as to why this works is that the carbon traces in the TPS can be "cleaned" to some degree by this process and do the job they were intended to do. But note that the TPS is a $300 item with no aftermarket replacements that I have seen. This is why I still do the accelerator pedal (but only 10 times) dance on cold weather starts. The more my rig is driven, the less the symptom appears.

3. My SVX engine, on a couple occasions, threw codes after a long drive in salty, wet road conditions. Disconnecting the main harness connectors (at the firewall, not at the ECU), cleaning them and applying copious amounts of WD40 eliminated the faults. That firewall-area connector bundle gets a lot more exposure to the elements in the Vanagon than in the SVX car installation.

4. It is worthwhile checking and cleaning the MAF sensor filament with MAF sensor cleaner, just to eliminate the possible problem of it being covered with dirt. In the SVX-to-Vanagon installation, it is very easy to incorrectly install the Subaru air filter and, in any event, the rear-engine install leaves more dust for the filter to deal with. The MAF sensor is easily coated with dust that gets past the air filter.

5. It is also helpful to carefully clean the electrical connector at the MAF sensor.

6. If you have hesitation or other running problems when the engine is fully warmed up, then do make absolutely certain that your oxygen sensor wires are not mixed up such that the 2-4-6 sensor wire is connected to the 1-3-5 sensor and vice-versa.


The SVX ECU, like most modern EFI systems, ignores the oxygen sensor signal during warm up until the coolant temperature threshold is reached. In the meantime, transient throttle enrichment is mainly controlled by the inputs from the TPS, not the MAF sensor, although the MAF sensor does contribute. If the TPS is not working properly, then there will be hesitation, aka bogging when the throttle is opened because insufficient additional fuel is being injected.
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'86 Syncro Westy SVX

[wasserbox]

No idea about performance claims, but the design addresses some issues I have with the original.

I have the original square version of this. It hits the bottom of the rear deck exactly at the spot that has been angled off on this model.

[BCgee]

Thank you each for the detailed feedback above. Howesight - I especially appreciate your experience troubleshooting potential TPS problems.

Presently my acceleration issues are two-fold. Cold conditions exacerbate a herky-jerky acceleration below 3k rpms (but not consistently), with a related inconsistent idle stumble. Second, the top end power and responsiveness in 5th gear is weaker than desirable on inclines, albeit driving at 6-8k elevation and my transmission has stock gearing. Conversely no problem holding a steady 65mph on flats.

Related note: I identified a failing coil pack as a leading potential culprit of erratic idle stumble and funky acceleration patterns and am replacing all coil packs and plugs proactively for a new baseline.

As to potential MAF sensor or TPS problems related to or contributing to acceleration challenges, I should note that I have installed an aftermarket VC Subaru air box and DIY CAI in the driver side D pillar. I’ve tested for leaks and feel confident the system, including the MAF, is functioning properly. That air intake modification was critical for me being a yearlong driver in snowy conditions; the stock SVX air intake drawing from the engine bay behind the rear wheel would suck in powder snow and create dangerous potential for hydro locking the engine.

I’ve also recently rebuilt a new exhaust system including new O2 sensors and feel confident they are in the correct locations. Acceleration jerky jerky symptoms have become worse since a recent road trip with wet driving conditions making me think that I may be experiencing cumulative electrical failures with my plugs given their exposed condition on the engine behind the wheels.

Coming full circle I am interested in the VC TB intake box because I’m aware of the NLA status of many SVX parts and reasonable potential for failure of my original circa ‘92 eg33 parts to fail. I try not to replace items unless necessary, but given my acceleration troubleshooting I was interested in others’ experiences. Everyone’s feedback above is very helpful to both brainstorming and being a better SVX Vanagon owner - thank you!

I’ll finish the plug and pack replacement, get some more miles under the belt, then assess whether I need to dig into either TB intake replacement and/or further work on the TPS system.

Thanks again for the insights SVX owners!
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1987 SVX Syncro Hightop

[BCgee]

Update here: full coil pack and plug replacement cured all acceleration symptoms. After several hundred miles and a hard look at the old plugs I’m positive the acceleration issue was linked to electrical shorts.

I’m still experiencing an erratic high idle/rpm around 2k when at a traffic light or stopped on traffic. Next troubleshooting will be taking apart and reinstalling, carefully, my modified SVX airbox and CAI up the drivers D-pillar. Will also clean the MAF and scrub engine grounds on the driver’s side chassis mount (single bolt that’s exposed to filth). One at a time of course.

Fingers crossed. Still not sold on replacing the TB with the VC model, yet.
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1987 SVX Syncro Hightop

[tjet]

I'm planning on installing this '89 ER27 into my Syncro by this summer. I'm either going to get a Megasquirt EFI system, or an SDS with the coil pack option.

I still need to figure out the accessory drive system, specifically the power steering pump. These engines never came with power steering. I'm hoping I can adapt an EJ22 power steering pump and alternator with all the factory brackets minus the AC compressor.

Here's my '90 EJ22 that I plan on robbing the accessories from:

https://www.thesamba.com/vw/gallery/pix/1890528.jpg

[r39o]

Riddle me this: Just how will you get this past the CARB?????
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"Use the SEARCH, Luke" But first visit the Vanagon FAQ!

1990 Multivan EJ 22, Rancho trans 0.82 4th, Small Car front AC, CLKs w/ 215/65-16, homemade big brakes 303mm, Konis, Recaros, etc....

Click to see my ads for Cup holders, Subaru clutch fix and CLK wheels (no wheels currently)

[tjet]

I have it registered in CT, which has a 25 year "rolling" smog test requirement.
The van now lives in California so it wont rust anymore then it already has.
I do plan on keeping my stock wbx engine if I ever need to get CA plates.

[r39o]

You have 90 days to swap plates to CA. The popo is very alert to this sort of stuff. You need smog every other year. Have fun!
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"Use the SEARCH, Luke" But first visit the Vanagon FAQ!

1990 Multivan EJ 22, Rancho trans 0.82 4th, Small Car front AC, CLKs w/ 215/65-16, homemade big brakes 303mm, Konis, Recaros, etc....

Click to see my ads for Cup holders, Subaru clutch fix and CLK wheels (no wheels currently)

[tjet]

Been there 3 years and all good so far, but thanks for the heads up.

[vandroid]

[j_dirge]

[flomulgator]

Would a troubled TPS sensor cause it to get stuck in the warm up cycle (high RPMs) on cold start on cold days? My van will retain a high idle (2,000 rpm) even after running for a while and warming the engine. If I cycle the ignition after warmup low idle (600 rpm) is restored. Symptom larger absent in summer.

Such a minor complaint in the grand scheme of SVX Syncro Westy ownership that I’ve largely ignored it but now I’m curious
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She's built like a steakhouse, but she handles like a bistro!

[BCgee]

[j_dirge]