Hi All,

My first proper post on these boards - even though I've been around a while - as I've always enjoyed reading through the discussions...this time however I need a bit of advice.

Have an 1994 FD and have recently had a new exhaust system fitted (decat), this was a new centre section and backbox (no pre-cat on the imports from Japan). This has obviously allowed the engine to breeth a lot more freely and has - in my opinion - caused a bit of a boost spike. It happens at around 4500rpm as the second turbo comes online. It's quite nasty, but I've been advised that it's ok and won't cause any damage...this I'm not sure I agree with however.

More than anything it's annoying, so I've looked into a way of sorting it out. From what I can tell I'll need to get a boost controller of some kind. Seen a how-to on fitting a manual boost controller but this doesn't seem to give too much flexibility and seems a compromise. Therefore I've decided on a proper boost controller and have narrowed the options down to:

1. GReddy Profec B II
2. APEXi's AVCR

These are just about in my price range. So the question really is this:

Would either of these solve the boost spike problem, and if so which is the best of the two for the job? I'm liking the GReddy at the moment, but that's probably 'cos it's cheaper.

A second question is about how easy they are to fit? This is my first RX-7 (and turbo'd car) so am a bit of a newbie. Have rebuilt piston engines in the past so am not bothered about getting my hands dirty, just wondered if it's better fitted by somebody who knows the ins and outs of the system rather than somebody that's following instructions.

 

I recommend the Greddy Profec Type-S over the B Spec II....

The toughest part of the EBC install is the wiring, not the physical install of components, which is actually fairly simple.

And NO, a large boost spike is NOT ok, especially with the stock ecu!

 

How tough are we talking, just a bit of a pain or nuclear physicist levels? Have never installed anything like this before and am having trouble finding any installation details (although have found some MBC stuff which seems ok). I've done electronics courses in the past so am hoping it's not gonna be too bad.

Will an EBC actually get rid of the spike altogether - with fine tuning - or is it something I have to live with?

 

On your scale, just a bit of pain...You will need a 12V ignition on source, you can get this at the driver's side kick panel, or splice into something else -- mine is at the ecu feed.

An EBC should be able to eliminate the spike totally, although you may find that leaving a little bit of spike leads to faster boost response....

 

Cool, doesn't sound too bad at all. Have found the Profec Type-S for a fairly good price too, out of interest what is the difference between that and the B II? Is it older/lower spec or both?

Cheers for all the info.

 

The Type-S is the same thing as the original Spec "B". No computerized control program, no fuzzy learning, no bullshit. Just two buttons and three *****. Simple to use, simple to setup, reliable.

 

Sounds good to me.

 

Ok, I've got hold of boost controller and am halfway throough installing it, but have a question...

So far I've removed the old hose from the primary turbo to the Wastegate Control Actuator, installed the new hose with the new valve unit inline and have located it in a cool place to the side of the headlight so it shouldn't get too hot.

From what I'm aware I now need to block off the hose running from the WG actuator to the WG Solonoid Valve...what's the best way to do this? I was thinking about cutting the hose and then sealing a bolt into it or something, are there proper fittings to block off that nipple or shall I go ahead and do it the cheap way?

Cheers.

 

Nope. Cut the hose, put bolts into both ends (nipple end, and solenoid rack end), secure them with zip ties, and you're done.

 

When I installed my ball & spring MBC's, I plugged the line by inserting a pill with no hole into the lines to the solenoids. It just looks neater, no bolt-heads hanging out.

 

Cheers for the info guys, will sort the rest of the install out tomorrow, then it's just a matter of getting the settings right.

 

With the main cat removed,i find it hard to believe tha you are having only "boost spikes".Usually,with a dp-midpipe-catback you are having boost creep,and a ebc cannot control it....

 

I did a bit of a test watching my boost gauge a few days ago and there are no signs of boost creep. I get the spike as the second turbo kicks in then the boost drops to around 6-7psi which it stays at until redline.

Will check it out again once I've got the EBC installed and can do some runs.

 

You've got a boost leak if your boost is dropping to 6-7 psi without a boost controller. Find the leak before you go trying to crank the bejesus out of the turbos to hit normal boost levels with the EBC.

When I say "leak", I mean either a phsyical leak in the intake piping, a vacuum control problem (not likely in this case), or the pill is missing in the wastegate line/wastegate solenoid is unplugged.

 

Hi Crispy Beef,

I'm doing the same job tomorrow with an HKS EVC to try and control a boost spike.

I de-catted last weekend and am now spiking at about 1bar or just over on the turbo transition - not good so have been taking it easy! Boost was normal before at about 0.7 bar, now am getting about 0.85 / 0.7 / 0.85 pattern (maybe slightly more) not including the spike. Are you still on the stock ECU?

Let me know how you get on and I'll do the same, cheers.

 

Have just had all the hoses replaced (and tested to 15psi) as I wasn't brave enough for that job at the time, so they should all be ok. All have cable ties etc. The only older hoses left are the ones connected to the actuators on the turbos. Also had a leak in the lower inlet manifold which was sorted with a replacement gasket. Since then the boost has been fine until I introduced the new backbox which is when the spikes started.

The car was pulling fine with the old backbox and the psi was as it should have been (10-8-10). Could it be a problem with the boost gauge?? Will check over all the hoses carefully while I'm finishing off the EBC installation, then test the boost by bringing it up slowly to see if there's any problems.

 

Hi,

Yeah, am running on the stock ECU, it is on my list of things to do but the EBC has taken priority due to it being cheaper and in thoery getting rid of the spike.

Will let ya know how it all goes.

 

just a question crispy,,,,, im looking into removing the stock cat,,,,did you put mid pipe in or silencer, (what is noise level like)
also what have you done with thae air pump and if you have removed it,,,what is your idle like,,,,? sorry to hijack

 

Crispy, if you're only getting 6-7 psi u dont need a boost gauge to tell you , does it feel slower? When u make 7psi it feels laggy, 10psi its quick , 12/13psi it kicks u in the back and says hold on!
The back box wont effect boost much but the de-cat deffo will and cause the spike.

 

Gd question, if I can answer too, I used a straight thru 3" s/s mid pipe from ebay, very gd quality and perfect fit. The noise level doubles basically lol, bit too loud for me but sounds great at WOT. In hind sight I'd use a silenced mid pipe I guess.

I left the air pump on; when I disconnected the pipe into the cat there was only a pin hole gasket (literally) that it blows air thru so cant see that it did much! Pipe now blows air to nowhere, which I can hear slightly, but thats normal. Cant see the point in taking air pump off altogether for what little gain you would get and risk upsetting idle.

 

Hi,

I was worried about the same thing, but in the end opted for a straight through non-silenced pipe from Dragon in Devon. With their backbox on it is a bit louder when the revs are up it sounds fantastic, and in low revs around town you get a nice burble that reminds me of a V8. The only drawback is if accelerate from low revs in the wrong gear it sounds like it's peferated...but that just reminds you you should have downshifted.

When I had the old HKS backbox on with the new centre section it sounded fine, will, would have no issues at MOT time.

Idle is great now the inlet manifold problem is sorted, idles just under 1000rpm and it's pretty solid.

As for the air pump, did the same as Trevrxuk and just left it, doesn't seem to affect anything so am happy with it as it is.

 

No, it doesn't feel slower, a motorbike will vouch for that too. Apparently the old HKS backbox I had was quite restrictive, with that on I didn't have the spike, but as soon as the new box went on spikes showed up on the first run.

 

Ok, EBC all installed and things are working just great, and the boost spike is history.

Haven't set the boost too high to start with but the pattern is about right; with WOT in 3rd I'm running 8psi, then a slight drop as the second turbo comes in then 8psi to redline.

Anybody out there running the Type-S and have a rough idea of where their settings have ended up? Will probably have a play with the dials tomorrow and work it all out, but would be nice to have a rough idea of what they should be beforehand.

 

Nice 1 Crispy, mine was a success too, spike completely gone.

HKS EVC turned off now gives 7 - 5 - 7 psi boost.

Turn it on and boost is the same on minimum, dial it up 1/4 and I get 10 - 8 - 10.

I've set it at 12 - 10 - 12 , need to think about an ECU now, what are you getting?

 

Cool. Sounds like a good day for both of us. Have you uprated any other stuff for the to cope with the additional boost or can the standard set-up take it? I would have thought a bigger intercooler and a few other things would be required?

Haven't looked into ECUs much to be honest, but I'll be doing a bit of research now that the controller is in and working. Just ordered some strut braces to tighten the handling up so that's the next thing on the list to do. Also have a few gripes around the car to take care of such as knackered door lock (inside), squeaky bonnet catch etc.

What ECU do you think you'll go for? Can start my research with that.