infernal

Hello all! Thank you in advance for your time reading this big-@$$ post of mine!

I recently bought an electronic boost controller and thought it would be a good time to up the boost a bit...

My supporting mods are:
A Walbro 255lph Hi pressure fuel pump, an Access-Blitz chipped ECU, an HKS intake, a 3" single exhaust with an 100cpsi converter and a Blitz SS BOV; everything else is stock.

I rewired my Walbro pump too, but did it in a different way... I just took the fuel pump feed wire from the relay under the dash that normally goes to the resistor in front of the airbox area, and connected it to the wire going back to the pump, actually bypassing the resistor/relay circuit. Is this a good move? I noticed the wire feeding the fuel pump relay (the one under the dash) from the fusebox (maybe?) is quite thin, but oh well... Now the Walbro sees 12.5 to 13V steadily on idle - not yet tested on boost.

I would to boost @ 0.8bar(11.6psi), so I decided to up the boost pressure to about 0.8 to 0.9 bar just to test. Needless to say, I was terrified with the results:

I did some pulls and recorded a crappy video of my gauges...

It seems that up to 0.7bar the AFR stays in the "oh sweet" levels, but after that it climbs quickly to the "oh $h1t!" levels!
I feel grateful that I didn't detonate... Or at least I think I didn't!

Here is the video.

Any help would be awesome, as I'm very confused...

I have numerous fears. Is it maybe that my fuel pump is not fed correctly when on boost? Is it possibly that I was shipped the Low Pressure Walbro pump instead if the High one?

Prior to the pulls, when idling my AFR was 16-17 due to the port air. Now, after the pulls it is 12-13, which means no more port air. So I removed the airpump belt and did 1-2 more pulls. AFRs still start to rise above 12:1 and thus I didn't push it.

I'm worried...

Thanks a lot in advance, and excuse me for my very long post - I'm anxious..

Marios

siikduke

iTrader: (5)

Do you have a fuel cut defender? If you don't you need one, stock ECU is programmed to cut fuel above 7.5 PSI~ Also, the boost controller doesn't up your boost level, it helps control it to be a certain PSI. If your wastegate isn't ported on your RX7, you will boost over 12 PSI easily. The boost controller will not stop the boost at 11.6PSI because the wastegate is what enables a turbo to hold a certain amount of boost constantly.

AGreen

iTrader: (11)

I don't know what an Access-blitz chipped ecu is, but a fuel cut defender would be my best recommendation too.

siikduke

iTrader: (5)

Yeah I was about to say also, if that "chipped" ECU doesn't have the FCD built into it, then he needs one.

lastphaseofthis

iTrader: (8)

you should get the rtek 1.8 and 4x720s, or rtek 1.7 and 2x720s before going much further, the stock fuel injectors run out of fuel on the stock turbo pretty quicky.

midnightbluefc

iTrader: (19)

yup sounds like u need an fcd and port your turbo if its an s4....

HAILERS2

I Googled this http://www.gtfours.co.uk/what/ecu/blitz/blitz_ecu.htm which is talking about a Toyota and Blitz ECU.

What caught my eye was about the second sentence where he talks about how most of the improvement was in the removal of fuel or making it leaner.

I have no idea if this guy knows what he's talking about or not, but if he is.......................then it MIGHT mean that the Blitz ECU's will work fine for a more or less stk car but when you remove the exhaust and put in one that flows much better, that might make the mixtures much too lean for the Blitz fuel maps.

This is just a GUESS and nothing more. Just something to think about. You might contact Blitz and see if they do remove the fuel cut of the stk Mazda ECU or not.

infernal

Hello all and thanks for the responses!

I have an S5 turboII. I haven't ported the wastegates yet, but I only experience creep in cold weather. Other than that only bad boost control.

Does anyone else have his pump connected this way? Is it bad to have it there?

I don't experience anything like a fuel cut. I had before with a stock ECU. This just leans out gradually but quickly. You feel no performance interruption while this leaning takes place...

I contacted Blitz but they told me that no info is available as it is discontinued and it is Blitz' policy to discard information about discontinued products...
The guy I bought the ECU from told me that it has the rev limiter, the speed limiter and the boost fuel cut removed, that it has refined injector duty and ignition timing maps, that it is for stock injectors, stock IC, free intake and exhaust and it is "suitable" for boost up.

Thanks HAILERS for the link!

You think I will be better of with an Rtek?

HAILERS2

You'd be better off with the RTEK 2.1 because you can adjust the fuel maps unlike the Blitz which you can't do much of anything with. Not saying its a bad ECU its just that it's not adjustable.

I'd never suggest a SAFC although you did not ask that question.

The bad apart of the RTEK is that I THINK they only make chips for USA models but I could be wrong. Read their site and or ask them.

I'm not sure how you did the Circuit Opening Relay under the steering column. I suppose like the attached jpg or similar.

Some people leave the Circuit Opening Relay alone and just go to the fuel pump resistor relay plug up front. Then just jumper one of the L/R to one of the L/G in the plug and bypass the resistor relay altogether.

I'd get me some long digital meter leads and probe the wire at the fuel pump connector back there and watch the voltage while driving in boost and ......see what you can see.

Turbonut

iTrader: (1)

Sure it's a Blitz? .7 bar is about 10 PSi so maybe that's the cutoff for the ecu. I installed a GForce ecu way back in '01 and it's been fantastic up to 12 lbs, that's the cut off. No problems at all on the S5 that we purchased new and only mod was a FD pump, front cat removed and Bonez used as the main cat. It ran just fine even with the OE main cat, but just liked the sound with the Bonez and wanted to ensure the OE cat lasted longer, so it sits in the garage.

Have the MBC set at @ 11 psi and one day years ago I was entering I-95, really had to get on it and I thought I blew the engine as the boost exceeded 12PSI and the nasty sound was heard. Long story short, the Hallman MBC stuck and the boost went crazy. Called Hallman and they heard of the problem, took it apart and reset and it's been fine ever since.

RotaryRocket88

iTrader: (7)

So this is just on 550cc stock injectors? In the video you've got 12.0-12.8 or so AFR in the 3500 - 4500 range when making 0.8 to 0.9 bar (11.6 to 13.0 psi)

A couple things are in play here. If the injector staging is at the stock 3800 RPM, your primaries will hit max duty cycle if you're making 10+ psi in the ~3300-3800 RPM range. Your walbro increasing fuel pressure is actually helping a little here.

That particular part of the fuel map needs additional fuel added to bring it down to a safer mixture. On my car, I have a significant amount of fuel added from 3500-4500 @ 10-14 psi. If I leave that area of the map stock, I can see 12.5 to 13.0+ AFR in those cells.

RotaryEvolution

iTrader: (30)

sounds like you need to think about going with an adjustable standalone engine management system and some fuel upgrades. the stock injectors will start to max out at around 11psi even with just the stock turbo. even with a walbro forcing fuel through their throat with increased pressure, which is just a bandaid for lack of injector sizing.

leaner AFRs/retarded timing during boost up is how many setups get quicker turbo spool, you can also achieve the same by increased fuel/increased timing. your chipped ECU could be programmed for the first example, which doesn't point to any real problem but could be as you get closer to maxing out the primaries during staging. at around the mid point i wouldn't aim for more than about 13.5 AFR at 11psi, beyond that is where you will be risking things if it gets much leaner.

when i tune i go for the second example which is more fuel and more timing, because generally it is safer in terms of fuel system stability issues. the stock ECU actually uses the first example of less timing and less fuel for higher EGTs during spool, which is not a good idea as you turn the boost up from the 7.6psi stock boost levels.

RotaryRocket88

iTrader: (7)

Just to add, S4 TII stock timing in the RPM range in question is going to be about 12 to 17 degrees BTDC w/ a 16 degree split for any boost level 8 psi or greater. Due to the LOAD based timing maps, no additional timing will be pulled for higher boost levels. But from what I've gathered, this is still pretty conservative timing. S5 TII timing maps will likely have even less timing since they use 9.0:1 rotors.

S4 TII timing: https://www.rx7club.com/2nd-generation-specific-1986-1992-17/stock-s4-turbo-timing-maps-warning-those-stock-ecu-943159/

infernal

Thanks again for all your replies!

HAILERS yeah I don't like the SAFC and cures like that at all... I believe lying to your ECU is like lying to your mechanic... Wouldn't like to mess up the timing either.
Yeah I rewired it just like that!
I'm thinking of moving on to something like a Megasquirt sometime... Don't know, I'm on a budget at the time being lol. Are they any good for rotaries?

Turbonut, meh it surely is a Blitz...



RotaryRocket88, yep all the injectors are the stock 550cc, recently cleaned and tested...
So this assures that they operate as they should and the only question is if they are sufficient.

Isn't it scary running that AFR with that pressure? Even though the timing there as you mentioned is conservative, I think I should have detonated, but I don't think I did... Can detonation also be heard from the exhaust? Cause mine is fairly loud and I can't hear a thing from the engine bay while pulling.

Before messing with the ECU, I've narrowed down my worries to my fuel pump and my FPR. I will test the pump tomorrow while boosting with a voltmeter, as HAILERS also suggested. I don't know how to check the FPR though... I don't have the tools. I think I can partially crimp the fuel return pipe from the FPR so that I can rise some more pressure and test, but that sounds like a really bad and failblog like idea.

Karack thanks for this clarification... So if I want to run the car properly at higher than stock boost even with the stock turbo I should get a standalone and alter my fuel system... So only solution would be to keep pressure at approximately 0.6bar till I do the upgrades? Does 0.6 seem safe enough in the video?
I think I will go the Megasquirt road.

Thank you all once more!

RotaryEvolution

iTrader: (30)

no, i think you mistook what i wrote. 13's AFR wise during mid RPM range is actually fairly normal for a conservative spool area timing setup. i wouldn't push it much past ~10psi though with the 550's, just saying i think you're worrying too much and should be looking more toward redline for leaning out issues which will tell you if your injectors and mapping are sufficient.

after the AFRs dip they should not pop back over 11.3 AFR towards redline.

RotaryRocket88

iTrader: (7)

I'd keep it at 0.6 or 0.7 bar (9-10 psi) at the most, as Karack is suggesting. The stock turbo gets too far out of its efficiency range at higher boost levels anyhow, and pressure will drop back down quickly.

In your 0.6 bar/9 psi run you start at 4000 RPM, but I'll bet if you started earlier (maybe 3500 RPM), you'd see a similar mid-12 AFR patch as engine speed increases. After 4k RPM, it hovers nicely around 11.5 AFR, and in your last run it even dips down to 10.5 AFR by redline. The injectors are likely at their limit, but the mixture looks ok up top.

In the middle, by 0.7 bar/10 psi you're probably maxing out the primaries under 3800 RPM. I've logged 550s maxed out in that area in the past.

infernal

Yeah it seemed really scary to me when I saw it passing 12s and still climbing...
I thought AFR drops (richens) again towards redline because the presssure also drops below 0.7bar...

RotaryEvolution

iTrader: (30)

yea, it's fairly easy to max out the 550's when upping the boost as they are set to hold on until that set point regardless if they should come on sooner or not. but under 13.5AFR at the staging point isn't super critical if you ask me.

from a tuner standpoint i see it happen alot in relatively stock cars without upgraded fuel system mods and none of them ever blew up. with a standalone and a different mindset you can change the way that staging point reacts but in almost all stock-ish cases you will have a lean spot during secondary injector transition.

this doesn't necessarily mean anything is out of whack but you do have to monitor it more closely which is why i prefer to tune it out with the alternate method. it does seem like your just pushing the 550's primaries to their limits in the upper boost ranges. this generally also isn't an issue with larger turbos as they usually don't spool until after that point anyways.

infernal

Thanks for the info and advice, Karack!

What bothers me is that the lean condition is continuing even after all injectors are online... But I'm also n00b!