oops i mean activate the solenoid. not enough current to activate the solenoid if theres a resistor in parallel with it.

Not a problem.

Parallel circuits define their own current. The solenoid will draw 0.4 amps and the 300 ohm resistor will draw 0.04 amps. The only way the resistor could affect the current in the solenoid is if it were a large enough current to significantly change the voltage drop across other components in the circuit (wire resistance, internal battery or alternator resistance, ECU transistor drop).

Normally the voltage drop across those components is negligible. If a high current were pulled through them, the voltage drop across them would increase correspondingly. It would take several amps of current (not 0.04) to cause a noticeable drop. That's primarily because their resistances are orders of magnitude smaller than the solenoid's resistance.

:)

this my sound like a newb question but whats the difference between boost creep and boost spike.

As the quote in the previous post indicates: a boost spike occurs for a short time at transition in a sequential system; boost creep occurs whenever the waste gate can't release enough pressure to prevent the boost level from increasing (creep). :)

Seems to me you can just unplug the wastegate solenoid for 7 lbs of boost. I'm thinking of rigging a switch to do this for a valet mode.

jwhite youre absolutely right i wasnt thinking. i will change the diagram and put the relay coils in parallel. as for the resistors do you really think the ecu can handle double the current draw?

I don't know why you say it will be "double". I believe the solenoids involved are all 30 ohms (measure them with an ohmmeter to prevent surprises). The resisors are 300 ohms. The resistors only add 1/10 the solenoid current (0.04 amps vs. 0.4 amps).

The 4R terminal is already controlling two solenoids in parallel, so it normally handles twice the current (0.8 amps) that 4T and 4S handle. An additional 300 ohm resistor will be a 5% increase in current. But since the 4R terminal transistor could conceiveably be nearing its design limit, you might try using a 1000 ohm resistor on that terminal. It would contribute only a 1.5% increase in current.

It's not likely that they used different transistors for different outputs in the ECU, so 4T and 4S can probably handle the extra 300 ohm resistors with no problem.

Yes, there are some risks, but since we don't know the specifications of the transistors involved, we must assess the risk and proceed accordingly. I believe there will be no problems. If you feel the risk is too great, keep both relays in the circuit (but DO wire their coils in parallel).

:)

well i said double because i thought i remembered measuring the solenoids at 300 ohms. its been a while ok.

I understand. That would be a problem.

I can't say that I've measured all of the solenoids myself or that I measured any of them recently enough to still be sure. I'm working mostly from the FSM here, not from my garage notes. Page F-194 lists the solenoids and points to pages F-93 and F-123.

F-93 says that the Turbo Precontrol and the Wastegate solenoids are 30 ohms. Page F-194 lists this page for the Turbo Control, Charge Control, and Charge Relief solenoids, but there's no mention of them on that page.

F-123 says that the Relief2 solenoid is 30 ohms. Page F-194 lists this page for the Relief1 solenoid, but there no mention of it on that page. This page is referred to for testing many of the "rats nest" solenoids. For example, page F-46 refers to it when testing Relief1. So it's likely that most of those solenoids are 30 ohms.

F-191 tells how to test the "rats nest" solenoids, and the diagnostic page for the Charge Control solenoid points there (actually it points to F-190), but no resistance value is given for those solenoids.

Obviously, the safest way to be sure is to measure the solenoid resistance while installing the circuit. After disconnecting the wire for the solenoid from the ECU, just measure the resistance from that wire to the common power point on the EGI relay (with the ignition off). If you find anything that's not about 30 ohms or 15 ohms (4R), find out why it's not one of those values.

If there is a solenoid that's 300 ohms, it could be switched by a transistor in the ECU with a low current rating. I that case you could probably just use a higher resistance "fake out" resistor, say 3k ohms, to keep the ECU happy.

Until somebody actually verifies all this and gets it working without burning up his ECU, it will be hard to say much with absolute certainty.

:)

The idea is an amazingly simple yet effective mod! I've had trouble with primary turbo issues when at the track (boost was fine above 4500rpms, but for some reason when I would come under 4500, the car would put out 0 boost until I got over 4500 again, which really sucked in some turns). I've soldered the wires to the switch this evening and will probably splice in the switch sometime in the next few days. I'm taking the car to Infineon on Monday, and I'll report back with the results.

I'm using Gene's method (no relays), and I thought Id fill you guys in on the switch I got from Aircraft Spruce. It's part number MTA-306D and cost $12 bucks plus shipping.

http://www.allenhah.com/Temp/Switch1.jpg

Thanks for all the helpful information guys! I'm not too worried about turning the car off when in NS mode since I plan on simply using the NS mode when I'm at the track, and as long as I remember to turn it back between sessions when the car's off, I should be cool.

Two words: HEAT SHRINK

:)

Sorry guys- haven't been on the forum lately. Good discussion, BTW.

Hope the switch works for you. You'll find that different tracks require NS vs sequential on others. Lots of fun to tinker with.

Good luck,

Gene

Well, I would have preferred if you asked first (and certainly would have given you permission), but what the heck. After all, it's nice to provide resources for the RX-7 community.

Just ask that you keep my link as a reference. Nice work, BTW.

Gene

Update:

Okay I had installed the switch per the directions (colors and wires matched up exactly as shown on Gene's site...make sure you're looking at the right connector to the ECU!), and I took it out for a spin. My boost would fall on its face every time I tried to get on the boost, so I figured I needed to reset the ECU. Did that but I still had the same problem. Turns out the switch had fried, so it was sending all sorts of wrong signals.

Went to radio shack today to pick up some switches, and I ended up getting a SPDT and DPDT switch since they didn't carry any TPDT. I wired it up, and my regular mode was back, but when I switched to NS, I had strange problems. It would give off really low boost (~4psi?) up to 4500rpms and then go to full boost after. Also when I let off the boost before 4500 rpms, it would give off a strange noise...kind of like a really slow and muffled blow off. I'm sure I wired something incorrectly, so I'll trace the wiring again tomorrow.

Strangely, it seems that my boost problem was fixed. My car would give off no boost under 4500rpms after a full throttle run past 4500 rpms for a while. Now it seems to get right back on it! I'll know more for sure when I get to the track.

Not to burst anyones bubble, but when you have a PFC and a Datalogit this is as simple as a few keystrokes.

Simply go to "Settings 1" in the datalogit and change the "Turbo Transition" setting low and high rpm transition points to less than idle RPM, even to 0. Viola! non-sequential, with no wire cutting.

I use this at autocrosses to get sequential spool on the start and then have non-sequential function for the rest of the time. I do this by setting the low rpm point to less than idle and leaving the high RPM setting stock. This means it switches to both turbos at the normal high setting point and then doesnt return to the primary until I either turn off the car or bring the RPM under idle by almost stalling it.

Just thought it might be a solution for some of you guys that just want to fool around with non-seq and have a PFC, and anyone with a PFC should havea a datalogit, I would almost rather have the datalogit than the commander, but thats just me.

I personally hate how loud the car is when non-seq, it made the decision quite easy for me to remain seq for daily driving.

Jon

edit: And the Datalogit also allows you to install a toggle switch for the 2 boost settings on the PFC, which means you could switch between any 2 boosts you want, not just limited by a resistor.

it does alot of other cool things too, but I'm not trying to sell the damn things, just telling you all what is out there.

Bringing it back from the dead! Any updates on people running the setup? I want to do it, but I am not a eletrical guru at all.. Infact it kinda confuses me.. So what has proven to be the best way to do it.. and it will work fine with a pettit unlimited ecu correct?

Ressurection time.

How does it work on a stock car and stock ECU for autox ?

:-) neil