OverEzzz

iTrader: (26)

Just as the title says, I can't make it past the first learning to idle step of installing the PowerFC. I've seen all kinds of posts with similar problems. I've used the search button, and tried several things I've found in my search. Still, no luck.

I'll try to be as descriptive as possible. The car mods are pretty minimal: Full exhaust, intakes, Koyo Radiator, and now a PowerFC.

I bought the PowerFC used on this forum. At the same time I became a member of the tuning group on yahoo. So, I'll start from the beginning. I clipped the proper wires when installing the harness, and started it up. The idle was really high (2-2.5K rpm) and bouncing. So I began going through the idle tuning notes. I'm pretty sure the accelerator cable and the throttle adjustment screw are exactly where they should be. I put the Air adjusting screw 1/2 turn out. Then on the the TPS. I could not get the TPS to quite read within the limits. So I replaced the TPS and followed a good write-up on properly setting the TPS. This one here:

TPS Adjustment

Now, I believe I have the throttle set-up exactly as it should be. The TPS is reading .4V on narrow range and 1.0V on full range. I verified the voltage using a multimeter. The throttle cables and throttle adjusting screw are not opening the throttle in idle position.

But still, it won't learn the idling procedure. I've also initialized the PowerFc several times. The idle just keeps bouncing. No matter how long I let it sit and idle. All of the typical problems are right there with a bad idle. The ride is rough, it backfires, and there is jerking on deceleration.

Any help would be much appreciated. If I should take any photo or video just let me know, and i'll post on asap.

cewrx7r1

iTrader: (2)

That TPS writeup was done by me before we had the PFC and commander.
Use the commander to read the voltages!

After installing "The USED PFC", did you initialize or in your case, re-initialze the PFC to set it back to stock values?

OverEzzz

iTrader: (26)

Yes, I have re-initialized the PFC. Also, the voltage readings on the PFC read the same, .4 on narrow and 1.0 on full.

What else can cause the PFC to not learn the idle?

thewird

iTrader: (8)

Did you disable the thermowax when you set the TPS?

thewird

cewrx7r1

iTrader: (2)

Bad O2 sensor, bad air pump, bad ACV, ???

OverEzzz

iTrader: (26)

Yes, I disconnected the spring which gets pushed by the thermowax. I did this to eliminate any possibility of the thermowax causing my problem. I also verified the TPS stays in the correct range after the car is warmed up.

OverEzzz

iTrader: (26)

I replaced the 02 sensor about 3 month ago. At the same time I eliminated the Air Pump. Sorry, I should have mentioned that in my original posting.

I would like to check for a bad ACV. Any useful links?

cewrx7r1

iTrader: (2)

Did you turn off the O2 feedback switch? No air pump, then no O2 FB!
Take off the ISC solenoid, clean it, verify that it works by apply 6-12 VDC.

OverEzzz

iTrader: (26)

I did try to turn off 02 feedback, but I didn't know no airpump means 02 feedback should be turned off.

I will take out the ISC for a cleaning this weekend and post the results.

Tks for the help

arghx

iTrader: (3)

Do you have a Datalogit? If so, can you post logs?

OverEzzz

iTrader: (26)

Sry, not Datalogit. I pulled my uim manifold today, and the wire which splits to the isc and tps is in pretty rough shape. I found a couple of places by the connectors where the inner wiring is exposed. My next step will be to replace this wire and give the isc a cleaning.

cewrx7r1

iTrader: (2)

Really, most likely an orignal engine harness which was **** when new.
Should be replaced with a newer - better version.

OverEzzz

iTrader: (26)

I agree with you. Most of the electrical looks to be showing its age. Can you recommend a harness at a fair price?

Grinch

iTrader: (2)

rywire makes a replacement 13b Mil-spec harness for around 650 don't seem to bad.
Rywire : Mil-spec Tucked 13B harness (FD3S/Rx7) - $649.00

thewird

iTrader: (8)

^ That is only for single turbo's or non-sequential setups.

thewird

Grinch

iTrader: (2)

sorry, I'm new to the rx7 world just picked mine up and was looking for new wiring and seen them on that site before. Again sorry for the wrong info

thewird

iTrader: (8)

It's not wrong, was just clarifying for other viewers.

thewird

OverEzzz

iTrader: (26)

So, a little update. I pulled the UIM this weekend and really sorted through things to see what was bad and what was not. I really shouldn't have ignored the vacuum lines this long. As mentioned before the wiring harness is pretty bad too. I think I got a little ahead of myself when purchasing the PowerFC. I should just take a step back and replace the wiring harness and vacuum lines.

I think this is a good time to also remove emissions, and perhaps go non-sequential. I will follow up on this post, but it may be a month or so before I get everything in order.

I appreciate the advice, and all of this headache has helped me learn the engine better.

If I go for the non-sequential mod will I save money on the harness?

OverEzzz

iTrader: (26)

I wanted to provide some closure on this thread for anyone facing a similar problem in the future. First off, my PowerFC purchase was really premature. In the PowerFC FAQ it states to make sure the car is running in good before installing. I thought my idle of 1200 RPM wasn't too big of a deal, but the higher than usual idle should have been solved before installing the PowerFC.

So, when I finally stop putting off the vacuum leak issue my problem was solved. The LIM gasket was in awful shape just like everyone warns. I bought a complete gasket set from atkins rotary. I've used about 3/4 of the gaskets provided in the set, and will use the rest when it is time to rebuild the engine. Good gaskets are so important. They have made a significant different in the engine behavior.

While I had the turbo and manifolds off I decided to upgrade the turbos to BNR stage 3's. I got in on part of a group buy and got a good price. While I haven't been able to push my car yet, I think they will be good to me for years to come.

When I went to the BNR's I decided to go non-sequential, remove all emissions, and go with the Rywire harness mentioned above. I have such a better appreciation for everything under the hood now. The Rywire harness is great quality, but only provides the essential pieces to run the single turbo or non-sequential setup. All unnecessary connectors are not part of the harness. Two of the big ones are the fuel temp. sensor and the idle speed control valve. Extra blank wires are provided in the harness. So I guess you could wire these items up and pin the blank wires into the harness.

So, 4 months later I finally have the car back together. The PowerFC learned to idle without a problem. Without an ISC the idle cannot compensate when the AC kicks on. I've found a happy medium in setting the idle to 950 RPM without AC. This drops the idle down to 800 with the AC on. Whenever the car has been running for a few hours on a hot day the idle creeps up to about 1050. From what I have read I think this is due to the harness not utilizing the fuel temp sensor.

I'm really happy with the way it turned out. The car is simple and behaves better. I know the block will need to be rebuilt eventually, and I'm looking forward to it. This RX-7 wasn't maintained the best when I bought it about 2 years ago. Every bit of work I do breathes a little bit of life back into it, and puts a smile on my face.