Hello -

I have a quick question for you all- Do you all have MP or Hi-flow cats with the PFC? If you are still running your stock main, how long has this lasted? My impression is the split air solenoid feeds the air from the A/P to the cat during idle, and the PFC does not have this hooked up. I have the PFC and have been running the stock cat for a few months now. Am I destroying the main cat? I am getting ready to do some major work and wanted to know if I should be looking at this as well. Thanks in advance to any and all responders!



Jon
'93 Touring
'85 GSL-SE

 

I had a hi-flow cat with my PFC for about 6 month then went to a MP. The A/P is still connected and working along with the ACV.

Where did you here this CRAP about the PFC not controlling the A/P and ACV?

 

Chuck -

On the installation of the PFC, the split air control solenoid connection is left disconnected. (clipped wire) I was wondering just what I was leaving disconnected so I researched it in the shop manual - this appears to control the air to the main cat. The port air solenoid is still hooked up, but I don't know its function. Could you help me understand what the ECU change affected with regard to the air pipe to the main cat? I just want to make sure I don't blow the engine due to a plugged/melted main cat.


Jon

 

Jon,

My PFC came from Ray so I did not cut anything or ever read/hear about that! I do not remember (need to look in the manual) how the full functionality of the ACV system works. But, I think the cat does not get air until past idling and actually driving, while the air pumped into the exhaust works up to abouit 3k under light loads. When my cat was still in, it never smelled bad as it was working fine.

I will have to look it up in the manual after getting home.

 

bhlokihl

 

My air pump leaks a little bit around the flange. At idle I can hear and feel it running (a little air sqeezes out the leak) , and I cut the pins on the PFC. I do not think that you are hurting your cat.

 

Chuck -

Mine came from SR as well, so my pins were clipped instead of the wires(probably the same way as yours), but it disables the same functions nonetheless. Thanks in advance for looking up the info - This would be good info to know and for an 'FAQ' for people looking to buy/install a PFC *if* there are more serious implications for the stock cat.


Jon

 

The only hurt you are putting on your cat would be due to the basemap of the PFC running so rich.

I only ran my stock cat for about 45 days before I replaced it with a bonez hi-flow...oh and that only lasted 3 days before I pulled the hi-flow off and went MP, so no worries about cat destruction any more...

k

 

yeah, good question, i've been wondering about this myself. have a power fc still in box waiting to go in.

just for clarity, the four clipped pins / cut wires are--

EGR switch input
EGR solenoid output
AWS solenoid output
Split Air Bypass solenoid output

so, losing the AWS is good, no one wants their engine racing at startup.
losing the EGR is probably ok. that exhaust gas makes a dirty corrosive mess, although the point of it is to reduce combustion temps which effectively raises the octane of your mixture. (prevents pinging) i'm going to rig up some kind of water/alcohol injection, so i'm not worried about that aspect of it.

but i've never seen a good explanation of the implications of cutting that split air bypass.

 

A. EGR switch input
B. EGR solenoid output
C. AWS solenoid output
D. Split Air Bypass solenoid output

Did not get around to looking at the manual last night, but about the above 4 controls.


A. California only models have the EGR switch to tell the ECU if the EGR valve is really working or not.
B. The EGR was removed for the 95 model car as it was not really ever needed for passing emmissions. The EGR worked only under light loads and not under boost so it did/does not affect fuel or combustion temps.

C. Most of you know about the AWS for 3000rpm startup. I like others removed it long years ago.

D. The ACV system does not and never did affect the engine operation while on heavy load/boost. The air pump turns off about 3000rpm even under light load. So it does not affect fuel or combustion temps.

Now I am going from memory here as I did not go over the manual last night. The ACV has about 3 solenoids; and there are about that many functions:
1. air is directed into exhaust manifold to help burn the rich idle fuel mixture and fake the O2 sensor to think that it is really leaner.
2. air is directed into the cat to help it burn off some of the unburnt hydrocarbons thus making the exhaust cleaner.
3. Unused air is routed out of the system back to the top of the stock air box.

Due to not running a stock air filter system and just dumping #3 directly to atmosphere, mine use to make that moo-fart sound at low speeds when lifting off the throttle. Since putting in the PFC, my moo-fart has stopped. Has anyone noticed this?

 

This is one of the first things I noticed.
Makes having an after market intake a much quieter affair.

 

After reading the RX-7 maintanance manual and viewing the diagram, I can not say what the split air bypass does. As shown, it is in parallel with another non controlled air path to the cat. It's valve functionality can not be detemined by the diagram. If it opens then it either allows the second passage way to work or it dumps air to atmosphere. But there is a larger valve just for dumping the excess air.

A different bypass valve for the exhaust is show in the diagram, and it's functionality is easily understood. It is the smaller of two pathways for air flow to the exhaust.

 

hmm, looks like we'll never know the mystery of the split air bypass, but have to trust Apex'i that it isn't needed...


the EGR operates up to 3850 RPM but should close under heavy load, so it has no affect at WOT...

most EGR systems are wide open under medium load. that is where combustion temps are highest.

i don't know about you but i'm not often above 3850 rpm in 5th. (about 100mph) so the EGR is very much in effect as you accelerate, say, from 70 to 100 under medium load on the highway, a situation i DO find myself in quite often.

so it may be affecting pinging more than you think.

anyway, i'd still be in favor of getting rid of it because of the mess it makes.