Hi everyone,

I tried searching about this issue, but honestly I'm not sure what could be the issue. When the car is fully warmed up, it will idle just fine, but after coming back to a red light, I notice that sometimes the idle will hang a bit higher, like around 1200. After hitting the accelerator pedal, it drops back down to around 800. Here is a video of the issue:



The car is a 89 GTUs, stock other than Atkins 6 port sleeves and Racing beat downpipe and presilencer.


This is my first RX7, so I am still learning my way around the car, but is 3rd gear acceleration this bad for all NA cars?


The above clip is the entire front straight away at Buttonwillow 13CCW. As you can see I only go from about 5500-7500RPM before needing to brake into the first turn. I checked the VDI and aux port actuators with a bike pump and they aren't stuck.

 

First thing to do would be is to lube up the linkage,cable etc on the Throttle body.
Your butterflies can stick if there is crap inside the TB.
Have you checked the venturi area for Gum/Varnish that may hinder the total closing of the Butterflies?

 

idle screw is also probably set too high.

seems your auxiliary ports are also stuck or not opening properly. try wiring them open and see if acceleration at high RPMs returns.

 

I bought some TB cleaner and will have a go at the TB tonight, as well as lube up all the TB linkages. Is WD40 fine for that?

Is there an easy way to wire open the aux ports on a S5? I can barely fit my hands to reach the front actuator. I know they're not stuck, I took a bike pump to the lines leading to the actuators and I can see the rods extending and hear something moving inside of the engine.

 

WD40 isn't a lubricant, i'm not sure why 99% of the world's population believes it is.

it's more of a rust preventer than anything else.


the s5 is a little tricky to tell if the ports are working or not, compared to the s4.

 

hahaha I read this and laugh because it is so true. WD40 was originally designed to displace water. I don't remember what I was watching but that is how the name of the product came to be . It's a water displacement that was formulated on their 40th try.


Edit : just looked it up its even on their website.

 

it was designed for military use as well, hence the rather dull name.

 

Oh, well it was what I have at home.


I'll pick up some white lithium grease tomorrow and have at the TB linkages.

I took the intake elbow off to look inside the TB, and it seemed pretty clean to me. No gum or gunk on the TB walls or the butterflies.


I am also getting some bucking/jerking at high rpm's, as well as the check engine light flashing very briefly while the car jerks. This is happening at 7k+ rpm. It kinda feels like a fuel cut, but I just replaced the fuel pump, filter, wires and plugs all within the last month.

 

try pulling codes before shutting the car off after the CEL triggers.

 

I Don't know why i didn't think about pulling codes in the first place.


Looks like i have codes 13 and 33...If I'm reading it right.

13 - Pressure Sensor (intake manifold pressure) - Fixed at 29.9 inHg

33 - Solenoid, Port Air Valve

 

check the pressure sensor at the RF strut tower and make sure its plugged in properly and the wiring isn't chafing against the chassis anywhere up to the firewall grommet.

also check your port air solenoid for cracked wires at the solenoid, the wires commonly fray off the insulation and short together causing surges to the whole engine control 12V system, not to mention burnt wires and possibly fuses/relays.

 

I took a look at the wires for both the MAP sensor and the port air flow. The wires didn't seem cracked or corroded in any way. Any part of the wires that were touching something else were either covered in a sheath or in electrical tape.

However I did notice that on the MAP sensor plug, there are only wires going into 3/4..err...prongs. Is this normal? with the harness plugged into the car, the right rear (think passenger rear wheel) has no wires coming out, while the right front and left rear (Passenger front, driver rear) both have two wires, while the last one has one wire.

Sorry I didn't take a picture of it, I went out to look at my car on my break without my phone.

 

i don't recall the s5 using all 4 positions, but i dont have access to all my manuals on this computer to tell you for sure.

maybe try disconnecting both solenoids on the ACV temporarily and see if that affects the hiccup.

 

I unpluged and repluged both the split air valve and the port air valve. I now no longer have code 33.


But I am still getting the high rpm hiccups and barely a flash of the CEL. Checked my codes again, and still have Code 13.

 

swap for good n350 pressor sensor. you could set a voltmeter up to test the stock one, but you'll need a vacuum pump too, the price of that is more then a used sensor.

 

He has a vacuum pump...the engine! While you're there, confirm the vac signal line isn't leaking.

 

The S5 pressure sensor has 3 wires (S4's have 4 wires). One wire is a ground, one is the Vref voltage (5 volts w/key to on) and the 3rd wire is the output wire (S5 FSM lists the correct voltage w/key to on.)

 

Just a little update.

I got a new used MAP sensor from someone on this board. My Code 13 did go away.

However, code 33 came back. -__-

 

Both wires to the solenoid should have 12 volts w/key to on.

 

Both wires need 12V? Wouldn't one be a ground?

The connector that connects to the white and black wire gets 12v, but the other wire does not get anything.

I ended up changing the solenoid, but to no avail.


EDIT/UPDATE: I found that the car has a N351 ECU, but N350 sensors in the engine bay.(MAP sensor and another relay looking thing next to the firewall) Would this have anything to do with my issues?

 

Another little update, I took a closer look at my ECU, and found an exposed wire. If i'm reading the diagram correctly, this leads to 2F, narrow range throttle position sensor.

 

I repaired the exposed wire, and found that the wire goes into the 4th pin on the middle connector. There is one pin with no wire attached to it, but since it's in the 4th pin over, that should be the 2H connector, or Pressure sensor. Still getting Code 33

However, I'm still having the same issues. I took a video of the acceleration so you can see what kind of problem I'm having.

 

Did you wire open your ports as suggested?

 

Not yet.

I haven't figured out a way to wire the S5 ports open while being able to fit my hands down where they are located.

 

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