djtech

...Because apparently this little sucker that controls a choke looking plate inside my throttle body on my '90 Civic is not working at all...I tested to see if there was voltage going to the solenoid that actuates it but there was none at any RPM...I cannot seem to find why there is none either...There is no error code...Anyhow I manually hooked up a separate vacuum line to the Tandem Control Valve and viola, it opened the plate completely full and instantly fixed my power/acceleration problems...Now my question is, why did that have such an effect and how can I somehow get that solenoid power to get vacuum to the valve...Can I just run a vacuum hose to it at all times and keep it wide open? Or is there a way I could rig it to some other circuit that would turn on the solenoid to let vacuum through if the temp of the engine hit normal temperature? I say this only because it doesnt run too well when it is cold with that valve on.

Thanks for any help!
Deej

SEA Hag

Check your wiring, I know that the ECU has a pin for the Tandem Control Valve.

serious

i know i'm gonna sound like a total d!ck for saying this, but, now might be the perfect time to do the dpfi>mpfi swap on your engine. about $250 and you'll get some nice power out of that engine.

as far as the tandem valve goes, probably the easiest thing to do would be run new wires to the ecu and connect them to the right pins. i don't have mt helms manual with me right now, but i'll look it up when i get home.

djtech

I actually noticed my car having a big loss of power then I found out that this valve was not functioning at all...No matter what temp or rpm...What I did was clamp the valve open at all times...I noticed a huge improvement...It was not running so rich and had much better acceleration...However though, on cold startups it was a bit rough...But the alternative is definitely not as good...What I am seeing is that I am not getting 12Volts to the solenoid that lets the vacuum through the tandem valve...I checked the fuse and its ok...I was thinking if I could just hook 12v straight up to the solenoid at all times just so it keeps the vacuum flowing to the valve...What do you think?

Deej

serious

sure, you could even rig up a switch inside so you can manually open and close the tandem valve.

you could even rig the tandem to a rpm activated switch so when you hit 4800 it opens. poor man's vtec

i would really recommend just doing the mpfi swap instead.


[Modified by serious, 2:24 PM 2/26/2003]

djtech

How musch is that swap anyhow and what things do you have to swap out?

serious

there are a hundred and one sites that'll tell you exactly how to do it. use the honda-tech search and look for "dpfi mpfi" and you'll find what you're looking for. you can buy pretty much everything you need off ebay in a day or two.

bascially you replace the intake manifold with all the sensors, the distributor, the ecu, and add an injector resistor box and have to do a little rewiring (not much, swap a couple wires and add a couple wires). the whole swap can usually be done for under $250 and will take you to around 105 lbs/ft of torque and around 100 hp. it's probably one of the best swaps for the money.

djtech

I am trying to troubleshoot the continuity to the ECU and from the solenoid via the orange wire and need to find out what PIN it is onthe ECU...Anyone know? I am assuming the ECU is providing the ground via this orange wire...Does it only provide the ground when the engine reaches operating temp? If so what sensor tells the ECU that operating temp has been met and can therefore go ahead and send out these other signals in relation?

Thanks
Deej

djtech

If I were to want to jimmy this thing, where would I find an RPM activated switch to hook this to and also where could I find a switch that would turn it on after the temperature met normal operating temp?

serious

dude, the rpm thing was just a joke....would be funny though....

here's a scan out of my helms manual. it should tell you what you need to know.

djtech

Thanks for the pic, that really helped...In fact after troubleshooting it, the actually Tandem Valve itself is bad...Does anyone know where I can get one of these? Apparently its just a solenoid type valve...I called the local Honda Dismantling store and they wont sell me just the valve, I had to buy the whole throttle body for $150...I only need this one little part though...Thanks

DJ