What is this sensor for ?

[mytta49]

What is this sensor for and what does it control, located near the firewall on the passenger side. Does it have anything to do with boost spiking? Lastly, what is the name of the sensor and part number if anyone knows.
Many thanks

 

[72firebird]

It's a 3 bar map sensor and the TTA was the only vehicle to ever recieve one from the factory. You can get them from almost any of the sponsors on here (I know www.johnsperformance.com has them but it looks like his site is down). It wouldn't cause boost spikes though.

 

[Quiky One]

www.alkycontrol.com or Razor sells them. All it does is measure boost. http://home.att.net/~alkycontrol/images/Components/map.jpg

Jason

 

[Quick6'n'-K.C.]

Make sure all your wastegate hoses are fresh.

Does the car have a adjustable wastegate rod, and is the spike only down low?

Does the boost finally creep up to a higher pressure the faster MPH you go?

BW

 

[mytta49]

Make sure all your wastegate hoses are fresh.

Does the car have a adjustable wastegate rod, and is the spike only down low?

Does the boost finally creep up to a higher pressure the faster MPH you go?

BW

1. wastegate hoses, Y fitting and the right orifice are new and installed prior to problem.
2. Alky kit installed (razors)
3. Turbo Tweak chip set up for street with alky
4. I took off the HD actuator and reinstalled the stock one.
5. Checked all vaccum hoses to make sure they are on right and are mostly new ones.
6. new wastegate selenoid

Here is the problem
With the original adjustable actuator, stock chip and no alky,
The boost was normal. I could adjust the rod all the way in to get 18 psi of boost and all the way out to get 12 psi.
Installed alky kit, HD actuator rod and Turbo Tweak chip set up for street and Alky.
My boost was going to 25 at WOT with the HD actuator and I couldn't get it lower even with extending the HD rod. I reinstalled the factory stock adjustable actuator and I have it threaded out to a point that there is very little pressure on the pin, maybe 1/4 inch or so.
Even with the stock actuator extended way out, my boost is now 21 at WOT.
I watched my autometer boost gauge and at WOT in first it goes to 21 lbls, then in second it only goes to 18, in third it goes to 17 and fourth its at 17.

Scan master shows that the readings are all well within range from what I have read on this board and I get 0 knock with the alky.
I know it has nothing to do with the alky kit which is working perfectly.
Not sure what else to change or look for ?

 

[Quiky One]

Could it be a false reading through the gauge? Maybe the gauge has gone bad. It doesnt make sense it just started happening after alky and chip.

Jason

 

[Razor]

The only thing you probably messed up will be the hoses going to the WG actuator.

Boost is almost completely controlled by the two hoses/Y/ and WG solenoid. So any breach in the air traveling from compressor to WG will creat higher boost.

Do this, run a hose straight from the compressor to the wastegate, this will setup your minimum boost. If this brings the boost down.. reattach hoses.. Next is plug the open hole on the WG solenoid thats on the valve cover... this should yield the same results.. If this works, check your "Y" and wastegate solenoid.

remember the "Y" has an orfice on one of its legs... the leg with the orfice goes to the wastegate.

Report back..

The MAP sensor has nothing with controlling/regulating boost.

 

[Quick6'n'-K.C.]

Sent you PM about the issue.

BW

 

[72firebird]

The MAP sensor has nothing with controlling/regulating boost.

correct me if I'm wrong, but I thought the MAP read the pressure and conrtolled the boost solenoid with how much air it is releasing out the other opening on it. Does the WG solenoid read the pressure also for it's own control?

 

[Razor]

correct me if I'm wrong, but I thought the MAP read the pressure and conrtolled the boost solenoid with how much air it is releasing out the other opening on it. Does the WG solenoid read the pressure also for it's own control?

Your corrected.. the MAP is only tied to the boost guage in the dash. That is it on the 1989 TTA.

The WG solenoid is "pulsed" by the ecm. The pulses vary depending on different conditions. Example in third, its pulsed more to reduce boost so it doesnt creep. Example.. you get knock.. its pulsed heavily to drop boost. But it doesnt read anything since its a solenoid. Just opens and shuts rapidly.. like a fuel injector for air flow.

Your computer has no idea how much boost your running.. its calculations are based on MAF readings. Once the MAF passes 255 grams... it loses how much air is going into the motor.

HTH

Afterm,arket computers like the one in my car.. FAST.. make fuel adjustments based on Boost and RPM. And there are conversions like the ME-r that use the 3 bar MAP for calculations.

 

[mytta49]

The only thing you probably messed up will be the hoses going to the WG actuator.

Boost is almost completely controlled by the two hoses/Y/ and WG solenoid. So any breach in the air traveling from compressor to WG will creat higher boost.

Do this, run a hose straight from the compressor to the wastegate, this will setup your minimum boost. If this brings the boost down.. reattach hoses.. Next is plug the open hole on the WG solenoid thats on the valve cover... this should yield the same results.. If this works, check your "Y" and wastegate solenoid.

remember the "Y" has an orfice on one of its legs... the leg with the orfice goes to the wastegate.

Report back..

The MAP sensor has nothing with controlling/regulating boost.

Ok reporting back.
My GN friend and I installed today a reprogrammed Turbo Tweak ALKY chip that Eric reprogrammed for me with lower boost (16 instead of 22). We also installed an RJC boost control which goes from the compressor to the actuator (eliminating the 3 hoses and Y) and set the stock actuator rod to the 1/8 inch tension as the instructions said. Also adjusted the RJC control screwed out (screwing in raises the boost) pretty much to see what the boost gauge would read.
We took it on the highway and at WOT the boost is only showing 12 psi and when I open the electric cutout it goes to 14.
Tomorrow will screw the RJC in a few turns and see if the boost goes up.
I probably should have done the chip and roadtested before installing the RJC since I know only one thing should be done at a time, but I think the problem was the Y and vacuum hoses even though I replaced them last year with a TTA orifice and I know it was hooked up right and tight.
Can anyone give me an opinion what you think brought the boost down, the reprogrammed chip or elminating the Y and using the RJC boost controller.

 

[Quick6'n'-K.C.]

The rjc controller since Eric would manipulate the wastegate solenoid to lower boost i assume.
Since the wastegate solenoid isnt used now with the RJC controller, your boost is lower, now you need to turn it up with the new controller.
BW

 

[mytta49]

Ok, as mentioned, yesterday the boost was 12 and 14 when I opened the cutout with the new alky chip and the RJC boost controller. Today I turned the RJC contoller in three full turns and the boost went to 15 and 17 when I opened the cutout. Later will turn it in some more once it stops raining here. Seems to be ok now.
Thanks to everyone for helping out, most appreciated.