Try and figure this one out

[shadowdude]

Here is the problem ,My 1991 shadow is cutting out.this is what it does,you drive it for 5 minutes or so and it goes through its two stage boost perfectly.Bleed the RRR so it would not dump to much fuel to fast.So i installed a cut out raiser,and it DOES work and hooked up right ,red to green with red tracer,black to ground on battery. I hooked up a exspensive fluke meter to the map and put pressure to the map up to 25-30psi,I adjusted the map till it read 4.189 on the fluke.then left the fluke hook up and went for a drive,car works perfectly ,map doesn,t go higher than 4.189 volts.then after 5 or so minutes of driving i get into the boost and it cuts out ever time.looked at the fluke meter when it was cutting out and it reads 3.4 to 3.6 volts .now how is it even possible for a car to cut out well below the limit ?? I cant not for the like of me even figure this out .it dont make sense ,every thing say it is working yet for some stupid reason it still cuts out once the car runs for 5 minutes or so.Any body care to take a guess ?? ,from all the post i have been posting you can tell this freaken car is jinxed big time.If i get rid of this problem ,then by rights it should be done and debugged finally.Help!!

[JDAWG]

do you have any codes?

[csxtra]

A couple of questions to clarify:
1. When is it cutting out (throttle position, speed, RPM)?
2. Has the car been idling at a high RPM lately?
3. Have you checked the output voltages from the Throttle Position Sensor?

A bad Throttle Position Sensor can cause something that feels like overboost cutout.

If the sensor is not giving the correct voltages based on the actual throttle position (such as the sensor shows that the throttle is closed (< 1V) like at idle), the computer will cut power when the RPM gets too high.

The TPS should output less than 1V when the throttle is closed, and 3.5-5V at WOT.

Measure the TPS output Voltages, you might find your problem, or at least you'll eliminate one possible cause...

[shadowdude]

The values for each of those first three are not dead acurate ,but it is usaully at half throttle,no more than that ,rpm wouldn,t be any more than 3000 to 3500 ,and speed is close to 30mph.The car has had a idle surge lately yes.no high idle just when you are at a light it surges up and down .I checked for a AIS code but it isn,t giving me any related to over boost except 45.No i havent check the TPS yet.I will put the fluke on it and see how the sending side goes through its numbers.a smooth transition in numbers will tell me its ok .I am currently trying to get to my friends place a bit away from here to use his old school OTC hand held with the 1991 cartridge.I will check the TPS ,but wouldn,t that trigger a code?

[csxtra]

I will check the TPS ,but wouldn,t that trigger a code?

I'm not sure if it will throw a code, but it sounds like what happened to my CSX in Topeka. After one of my passes, the car had a high idle, like a vacuum hose blew off, but all the hoses were connected. On the way back to the hotel from the track, when I took off from a stop at more than 1/4 throttle,the engine would cut out hard at about 3000-3500 RPM for a second, then come right back as the RPM dropped.

I hooked up my OTC scanner, and sure enough, I was getting about .6-.8V for the TPS, no matter how much throttle I gave it. Jason Trotter happened to have a spare I could borrow, which I swapped in, and that fixed the problem.

The procedure you described about how you plan on testing the TPS is exactly how I tested mine (measuring resistance with the TPS unplugged and the engine off) to be sure that the TPS was the problem.

I hope this helps.

[shadowdude]

It does help alot ,these problems can take for ever when you are trying to figure it out by your self.With yours and others advice and info it can speed it up when two or more heads get to figuring.I will check the TPS and let you know what i find.thanks ,i will post back soon.