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Just got my 1987 Shelby Lancer back together (Started with boxes of parts) and when you step on it, it misses at about 4500 RPM and the boost is limited to about 5PSI. It has a FWDPreformance computers, should be around 17psi.

The odd part is the Snap-On diagnostic computer shows 144KPA or 20PSI of boost (see attached).
-- Is the TPS correct? 3.7 volts?

I can swap MAP sensors, but I suspect the Boost Solenoid might be bad? I checked all the Solenoids and they show about 34 Ohms of resistance which seems about right.

Best Regards, CSXVNT12
1987 Shelby Lancer 5000RPM INJ-3.5_Map-`5-5_20200620_123552.jpg

24,586 Posts
I am assuming this is at WOT since it shows 5000+ RPM's and TPS voltage @ 3.7 volts.
You stated the engine is "breaking up" at 4500 RPM and will not build more than 5 lbs of boost, according to what, boost gauge?
You also seem to be tracing the wrong issue, you are looking for a lack of boost issue when you should be checking basics to see why you are "breaking up/misfiring" @ 4500 RPM's.
Always, Basics First unless you have a Hard Fault.
1)Have you verified Ignition System Capability (new parts do not always = good parts)
a)You need to verify the system is capable of producing and maintaining a minimum of 25 KV at all 4 cylinders.
IGNITION - Adjustable Spark Tester.jpg

2)Have you verified 100% that Cam and Ignition Timing are correct.

3)With the scanner what is total spark advance reading before and when the problem is occurring?
4)Are you seeing any knock retard?
These specs are from my car, all stock 2.2L VNT if you would like to compare.
Sensor Values 1.jpg Sensor Values 2.jpg
5)TPS voltage above 3.50 volts = WOT to the engine controller.
6)You can use a vacuum gauge and handheld vacuum pump along with "Actuator Tests" to verify Baro Solenoid and Wastegate Solenoid operation.
7)I am assuming you have a 3 Bar Map installed since you are running above 14.5 Lbs of boost? (2 Bar)

Also to make things easier change the readings to US measurements, makes it easier.
I hate that Metric is the default on the MT2500.
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