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420A 420a bad cps sensor or ASD relay

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langelg6

Proven Member
52
13
Nov 4, 2019
Hammond, Indiana
1995 Eagle Talon Esi
420a N/T manual transmission

Was driving in the city was accelerating when the car just shut off as if someone turned the key off.. mechanical whirring of fuel pump was no longer present. once I got the car home I ordered a wally as I plan to turbo in the future, dropped it in still no start.. I don't hear mechanical whirring put im getting pressure at the rail

next I test for spark with a test light, no spark across 4 cylinders (DID NOT TEST COILS)

I listened to each injector with no clicking pulse present in any injectors

My battery is pretty new only being bought in December and as I was cranking car for various tests, it was losing cranking power fast but my lights and battery voltage is fine

I bring out the code reader and 5 codes we're present in the system

P0505 - IAC CONTROL SYSTEM
P0117 - ECT SENSOR 1
P0412 - SENCODARY AIR INJECTION SYSTEM SWITCHING VALVE A
P0121 - TPS SWITCH A CIRCUIT RANGE
P1391 - INTERMITTENT LOSS OF CMP OR CPK SENSOR SIGNALS

For P0117 the connector to the ECT has been broken off and has been like that for awhile before no start so doubt its due to this

For P0505 I assumed a dirty throttle body but that wouldnt stop spark and fuel together

For P0121 my diagnostic tool reads 12.5% throttle input without hitting the gas and like 77% throttle and WOT. At one point I had a no start and I pulled the TPS and sprayed electrical cleaner in the connector and sensor and it fixed my no start but still the symptoms of this no start dont match to the first, then again I didn't test for fuel or spark on my first no start.

so that leads me to believe the cps was fried, I jacked the car up to check the wiring and made sure everything's connected on the back of the engine and everything is tightly.. there is one connector by my throttle body its a 4 pin connector with a yellow wire/blue stripe, grey wire/blue stripe, solid grey, solid orange wire.. No idea what that is

My EGR is capped off so the wiring isn't melted in that area.. The symptoms match for a cps imo with fuel, spark and loss of cranking power...

And P0412 is some sort of system for 95 N/T only.. I was told there is a recall for this but I called my local Jeep/dodge/chrysler dealers and they told me the only 2 recalls ever put on my car was for a fuel pressure regulator and a ball joint issue that got taken care of in 2001

Weirdly enough I was checking codes at 1pm and went again at 3pm without doing anything to the car and somehow 2 codes deleted themselves off P0505 - IAC and P01391 - CPS or CMP just vanished
 
Last edited by a moderator:
Impatient much?

Sounds like a crank or cam sensor, both of which are notorious for going bad on the 420a. Crank sensor is sposed to control spark timing, cam sensor controls injector.

Also, fix the coolant temp sensor. It's probably defaulting to -40* and trying to dump a bunch of fuel for a warm-up cycle, probably clogging a cat or exacerbating the current issue possibly.

Not sure what connector you have that's not holes up, but it makes me think of a solenoid or vsv wire. Post a pic.
 
https://www.obd-codes.com/p0412 <-- great site for looking up codes

The cam positioning sensor is driver side of the engine on the exhaust side, not sure what connection you're talking about with the 4 pin. The only other 4 pin connectors near the throttle body I can think of are the TPS and IAC. If your coolant sensor is not connected it will without a doubt cause hard starting or not start at all and engine will die when you come to a stop.

For your TPS there is a test to check if it's good and if its calibrated properly (we dont really calibrate ours for the 420a, it just needs to be installed properly) like I said before 12% at idle foot off the throttle is normal. Check it, if it's bad replace it. I can send you a picture of the testing procedure if you have a multimeter.

Also it sounds like you IAC is going bad, these are a fairly common failure on our cars. Get a standard motors BLACK color IAC valve, I can run you through the idle relearn it's a simple but lengthy process.
 
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