Hey all, one of my personal Crossfires has been giving me some crap. I'll try to keep it short but informative.

Type of car- 2007 Roadster, automatic trans, 92,000 miles. Owned for 10 months, bought with 87,000 miles.
Parts replaced in that time- plugs and wires, fuel filter, vacuum hoses, MAF replacement, CPS replacement, RCM replacement, (used but working) coil replacement, fluids, oil level sensor, oil pan resealed, VC & breathers resealed, all normal maintenance-y items us crazies tend to do. Replaced aging battery with a new one and replaced alternator with a new Valeo unit due to an over voltage issue while stored for the winter.
Issue- on a cold start and run, the car stumbles/cuts off during all types of acceleration and it'll last approximately 3 miles before it stops, never to do it again until the car is fully cooled off. It's more of a "bucking" feeling, kind of like fuel cut off or power loss, and lasts maybe half second each time it does it.
Tests Performed- scanned for codes- NONE & none stored (used a Launch Millennium 90 Pro), fuel pressure tested and found it to be a little low at the key on position, changed the filter which corrected that anomaly but did nothing for the bucking. Visual inspection of all hoses, replaced breather hoses, T-junction, MAF housing to breather hose. Opened the RCM/ECU box and visually inspected wiring. Decided to replace the RCM "just in case". Changed the CPS just for fun.

In a desperate move to find and correct the problem I googled the symptoms and just like when you google your cold symptoms, I found all sorts of possibilities ranging from internal engine issues to a failing transmission. I bought a valve body and installed a TransGO kit along with a new OEM conductor plate and new shift solenoids. This was the only thing that seemed to lessen the bucking feeling but it's still there. I really don't think the issue is in the transmission as it feels very much like fuel cut off. Feels like someone shut the car off for half a second then said "just kidding" and turned it back on. Very odd, very random event. Sometimes it'll do this right from the moment I throw the car into drive and other times I can get a quarter mile before the bucking starts.

Im really at a loss and don't want to throw parts at it anymore. Any advice would be appreciated! Pic of the car for attention

 

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Wow, seems you have done quite the shotgun parts replacement to figure this one out. I have only one suggestion (happened to me years ago to my 08 coupe). Take your RCM off (FIRST TAKE NEG BATT CABLE OFF), and open the connectors ONE AT A TIME (take pictures showing where each wire goes into the connector for when you check and verify no damage) to inspect the 90 degree connectors that are attached normally to the pins on the RCM. I had (if I remember correctly) three or four that had separated at the 90 degree and was disconnecting occasionally. I further inspected those defective crimped connectors and speculated they were not crimped correctly (not aligned when crimped and cracked over time) during the wiring harness assembly. Once I replaced the damaged ones, the car hasn't cut off like it had since (except for a strange glitch recently that went away). Good luck!


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Before engaging transmission and moving car let it warm up so that thermostat has opened and temperature needle has risen to first mark.

Here are a few Maybes:
At cold startup does the RPMs drop from 1200 to 750~800 after 45 seconds?
Do not move car until auxiliary air pump has stopped running.
Turn traction control off.
Sticky/dirty throttle valve
Sticky/dirty EGR valve
Accelerator pedal

The cars are twenty years old; Most of us get a little cranky with age.
Good Luck.

 

You mentions CPS Replacement
have you replaced both crank and cam sensors? If yes, were the replacements Bosch?

I had experienced “bucking”, replaced both and my issue went away.