Hello all. I would like some input from members who may have experienced what i have been experiencing with my car. My car is an 03 base model with full exhaust and an ecs supercharging kit (1500 base kit). The car has approximately 10,000 miles since the supercharger upgrade. Its got 21,000 original miles. The car was tuned by Doug at ECS. It made 550hp and 489tq.

Within the last 800 miles, on 3 occasions ive been driving the car at a comfortable cruise speed above 50mph and the car will abruptly lose speed with a sort of jerking motion. The whole event only lasts about a split second, not too dramatic. It will jerk once or twice very quickly and then go back to normal. It sort of felt like something behind the car had it on a rope and just tugged it once or twice. Its only happened 2 or 3 times in 800 miles.

Ive never experienced this on any vehicle so i dont know where to begin with diagnostics. I do my own work so i can check things out, but i wanted to see if anyone else here has experienced this before.

My first suspect is the clutch because its still original, but ive never been in a car with a slipping clutch to know what it feels like. The car is still holding RPMs and accelerating as expected all the way to redline, although i have always purposely slightly short shifted the car. I change the clutch fluid weekly via the ranger method and the dot 4 fluid stays clear. There hasnt been any pinging/metalic/knocking sounds.

Second suspect maybe a bad spark plug(?)

Any opinions would be appreciated.

Thanks!

 

You should always scan for codes…if you don’t have a scan tool use the DIC and let us know…this can be a few things so I won’t even try to guess.

 

ill do that right now and report back...

 

The only codes my car is throwing on the DIC are:
RFA: 2100, 2105, 2110, AND 2115. (All TPMS codes)

This is because im running the car with no tpms sensors, have been for years. It hasnt been a problem so id say its safe to dismiss that as a cause.

 

Hmm. Bad fuel?
Could TPS cause that (though I suspect you’d be seeing error codes for that)?

 

RECOMMENDATION! Start by reading the DTCs as the car sits. If you have too many to list and decipher, you can CLEAR/RESET all the DTCs.
NEXT: This is the important part and proper steps to help figure out where to start:

With a clean DTCs slate, the very next time it farts, IMMEDIATELY look at the CEL indicator and see if is flashing. A flashing CEL normally indicates an engine misfire. It will flash during the event and stop when the misfire stops. A FLASHING CELL, normally sets a PCM P-0300 DTC.

NEXT: Safely pull off the road and stop the vehicle. WITHOUT TURNING OFF THE IGNITION, press and hold the RESET button to clear any messages displayed in the DIC. Then use the OPTIONS and FUEL buttons to enter the C5 internal DTC reading routine. Enter manual mode and scroll through ALL the modules and report any and all DTCs that are present.

I seriously doubt you have a clutch issue. It Sounds like you lost Power to the PCM for an instant and then regained it. Just like you turned the ignition switch off and then back on. If that sort of problem happened, it normally does NOT leave any DTCs.

Reading the DTCs will tell us if a monitored module is having an issue. If no DTCs are present, we will be looking foe a POWER or GROUND disruption somewhere.. FIRST STEPS!

Bill

 

Hi Bill. I suspect this could be a cause. My car intermittently cuts power to the instrument cluster. When this happens, the parking lights and hazard indicator flickers. Ive check ALL of the grounds and they all look shiny and silver. Ive also opened up the accordion connectors in the doors and tightened them up. This didnt solve the issue with the cluster. Bad cluster(??) Bad BCM (??) These elec issues are the c5s only real sin as far as im concerned but its still a pain! The battery is the reccomended AGM GM brand replacement new as of >1000 miles ago.

 

Bad BCM/PCM,,,NO,,, BAD CONNECTION in the ignition switch or pins supplying the switch power. The cluster is a good visual indication that itS loosing power and GUESS WHAT FEEDS THAT FUSE??? One of the contacts inside the ignition switch. Heres a FREE EASY thing to try. Disconnect the neg battery terminal. . Disconnect the TWO connectors on the ignition switch. Examine the male and FEMALE PINS. Conduct a pin PUSH/PULL TEST on the female pins in the harness connector of both connectors. Tighten up any female pins that fail the push pull test! Shine up any burnt, corroded crusty male pins.
BET YA, you find loose spread damaged pins. There's your issue!!!
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OH, I helped TWO other forum members with this very issue in the past couple of weeks. BAD/SPREAD FEMALE PINS in the ignition switch connector.
Bill