TLDR: On the way home from some mildly spirited driving, got a SERVICE TPMS message and vehicle started to run rough. Did not get any other error messages, and did not get a reduced power message RR tire PSI read Xxx. Once home checked some stuff with TECH 2 then it would crank, but not start... until the starter broke...SIGH.... again.

98 Coupe AUTO.
Mild 224 cam, LT Headers

DIC
C1255H, C1278H
U1064
C2110H

Trying get this beast running well enough to sell after 3yrs down for a burnt EBCM and Harness after it shorted and caught fire in 2019. Went surprisingly well except for the FLEA BAY starter shelling-out on the first crank attempt. Repaired all that along with a "mouse-chewed" TPS wire and have been going on short drives for the past month without incident. Today did a 20 mile out and back with some spirited low and high speed acceleration. Again, with no issues. Prior to leaving the house I noted that the right rear tire PSI was blank, but since the car wasn't limping or throwing codes and I knew it was serviced to 30psi I took it.

OTW home, slow and steady at 65MPH, it threw the "SERV TPMS SYS MESSAGE" and started to run roughly with some engine vibration, which I assumed was it going into LIMP MODE. All pressures and TEMPs were perfect and it wasn't making noise. The only exception is the RR tire which changed from "blank" to "PSI Xxx". I also never got a REDUCED ENG POWER or ABS message nor a check engine light. It was like everything was fine...

Once home, I tried to deleted the TPMS (with a TECH2) to see if that would fix the engine issue. Its a 98 but I did the 02-04 TPMS/FOB sensor modification a few years so I had to select 02 on the T2 to get the right menu.

Anyway after dicking around with that, the car would crank but not fire (i could smell gas in the engine bay). After about 6 crank attempts my second, 2 month old FLEA-BAY starter, shelled out, so I'm dead in the water until I swap that out.

Suppose my question is; could the NO START be related to the TPMS issue, or maybe something I did (or didn't do) in the TECH2 menu's? I changed out the antenna thingy for the key FOB when I modified the TPMS, so I'm wondering if when I turned that off, could it be theft deterrent thing preventing the start?

TIA

 

All I can say is to post the trouble codes from the DIC, to have some chance of determining why it is not starting, sounds like it could be the seriel data system.

 

C1255H - ECU Malfunction - BCM, ABS
C1278H - TCS Temporarily Inhibited by PCM - BCM, ABS
U1064 - Normal Software Function, History status upon ignition cycling - All Modules, Datalink Communications
C2110H - TPM tire pressure monitoring malfunction

Guessing the toasted BCM is not fully / correctly repaired or replaced or that you have more dead wires to locate and replace.

 

The TPMS is in no way related to your crank no start…and you don’t buy parts for your car like a starter off EBay !!…get your starter replaced and since it was changed previously check your crank sensor wiring while your down there…that can give you a crank no start…maybe an ignition problem since you can smell fuel.

 

The repair is solid and has been driving fine until yesterday and i did not get the ABS light. Just o make sure i also did a test with the tech 2 and it passed fine.

 

I'll give that a look. Do you think the TPMS issue and immediate reduced power/vibe is just a coincidence?

 

Just a coincidence with the TPMS. I've had intermittent TPMS issues over the years, even with new sensors. Still get a random no reading here and there. None the less my car has never had a no start issue or any issues other than not reading tire pressure when the TPMS fault appears.

 

Post script...however; I've had reduced power occur due to a frayed wire in the passenger side door loom causing a short. Which I determined was an issue based on logic after chasing the root cause of a random reduced power issue. Wires tend to be the culprit for many random issues. My wife's SAAB 9-3 fell victim to rodents chewing **** up. Chased that problem for months. Which caused intermittent no starts and dash going haywire on occasion.

 

Wow, from a wire in the door loom? I'll get the starter in --super fun with long tubes-- then start trying to troubleshoot. Sucks with no codes or anything else to go on except it running rough before i shut it off.

 

Yeah it's a legit issue that has occurred on a few C5's. It doesn't come up much in the forum but it is in fact something that can happen. It was on my passenger side, which got very little use over the years. Pulled over one day to let my wife run into a store and it happened. Which got me thinking and investigating. Found a thread on this forum where it happened to another member. Well low and behold I too had a tiny exposed wire in the loom causing the short. Taped it up in 2009 and never had the issue again.

A rough running situation doesn't sound like the same issue. I was getting a reduced power message on the dash but car ran fine. I would investigate those chewed/ repaired wires if I were you. Then look to confirm everything is plugged in correctly and wires not damaged (MAF, EBCM, TB etc). Easily accessible stuff first.