2003 venomous

Cliff notes: 05 CTS V with 98k miles had a leaking PS hose and water pump. I decided to fix them and in the process the ordeal snowballed with motor, trans, and subframe being pulled to address many pitfalls....I now have ported heads, torquer V4 cam, TPIS modded intake and 90 mm TB, new oil pump/timing chain, headers and a few other small things.

Fast forward to present day, car will start and run (kind of, very rough idle and not consistent RPM's, fluctuates when it stays on) but throws a P0068 code and runs like crap. I used to be able to get it to idle properly if I try to start in clear flood mode, not crank over and run; just mash the accelerator to the floor and turn it over. Then, turn car off and take foot off the accelerator. Restart and it would idle fine. Did this several times before I was able to get the car on the road for a test ride so I thought it was a relearn of some sort that was needed.

The test ride was a failure; as soon as you come off the throttle after initial gas (i.e. shifting from first into second gear) it went right back to before. Choppy, erratic idle that was as if it was misfiring. I contacted TPIS as they wrote the tune and I tried a few things as per their request. I will say the TB opened with throttle input when the P0068 code was not present (after it is cleared or the accelerator to floor method is used); however, if the car is throwing the code and not wanting to idle, the TB does not move at all when accelerator is depressed; this has been verified (not speculation). When they all checked out, TPIS had me send in my TB/TPS, MAF, MAP, and PCM so they could run a few tests and help me out. They installed the parts on their car and ran the tests; no issues found.

I got the parts back and I am stumped.....installed the parts and the car wont respond to anything and the clear flood method no longer works. Seems to be getting progressively worse. I have been leaning towards two options, but I wanted to get some insight from those that may have gone through this issue before. I have checked all grounds and nothing seems out of place.

Any advice is greatly appreciated. Let me know if anything needs clarification.

Bio248

read nothing about a tune in there.

2003 venomous

There was a sentence stating TPIS wrote the tune, I told them what I had done to the car and they wrote it. I can not elaborate on the tune as I did not write it and don't know the parameters.

Was a one liner, so it may have been missed. There is no way the car would run if it had stock tune in it at this point.

jmilz28

iTrader: (13)

A hands on dyno tune would be preferred...by a lot. This strikes me as either a tuning issue/bad tune or some install SNAFU or mechanical problem, perhaps a combination. Is that P0068 the only code present? How did it run before? Codes then? Fuel pump and filter status? New plugs, what kind? Did TPIS tune for your specific injectors and what are they? Who ported the heads and what are they? Pushrod length? How old is your battery? Have you checked the cables and connections? Checked ALL your grounds? Where are you located? There are a TON of variables to consider before any reasonable even half *** guesses can be made...

2003 venomous

Could be any one of many things, just trying to get some insight. Ran fine before the mods, no codes. The car has the ability to idle smoothly and send progressive signals to the TPS via APP sensor, the scan tool was showing seemingly normal values and as soon as the code came on, the car instantly reverted back to a crap idle and erratic TPS and Calc Load readings. Just fiddled with the car and it set a P0068 and now a P0300. Voltage is at 12 volts, battery was purchased 6/14.

Car has new stock plugs gapped to stock specs with new plug wires. Fuel system (pump and filter were not showing signs of disrepair before the mods and when it idles fine, it has the same components as it does when it goes crap instantly) is all stock down to injectors which I had cleaned at the same time TPIS did the intake mod. I have a TSP package with ported heads, new springs, cam and the pushrods they spec for that application.

I have checked all connections and grounds and I cannot find any culprits there. I do believe something electrical is causing the issue, just need to figure out what that is. I can hear the throttle blade moving sometimes, and other times nothing. This is what is leading me to believe its an electrical problem.

Does that help? BTW, I live in SA TX area

1BADCTS

iTrader: (17)

http://www.cadillacfaq.com/faq/answers/etc.html could try this if you haven't already

2003 venomous

I did try that one, it unfortunately did not solve my issue.



I also read that if you depress accelerator to the floor, the car should only crank over; not start if the accelerator pedal position sensor is functioning properly. What is the validity to that?

bmylez

iTrader: (3)

Yeah pretty sure pedal to floor shuts off injectors and car should not start.

SE-R Spec

iTrader: (2)

Is your MAF sensor facing the correct way? Also what TB do you have? Is it LS2 or some other brand? Either way, you should have had to put a new connector on to fit the TB from the V harness. Recheck that wiring and you should find your problem according to your narrative.

philistine

iTrader: (2)

1. Check for vacuum leaks
2. Clean MAF, check for broken wires
3. Inspect MAP sensor, check for broken wires

What kind of timing chain did you install and was it clocked correctly?

Try this for checking vacuum leaks:
https://www.amazon.com/SEPTLS7478OZS.../dp/B00H895GH8

2003 venomous

MAF can only go one way with the K&N kit I have. It was verified to be correct as well as the wiring harness. The TB was a modded unit from TPIS and its plug and play. I sent them my old working unit and they did the conversion.

2003 venomous

It has a steady 17 in.Hg of vacuum (or as steady as the cam can have) at idle. It has the ability to idle and drive in first gear, once you shift to second it's all over. MAF and MAP were sent to TPIS to verify their working condition and they were both good (along with TB and TPS)

I can have it idling with the scanner hooked up and watch (and hear) it go "crazy" on the scanner via the ABSLT TPS (%) and CALC LOAD (%) tables.

Car has an upgraded LS2 timing chain and is clocked correctly. If the car isn't throwing codes and acting up it idles great. Had it idling for a total of about 20 mins and if the chain was off it would have been noted then

Bio248

put the stock throttle body back on for a quick test drive.

heavymetals

iTrader: (3)

Double check to make absolutely sure the plug wires are making contact with each plug.

BudRacing

iTrader: (3)

That was my first thought, but it sounds like the harness was modified for the new TB?

OP, Have you tried unplugging the MAF altogether?

Anthony Toal

You sure you have the right timing and chain? The rise points can be different for the cam position sensor
I have seen these in most ls1/ls6 and older ls2

but also this in newer ls2 and ls3

I havnt had a chance to see which one the V has, im sure someone will chime in, but I have seen other cars run sporadically with the wrong cam gear before.

Naf

iTrader: (1)

Its probably your tune or a forgotten ground

Reflash the original tune in and check, dont worry your nbo2 will give you some support in the mixture

2003 venomous

Bio 248: Old TB was sent out and disassembled and parts used for my new TB. BudRacing was correct. Did not unplug MAF and try as it was always throwing a code. Could try that and see....

heavymetals: I will recheck the plugs, can't hurt to verify at this point.

Anthony Toal: I would be skeptical if it has never run right that I might be off, but it has run correctly and idled before. It can instantly go bad after idling fine for 10 mins with a steady idle and no codes.

Naf: I am thinking the same; as in the tune. I had this problem before and chased my Cobra for two months with a remote tuner and did all kinds of tests and checks/rechecks, etc....turns out SCT was not embedding the file on my car when downloaded and it was running a stock tune. This was after mods and the car was on an E85 return style fuel system with a big blower and Bosch 105's.
A new PCM is en route to test the PCM/tune theory on this car as well. Problem is, tuner has turned off Misfire DTC and it threw a P0300 code last time it was run.

Again, thanks for the advice and I will check a few things out as well.

2003 venomous

......well after a few months of back and forth talks with the previous shop and lack or results (sent multiple pieces back to them and they flashed another PCM), a friend of mine offered to try his tuning at the car. We bought HP Tuners and he is remote tuning the car.

In the end, there was a ground that was a little worrisome, so I replaced it thinking I won the battle. It was not the case, car still ran like crap and kept throwing codes. After researching and learning some things; my buddy increased the values for the MAF table and that has cleared the issue. The previous tunes value was set to low and would trigger a P0068 MAF code almost immediately,

Fast forward to present, the speedometer was working fine until I plugged in HP Tuners two weeks ago; now I have no speedometer, just a stuck odomoter and working lights. I am wondering if the VSS took a crap, but it seems so coincidental; thoughts on that one? I have been reading and trying to determine the location of a fuse in the speedometer harness and have not been able to locate one/it. Question is does one exist and if so, where can I locate it?

I need to get this operating so I can test drive the car and get some logs after it has leveled out some of its engine parameters/values.

Any help is appreciated and thanks for the help.

Naf

iTrader: (1)

Pm sent, let me have a gander at your tune.