The dreaded P2135

[hesster]

Went into limp mode today while coming home, got the car home in the garage thankfully. Now it cranks but wont stay started. Scan read P2135, so I cleared the code but still no start.
Looking for member experience and input on resolution.
Car is 2010 LS3 with a Whipple and Cam.
When I built the car 5 year ago I removed and painted the throttle body, so it has been off the car at some point. Had a dead/no start a few years back, cleared the code and all was well.
Last few years the car would take 2 to 3 start attempts until it fired. Today went into town, and after returning to the car and it took 5 tries, seemed to run fine but puked 100 ft down the road, and limped home.

So - wiring harness and connections seem fine at the throttle body, and at the connector at the other end of the Whipple extension TB wiring harness. Car is just used for occasional romps and car shows. I do have a 1/2 tank of old last years gas in it since I cannot siphon it out.

Anyone please provide fix solutions:
1. Replace the TB sensor only? If this is a common fix, just unbolt the sensor and replace it? Or the whole TB? (part #/source recommendations?).
2. Inspect and check connections on the Pedal sensor? What is the removal process, it's tough to get at. Has a cover and numerous clips, one of which I already broke trying to disconnect the cover and inspect connections.

Right now it is car show season here in MI and I have a expensive boat anchor in my garage!

[hesster]

I found this thread which has some diagnostics to determine fault indications, the test determines if the faults are either the ECM, or if all test normal at the TB harness connection with these pin tests, then it is the throttle body itself being bad.

So I will try that process, but first more checking for the obvious.

Battery (original!) voltage is good @ 13.7v static. Always on a trickle charger. Disconnected the Positive/Negative terminal and hope that "resets" the ECM. Will then dig out the Whipple TB extension wire harness which is buried under other wires and recheck connections/pins at both ends (one end is the TB connector). Read that sometimes these extension harness' can be suspect, but JC it's been on the car for 7 years.

So how to get at the Accelerator Pedal sensor - remove the whole pedal? I would guess so as it is sold as assembly (no separate sensor available). $78 from GMPD. Don't know if there is a test to determine if that sensor is at fault.

And, the stock TB is also sold as a assembly PN # 12605109 @ $300+ from GM Parts Giant.

So hate to throw $$ at this, but at some point expense is not the key consideration. Performance and reliability is.

https://www.camaro5.com/forums/showthread.php?t=583099

[hesster]

Editing this post for documentation of what my plan is to resolve the Throttle issues. It seems this issue is all over the Forum so maybe it will help others.

I am now taking the shotgun approach to this, as it is a huge PIA happening right in the middle of car show season here in MI.
1. Took apart the existing TB after I got the special security Torx bit to get the cover off, found no visible issues, nor any OHM readings out of parameter (there is a test procedure on the WEB). Have a new one on hand to install anyway. Noted that my existing OEM TB has a 3/16" hole drilled in the TB Plate! My tuner said don't worry about that? Prob did it to to get a better idle with the Blower big BT Cam.
2. Ordered a new 94R Delco AGM battery, coming this week. Still using the OEM 13 year old battery, but it always is on a tender and seemed to have a full 13v charge, but it is time to retire it as part of this issue. I added extra grounds in the trunk and engine bay a few years back as recommended in the forum.
3. Since the TB "seems" OK, ordered a new Accel Pedal. Don't know if it is faulty, but it is in the loop for popping the various Limp Mode and Throttle Codes. Gonna pull it out and see if I can take it apart and inspect for issues, and replace it anyway.
4. Gonna check all wiring and connections. Maybe something is loose or pinched during the Whipple install, or as a result of installing the Catch can or engine dress items.

Action plan (some pics maybe along the way?) to assist others that have this GD issue:

- Inspect Metal ground strap on Passenger Side Harness for rub through. Wires and hoses are really tight in that area. The Whipple extension harness connects to the original TB connector. I pinned out the Whipple Harness, it is good.
- Check MSD Fuel Pump Booster Fuse Tap in the trunk fuse block, it is plugged in the FSCM slot. Maybe bumped it when putting stuff in the trunk.
- Check relocated MAP sensor and extension harness connections on rear of manifold.
- Check IAT sensor connection at rear of Whipple Manifold. It is relocated there from the Intake Tube as part of the blower package.
- Check MAF Sensor, it looks immaculate and I don't think this is a contributing factor in throwing Limp or Throttle codes. Hope I can read any values on the SCT-X4 if I get it running.
- Check BAP line connection from the MSD Booster to nipple on rear of Manifold. I tapped into this when adding a boost gauge.
- Recheck my Elite Catch Can installation. I never see much oil accumulation in it since I installed it. https://www.camaro5.com/forums/showthread.php?t=574493
- Finish all of the above, then connect my SCT-X4 and try to start the car on the year old gas. Not sure what to look for other than throwing codes, but will use the gauge reading feature on the SCT for Pedal Position Volts, and ECT Angle Actual. Probably some other things that can also be looked at, but need to figure out how to do that and interpret the data for root cause.
- If the start and die condition persists, try to drain the old gas and add new. https://www.camaro5.com/forums/showt...=267747&page=2
- If the issue still persists, what's left is the ECM, UGGH!, and I sure hope it is not the issue given the custom tune. I have moved and now am hour away from my Tuner, so it would be a tow to get the car there. I imagine a Dealer won't touch my highly modded car. Or - is it possible for him to send the tune to me and download it to the SCT-X4 and I could reflash a new ECM that I would install? Seems Jannety does this?

Any input is welcome!!!

[KillboyPowerhead]

Do you remember when it started taking a few tries to start? Right after installing the supercharger; cam; after a tune? How long does the car run before dying? Don't suppose you have HP Tuners to scan while it's running? Drilling a hole in the TB is a quick/cheap way to get the car to idle better but really should be done via the tune; newer cars are torque-based and you can play with the torque models to get more or less airflow - open or close the TB - as desired.

If/when you replace the gas, battery, TB/sensor and pedal/sensor and the issue persists I'd think a connection issue (wonder if you may need the torque models adjusted too, unless you drill a hole in the new TB). Also make sure to do the TB relearn procedure, assuming the car stays running.

Guessing you don't have a throttle controller, but if you do I'd remove that too until the car gets/stays running.

[hesster]

Thanks KP -
"Do you remember when it started taking a few tries to start? Right after installing the supercharger; cam; after a tune? " My first bout with a total no start and codes was back in 2017, and had the Whipple installed in 2015. In between that time I was modding the car with suspension and body panel items, so it could be something I may have done. So no codes or issues since 2017. The start and die issue has been going on over the last 2-3 years, but it always fired and started after 2-3 tries. Was puzzled why this was going on, thought it was just old residual gas mixed with new. No Sta-Bil, don't think it is good for a Blower car that wants the best Premium available. During this time I was just adding new gas to the previous years gas, enough to last the summer for car shows.

"How long does the car run before dying?" Sum Bitch barks and dies immediately.

"Don't suppose you have HP Tuners to scan while it's running?" I have a SCT-X4 which can read and clear codes, and data log. Not familiar with a "scanner", would that help read, diagnose, and fix problematic operating parameters? And is it different than my SCT?

"Drilling a hole in the TB is a quick/cheap way to get the car to idle better but really should be done via the tune; newer cars are torque-based and you can play with the torque models to get more or less airflow - open or close the TB - as desired." Yep - my tuner said no big issue, it would relearn idle. I can always swap the plates (with hole) to the new TB.

"If/when you replace the gas, battery, TB/sensor and pedal/sensor and the issue persists I'd think a connection issue" - agree, hence my laundry list of inspection items.

"Guessing you don't have a throttle controller, but if you do I'd remove that too until the car gets/stays running." I don't have one and would never entertain using one given the codes I already have experienced.

[gtstorey]

Did you ever go through the trouble shooting procedure you linked in post 2? That looks like its from the service manual. Of course intermittent problems cam be hard to trouble shoot.

[KillboyPowerhead]

Don't know anything about the SCT but looks like a handheld like AutoCal. With HP Tuners you can log 100's of parameters - just about any signal to/from the ECM and TCM as well as any math/calculations within the computers - which may help diagnose a given issue. In your case since it dies right away I don't know how useful it would be - it may tell you nothing or everything. Can also read/clear codes.

I had Reduced Engine Power (REP) once due to the throttle controller (hit the pedal quick a few times in quick succession), and it threw a code saying that the voltage coming from the pedal wasn't what it expected it to be (can't remember exact code as it was years ago). Just pulled over, turned off car and restarted and all was good, and cleared the code when I got home. Since yours dies, and does so right away, gotta think it's more than just the signal from the pedal or TB (I've also unplugged my TB connector while the car was running to try and troubleshoot something - car started running/idling like total crap but kept running, didn't die).

Will the car keep running if you press the pedal, to open the throttle some more? Guessing it won't though.

[hesster]

Thanks guy's, any and all input is welcome.
Found some time today to pursue some of my listed debug items.

I am thinking my TB and Pedal are OK, no evidence of wear, shorts, etc. Everything under the TB Brass Cover is clean and no wear. Ohm tests also don't indicate anything amiss, sweeping/actuating both TB and Pedal shows resistance variation as desired. But that is resistance, voltage tests may be a different story. Ref the pics, the one of the TB Ohm tests on the sheet is pretty cool, I did it on the Old and New TB and they are close leading me to believe it ain't the TB that is bad.

I see no indication of blown fuses, chaffed wiring, bad connections, stuff unplugged, or anything in my laundry list of things to check that is a "Red Flag".
So it would of been great to find the "Ahh Ha" root cause, but not yet.

So I have not run the electrical tests yet. Waiting on the new Battery any day and will install that, reinstall the old TB and Pedal, then and try those electrical tests, and also hook up my SCT-X4 to look at any related parameters with the key on. But don't really know what to look for. The old Battery has been disconnected for days now, so everything should be discharged. Then try to fire it up, w/o depressing the pedal, and or then cracking the throttle open.
If it starts and dies, then I will install the new TB and Pedal and try again.

[gtstorey]

I don’t know that I would expect anything visible in the throttle body as a problem to cause this code. They are very sensitive to these voltage issues.

[hesster]

Part of the plan was to get some or all of the old gas out of the car and start with fresh premium and a touch of ISO HEAT for any water remaining in the tank, if any.

Followed "TLSTWIN's" procedure, and it works pretty good. Got 6 gal out, and that is prob most of the less than 1/2 tank sitting in the car. Not sure if all of it is out given the gas is siphoned via the fill side and the tank is a saddle design. Better than nothing.

Process:
1. Pull Passenger Rear Tire.
2. Disconnect Fill tube rubber hose by removing the clamps, and pry it off with a little WD40 to help.
3, Stick your 3/8" fuel line from your own evac system and pump it out. Mine is a simple lawnmower battery, small fuel pump w/filter, and a switch.
4. Replace hose, tighten clamps, install wheel.

Done!

Some pics hear to show what I did.
Also, received the Battery today and put on the charger.