Symptoms and Causes

[jimmyblue]

This thread is for simple concise troubleshooting factoids.
What the car did, and what caused / fixed it. Add your
"aha!" bullets.

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2000 Camaro SS with P0507 Idle Speed High and P0171,
P0174 Lean Mixture codes (both banks).

PCV hose between valve and TB had a hole in it.

[rive7390]

I received my tuner yesterday and I ran into this problem (Boot loader request timeout - failed)

did a search and fell upon this thread and bought a new battery. The battery took me roughly an hour to change (f'in corrosion). Needless to say, I had to replace both terminal bolts.

Anyhow, after putting the new battery in it still gave me this issue. I'm thinking "wtf...." So, I just let my car run for a bit (giving the batt some charge), turned it off, turned the key to run position and the scan went through.

Hopefully I don't run into this problem every time I want to do a tune. Car Details in Sig.

here's mine... lets get this thread started!

[MMGT1]

1:AFR jumping from PE to stoich launching at the track

Need to set Traction Control AFR to match PE AFR-no more problems!

2: Trans slip and "shudder" shifting at WOT

Need the WOT Shift Speed and the Part Throttle Shift Speed to match at 100% throttle-no more problems!

2000 Grand Am 3400

[blownbluez06]

Any SD tune i.e. 1, 2 or 3 bar tune. Car won't idle. Solution make sure you have the MAF set in the DTC's under Engine Diagnostics to 2 No MIL light. If you set it to "3" No Error Reported, it will remove the MAF from the system entirely and even though it is not being used, it's still used for calculations.

[ViaBellator]

Just a couple of quick ones I've dealt with lately.

Issue 1 - LS2 402 - Flashing CEL. Multiple misfires on 4 and 7. Tested wires, plugs, coils, compression, etc. No joy.

Fix - CKP Variation learn procedure (AKA Case Learn). Apparently L67's aren't the only one in need of one of those after all.

Issue 2 - Wildly rich LTFT's on one bank. Eventually leading to misfires. No codes other than rich bank 2. Open loop ran great. Closed loop = misfires, rough idle, rough cruise. WOT ran fine.

Fix - replaced O2 sensor. - The sensor was reading rich causing the ECM to pull fuel. The lean condition that created was causing massive misfire issues when the car was in closed loop and LTFT's were in play.

[SweetS10V8]

Histograms: Spent more than a few hours figuring these out. Simple fixes.....

Issue 1 - Could not get an extremely simple "Commanded Lambda" custom PID to work(Which is Commanded AFR/Stoich), kept getting "unsuported parameter" when I started the log.

Fix- You can not use [SENS.121] "Commanded AFR", it wont work. You must use [PID.6000] Air Fuel Ratio Commanded Low Res or [PID.6001] Air Fuel Ratio Commanded High Res

Issue #2 - While trying to MAF only tune I couldnt get the historgram to work, as in issue #1.

Fix- Same type of fix, I was logging "Mass Air Flow (SAE)" which wont work, I needed to be logging "Mass Air Flow (Hz)".

[NassyVette]

Issue: Car idles abnormally and tuning is difficult.

Fix: Change the TB scaler from .0255 to .0320

[alwcurlz]

1999 Chevrolet Silverado Z71
5.3 V8, 4L60E
143,000 miles.

I had a problem with starting once the engine was warmed up. I found that my fuel pressure regulator was bad. I pulled the vacuum line off, and fuel came out of where the hose connected. NOT supposed to be fuel there! I replaced that regulator, and the problem was solved! Also, the little rubber elbow attaching to the regulator should be examined as mine had a small hole in it as well from mfgr defect where it cracked.

[Twitch]

Issue: Car idles abnormally and tuning is difficult.

Fix: Change the TB scaler from .0255 to .0320

Dumb luck that I stumbled across this post the night before I upgraded to a 90mm TB. Wasn't even looking for it
Thanks

[Google]

if ve is correct and the only problem is afr while warming up and afr corrects to commanded about half way into the warmup then look at your volts and see if they are higher then normal during warup. if yes you can adjust the injector offset vs. volts vs. vacuum to correct the rich/lean during warmup.

eg; startup alt volts is 13.4 warm and 14.0 - 14.3 cold starting to half way warmed up.

I have seen alot of injector data needing tweeked for this. hope this helps anyone that may read this.

[BRAAPZ]

01 Suburban 1500 4wd, 5.3 LM7.

Symptons;
Idle speed underswings engine almost stalls, sometimes did stall when coming to a stop. Another side effect that is directly linked to this is Sometimes the trans will hang in 2nd gear at light throttle acceleration not shifting up to 3rd.
No codes thrown, no DTC's.

Cause;
BAD TPS. Specifics covered here;
http://www.hptuners.com/forum/showthread.php?t=28366

In short the TPS was intermittently registering no less than 10-12% at closed throttle and sometimes not registering throttle movement below 25%, showed up in a data log.

[smithers]

Issue: Car idles abnormally and tuning is difficult.

Fix: Change the TB scaler from .0255 to .0320

This seems like the incorrect way to fix an abnormal idle issue and causes other underlying ones. Does anyone verify these Symptoms / Causes / Fix threads?
ETC Scalar is just a physical measurement of the throttle, and a 0.0320 is telling the ECM a throttle size of approx 69.5mm.

[iced98lx]

This seems like the incorrect way to fix an abnormal idle issue and causes other underlying ones. Does anyone verify these Symptoms / Causes / Fix threads?
ETC Scalar is just a physical measurement of the throttle, and a 0.0320 is telling the ECM a throttle size of approx 69.5mm.

You'll notice he's specifying that he put a 90mm throttle body on an older corvette normally equipped with a 78mm TB, so in this case, this is the correct fix vs drilling a hole in the tb or some other awkward fix.

[smithers]

You'll notice he's specifying that he put a 90mm throttle body on an older corvette normally equipped with a 78mm TB, so in this case, this is the correct fix vs drilling a hole in the tb or some other awkward fix.

Again, you are incorrect as well - NassyVette suggested value is NOT the correct fix and drilling an ETC is out of the question period.
If you pay attention, I am aware that a 90mm ETC is replacing a 78mm ETC. Who said anything about drilling? thats not the issue, the issue is the value he states works, clearly he fubbed something else up to make it seem to work... but the beauty of ETC scalar is its a PHYSICAL measurement, Telling the ETM how big of a throttle is on the car, and that number SHOULD NEVER CHANGE. If your car runs like crap when putting in the PROPER VALUE, somewhere else in the tune is not correct or needs adjusting.
Again, 0.0320. is NOT the correct value 'fix' for this problem.

If you read what HPT says it stated:
This value is used to convert from desired Effective Area (mm2) to desired ETC percent.

Perhaps this may help you with your decision:
WORKSHEET

The problem is the value he used for scalar, as I stated, with the calculation, he is telling the computer his NEW throttle is now SMALLER than stock (69.5mm), rather than larger...(if you re-read my last post) I have done a couple 90mm from stock 78mm corvette vehicles
the ETC scalar number for a 90mm is 0.0191 NOT 0.0320. SMALLER number gives LARGER physical size for the ECM to work with... not the other way around.
ETC SCALAR is a physical SIZE of the throttle based on mm squared area to determine percent throttle.
look at it as step increments. If your throttle gets larger, you want a SMALLER step or move in the throttle plate to EQUAL the amount of air that would have flowed through a smaller throttle... via versa, a smaller throttle would have to OPEN further to get the same amount of air as a larger one.
LARGER the throttle, SMALLER STEPS... means, SMALLER ETC Scalar, not larger as NassyVette did.
He is telling the ECM that his throttle is 69mm, well, it isnt, its a 90mm.. but every PERCENT the throttle moves, the computer THINKS its only changing x amount of air (calculated off of a 69mm area), when in fact its much more...

[Driver]

So I have a 92mm TB and a stalling issue, my mail order tune has 0.0255 in the ETC area scaler. If I change to 0.0188 will this effect anything else besides idle?

[smithers]

So I have a 92mm TB and a stalling issue, my mail order tune has 0.0255 in the ETC area scaler. If I change to 0.0188 will this effect anything else besides idle?

two things:
I don't think the sticky section is appropriate for random discussions, regardless. I wanted to argue my point across that the information given vs a fix was incorrect on the sticky section.

Im going to take a wild guess, but I doubt your 92mm throttle is Electronic, or ETC. which is the discussion at hand, and since it is not, ETC scalar adjustments wont do you any good. Your throttle is cable driven, correct? 02 ECU, probably, Newer vetts etc had Electronic Throttles.
ETC affects ALL throttle operations from idle to WOT, because it tells the computer the physical size.


Stalling = IAC needs possible tuning, and Base running airflow is out. And you guessed it, a mail order tune is your first problem.

Russ Kemp IDLE RussK idle is what you need to be doing and will more than likely solve your issue.

[redhardsupra]

better TB resizing spreadsheet:
http://www.marcintology.com/tuning/TBresizing.xls

[blownbluez06]

So with your spreadsheet, you take your existing throttle body with the factory scalar and divide it by the numerical value representing that percentage?
For example 78mm throttle body to a 90mm throttle body is 133% change. .0255/1.33 is averaged out to .0192.

[redheartbeat]

2000 Camaro SS with P0507 Idle Speed High and P0171,
P0174 Lean Mixture codes (both banks).

PCV hose between valve and TB had a hole in it.

GM also says to check the o-ring around the end of the master cylinder where it goes into the vacuum based brake booster.

[BULLITT]

tune looks fine when i drop it in gear the timing and tourque mangement start jumping like crazy killing the throttle in P/N in gear has very little power what could cause this im new to this the tuner that installed tune car has a t66 front mount with 44lb injectors and no dtc till after the loss of peddle oncw the timing starts jumpin then it misfires what will fix this issue