wheelin today and a couple of issues

[timgco]

Went out wheelin today with the CO group. Had a blast. The H3 did very well with two exceptions.

1) I got up to around 13,000 ft and the truck started sputtering and I had almost no power. Foot to the floor in 4LO locked and wouldn't move but 1 mph. It did this for a couple hundred yards. I shut the truck off, and the problem stopped, but the check engine light was still on. I cycled the engine on and off a few more times and still no problem and the check engine light out.

egine power reduce, stabilitrack off, stabilitrack failed. It flashed these over and over durring those few hundred yards, had the little engine light on, and than it went back to stabilitrack off. no more issues.

2) The dumbass that changed are oil last didn't put the bolts back into the skid tight, so we lost one and the other was barely hanging in there. Also missing were the two bolts to hold the UC protection through the skid plate. Anyone know what size bolts I need to get for the back of the first skid plate that has the H3 logo on it (need two) and also for where the next shield goes where the UCP protection mounts to (also need two)

Other than that, it was a lot fun today!!!!!

[HummerNewbie]

Sorry about the issues Tim but glad you had a great time. I would also like to thank you for reminding me I need to climb under there and check all the bolts before the upcoming trip

[marin8703]

One reason that I know of the engine going into reduced power would be high temp. If it over heats it goes into reduced power mode in an effort to reduce engine temp by reducing power output while keeping fan and cooling system at max.

I would have said its normal for all vehicles to loose power with altitude increase because of lower concentration of oxygen which is needed for combustion to occur, but since it was ok after restart it leads me to believe its an overheating issue. I might be wrong, wouldnt be the first time!

oh and it also could have detected a misfire and went into "protect" (reduced engine power) in order to prevent it from misfiring again, keepin the engine safe or sum like that.

What was your temp gauge showing? and what temp were you playin in?

hope i was of any help.

[timgco]

[quote=marin8703]One reason that I know of the engine going into reduced power would be high temp. If it over heats it goes into reduced power mode in an effort to reduce engine temp by reducing power output while keeping fan and cooling system at max.

I would have said its normal for all vehicles to loose power with altitude increase because of lower concentration of oxygen which is needed for combustion to occur, but since it was ok after restart it leads me to believe its an overheating issue. I might be wrong, wouldnt be the first time!

oh and it also could have detected a misfire and went into "protect" (reduced engine power) in order to prevent it from misfiring again, keepin the engine safe or sum like that.

What was your temp gauge showing? and what temp were you playin in?

hope i was of any help.[/quote
Thanks for the input. The truck did have multiple missifres in a row while it was doing this. The temp stayed the same all day at normal.

I did have this happen in my SUT when I had it. It needed a computer upgrade and a new fuel pump/ sending unit, but the engine light never went back out. Same symtoms at altitude only.

[usetosellhummer]

bummer

[HummBebe]

I'd say it was a dealer issue for sure.

Although, mine has had brain farts, I mean computer brain farts.And as you cycled a couple of times and it went away, so did mine.

13,000ft is proabably the highest and H3's ever been, LOL, you may be breaking the altitude record.

It is possible to have a bad temp sensor, you may have been running hot and not known it.


Good luck

[lotus4s]

Just a WAG (wild ass guess) but maybe the ECU was confused on the air/fuel mixture due to the altitude and needed time to readjust the parameters.....

[Michael1]

Originally Posted by HummBebe

13,000ft is proabably the highest and H3's ever been, LOL, you may be breaking the altitude record.

GM tests to the top of Pike's Peak, which is 14,110 feet, so he should be OK there. I would say Stabilitrak engaged for some reason, and cut power.

Michael

[f5fstop]

I would rule out an overheat problem due to the restart. If the engine is overheating and the PCM goes into limp mode, a fast restart is not going to cool down the engine. If you sat for a few hours, I would agree. Just computer has no control over the cooling fan; it's mechanical.
In addition, I cannot see any relationship to stabilitrack and engine overheating.
As altitude increases, HP reduces, but so does resistance in the air, however, the overall result is less HP. One reason why forced induction systems excel in higher altitude.

Misfire would be a good guess, possibly the cylinder head is one of the few that will need replacement.

My guess would be the computer needed to be reset by a engine cycle off/on. I would head to the dealer, or find someone with a tool to find the codes, they stay in the PCM for quite a few engine cycles; up to 80 for some codes. Misfire codes (P300+) will stay for quite a few engine cycles.

[timgco]

So the dealer is telling me, that the B&B Exhaust is the problem.
WTF- I haven't had problems before and I find it hars to believe that a catback exhaust is all of the sudden causing issues after 10,000 miles.


Codes were:
P0068 Poor flow
P0171 Lean Code Bank 1
P0121 Throttle Position Sensor Performance
P0016 Map Sensor

Now what?

[f5fstop]

Dealer full of BS.

Let me ask, where your wheels turned? Were you going up or down? Did you get a code? At anytime, did any of your wheels leave the ground with the stabilitrack turned off (manually or via the system).
I actually met up with the head of programming yesterday for the H3, he was in our shop doing some test cals on some vehicles. I asked him about this condition, and also a condition I had in Moab a few weeks ago (4-Wheel drive failed). For mine, I just turned off the engine and restarted and the system worked ok, happened three times over five days.
He admits that sometimes, the computer just gets mixed up and a restart will usually set everything right again. That is one reason why the cals change. As much testing as GM can do, we as customers seem to be able to do things they never thought of or tested for. Therefore, as time goes on, they learn these problems and adjust the cal to solve the problem.
He is always working on new cals, and when the cal is finished they must not only be tested, they must be certified if it is an engine cal.
Not saying that is your problem, but I would love to find out what code was retained in the PCM.
As for the exhaust, I cannot imagine what could cause a new cat back exhaust to cause the condition you had.

[HummBebe]

Originally Posted by timgco

So the dealer is telling me, that the B&B Exhaust is the problem.
WTF- I haven't had problems before and I find it hars to believe that a catback exhaust is all of the sudden causing issues after 10,000 miles.


Codes were:
P0068 Poor flow
P0171 Lean Code Bank 1
P0121 Throttle Position Sensor Performance
P0016 Map Sensor

Now what?

Could those codes be intake related rather than exhaust related?

[timgco]

Originally Posted by f5fstop

Dealer full of BS.

Let me ask, where your wheels turned? Were you going up or down? Did you get a code? At anytime, did any of your wheels leave the ground with the stabilitrack turned off (manually or via the system).
I actually met up with the head of programming yesterday for the H3, he was in our shop doing some test cals on some vehicles. I asked him about this condition, and also a condition I had in Moab a few weeks ago (4-Wheel drive failed). For mine, I just turned off the engine and restarted and the system worked ok, happened three times over five days.
He admits that sometimes, the computer just gets mixed up and a restart will usually set everything right again. That is one reason why the cals change. As much testing as GM can do, we as customers seem to be able to do things they never thought of or tested for. Therefore, as time goes on, they learn these problems and adjust the cal to solve the problem.
He is always working on new cals, and when the cal is finished they must not only be tested, they must be certified if it is an engine cal.
Not saying that is your problem, but I would love to find out what code was retained in the PCM.
As for the exhaust, I cannot imagine what could cause a new cat back exhaust to cause the condition you had.

I was headed up hill. Display said reduced power or low power (cannot rememeber). Satabilitrack off/ stabilitrack failed- was in 4lo headed up hill. Engine was chugging and missifred until it died. The more gas you gave it, the harder it chugged and missfired. On the way back down this same hill, in the exact same spot (same elevation) it did the same thing and died.

Both times, I just shut the truck off and restarted. After 3 restarts, the engine light went back off and just flashed stabilitrack off. Was also still in 4lo.

The dealer is driving it home tomight to "reset codes". Not sure what 250 miles wouldn't have done already unless they have to clear the codes and than isolate codes again.

I also called another dealer and over the phone, giving them the codes and deffinitions, they are leaning towards a sensor having to do with air intake or "high altitude" computer uprgade. I athan asked them if this was the same thing as a ID10T upgrade. They didn't get it.

F5- what do you think I should do at this point. I will not let them take my exhaust off and charge me for it either.

[f5fstop]

Dealer can reset codes with a Tech 2. If he is trying to duplicate the problem, he might have to go on a high-altitude trip.

Didn't see the codes earlier.

P0068 Poor flow (with this code, the airflow is actually larger than expected)
P0171 Lean Code Bank 1 (Do you have an aftermarket air filter?)
P0121 Throttle Position Sensor Performance (TP sensor 1, and is related to a larger than expected intake of air)
P0016 Map Sensor (This code is set due to a camshaft position sensor pulse occurs during the incorrect crank position).
Either 68 or 121 can cause the PCM to go into reduced power mode. I'm guessing, and that is all it is, the PCM got a bit mixed up for some reason. One of the sensors that the PCM uses to monitor airflow (TP/BARO/MAP/IAT/MAF/RPM) could be failing, but not sure which one; it should set a code.

However, I do not see how a cat-back exhaust would cause any of these problems. If you had installed headers...maybe. But a new lower restricted exhaust and new pipes after the muffler should not cause any of these problems. I would ask the dealer to substantiate why he even thinks the exhaust will cause this problem.


How is your idle now that you have returned to the 6K range? That P0016 is out of place. If you had that one, and some P0300+ codes, along with a rough idle, I might suggest a cylinder head issue. But the cylinder head issue does not shut down the vehicle, it only causes a rough idle and sets codes.

I can find nothing in preliminary reports or in bulletins; other than for 171 where it states the air filter can be restricted, or PCV hoses kinked.

I will print this off tomorrow at work, and if the programming dude is around I will show them to him and see what he thinks.
I know he is hot and heavy on a new chassis cal that has to be released, but it outputs chassis codes when the condition happens, and so far, only a half-dozen complaints from customers, but quite a few from some engineers running the trails somewhere in the US.

DTC P0016
Circuit Description
The powertrain control module (PCM) uses the crankshaft position (CKP) sensor and the intake camshaft position (CMP) sensor information to monitor the correlation between the crankshaft and intake camshaft position. If the PCM detects a CMP sensor pulse occurs during the incorrect crank position DTC P0016 will set.

DTC P0068
Circuit Description
The powertrain control module (PCM) uses the following information to calculate an expected airflow rate:

? The throttle position (TP)

? The barometric pressure (BARO)

? The manifold absolute pressure (MAP)

? The intake air temperature (IAT)

? The mass air flow (MAF)

? The engine RPM

If the PCM detects the airflow rate is more than expected, DTC P0068 sets.

DTC P0121
Circuit Description
The powertrain control module (PCM) uses the following information to calculate an expected airflow rate:

? The throttle position

? The barometric pressure (BARO)

? The manifold absolute pressure (MAP)

? The intake air temperature (IAT)

? The mass air flow (MAF)

? The engine speed (RPM)

If the PCM detects the airflow rate is more than expected, DTC P0121 sets.

[timgco]

stock air filter. The only mods done to engine would be the cat back B&B Exhaust. This truck has also had a trans replaced. I'm not sure on the air filter hose/ intake being kinked or blocked. I honestly have neverr had the aibox open yet.

They arer still blaiming the exhuast.

[f5fstop]

Not saying this is it, but you mentioned trans replacement....

Subject: P0101 P0106 P0121 Poor Acceleration and Detonation in Gear - keywords chuggle converter drive forward fuel hesitate idle information launch load low misfire miss performance power reverse stall surge #PIP3144A - (11/22/2005)



Models: 1996-2006 All General Motors Passenger Cars and Light Duty Trucks




--------------------------------------------------------------------------------

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:
Customer concern of poor acceleration, detonation or "ping" at idle in drive or reverse, and/or possible DTC P0101, P0106 and/or P0121 set in the PCM. The vehicle will perform properly after attaining a speed of about 30 - 40 mph. The condition may also be described by the customer or the dealer as a hesitation, stall when putting into gear, surge on accel (similar to hitting fuel cut or rev limit). The ultimate cause may be a non-holding torque converter stator or damaged stator support shaft within the automatic transmission.

Recommendation/Instructions:
The following checks should be performed in the event that normal engine driveability checks have not resolved the detonation or "ping" at idle in drive or reverse, lack of power from a stop, stall, surge on accel and or hesitation complaint.

The transmission oil cooler outlet line (line to the cooler) should be checked for excessive heat. The Tech II scan tool may be helpful on vehicles equipped with the transmission fluid temperature sensor in the cooler line (mainly front wheel drive). On vehicles that do not have the temperature sensor in the cooler line a temperature probe should be used to check the temperature. The temperature readings should be compared to a like vehicle with the same powertrain option content.

In the event the engine is not producing sufficient power the transmission oil temperature at the outlet cooler line will not be excessive and should compared closely to the like vehicle.

In the event the transmission torque converter stator or stator support are damaged the transmission oil temperature at the outlet cooler line will be excessive to that of a like vehicle.

A stall test (brake torque) may point to a damaged torque converter, the stall RPM speed will be lower then a like vehicle. However, poor engine performance will also produce a lower stall speed RPM.

If the torque converter stator or stator support is suspect, the transmission should be removed and the stator support inspected for spline damage. If the stator support splines are damaged the transmission should be repaired and new torque converter installed. If damage is not present on the stator support the concern is either internal to the torque converter stator or an engine performance concern.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.

Hitting a fuel cutoff limit will be like your symtoms, floor the accelerator but nothing happens, vehicle slows.

[HummBebe]

By jove I think he's got it

[f5fstop]

Originally Posted by timgco

stock air filter. The only mods done to engine would be the cat back B&B Exhaust. This truck has also had a trans replaced. I'm not sure on the air filter hose/ intake being kinked or blocked. I honestly have neverr had the aibox open yet.

They arer still blaiming the exhuast.

Have them give a definite reason why the exhaust would cause this problem. Dealers are notorious at blaming something on an aftermarket item, with no proof or experience when they fail to find the true problem. They may not be able to find the real problem, not due to their incompetence, but due to the fact that once in a while these new vehicles will exhibit a behavior that can't be explained.

I will check today, in case I'm wrong, but I have never in my life heard of a cat-back exhaust causing any problems with the engine or trans, and even early in the AM, I cannot conceive of what the exhaust would do to cause the problems you stated. If the exhaust was clogged, yes, but if it was clogged, it would not run ok afterward either. And what normally clogs exhaust systems, catalyst material discharged from the catalyst due to backfires. This you don't have, so I rule out the exhaust.

The exhaust is a static device, if it was causing problems, it would cause problems all the time at high altitudes, a restart would not fix the problem. (Just my opinion.)

I'm still thinking the PCM or a sensor "farted" and the restarts fixed the problem, similar to my 4-wheel drive problems on the trip. The trans bulletin is just a "maybe" since it does show some of you symptoms. Problem is you have those other codes too.

[h2co-pilot]

F5 is a such a Sweetheart - always helping out.

Hope you get it straight Tim.

[Ipedog]

All hail F5