6.0L..Idle,Off Idle..Low power

Arnold · January 08, 2013, 11:58:39 AM

I am not really a fan of these. My g/f has one..and I know a few others that do too. I just think they have too little low end..too little h/p and burn way too much gas. I think they are sort of ok for a truck..light towing etc.

My 94 1 ton extended van has a 5.7 truck engine and has 10 times the torque at very low speed..idle,right off idle. Makes my g/f and others seem really weak!

Now to my 6.0. Mine has just very little power at idle..or even off idle.
Considerably less than my g/f's and embarrassing compared to my 5.7
I know they come in 300,325 and 345 hp versions. Mine is a Police Unit that has 380 hp. Almost all of them here(Canada) are the 300 hp units.

At about 1500 rpm mine seems to wake up. Much,much more power than the other 6.0's. This is a very,very strong engine with very little throttle needed at 1500rpm.The power goes up exponentially until at least 2500. Put your foot down at 1500 rpm and up in any gear and there is some serious power there. 30mph full throttle downshift and there is a real kick! I am not concerned with mid range..or hp. There is plenty of that. Just idle and off idle. There is no hesitation,bogging and it feels crisp..not loaded. And considerring..it is really good on gas!

It shows no codes. New plugs,wires. A filter is good. Just whatever maintenance it should/should of had it has had.I would like to check this out to a small degree. I know nothing about newer f.i. engines.

I can see some loss of low end due to the factory Police exhaust..
3" pipes..duals..right from the exhaust manifolds back..dual cats.. no resonators..and nothing in the way of a muffler. This is a way too loud,noisy,rumbly truck. Real nice! in small doses. I don't think all the lo end is lost there? I dunno.

It also has a large throttle body..that could be some too. I dunno.

Any ideas on what to check out?

Thanks very much!

I would just hate to have to pull this engine and stick it in something that weighed half as much

wayne petty · January 08, 2013, 07:26:09 PM

arnold... can you get some free time to give me a call???

so i can go over this...

there are a WHOLE BUNCH OF THINGS TO LOOK AT...

that will NOT SET A TROUBLE CODE...

this is going to require a scan tool that reads LIVE DATA STREAM.... so we can see what the system is doing..

also... did i hear you say that your truck also weighs 1000 or 2000 pounds more than a conventional model???

does it still have the ARMOR plating that was installed by GM??? kinda hard to remove sometimes...

i am also under the impression that police specials also are capable of 120MPH... as they are delivered... hence the larger flowing injectors and the high speed ratios in the drive axles... make for slow take offs unless you drive it like you stole it...

a PM with my phone number is coming your way...

wayne petty · January 08, 2013, 08:08:16 PM

the best idea is to take a test drive with your scan tool plugged in...

looking at the live data stream

pay attention to the

short term fuel trims..

and the

long term fuel trims..

the percentages need to stay within about 10% of 0... if the truck is running properly..

some scan tools display load percentages..

if your scan tool will take snap shots and can download to your PC...

can you take a snap shot with the KEY on. engine NOT RUNNING DEAD COLD and post the data stream recording so i can decipher it..

can you take another one at idle.. fully warmed up...
and post that..

can you take one at a moderate speed... 25 to 35 MPH at a steady throttle position... on a level road...

if your scan tool will do these...

do that with your friends trucks also.. so you can compare the readings...

yes its COMPLEX...

Arnold · January 09, 2013, 12:06:34 AM

Wayne..
Thanks! for your help..

(as always!) I will take you up on your offer and call you sometime! Thank you!

I do not know if my scanner does live? Somehow..I don't think so.
It WAS pretty good in it's day.I will have to look at it..and the manual.

Another problem..is that Police vehicles up here(Canada) they do not conform(or didn't use to) to emmissions regulations. They got around that by licensing them as "off highway vehicles" then registerring them to "His Majesty The King" I kid you not...that is what they used to do!
BEFORE the very first roller cam 350's/5.7s..AND the Ford Modular V8's
were even available..the cops had them in their vehicles. They ran no cats on early 5.7's..when ALL other vehicles..including other 5.7s had cats.The "Y" pipe on those vehicles..was not available..even from GM!

This could be big problem in so far as me looking into this as my truck has a "GMC Truck Heavy Duty" Emmissions status.

"Armor Plating"

I dunno about that..but it does weigh in EMPTY at 6700lbs! That is about 1500 lbs..heavier than my buddies Yukon XL 4x4 1/2 ton. My g/f has an extended cab h/d 3/4 ton 8 bolt wheel 4x4. We have the same tires. My truck sinks like a STONE! compared to hers in firmer snow.

Sure doesn't feel like there is anything wrong with this thing..
considerring just how powerful it is and how well it runs. Feels like other
"cammed" engines in terms of idle/off idle. Just has no power at idle/off idle with very little throttle :evil: : Maybe I will have to live with it. Oh well..Sure is powerful!
It is SOMEWHAT FUN

as in I drive it in 2wd almost all the time.
IF there is ANY snow..a bit of throttle..not much power..a bit more rpm and the back wheels break loose and then the locker kicks in really aggressively! That is what Hot Rodding is all about right. At 95km hr..almost 60mph..Even a skiff of snow on the road..full throttle..in 2wd..this thing will really seriously spin the tires! And it has GREAT! exhaust note

Yes..one does get sick of the noise this thing makes

Every time I drive this thing(not my daily driver) I cannot believe that something this big and heavy can be this powerful.

And it was cheap to purchase.Really good on fuel for a 4x4 truck.Really cheap insurance. Is big..roomy..4x4..and has a snowplow.
Perfect mechaniclly. Body is very good.

Nice Toy. Just has no power idle/off idle with little throttle.

I dunno if it would do an honest 120mph. Probably..sure packs a wallop from 50-80mph.

I talked to a cop up here and he said the big Police Suburbans live a charmed life up here. He said they are so big and noisy..that when you put the lights on and put your foot down..NOBODY wants to find out IF they can get away. Or wants to get run down. Regular patrol cars the odd person does try to run. Not from these things.Mine was an unmarked highway patrol unit.

wayne petty · January 09, 2013, 12:22:53 AM

Mine was an unmarked highway patrol unit.

HIGH SPEED GEARS

probably ballistic armor... this was a truck for the police in areas were they hunt with high powered rifles.. right..

what brand and model scan tool do you own...

i will look up the manual if i don't already have one.. see if it does do live data.. i have been playing with scan tools since 1981.. when i had classes at GM TECH center in burbank.. on feedback carbs.. i had the one before that on the C3 system.. where you could only get trouble codes and had to use digital volt meters to measure each circuit picked out by the trouble codes.. so i learned this early ... you should see the magic i can do with dead 76 to 79 sevilles and eldorados with bendix electronic fuel injection..

got a harbor freight around??? the 98614 is a cheep scan tool that does amazing things within reason.. like live data and graph the sensor data ...

http://www.harborfreight.com/can-obd-ii-code-reader-eobd-scanner-98614.html

start reading in section 5.3 does not matter if you have a different scan tool.. just for the knowledge..

http://manuals.harborfreight.com/manuals/98000-98999/98614.pdf

lets see... scan tools..

an early autoxray obd1 gm ford mopar
actron CP9110 obd1 gm ford
OTC monitor extended.. obd1 and obd2 through 98 since that is the last cartridge i have... but it does GM ford and mopar ... but also most of the obd1 asian imports starting in the i... a whole bunch of cables..
the 98614.. which i grab first for obd2 cars..

sounds like a FUN TRUCK...

wayne petty · January 10, 2013, 10:53:38 AM

i have a question...

are the throttle body shaft bushings worn... allowing the throttle to wiggle around when part way open???

(o ) ( o) bad

(o) good

why.. this allows the throttle to close to a slightly different angle that effects the TPS voltage signal back to the PCM...

if the minimum voltage varies when the throttle closes.. it will freak out the computer and prevent it from dropping into the idle fuel control circuit.. it will also leave the computer programming in acceleration mode... so instead of coming off idle programming.. its already in acceleration mode so its going to be too rich for proper power out put and idle transition to cruise programming..

if the throttle shaft bore is worn.. the throttle could be opening without the TPS responding properly.. causing your issues..

this is one of the reasons one needs to view the live data on the scan tool..

first step when i plug in after i check for codes...

engine off.. i look at the TPS voltage... slowly depress the throttle as i watch the TPS signal... all the way to WOT.. . then slowly all the way till i can remove my foot from the pedal... i am looking for dropouts in the signal voltage...

i then work the pedal a few times at different speeds.. each time taking my foot off.. to see if the TPS voltage returns to the EXACT same fraction of a volt...

if it comes back to different voltage readings. the shaft bore might be worn...

one can also look at the injector pulse width...

things vary.. but 1.2 to 1.4MS injector pulse width at idle is expected..

look also at the MAF sensor.. V8 engines are usually about 0.6 grams at idle..

i know this is more than you ask for...

Arnold · January 10, 2013, 02:55:20 PM

Quote from: "wayne petty"i have a question...

are the throttle body shaft bushings worn... allowing the throttle to wiggle around when part way open???

(o ) ( o) bad

(o) good

why.. this allows the throttle to close to a slightly different angle that effects the TPS voltage signal back to the PCM...

if the minimum voltage varies when the throttle closes.. it will freak out the computer and prevent it from dropping into the idle fuel control circuit.. it will also leave the computer programming in acceleration mode... so instead of coming off idle programming.. its already in acceleration mode so its going to be too rich for proper power out put and idle transition to cruise programming..

if the throttle shaft bore is worn.. the throttle could be opening without the TPS responding properly.. causing your issues..

this is one of the reasons one needs to view the live data on the scan tool..

first step when i plug in after i check for codes...

engine off.. i look at the TPS voltage... slowly depress the throttle as i watch the TPS signal... all the way to WOT.. . then slowly all the way till i can remove my foot from the pedal... i am looking for dropouts in the signal voltage...

i then work the pedal a few times at different speeds.. each time taking my foot off.. to see if the TPS voltage returns to the EXACT same fraction of a volt...

if it comes back to different voltage readings. the shaft bore might be worn...

one can also look at the injector pulse width...

things vary.. but 1.2 to 1.4MS injector pulse width at idle is expected..

look also at the MAF sensor.. V8 engines are usually about 0.6 grams at idle..

i know this is more than you ask for...

Wayne..Thanks again(as always) for your help :!:

I DEFINITELY need a new scanner

..I was already sort of looking around to get one that will do the transfer case codes..(C..chassis codes) anyway. I have found looking around VERY CONFUSING :evil:
I am pretty computer illiterate and am sort of thinking along the lines of one that will record and play back live data..maybe graph it.AND do..at least C codes. ONE DAY :cry: I will need them.
The Harborfreight one you pointed out..Thanks! I read a few things that said it will not do chassis codes like that? I dunno.

Also I read about problems with the ones that load stuff to your laptop the you need Windows Vista or 7..I dunno about that stuff..just whatever was the latest one in the fall of 2011 when I got this lap top is what is in it..my buddy put it in..I think Windows Enterprise? I dunno

Some need adapters or stuff loaded in order to do some stuff.
A fair bit written about those Harborfreight ones..you go to load stuff or update them and that is the end of them. I dunno about stuff like that.

There was something I read that said ALL EOBD will do ALL manufacturers codes. Ahh..NO..I did read enough that that ain't true.

There is an Actron..does graphs..records..play back..I have emailed them to ask if they can do C codes..Chassis codes. Haven't heard back.
There are scanners on Ebay that say they do live for $30 bucks or something.

Good questions..I do not know if the TB shaft bushings are worn? I will have to check. Or TPS.

I get the feeling from driving this thing there ain't nutthin' wrong

I just made a trade off for idle and off idle power.
I can..(might have to live with that) :?: Is it worth it :?: I could..and would swear that this thing has a "cam" in it. I don't know. I would not doubt it. Don't know how to find out other than degree'ng it.? I am not going to bother doing that.This thing just does produce exponential power output as it climbs even from 1500..sure feels really cammy around 2500-3000. I don't think I have taken it above 4000..never even let it shift at full throttle. I get the feeling the transfer case would not take much of that.

Just needs to GO ON A DIET! and lose about 4,000 lbs and put this motor in a HOT ROD!

I have had a lot of hi-perf engines..and this one is right up there with just about any factory engine.
6.0 L's are not known for "coming alive" ROFL NO KIDDING.

This thing sure is.

Thanks for the encouragement..I HAD work to do. NOW I need to go for a rip in it

If the throttle bushings are NOT WORN..they MIGHT be from my steel toed work boots when I come back

There WAS a tsb out a lifetime ago..I have it somewhere..on worn throttle bushings in Rochester carbs on Police vehicles

rooster · January 10, 2013, 04:22:40 PM

What year car are you wanting to get a reading from?

OBD 1 or OBD 2

For OBD2 you can use this software and get live data, I"m just learning it!
http://www.obd-2.com/

wayne petty · January 10, 2013, 04:46:37 PM

yea... the HF98614 WILL NOT do C codes.. it will NOT do B codes...

it will ONLY do P0000 codes... it is generic... but its cheep...

to get a full function scan tool... to do all the codes..

you are probably going to want to examine something in the OTC 3499N kit... can be had for 500 bucks..

it does OBD1 and OBD2...

http://www.americastoolwarehouse.com/automotive-tools/OTC-3499N.html

i am looking for a manual before i give the approval..

i think rooster is under the impression we are talking about your 1994 model.. this is a 2001 C2500HD if i recall..

rooster showed me some PC software for OBD2 a while back...

here is some more info

http://www.genisysotc.com/pdfs/DriveabilityDiagnostics.pdf

here is a link to some PC based programs that i grabbed from roosters emails...

http://www.obd-2.com/

Arnold · January 10, 2013, 06:21:31 PM

Quote from: "wayne petty"yea... the HF98614 WILL NOT do C codes.. it will NOT do B codes...

it will ONLY do P0000 codes... it is generic... but its cheep...

to get a full function scan tool... to do all the codes..

you are probably going to want to examine something in the OTC 3499N kit... can be had for 500 bucks..

it does OBD1 and OBD2...

http://www.americastoolwarehouse.com/automotive-tools/OTC-3499N.html

i am looking for a manual before i give the approval..

i think rooster is under the impression we are talking about your 1994 model.. this is a 2001 C2500HD if i recall..

rooster showed me some PC software for OBD2 a while back...

here is some more info

http://www.genisysotc.com/pdfs/DriveabilityDiagnostics.pdf

here is a link to some PC based programs that i grabbed from roosters emails...

http://www.obd-2.com/

Thanks Wayne,Rooster..
I am not going to spend $500 now..I will have to wait until they
come down in prce..what I have read that people do to get C codes..(and others too) If they have Onstar(or if it has expired they re-new it) Onstar sees the code..calls you and wants you to make an appointment at the nearest GM dealer. The operator has ALL the info INCLUDING codes in front of them. You just ask for it and they give it to you!

My 1994 1 ton extended 5.7 van..right. IF they even made MD or HD 350's/5.7's in 1994(I dunno maybe they did) THEN SOMEHOW one ended up in that thing.Man that thing has low end! I literally just got it stuck about 1/2 an hr ago :evil: .Rocked it out between drive and reverse.No gas. Throttle :?: WHO NEEDS one of those?

Yes..my Police 'Burb is a 2001 2500.

Thanks again!