Looking for some input ?

[cmd]

I have a 2003 H2 and have noticed that the acceleration is not consistant to where you put your foot into the pedal. The truck does not have much mid range, you put the pedal down and down and it will kick down a gear eventually, however does not seem right, no codes have come up and it has run this way for some time, and as i said it is not consistant. At a set of lights there is no hesistation on take off, lots of pickup, only when under load for a period of time during travel.
Any ideas would be appreciated, i have been thinking fuel? maybe a regulator?.

Thanks

[hummer74]

i know my rig, and other vehicles for that matter, have different tendencies in different weather. mine loves cool dry weather. a little slower in real cold, hot or humid. maybe thats it?

[MONSTERMATT]

throttle body can be sprayed with something i would assume? and that something would be?

[tomp]

Originally Posted by cmd

I have a 2003 H2 and have noticed that the acceleration is not consistant to where you put your foot into the pedal. The truck does not have much mid range, you put the pedal down and down and it will kick down a gear eventually, however does not seem right, no codes have come up and it has run this way for some time, and as i said it is not consistant. At a set of lights there is no hesistation on take off, lots of pickup, only when under load for a period of time during travel.
Any ideas would be appreciated, i have been thinking fuel? maybe a regulator?.

Thanks

I think I know what you are saying. You need to understand how an ECM map works to be able to understand why it does this. The load placed up on the vehicle affects Manifold Absolute Pressure (MAP) which affects the which timing tables are used within your ECM. The more load that is placed on the vehicle, the lower the timing will be. It is designed this way to prevent detonation.

Different things can affect MAP such as wind pressure, towing, vehicle weight, outside air temp and humdity, etc.

Hope this helps...

BTW, adding a programmer can help overcome some of this. However, please note that most canned programmer packages (not custom mapping) only make changes to the upper throttle positions and this is why they make the claim that they do not affect mileage etc.

[HUMMERcustoms.com/TAZ]

tomp hit the nail on the head about mapping. Also on the canned programers you have to do something else to get lowend.

Long tube headers as short will not help enough. Dual exaust true twin duals using Flowmaster my favorite. Dyanatech stainless catback header system tuned to work together.

Even better would be a good software tune to go with this instead of the canned tune. but, the canned tunes do work good with add-ons and don't forget the cold air intake also. All these together can get good performance. I was able to push my rig with canned tune to 400hp at the ground. Leave one out and you have weakened the end game.

Cleaning of throttle body is important as well as MAF wire that collects dirt.
If You look at it after each air filter change you will see which air filter is doing the best job. What ever passes through air filter shows up on the little wire. Be very careful cleaning this wire que-tips and alcohol. Shoot cleaner in throttle body with a high rev at small sprays as it will choke the engine down quick also use rag and clean intake of throttle body of the dirt that collects in front of butterfly and behind from poor air filtering mixed with some carbon. Spray cleaner on rag and just rub it off this makes sure you get proper idle and it not fluctuating on You. Plus if butterfly is not closing all the way then you will get false readings on other sensors as they are all tied together one way or another. Use some tank cleaner as there must be some help from it if nothing else cleaning the fuel lines and making fuel filter cleaner from deposit of petroleum in fuel, It has a tar substance that even though fitered out is still present and gums the fuel filter like it does the throttle body. It in thick enough form is a carmel crystalized looking stuff. If You ever bought and old motorcyle and fuel left in carb for long time you would have seen it. Use bottled heat to clean water out of tank. If you are not in habit of keeping a full tank in cold weather condensation will build up water in tank. Full tank each fillup will prevent this.

Well enough tips for the day. Bed time. Good luck.

TAZ

[cmd]

you guys are great, i am going to clean the throttle body again, the dealer did it apparenty and i used the throttle body cleaner on the air flow sensor, i did however not wipe it down in any way.
What kind of plugs do you guys run?
I changed my plugs recently and went with NGK Iridium IX, i was at a NGK workshop and they advised that due to ethanol blended fuels to go with a plug one heat rating cooler and to gap them at 0.040". The truck does run slightly better than it did i have to say.
This is Technical Bulletin from NGK no.NGKSP-0506-3, it does explain "in the Canadian Marketplace".
Any air filters recomended, will a high flow filter effect the maf operation.

[obzidian]

also, adding to tomps explanation, your tune as tables dedicated for your shift points. Shift speed, mph points, WOT shift tables, etc... all work together. Can you explain at what rpm this happens more frequently at?

Anyways, combined with a wack, twin timing tables and most likely a peaky ve table, combined with a stock stall converter, might yield into some deadspots in the trans/rpm range.

I would love to get my dynatechs in and see how well they would do with the stock exhaust. Then add a cutout and see what that those...

long tubes, like TAZ mentioned, should wake her up a bit, and with a intake, you should feel, if not hear, some difference in performance.

[HUMMERcustoms.com/TAZ]

This my personal opinion from my motorcycle days as well as wave runners.

NGK NO GOOD KRUD

If I'm wrong please show me my errors. These plugs have caused me more trouble than the cheapest socalled American brand made.

I'm open to all ideqas of what plugs we should run in these rigs. We have been running iridium AC Delco and Champions.

But, on my 99 Silverado i went to 4 post Bosch iridium and could feel seat of the pants difference. Not great but, enough. I'm not do any plug chnages except when i start up on boost i will need to drop to a colder plug.

I would really like to here opinions on this from guys who are use to building power in late model rides. I know the iridium was designed to increase plug life. I could care less. I want the best firing without failure as i will most likely add a spark doubler kit just as I added the Keene Bell boost a pump kit to fine tune the fuel pressure once We have it at general numbers that it should be in. I will use A/F lights to jus watch fuel pressure guage and fine tune the lean out a tad more by looking at fuel pressure guage and lights.

So I'm just as interested in advice on plugs as this is something i have been lacking in checking up on and it is as important to the whole project as any of it is.
Thanks for all who help

TAZ

[obzidian]

i also run the 4 post platinums in the rig... she feels a bit more snapier but its plugs, im assuming we could tune out more power since these have more spark energy.

As for high performance stuff, some guys on the boards use the t55's (tr6 for boost) i use them and haven't tried much else. Its a touchy subject and im gonna experiment a bit on the camaro.. but they have worked for me, without really knowing though the differences between a set unless from what i gather from ya'll.

What kind of problems were ya'll exhibiting with the ngk? Just band craftmanship, spark energy delievery, etc.?

[HUMMERcustoms.com/TAZ]

NGK were always fouling bad no matter what i have used them on. Even in a chainsaws.

TAZ