truck runs very bad - spark plugs or chip?

[rxsyclone]

I have a Sy with 31k miles on it, hi-flow cat, drop in k&n filter and a 10n1 chip (with a 3-bar map of course). I just replaced the cap and rotor, but not the plugs and wires (been on backorder FOREVER from ATR). It runs perfect stock, but with the chip it ran very bad until I realized that I needed a 3 bar map. Then it ran fine (according to a reputable shop that checked it and my wife who drove it home ). But when I went to drive it it hesitates really bad every 5 seconds and stalls at every stop on every setting.

Does anyone know - could it be an ignition problem that just recently got worse (can plugs and wires make a truck run THAT bad??) or is the chip misbehaving all of a sudden, although it seemed fine when they checked it at the shop and my wife drove it 100 miles. Or did the engine just freaking blow (or maybe a vaccum hose from running 16 psi for the first time). Needless to say I will investigate more but I am extremely tired and frustrated right now. My plan:

Try to change the spark plus and use any new wires I can get for now
See if the truck is back to normal on the stock chip (will it run with the 3-bar ms still on?)
Test the compression
Look for cacuum leaks I guess

PLEASE HELP

Everybody that worked on the truck and the guys who sold me the chip have been really cool and helpful but it's after business hours right now and man I am frustrated!!

 

[leroy]

Re: truck runs very bad - spark plugs or chip?

Switch back to the stock chip and 2 bar MAP sensor. Some of the old 10-1 hardware wasn't too robust.

HTH,
Jim

 

[GM TURBO]

Re: truck runs very bad - spark plugs or chip?

I thought the original 10-1 was a 2-bar chip and the Ultimate evolved in to the 3-bar.

 

[JustBeachin]

Re: truck runs very bad - spark plugs or chip?

QUOTE=GM TURBO]I thought the original 10-1 was a 2-bar chip and the Ultimate evolved in to the 3-bar.[/QUOTE]

:stupid:[


My old 10-1 used the 2-bar, and my ultimate uses the 3-bar. Switch back to 2-bar and stock chip and rule out the 10-1.


Then check the wires, etc. Also, stumbling under throttle has been linked to clogged fuel filters, if you haven't replaced it, now would be a good time.

 

[rxsyclone]

Re: truck runs very bad - spark plugs or chip?

Fuel filter was changed 500 miles ago and I was told that the 10n1 purchased a month ago needs a 3 bar. It is really weird that my wife was able to drive it for a while without problems. I am anxious to see how it runs with new plugs and wires ( I got 2 of them out last night and they look very old, rusty and dirty (they might be the originals!)
I can always go back to stock and hope it work fine (it did in the past) but the whole point is to have the IC pump running all the time and first time boost disable off, as well as the security mode. I'm guessing the stock chip runs only on the 2 bar sensor. I was told by experts that the 10n1 needs the 3bar, I will try to confirm today and work on the plugs some more. Thanks.

 

[blk00z28]

Re: truck runs very bad - spark plugs or chip?

I was told by experts.

Might I ask who these experts are?

I dont mean to hate, but anyone outside of this fourm I would not think to be a expert on our trucks.

 

[rxsyclone]

Re: truck runs very bad - spark plugs or chip?

Ok, sorry I was being vague. I normally don't mention names even though I had a good experience this time and am very satisfied with the service. The shop is SS performance in South Miami, I think there are many FAST members who go there and Gary from the forum recommended them when I e-mail him for advice (which I apprectate). They did some suspension work which came out great, and found that I was running the stock map sensor with the performance chip. They replaced it with the proper 3 bar and it ran good when they tested it. My wife drove it for quite a while and it also ran good. I guess the original stock 1991 spark plugs and wires finally gave out. I replaced the cap, rotor , fuel filter and cat. converter, but I never got around to doing the plugs and wires, and now that i'm in the (PITA) process, they don't look too good. I really hope the truck finally runs good when I get these things out and new ones in. Thanks.

 

[rxsyclone]

Re: truck runs very bad - spark plugs or chip?

On a side note, am I confusing 1,2 and 3 bars?

Is stock a 1, or 2 bar? (maybe accounting for atmospheric pressure?)

In any case whichever one I'm running I'm sure is the right one because the shop replaced the stock one with it.

 

[AlaskaTy]

Re: truck runs very bad - spark plugs or chip?

On a side note, am I confusing 1,2 and 3 bars?

Is stock a 1, or 2 bar? (maybe accounting for atmospheric pressure?)

In any case whichever one I'm running I'm sure is the right one because the shop replaced the stock one with it.

wave your arms all around in the air. What you're feeling is 1 bar (it is standard atmospheric pressure at sea level). I'm not entirely sure, but I would imagine N/A cars to have 1 bar MAP sensors (given that they don't use MAF). Stock we use a 2-bar MAP because are computer regulates are turbo to 14lbs (about 1 bar). Add 1 bar "boost" to 1 bar atmospheric pressure and you have 2 bars. Now if your making over 14.7lbs of boost then you need a MAP that can register another bar of pressure ie: 3-bar. It's been a while so this may be a little "muddy" but I hope it helps.

 

[SY2932]

Re: truck runs very bad - spark plugs or chip?

I thought the original 10-1 was a 2-bar chip and the Ultimate evolved in to the 3-bar.

Correct, the 10n1 chip utilizes the 2 bar MAP sensor, NOT the 3 bar one. If you have any doubt which one that you have in your truck, check the color of the socket on the bottom:

"MAP sensors, stock 2 bar on left (orange/red connector) #16009886 and 3 bar on right (black connector) old number is #16040749 new # is #12223861."

Having the wrong MAP sensor WILL make your truck run horribly.

After you get the right MAP sensor in there, double, triple and then quadruple check the connections on the ECM. You wouldn't believe how may folks botch installing these chips... You can see a detailed how to here. Don't let the two bottom pics of my ECM blind ya.

As mentioned above, the stock MAP sensor is 2 bar. From syty chips:

"What’s a 3 bar chip and why is it better than a 2 bar chip?
To answer this question you must understand the ECM (your engine’s
computer). Late model GM vehicles use one of 2 methods to determine the
engine’s fueling needs: mass air flow or speed density. Mass air flow uses a
sensor that actually measures the amount of air going into the engine, and
from other data (engine speed, throttle position etc) can calculate the exact
fueling needs. Speed density measures the manifold pressure, and its
changes (along with engine speed and other related data). On a naturally
aspirated car (non supercharger/turbocharger) a 1 bar map sensor is
needed, as the engine only operates in vacuum. The 1 bar map sensor can
read from about 14.7psi vacuum (or negative pressure) to atmospheric
pressure (0 psi). A 2 bar map sensor can read from 14.7psi vacuum to 14.7
psi positive pressure (one bar vacuum, one bar pressure greater than
atmospheric). In the same respect, a 3 bar map sensor reads from 14.7psi
vacuum to 29.4psi positive pressure." HTH's

 

[92Typhoon1679]

Re: truck runs very bad - spark plugs or chip?

Try unpluging your O2 Sensor and see if it still runs bad it helped me find the problem
When you unplug it the computer just stays in open loop and doensnt change the fuel ratio.

If you have a Datameter try looking at the Oxygen Sensor i had simlar problems my Oxygen Sensor read a constant 5 volts which ment it wasnt working plus my Fuel to Air Ratio gauge didnt even move.