Does anyony have Experience with?

I have a 94 gmc sierra 1/2 ton 4wd ext cab with 200,000 on the clock. The engine runs fine, no leaks and doesn't use oil. The problem is power. When taking off the engine runs awful until 2500 RPM then it's like a switch, bam more power is there. Does anyone have experience with chips or tunes on this thing? I would like to get one if i can see a difference in power at lower rpm. Gas mileage is already 10 so maybe it could be better, especially if i had power in the rpm range it's always in. Overdrive on the highway it runs at 2000 rpm, right where i need some help.

I have done air filter
plugs
wires
cap
Rotor
thermostat
ecu temp sensor
2 tps sensors
exhaust, no cat
checked timing

all of these made it a little better from where i started, but it needs more help. It doesn't miss out, but there is some hesitation if you goose it at idle. Any suggestions? Does anyone have experience with a chip on THIS ENGINE?
:banghead:

Is the Check engine light on? Does this happen when the engine is cold? Or only when the engine is warmed up? The reason I ask is that is sounds like you have an issue when is closed loop mode. At high RPMs, the ECM will switch to open loop.

Have you had the engine scanned to see what the ECM is doing?

You don't list 02, Fuel Filter or MAP as being replaced. Make sure the vacuum hose to the MAP is not cracked.

Fuel pressure should be between 9 and 13 PSI and should be checked.

//2000CAYukon

I'll look into those things. Check engine light is not on and it does not have any codes logged. It has come on when the tps was bad and when the egr valve went out, but has not been on since they were replaced. And it does this warm or cold. The hesitation seemed to be worse over the weekend as well. I was pulling a trailer and got 6.6 mpg and it about died going through an intersection when i hit the gas.

Was the EGR replaced? (you said it went out). Does the EGR solenoid hold a vaccum?

The EGR solenoid is controlled by ECM to allow vacuum to open the EGR valve.

You should try to pluging the vaccum line to the EGR valve just to see if the problem goes away.

//2000CAYukon

Oxygen sensor maybe? Did you also repalce the ignition module in the dist?

Save yourself some grief, don't use anything but AC Delco for ignition parts, the rest is junk IMO and most all of it comes from China. I checked locally once at Napa, CarQuest and Auto Value and thier brand parts all were imported from China even though they came in a well known name brand box. I told them I wanted USA made parts and they sent to the GM dealer. Reason they sell the imported? Costs less and 90% of thier customers only care about that. I had a friend who used CarQuest brand parts and was having a wierd stalling and no start issue with his truck. He could not figure out what was wrong. Finally he got tired of fooling with it and took to a local shop where a ex-GM tech was owner. On a hunch they replaced the new module with a AC Delco and the truck has never stalled since, about 3 yrs now.

Another common issue with the TBIs is the pickup coil and/or weak magnet on the dist shaft; however, this usually results in a miss fire at low rpm and a rough idle.

I agree with Z15 on using AC Delco Parts.

//2000CAYukon

I had a similar problem with a 98 suburban, turned out to just be a plugged up fuel sock strainer in the tank. The truck had a lot of miles and plenty of crap in the bottom of the tank, you may want to check that out, my truck woke right up after flushing the tank and replacing the sock....:naughty:

I used all AC Delco parts. I've been burn't to many times in the past with aftermarket crap. I don't believe it would be the fuel strainer as when the truck is to the floor it doesn't seem to be starving for fuel. Only at part throttle below 2500 rpm is where the real issue seems to be. I have seen some abnormal coloring and dust patterns on the coil and was wandering if there would be any issues there. I have not changed the module on the distributor, my experience has always been that they are either good or bad. I will change it if necessary. I have not had time to check the map sensor. The egr valve was throwing codes and giving the check engine light but everthing was corrected when it I replaced it.