My Tahoe is having an acceleration issue

[richienewman]

I have recently spent many hours of labor and money into my 97 two door Tahoe. I have done the fuel pump, fuel-sending unit, stabilizer links, intake manifold, and water pump. The truck is in Mint shape, and I’m having an acceleration problem. See, it drives fine under normal driving conditions. Say I want to pass somebody on the highway, and I need to accelerate. Well, the truck will rev up, but does not increase in speed. I thought it may be a transmission problem, so I brought it to a transmission place. They said it wasn’t the transmission and it may be an exhaust problem. I brought it to an exhaust place, and they said it wasn’t the catalytic converter either. Possibly it may be the fuel filter, but who else has had a similar problem? Could it be a faulty fuel pump, even though it’s only a few months old?

[krazibimmer]

it sounds like transmisssion problem to me. sounds like the transmission is either slipping or jumping out of gear. you should bring it to couple other trans shop and see what they say.

[snakizzle]

Have you tried replacing the fuel filter. I had the same issue a few months ago. The dealer could not figure out the problem. I replaced the fuel filter and that was it. One of by friends told me about the fuel filter. Something about a sensor that reads the flow of fuel. If it doesn't have the correct fuel reading then the transmission will not shift. He told me to start with the fuel filter.

[jcooley]

I have had the same problem that you are talking about. I have a 99 Tahoe Z71 model. I the fuel pump went out, and I replaced it and the fuel filter. I've had new plugs and wires put on it. I've had the transmission checked out by Mr. Transmission and they said it was fine. I took it to a local muffler shop and they said the catalytic converter was fine as well. The truck drives fine. But has no acceleration whatsoever. When going up a steep incline or hill it acts like its on it's last breath. I've even heard some clinking noise coming from the engine. Nobody seems to know what it is. You know how most trucks downshift when under strain. It seems to downshift only as a last resort. You'll almost be at the top of the hill before it downshifts. I've even tried to run several high octane tanks of gas in it. Nothing. If you find out something please let me know. Thanks. Jason

[sa200]

check the engine timing.

[jbbernhard]

i have the exact same problem with my 97 tahoe 58k miles. just change the wires,plugs cap and rotor and just bought a mass air sensor for $235 and installed it and still have poor accelleration and also random misfires. what is the solution. this is already cost me $500 and its must be a simple lilttle thing? please help.

[Orion 762]

My 95 tahoe (223,000 miles) just started having the same symptoms. Accelerates ok in the low gears, but at hiway speeds, no power to accelerate. Engine will rev, but no change in speed until a down-shift. After the downshift and back in 4th, there's a "chuggle" where it feels like the engine is dying (but rpm stays ok).

Other notes: I checked the tx fluid, and it appeared "over full" and had lots of air bubbles in it.

Please advise where to look first . . . Orion 762

[jcooley]

Originally Posted by Orion 762

My 95 tahoe (223,000 miles) just started having the same symptoms. Accelerates ok in the low gears, but at hiway speeds, no power to accelerate. Engine will rev, but no change in speed until a down-shift. After the downshift and back in 4th, there's a "chuggle" where it feels like the engine is dying (but rpm stays ok).

Other notes: I checked the tx fluid, and it appeared "over full" and had lots of air bubbles in it.

Please advise where to look first . . . Orion 762

I posted earlier about the same issue that you are having. I had two seals leaking that was causing me to lose oil pressure that was causing the engine to hesitate until the pressure built up. I had these two seals replaced and amazingly corrected my problem even though the dealership said that I needed a catalytic coverter. I've had it checked out twice and there wasn't anything wrong with it. They also did what is called decarbonizing. Which is pretty much cleaning the build up in the fuel injectors, or so I'm told. This helped some, but after the seals were replaced my problems were over. If I may make a suggestion...I would watch your oil pressure gage and see if there is any flunctuation there which shouldn't be other than your normal acceleration. Might not hurt to have your catalytic converter checked out at a muffler shop, usually do it for minimal or no charge. Hope this helps.

[jcooley]

As for the misfire issue, my brother was having the same problem with his tahoe at one time. Finally replaced the battery cables and hasn't had the problem since. His tahoe would actually go dead going down the road. His wasn't misfiring, it just would act as if the battery was dead. Not sure if this is what you are having since you said misfire which means to me its turning over but won't crank. Anyway just thought I'd throw my 2 bits in. Later.

[jcooley]

I had the same issues that you are having and finally got them fixed. I had an intake leak and an oil leak fixed. The oil leak was causing me to lose pressure as well as the intake leak. After having these fixed I have no acceleration problems and it runs like it should. I have exact throttle response, when before it would just seem to bogg down and finally kick in. Anyway, hope this helps.

[Orion 762]

jcooley . . . . do you recall "which" seals had to be replaced? Were they "main engine seals"?

My oil pressure gage runs about 60 (psi??), but has always dropped to about 40-45 when idling a while. Goes on back up to 60 at hiway speeds (and stays near there, even when this TX like problem shows up). I do have "some" hesitation though . . . when I first go from say idle to 1/4 throttle, there's a "momentary" (maybe 1 second) delay before the engine catches up. My Tahoe has Throttle Body Injectors over the two carb. throats . . . and I've just assumed that my "hesitation" was probably these injectors getting worn. 220,000 miles is a long way on the same injectors (or the same TX for that matter).

I'm also wondering if it can be a simple vacuum leak??

Can having an "overfilled" tx fluid contribute?

What about the foam/gas bubbles in the tx fluid?

Any more help is appreciated!

Orion 762

[BowtieFreak]

I was having similar troubles with mine a while ago. Give it some gas, engine and tranny would kick in, but there was no acceleration. Had the dealer look at it, was a bad fuel filter. It was pretty clogged up, which lowered the fuel pressure that basically caused the computer to go crazy.

[Orion 762]

I finally found the "acceleration culprit" for my 95 Tahoe. It was the "catalytic convertor" with a partial blockage.

I "fixed" all the simpler things first: plugs, wires, distributor cap, rotor, TBI kit, and replaced the Idle Air Control valve on the TB. Even changed thermostat (to get 195 oF) and did a timing check.

The next hint of where the problem was, occured during a vacuum check. Just "curb revving" the engine while watching the vacuum gage, I noted that the the vacuum "dropped momentarily and erratically" while revving. And this "drop" coincided exactly with a slight "rattling sound" from the converter under the passenger side floorboard. (I had heard this rattling sound for years . . . it would come-and-go, and I "assumed" it was simply the heat shield on the converter rattling a bit.) To see if the converter was really the problem, I torched a 6"x6" hole in the converter . . . and removed all the "stuff" in there. (The rear half of the converter material was already broken into several pieces . . hence, the rattling sound.) With the converter essentially "out of the loop", all the TX type symptoms disappeared!

Now with a new exhaust system, she runs almost "good as new"! Not bad for 226,000 miles, I guess.

Orion 762

[99HoldenTahoe]

I have a '99 Chevy Tahoe C1500 2WD with acceleration problems as well.
I'll floor the gas pedal and the engine will respond and rev like it should "WAAAAAHHH", but it won't accelerate. It will keep the same speed. I just bought and installed the $300+ MPFI spider upgrade, and had great results with torque and power, but the acceleration problem still exists. Should I try the FUEL FILTER?

[j cAT]

Originally Posted by 99HoldenTahoe

I have a '99 Chevy Tahoe C1500 2WD with acceleration problems as well.
I'll floor the gas pedal and the engine will respond and rev like it should "WAAAAAHHH", but it won't accelerate. It will keep the same speed. I just bought and installed the $300+ MPFI spider upgrade, and had great results with torque and power, but the acceleration problem still exists. Should I try the FUEL FILTER?

if the engine revs and your vehicle don't move faster I would say a transmission slippage issue. could also be the transmission is not down shifting when the throttle is nailed to the floor .

If the exhaust is restricted it will not rev quickly and bog down.

same bog down issue , if the fuel delievery is gunked, restricted, low fuel pressure.