Floor it, and nothing...

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1

12guns

10 Year
Joined
Feb 20, 2012
Threads
36
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395
I've been at either a full stop or barely rolling, turn the wheel and floor it (not completely) and I get a MAJOR hesitation. I did so when pulling out into traffic or pulling from a stopped traffic lane into a fast moving lane. When I let off the gas and push again everything is normal.
I started with cleaning the throttle body. It was dirty and needed a good scrubbing. I also cleaned the mass airflow sensor but it still hesitated on me just a day after cleaning. Is there a built in safety feature that won't let you goose it if the wheel is turned? What else should I check? I haven't taken the time to try to recreate the problem, it just happens on its own and normally when o least need it to. Thanks for any pointers.
 
I have the VXR with 4.7 V8 and full time 4x4 and I can floor it while turning without issue. It even dose a little hop when the power pulls past the traction on the 35's.

I think you may have a starvation problem? How low was your fuel? Fuel pump?
 
^this sounds most reasonable if the wheels are slipping. Does it happen going left and right? Does the steering feel normal, I guess it's possible the pump could bogged down and cause a hesitation. Other than that I'd check all the vacuum hoses, looked for chaffed wiring, check the main grounds.
 
Does sound like fuel starve issue. Getting gas, while tanker truck filling gas station storage tanks will loosen crud. Sediment in your gas tank perhaps, but would think turning & accelerating (movement) would have opposite effect.

Could fuel pump have come loose? Any smell of gas?

I'd start with easiest working thought fuel system inspecting fuel & vacuum lines along with coils & wires
Then pressure test of gas cap.
Also add a can of 44K to 1/2 a tank of gas and drive until empty.
Next step would be to pressure test fuel system, this will be problematic duplicate turning & accelerating, even for shop.

Not part of your issue but you did disconnect battery for 30 minute while cleaning MAF, per FSM. This gets overlook all the time, important as it reset system.

I mention these examples to illustrate how these issue can be difficult to find:
I had very similar issue in a 1969 GTO. We looked and looked for the longest time with our thinking leaning to a fuel issue and secondly spark (coil, wires or plugs). Ultimately it turned out to be a part was missing off a high performance distributor. This part was a seal (O-ring) between cap and body of distributor, which is not normally used. The distributor cap would shift just a bit on turning & acceleration causing a short circuit. Although we no longer have distributors short could be issue.

Saw similar issue on a customer car, so we rebuilt carburetor which work for a few days, then issue started again. Rebuilt again and replaced fuel pump & filter, worked for a few days. Third time we found egg residue around gas cap area. Flushed fuel; system and installed locking gas cap... Issue solved.

Hope it's and easy and cheap...good luck.
 
Sorry for the delay in responding...busy with a new job. So I tend to think its not a fuel starvation issue. I can floor it any other time and it takes off normally (like a water filled school bus). I'm thinking either VSC kicking in or possibly a TPS or something. I'll dig deeper and check some things mentioned here. Thanks!
 
12guns said:
Sorry for the delay in responding...busy with a new job. So I tend to think its not a fuel starvation issue. I can floor it any other time and it takes off normally (like a water filled school bus). I'm thinking either VSC kicking in or possibly a TPS or something. I'll dig deeper and check some things mentioned here. Thanks!
Click to expand...
If VSC kicking in you should hear the sound of ABS (hate that sound) kicking in.
 
12guns said:
Sorry for the delay in responding...busy with a new job. So I tend to think its not a fuel starvation issue. I can floor it any other time and it takes off normally (like a water filled school bus). I'm thinking either VSC kicking in or possibly a TPS or something. I'll dig deeper and check some things mentioned here. Thanks!
Click to expand...
Silly question perhaps, engine at operating temp and RPM does or does not drop during this hesitation?
 
Previous suggestions are good diagnostically, start there. Although, I wonder if this could be a transmission issue. If the trans is not downshifting under load you'll feel a hesitation and "When I let off the gas and push again everything is normal" could be allowing the trans to down shift. I've had similar symptoms in 4low on steep inclines.
 
varythings said:
Previous suggestions are good diagnostically, start there. Although, I wonder if this could be a transmission issue. If the trans is not downshifting under load you'll feel a hesitation and "When I let off the gas and push again everything is normal" could be allowing the trans to down shift. I've had similar symptoms in 4low on steep inclines.
Click to expand...
I was wondering same thing. RPM drop would point toward fuel/spark. RPM not dropping points toward transmission or ABS. Low transmission fluid level may further be effected be turning/accelerating and cold.
 
You could put a vacuum gauge on the inlet manifold to see how the engine is running. I can't remember the exact procedure for this but you normally get a booklet with the gauge to tell you what to look for, it will pick up misfires, air leaks, air restriction and so on. I used to use this method when I was a master tech 10 years ago. But it sounds more like air or transmission to me unless you can feel some kind of mis fire. Also traction control would do this as if it is a fly by wire throttle when you floor the throttle the ecu manages the way the power is delivered.

So when you put your foot down, you don't open the throttle you just tell the engine ecu you want to go faster, that then controls how the power is delivered, it can feel like a flat spot or hesitation at times if your asking it to do to much, but this shouldn't feel like a misfire.

Hope this helps
 
It happened again today. Driving about 20 mph, floored just for kicks and absolutely nothing happened. I kept my foot on the gas and it just coated as if I put it in neutral. Cleaning the throttle body didn't do any good. I do some searching on throttle position sensors and such and see if this has been documented before. Any other thoughts? Transmission is strong but I suppose there could be a sensor or something that could be bad? I can't recreate the problem. It just randomly happens.
 
12guns said:
It happened again today. Driving about 20 mph, floored just for kicks and absolutely nothing happened. I kept my foot on the gas and it just coated as if I put it in neutral. Cleaning the throttle body didn't do any good. I do some searching on throttle position sensors and such and see if this has been documented before. Any other thoughts? Transmission is strong but I suppose there could be a sensor or something that could be bad? I can't recreate the problem. It just randomly happens.
Click to expand...
What happens with RPM?
 
Bomar said:
TPS maybe?
Click to expand...

That is my guess or the IAC sensor. I had a similar issues when these sensors were failing in my 04 Tacoma. But it had nothing to do with if the wheel was turned. It started as a slight blip in the throttle and as it got worse eventually ended up going into safe mode a bunch of times which will basically lock up the throttle body.

Cheers
 
My friends TPS was going bad on his 2000 and had similar symptoms. Then eventually just stopped working one time.
 
No change in rpm's. It normally happens after coasting so rpm's aren't up much anyway. But, no "missing" or sputtering.
 
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