Question: Acceleration Hesitation

[Best Vette Yet]

I am experiencing an acceleration hesitation issue with my 03, C5, 45000miles, vette. This occurs between 2000 and 2400RPM. It occurs during acceleration from stop or even acceleration on the freeway. The hesitation lasts for a second or two then it clears and the vette accelerates normally. I have been stopped in my driveway and have slowly revved through the RPM range from 700 to 5500RPM. At 2000RPM, the hesitation begins and the motor will not accelerate further. There is a sound, almost like the rev limiter is kicking in. If I give more gas, it slowly goes to 2400RPM and then revs freely above that. If I am stationary and I rev with WOT, there is no hesitation. The only mods I have at this stage is the Granatelli MAF, the Vararam intake and the Corsa Touring exhaust. Any thoughts out there?

 

[LLC5]

I am experiencing an acceleration hesitation issue with my 03, C5, 45000miles, vette. This occurs between 2000 and 2400RPM. It occurs during acceleration from stop or even acceleration on the freeway. The hesitation lasts for a second or two then it clears and the vette accelerates normally. I have been stopped in my driveway and have slowly revved through the RPM range from 700 to 5500RPM. At 2000RPM, the hesitation begins and the motor will not accelerate further. There is a sound, almost like the rev limiter is kicking in. If I give more gas, it slowly goes to 2400RPM and then revs freely above that. If I am stationary and I rev with WOT, there is no hesitation. The only mods I have at this stage is the Granatelli MAF, the Vararam intake and the Corsa Touring exhaust. Any thoughts out there?

I would start by removing the Granatelli MAF, installing the OEM MAF, and then test driving to see if the problem is gone. Good luck with it.

 

[Best Vette Yet]

I would start by removing the Granatelli MAF, installing the OEM MAF, and then test driving to see if the problem is gone. Good luck with it.

Thank you, I will try it this weekend if the weather is good. My vette still has the original washer fluid from the Bowling Green Factory and the original wiper blades; it has not seen rain or snow in its life.I will keep the forum posted.

 

[Toms007]

The aftermarket MAF would be my first thought as well. Keep us posted.

 

[BigJimZ16]

I had similar problems with my '04 vert when I installed the Granitelli MAF, later heard from others what junk they are. Replaced it with a MAF for a '04 Z06 cured my problems.

 

[Hib Halverson]

No doubt the problem could be the aftermarket Mass Airflow Sensor but it is interesting the differing impression of the Granatelli MAF.

Four years ago, I installed a Granatelli MAF on my '04 Z06 as part of a magazine story I did for "Corvette Enthusaist". It has functioned flawlessly and was responsible for a modest gain in performance.

I have been happy with that product.

 

[Huskerman]

This is off the wall but with the Vararam what type filter does that use? If it is one that you oil to make work there is the outside chance that if its over oiled the excess oil can be causing the MAF to stumble........Maybe get some MAF cleaner and then try it again.....just thinking out loud.....

 

[Best Vette Yet]

No doubt the problem could be the aftermarket Mass Airflow Sensor but it is interesting the differing impression of the Granatelli MAF.

Four years ago, I installed a Granatelli MAF on my '04 Z06 as part of a magazine story I did for "Corvette Enthusaist". It has functioned flawlessly and was responsible for a modest gain in performance.

I have been happy with that product.

I have had the Granatelli MAF installed since 03 BUT, here is an issue. When I first installed it the vette would constantly surge if I had it in cruise and was doing 50 to 60 MPH. This issue has caused some damage to my vette as there is a "whine" at 1500RPM and it is not coming from the rear end either. It is in the front of the car possibly on the back end of the motor. This "whine" drives me crazy and the agents are telling me that this is common ... oh well. Anyway, continuing with the story, I called Granatelli and talked with Mr. Granatelli in person (I believe that he has since passed away). He told me that there was nothing wrong with the MAF but that I would have to purchase a modified MAF to see it it would alleviate the surging. He also said that modified air intake systems were prone to extreme turbulence and that was one of the reasons why the vette was surging. He sent me an MAF with the screen still in, one which looked like the stock MAF, and it took away the surge. About a month or two later, I noticed that all the advertising for the Granatelli MAF had changed and that he was now advertising a MAF for a stock air system and a different MAF for a modified air intake system. From this change, I am assuming that I was not the only person who was having issues with his MAF as I doubt that he would have changed his design due to one complaint from a little guy like me. I have also since noted, when my vette went into service for an oil change, the tech working on my vette did a quick diagnostic and came back to me saying that my vette was running VERY lean when reaching 100MPH. He attributed that to the modified MAF and I was advised then to replace it with the stock MAF. Winter came on strong and my vette went into storage. I still have copies of the emails exchanged between Mr. Granatelli and me if you are interested in perusing the topic further.

BTW, Hib, if you still have your Zo6 MAF, put it in a box for me I will install it in my vette.

 

[Best Vette Yet]

and

This is off the wall but with the Vararam what type filter does that use? If it is one that you oil to make work there is the outside chance that if its over oiled the excess oil can be causing the MAF to stumble........Maybe get some MAF cleaner and then try it again.....just thinking out loud.....

Thank you Huskerman. If after installing the OEM MAF there are no further issues, I will clean out the Granatelli MAF and reinstall it just for the test. Any thought on what I can use to clean the MAF as it seems to be very fragile and I don't want to "screw it up" any further.

 

[Toms007]

There are cleaners designed specifiically for the MAF, get some of that. Parts stores should carry it.

 

[Huskerman]

There are cleaners designed specifiically for the MAF, get some of that. Parts stores should carry it.

Ya what Toms1 said.......