C4 Hesitates

[TACSC4]

I have a 1988 Corvette that I installed a Hypertech Power Chip on I have also done the following:

Installed:
160 degree thermostat
Excel 24# fuel injectors
High volume fuel pump
adjustable fuel pressure regulator
new wires and #5 rapid fire plugs
intake manifold gasket
K&N open air system
air foil
and a TPS

When I am at a stop and I punch it, the car takes off then hesitates (for a split second) then takes off again, this just happens periodically. I was wondering if the chip has anything to do with this, and also if I have to put my stock chip back in can I still run the 160 degree thermostat or would that have to be replaced as well?

Any help would be appreciated
TacsC4

[Vettefan87]

I do not think that the chip is making it hesitate, and if you take out the chip and put the stock one back in I do not see a reason why you would need to change the T-stat.

[-=Jeff=-]

yes, you can use the stock Chip with the 160 T-stat. Also do you know what your fuel pressure is set at? I am guessing you are getting too much fuel since you have 24# injectors and a High volume Fuel pump. You would need to run less then stock fuel pressure since the stock injectors were 22#.

or runt he stock fuel pressure and get a PROM with the injector constant changed to the 24# injectors. I know Hypertech doesn't do this

[plumcrazy]

i thought if your stat was to cold and the engine never reached the operating temp in the prom the fuel and timing would not be advanved because the car is never at set normal operating temp?

[Hib Halverson]

The L98 in your 88 is not modified such that it needs most of the fuel system stuff you've added. In fact, some of those parts might be a mismatch and could be contributing to the problem.

First, I'd check all vacuum lines to make sure you don't have a vac. leak.

Next, if the fuel filter has not been replaced in the last 15,000 miles, I'd replace it. Use an AC Delco.

After changing the filter, replace the aftermarket adj. pressure regulator with an OE part and run the fuel pressure tests in the service manual. If the tests fails, troubleshoot per the manual and repair accordingly. Such repairs may include removing the aftermarket fuel pump which you don't need anyway.

I'd remove the 160 T-'stat and replace it with a 180.
I'd take out the "Excel" 24 lb/hr injectors and replace them with either stock Delphis or RC/Engineering Lucas injectors of the stock flow capacity. Your engine does not need 24 lb injectors and, in fact, on a stock engine, they can cause driveability problems.

Your list of mods ended with an incomplete sentance, but I think you were indicating you have some kind of device in the TPS circuit that fools the ECM. Take that off, too. Reset the TPS adjustment to stock.

Now, road test the car and see if the hesitation is still there. If it is, I'd buy three bottles of Red Line Complete Fuel System Cleaner and run them through the engine, one bottle per tank of gas for three consecutive fill-ups.

If the hesitation persists, I'd take out the Hypertech calibration and road test. If it's still there, then come back to this thread and we'll kick the problem around some more.