Hesitation than cleared itself

[Vette73]

Took the car out again tonight...I'm reading that the car runs off the primary fuel pump once the temp reaches 176 degrees...

After about ten mins or so the symptoms started again.....Very rough running till I hit about 3,000 rpm than it would jump...

Im thinking maybe the primary pump is going.......What's the easiest way to check this? If it is , don't the Z use the same pump from a 96 Chevy suburban?

[GOLDCYLON]

Originally Posted by XfireZ51

Was ur MAT sensor relocated?

Ahem Dom is on point did you relocate the sensor? Are you thinking open loop close loop Dom

[Vette73]

Yes....MAT sensor is relocated to the lower front part of car......

????

[Vette73]

I would take a photo of relocation but I never seem to be able to load a photo on this site..

[XfireZ51]

Originally Posted by Vette73

I would take a photo of relocation but I never seem to be able to load a photo on this site..

Relocating the MAT to the front without making corresponding changes to the calibration will cause fueling issues. The MAT table values assume that the incoming air will be at about the same temp as the coolant(~ 80C). However, moving the sensor to the front, the ECM never “sees” that temp. It always thinks its colder than it is. It may have run ok when temps were warmer perhaps because it was tuned w that “temp” and the VE table basically compensate somewhat for that. But once the intake air temp drops and gets cooler, the ECM can’t correct enough. The intent of the MAT/INT sensors is to modify fueling based on intake air temp so as the air temp rises and falls, the ECM changes Pulse Width to compensate thus maintaining a consistent fueling. The cooler the air, the more fuel due to air density. That’s why the motor changes the way it is running while sitting at idle, because intake air temp changes. With unmodified MAT table values, the ECM is doing one thing while it should be doing something else.

[Vette73]

Not too familiar with this...Only thing I can say is, I relocated this about 3 years ago and use my car all year round..

Dempsey gave it the Dragon heart package w cams last December...When I picked up the car temps were in the 40's and it has run fine up until like I said a few days ago..

[XfireZ51]

Originally Posted by Vette73

Not too familiar with this...Only thing I can say is, I relocated this about 3 years ago and use my car all year round..

Dempsey gave it the Dragon heart package w cams last December...When I picked up the car temps were in the 40's and it has run fine up until like I said a few days ago..

Well u r providing new information. May very well be a pump issue.

[Vette73]

X-FIRE Thnx for looking out..Will be travelling for a week..When I get back will check the pumps...

[RichS]

It's easy enough to check the pumps and pressure using the tips from this site. You need a volt meter and a pressure gage. My pumps tested good but I replaced them because I figured they were 23 years old, and had Phil do a regulator for me to since mine seemed to stick once after sitting over the winter. Very easy to replace the pumps if needed.