88 Driveability

[WTS]

Diagnostics show rich condition. MAF OK, EGR OK but car does not have the performance it once had. Anyone have any ideas?

 

[Schrade]

No codes?

Any loping idle? How's fuel pressure (this is really important, is SO many ways)...

 

[WTS]

Fuel Pressure within Spec and idle is reasonably stable.

Regards

WTS

 

[Schrade]

Fuel Pressure within Spec and idle is reasonably stable.

Regards

WTS

Reasonably? With A/C off, it should be totally stable.

Do a vac leak test. Follow instructions to a 'T'.

No one got the proper technique for vacuum leak detection... :confused

FIRST; block the pedal, or block the throttle linkage. YOU HAVE TO DO THIS TO GET A STEADY IDLE , around 1,250 rpms, or a little higher. If you don't, you can fish a propane hose, or WD40, or Krylon, or hair spray, or pee, anything, until you need a sweater in Hades, but if the motor is lopin' already from a vacuum leak, you ain't gonna' find any vacuum leak, unless it's so big that Little Jack Horner can stick his thumb in it and pull out a pineapple NOPE.

AFTER you et a steady idle, THEN, you can spray starting fluid everywhere - that's the best detector, because it's vapor pressure is very high - a LITTLE at a time, until you get the SURGE. Follow the vacuum lines to the EVAP cannister too. You might even have to follow the EVAP lines from the EVAP cannister to the gas tank too, but that vac leak will show up as a DTC 32 EGR fault, and won't normally show as loping idle, unless the EVAP cannister has been by-passed (been there, saw that uh-huh).

If you get a surge in a tight spot, and can't tell it, light a book of matches, blow out the match heads while they're still burnin', and feed the smoke to the tight spot.

Fear not the starting fluid; you cannot put the can down fast enough and light the matches fast enough to catch the starting fluid, because the vapor pressure is so high.

Bookmark this post YUP.

Wrench Wizard OUT!

 

[vetteboy86]

I was thinking fuel injectors possibly. How many miles are on them? Have you ran any fuel injector cleaner?

I agree with the idle. It should be steady. I actually ran into a problem with a gauge once. It actually was telling me that the fuel pressure was jumping between 40 and 50 psi constantly. I put another gauge on it and it was rock solid.

 

[WTS]

I will give this a try !

I did find a damaged vacuum line between the vacuum solenoid and the EGR which has been repaired.

The timing was a bit off and was sitting about 4 degrees BTDC instead of 6 degrees. this too has been rectified.

I have not driven the car since the minor repair and timing adjustment so maybe the vacuum leak I had was the issue.

Thanks and regards

WTS

 

[WTS]

While monitoring fuel pressure I do have pressure bleed off. Initially when the Key is turned rail pressure is between 42 and 45 Psi. After about 10 minutes or so the pressure bleeds off to about 25 to 30 Psi. While the car is running the pressure is maintained to approximately 35 Psi.

If the car has been running and is at operating temperature once stopped it is difficult to get started again. I am convinced that I have some leaking injectors causing the engine to flood.

This also supports the observations with respect to the drop in fuel rail pressure when the car is off.

Thanks

WTS

 

[Schrade]

While monitoring fuel pressure I do have pressure bleed off. Initially when the Key is turned rail pressure is between 42 and 45 Psi. After about 10 minutes or so the pressure bleeds off to about 25 to 30 Psi. While the car is running the pressure is maintained to approximately 35 Psi.

If the car has been running and is at operating temperature once stopped it is difficult to get started again. I am convinced that I have some leaking injectors causing the engine to flood.

This also supports the observations with respect to the drop in fuel rail pressure when the car is off.

Thanks

WTS

That is not too bad, I don't think... Get feedback on that from Jon Banner at the other vette forums. He has a few vid stickies in C4 tech/perf addressing that very thing.

Ask him who was first to tell him and the 'other' forums administrators to put his vids up as stickies (and ask him also if he remembers what the admins at first told me and him about doing it :eyerole , for 'sponsor' reasons (I still got that stupid response PM), and take a look NOW )

 

[G Winter]

Jon Banner, be it senior or Jr know injectors. I bought a set from them, couldn't be happier. Engine never ran this good in the 5 yrs I have had it.
FIC seems like a good place.

Glenn

 

[gmjunkie]

Jon Banner, be it senior or Jr know injectors. I bought a set from them, couldn't be happier. Engine never ran this good in the 5 yrs I have had it.
FIC seems like a good place.

Glenn

It's FIC for me and my customers!!
Great Service,Great Support,Quality Products!!

www.fuelinjectorconnection.com

Tell'um the Old Fart from Old Fort sent ya!!

 

[WTS]

Thanks for the reply !

A new set of injectors would likely be the best way to go.

Regards

WTS

 

[Schrade]

Your bleed-down time was NOT too bad. I think in fact it is GOOD, because pressure loss DECREASES as time goes on. For example, you might lose 5 psi in 12 minutes, but in the NEXT 12 minutes, you lose only half as much again - 2.5 psi, and half again in the 3rd 12 minutes - 1.25 psi. Like half life of radioactive waste.

I think you should write down exact bleed down time, and if Jon/FIC says it's too much, THEN do an OHM test cold, AND HOT. I wouldn't spend cash on injectors until then, unless you're rich; can I have some cash?