Stock sensors should stand up to a bit of lead, but there's always the chance that they were contaminated. I've been running C16 leaded fuel for years, and at least one of the stock O2 sensors still seems to cover a normal range..... its an open-loop tune and the sensors were just left there to satisfy a visual inspection and plug the holes in the headers.

 

We scanned the vehicle yesterday. Here's what we found. O2's read lean at idle. Speeding the engine up makes the O2s read correct. While the O2's read lean at idle, the fuel trims eventually max out. Engine runs rough at idle but there are no misfiring cylinders.

Speeding the engine up say to 2000 RPMs just sitting still makes the O2s start to switch from high to low like a normal O2. When that occurs, the fuel trims come down to normal level.

At idle the IAC counts go to 0 even though it's still running (albeit rough).

There is a definite hiss somewhere around the intake AND removing a vacuum hose withOUT plugging it makes no difference to the idle.

I surmised that the problem is a vacuum leak. Any reason to think that is incorrect?????

 

You've got three things telling you the engine is getting air from somewhere other than the IAC circuit....

-IAC bottomed out a "0"
-DTC 64 and 160 BLM's
-idle jumping to 2,000rpm

My engine had a surging idle once, and I traced it down to the vacuum hose connected to the power brake booster. Jiggling the connection to the booster would allow air to enter at that point.

 

UPDATE

well found the hissing sound.....
the passenger front injector oring had a bit of a tear (guess i should replaced all the orings the last time i took the fuel rail out)....all are replaced now.
This was isolated by spraying various hoses, etc around intake with starter fluid. When I hit the injector area the car would almost would stumble and almost die.

However,
fuel trims are still wacky

more info obtained today.
when the car is at idle and in park the iac goes to 0 and l/r banks go to 160
when car is in overdrive with brake applied the iac counts stay around mid 20s and fuel trims drop to around 130-138 range both banks.
Car still runs near perfect with throttle applied 128 range and now when off throttle the car does not seem to max out at 160 any more.

 

It would appear that you still have a vacuum leak. Have you tried removing each hose one at time from the intake and capping both sides of the connection???

Also as far as spraying a liquid, I think starting fluid is too thin. You need a thicker fluid like PB Blaster to fill in a leaking crack better to point out the problem.

I think you have a leak else where. Don't forget the TB top and rear and the 2 intake gaskets.

 

Just like the title says. Do you have an update?????

 

no. nothing new. I have not had a chance to mess around with the car much but do have some time this week. I am about at the end of my ability to track down this problem and may need some more assistance. So if your willing to take another look and maybe try to track down the vacuum leak or other problem let me know. Thanks again for all help provided so far.
Rob

 

Have time during the week but this weekend got the RIR race so sat. is out.

 

what time during the week...are your mornings available? Right now I am working noon to midnight mon-sat. Have sun off though.
thanks
rob

 

Early is ok like 7 to 8:30

 

that sounds great how does thurs. morning sound? and at your shop??

Thanks,
Rob

 

Sounds OK.

 

ok will be at your shop at 7.
Rob

 

I'm usually a little late. Give me a few give or take 15.

 

cool will be there, thanks again.
rob