My car sometimes dies (the RPMs dont stop at 1K) when you throw it in neutral as you are approaching a stop light/sign. if you blip the throttle after you throw it in neutral the car will act right and the rpms will stop and stay at 1K rpm. I am not throwing any codes. I was wondering if I could borrow the IAC from someone's 99 SS (or compatible vehicle) for testing purposes.

The further north you are, the better.

Also, if you have any recommendations as to any other testing that I can do to nail down what my issue is, I'd really appreciate it.

Thank you

 

Bad intake gaskets or leaking pcv hoses?

I have a spare IAC but I'm in Houston.

 

this is embarrassing. the car used to idle high but the actual problem is that it dies after you throw it in neutral when approaching a stop light/sign. the OP has been updated.

i'll check those items.

mail that IAC to me for testing!

 

You've probably got a vacuum leak. Check the usual spots like the pcv hose, intake manifold bolts, tb gasket

 

I'll check those items and report back. Thanks.

 

i checked this morning and it is definitely not intake manifold bolts and PCV hoses. I'll be checking the rest of the system for vacuum leaks tonight. If i dont find anything, I'll probably just buy a new IAC from RockAuto and see what that does for me.

 

Unplug the iac to see if that changes anything.

The pcv valve itself can be bad and cause the engine to suck more air in than it should. You can test that by just capping off the intake manifold nipple behind the throttle body.

My 98 use to have a similar problem but only when it was cold, trying to go into reverse would kill the car. Took a few years but I figured out when the fast intake manifold was purchased by the previous owner and installed by a reputable local shop they forgot to bolt down the bottom throttle body bolt. I mean the shop kept the car for 3 extra weeks trying to tune it for the PREVIOUS owner, and I drove the car for four years like that, but yeah mine was a vacuum leak at the throttle body. The bottom right tb bolt to the intake was too long to go onto the fast intake so it would bottom out on the intake manifold without actually tightening the TB enough to seal it.

 

I had the similiar issues. IAC fixed it.

 

i ordered the IAC last night.

the car does not want to start now.

i rented a fuel pressure gauge from o'reillys and this is the result. can anyone tell me if my fuel system is functioning as designed or not? this is my first time to use a fuel pressure gauge. my fuel system consists of the racetronix pump and harness, as well as the red ford 30 pound injectors, which i believe are like 36 pounds @ GM fuel pressure. the car is tuned and should be calibrated for the larger injectors. keyword there is should be. so just to make sure, i am seeing 20 pounds when the fuel pump primes, 60 when cranking the engine and 48 when i stop cranking the engine. I am not throwing any DTCs.

 

looks like it may have been a relay problem. i replaced the IGN relay with another and it fired right up. i put the old relay back and the problem reappeared.

NOTE: How do you even test relays AND fuses to see if they are good or not?

 

 

so i replaced the Idle air control. the problem where the car dies when you push the clutch in as you are approaching a stop sign or stop light has improved but is not eliminated. there are situations where the car acts properly, there are situations where the car wants to die but does not actually die and there are situations where the car actually dies.

is there anything else to check besides the tune? I dont have any codes on the dash.

thank you

 

If I'm keyboard diagnosing stuff it sounds like the tune is messed up and the car is flooding itself when you depress the clutch. Has it actually been on a dyno with a wideband hooked up to it or are you getting a street tune by a buddy.

I pmd you my cell number if it's something besides the tune I can try to diagnose it. Otherwise I have 2 running 6 speed fbodies we can compare sensor readings against

 

Your thoughts echo those in my other thread.

https://ls1tech.com/forums/pcm-diagn...ight-sign.html

This car was on SNL's dyno with a wideband hooked up on 2/6/2016.

PM received sir!