fast idle and no fuel cut

[cjridert1]

I bought a 1g TB from a kid because mine wasnt working right, unfortunately he sent me a huge piece and have the same problem. Idle is @ 1500-2k always. I blocked off FIAV + ISC and got the idle down to 900 = perfect. However, every time I even rev it, the idle would not hold consistent between each time the car idled. BISS is bottomed out

Also, when driving - the car no longer initiates fuel cut when decelerating with foot off gas. TPS is adjusted correctly. You guys have any ideas? I would appreciate any help. Thanks!

 

[yokotabrat]

Have you verified there aren't any boost leaks?

For the deceleration problem, verify the idle switch (closed throttle switch) on top of the throttle body is operating properly.

 

[cjridert1]

Have you verified there aren't any boost leaks?

For the deceleration problem, verify the idle switch (closed throttle switch) on top of the throttle body is operating properly.

I did a boost leak test - found a small one and took care of that, however the system wont hold air. Air passes right thru the TB. I am currently guessing maybe an intake manifold gasket - what do you guys think? Thanks for the reply


** I have used 2 diff Idle positions (2 diff TB's), I guess both could be bad - any other reason no fuel cut would happen

 

[RedTalon95]

If it's leaking at the TB that's why your idle is so high. Fix the leak there, most likely the gasket or possibly the seals.

 

[cjridert1]

If it's leaking at the TB that's why your idle is so high. Fix the leak there, most likely the gasket or possibly the seals.

No leaks from the TB, however air passes thru it into the head and no pressure builds.

 

[yokotabrat]

** I have used 2 diff Idle positions (2 diff TB's), I guess both could be bad - any other reason no fuel cut would happen

More than likely the throttle body is just not grounded anymore. There's supposed to be a small "L" bracket that's goes under one of the top corner bolts and then screws into the top of the throttle body. This grounds the throttle body to chassis ground so the ecu can read the idle switch. If that bracket is missing, you'll more than likely need to run a wire to the throttle body to ground it. If you have a multimeter, that will tell you for sure if the throttle body is grounded. Just measure resistance from the throttle body to somewhere on the firewall or intake manifold.

 

[cjridert1]

More than likely the throttle body is just not grounded anymore. There's supposed to be a small "L" bracket that's goes under one of the top corner bolts and then screws into the top of the throttle body. This grounds the throttle body to chassis ground so the ecu can read the idle switch. If that bracket is missing, you'll more than likely need to run a wire to the throttle body to ground it. If you have a multimeter, that will tell you for sure if the throttle body is grounded. Just measure resistance from the throttle body to somewhere on the firewall or intake manifold.

Right on man - thanks much! Any ideas on the high idle? (does the intake mani gasket sound resonable?)

 

[yokotabrat]

No problem.

Intake manifold gasket is a possibility as are the injector seals where the injector goes into the intake manifold. You should be able to hear those during a boost leak test, though. How are you doing the boost leak test?

 

[cjridert1]

No problem.

Intake manifold gasket is a possibility as are the injector seals where the injector goes into the intake manifold. You should be able to hear those during a boost leak test, though. How are you doing the boost leak test?

I actually put some gasket seal where the injector and seal meet to rule this out. The seals werent new, but didnt look to be/feel to be old and unhealthy. Should I order a set anyhow? Last boost test was done right @ TB elbow (NO IC piping).

 

[cjridert1]

ok - put a new intake mani gasket in, found a couple small boost leaks and fixed them (including TB seals). Put it back together and NO GOOD. I blocked off fiav/isc with BISS in entire way and can get a reasonable idle (1k), otherwise the idle is too high. If I just block off the ISC, idle sucks again (~2k). I have 3 isc's around, hard to believe they are all bad? Ideas anyone? Thanks for the help as of this far!

 

[yokotabrat]

How are you blocking the FIAV and the ISC? If you can, I'd block the FIAV and leave the ISC operation intact and continue testing in this configuration.

Do you have a multimeter? Here is how you check the isc: DmTaLoN's Idle Speed Control Test/Fix Page!

If any of the coils in the isc are below 30 ohms, there's a chance the chips that drive the isc coils are damaged and would need to be repaired. This includes any of the other iscs you may have tried that you have laying around.

Has the EGR been blocked off? If not, you can try that.

 

[cjridert1]

How are you blocking the FIAV and the ISC? If you can, I'd block the FIAV and leave the ISC operation intact and continue testing in this configuration.

I have 2 diff plates Im using (not simultaneously of course) - one blocks everything, other has 2 channels cut in it to let the ISC work.

If any of the coils in the isc are below 30 ohms, there's a chance the chips that drive the isc coils are damaged and would need to be repaired. This includes any of the other iscs you may have tried that you have laying around.

Well, 2 were bad. The one on the car was out of range a little (~38 ohm average). This is probably fine I would think?

Has the EGR been blocked off? If not, you can try that.

EGR was blocked off before then the car started smoking under boost so I left it alone. Ill block it off again - what do I do with the 2 vac lines for it? plug, converge?

Thanks for the help

 

[yokotabrat]

Well, 2 were bad. The one on the car was out of range a little (~38 ohm average). This is probably fine I would think?

The 2 that were bad, what did they measure for resistance? Did you hook those up to the car at all?

EGR was blocked off before then the car started smoking under boost so I left it alone. Ill block it off again - what do I do with the 2 vac lines for it? plug, converge?

You'll have to trace the vacuum lines back to their source. I think they go back to the throttle body ports, but it's been a while since I removed all that stuff. If so, you can just remove the vacuum lines and plug the ports on the throttle body. If you don't need emissions, you can remove all the vacuum lines associated with the emissions equipment too.

 

[cjridert1]

The 2 that were bad, what did they measure for resistance? Did you hook those up to the car at all?



You'll have to trace the vacuum lines back to their source. I think they go back to the throttle body ports, but it's been a while since I removed all that stuff. If so, you can just remove the vacuum lines and plug the ports on the throttle body. If you don't need emissions, you can remove all the vacuum lines associated with the emissions equipment too.

All right man - got it working finally! Removed egr/vac lines/whatever else and played with my dsmlink a bit. The idle switch wasnt working apparently - must be shot I guess.

There was a blown coil in each of the bad ISCs - I did try these to see if it made a diff though.

Thanks for all the help!!!