2G Rough Idle

[one_time]

I've got a 97 GSX turbo and we just rebuilt the whole 4G63 engine because one of the balance shaft barings went and caused havoc inside the block....we used the shaft eliminator and put a stubby shaft in had the whole head redone professionally and put it all back together. With acceleration it runs great but when idle it runs like crap...

Here is a video of what it sounds like when idling and some slight acceleration

YouTube - ‪Video-0010.3gp‬‏

We replaced the fuel filter and cleaned the injectors still the same issue....Took off the MAF sensor and that's working fine...

It smokes a bit and sort of smells like unburnt fuel blue smoke we figure is from all of the cleaning crap we put in it while rebuilding it....

We're at a loss as to why it's so crappy on idle does anyone have ANY ideas????

I'm sorry I forgot to add the exhaust leak is fixed...most of what you're hearing there is exhaust but that's fixed the idle is still messed up like it's flooding it's self out or starving for fuel but we checked the whole fuel system and it all checks out...

 

[ericemery]

I cant tell from the video, but is that blow off valve recirculated?

If you have a boost leak, allowing un-metered air in, it could cause you to run like crap. but that would cause you to run like poo all the time, especially under load.

If you know your MAS is good, this thread might help point you in the right direction.
http://www.dsmtuners.com/forums/newbie-forum/217402-isc-help-please.html

Just to make sure you have Base idle set properly. process of elimination, starting with the free stuff.

 

[one_time]

I cant tell from the video, but is that blow off valve recirculated?

If you have a boost leak, allowing un-metered air in, it could cause you to run like crap. but that would cause you to run like poo all the time, especially under load.

If you know your MAS is good, this thread might help point you in the right direction.
http://www.dsmtuners.com/forums/newbie-forum/217402-isc-help-please.html

Just to make sure you have Base idle set properly. process of elimination, starting with the free stuff.

The blowoff valve works like it's supposed to

We're not noticing any boost leaks it runs fine under a load

the BISS screw was set to half like we read on another forum then we were going to adjust it once running to our liking but this rough idle happened and when turning the BISS screw there is no change in the idle situation...

We did take the MAS off and made sure it is working properly...

Tomorrow we're going to mess with the info on the link you gave with the ISC and see if it's the IAC will post if that's the issue

 

[low_n_slow95]

im in the same boat man. just did a head gasket and when i put it back it it idles like that now. did you delete the EGR? i havent drove mine yet but at 1100rpm it starts to clear up but i can still hear a miss.

 

[Absit]

Check your timing.

 

[low_n_slow95]

Timing is dead on. The notch on the crank pulley lines up, the marks on the cam gears lined up and the dowles on the cams are straight up

 

[Janaelen]

Sounds like my 97 GST did before I fixed it. My problems were due to a bad ECU that resulted in a VERY rich idle condition. It eventually fouled the plugs after a 10-15 minutes of idling. I would check the plugs and see if they are black and moist. If so, then you're more than likely running rich.

Another thing to look at is the power transistor (ignition module). Mine was also bad on my '97 which prevented me from going past 4.5k RPMS. Once the ECU and the power transistor was changed, the idle is solid and it revs to red.

Please keep in mind that the 2 things I reference above were found AFTER the normal trouble shooting process: check CEL's, vacuum leaks, boost leaks, sensor readings and compression/leak down.

Good luck

 

[92AWDHX40]

Terry's Talon Troubleshooting Tips #3 - Fast Idle (aka. Idle Surge)

 

[one_time]

Just checked the plugs they're black but not moist...it's running lean

 

[92AWDHX40]

Do you have a tuning device did you try any of the mentioned things in the thread. A boost leak testn
i would check everything, you would be surprised at the things that can happen.

 

[one_time]

No boost leaks....we tested the ISC today and it's working fine...like low n slow timing is dead on

We can push ours up over 4500 with no problems the only problem we have is while it idles...messed around with the BISS screw more and idle jumped from like 4 to about 9 but no change in the roughness...


We're going to test the ECU and the power transistor

ECU is fine....cleaning the throttle body now...see if that helps any

 

[lastshark08]

Sounds like my 97 GST did before I fixed it. My problems were due to a bad ECU that resulted in a VERY rich idle condition. It eventually fouled the plugs after a 10-15 minutes of idling. I would check the plugs and see if they are black and moist. If so, then you're more than likely running rich.

Another thing to look at is the power transistor (ignition module). Mine was also bad on my '97 which prevented me from going past 4.5k RPMS. Once the ECU and the power transistor was changed, the idle is solid and it revs to red.

Please keep in mind that the 2 things I reference above were found AFTER the normal trouble shooting process: check CEL's, vacuum leaks, boost leaks, sensor readings and compression/leak down.

Good luck

I think you have something electrical a mis there. I was having the same problem with fouling out plugs and turned out info wasn't getting to the ecu. Make sure that with all of your swapping of parts that you didnt miss plugging something in or break a connection somewhere. My car stayed in closed loop and ran very rich so it would drive but just not right at the lower rpms. Found out I had openings for a bunch of sensors in my harness.

 

[one_time]

Here is the idle after new plugs and exhaust leak fix

YouTube - ‪2011-06-20_20-10-55_417.3gp‬‏

 

[snowborder714]

You need to recirculate your bov.

Did you actually do a boost leak test? If so, how many psi did you test up to, and how long did it take to bleed down to 0?

Have you verified your spark plug wires are in the proper order?

If you have a 1g CAS (I can't tell), have you checked timing with a timing light?

 

[one_time]

You need to recirculate your bov.

Did you actually do a boost leak test? If so, how many psi did you test up to, and how long did it take to bleed down to 0?

Have you verified your spark plug wires are in the proper order?

If you have a 1g CAS (I can't tell), have you checked timing with a timing light?

Wires are in the proper order....we're going to get a boost leak kit tomorrow and it's a 2G

 

[hoby0316]

Check timing at idle with light. Check for boost leak at the level you are running if you haven't already. post results.

 

[ktgurl87]

Swear that sounds like the hubby's GST when the timing jumped a tooth. Just enough to throw it off, but it ran perfect up and down the street. That sucker had the original mitsu timing belt on it :\

 

[avengerscoot]

do a boost leak test and check the mas...try tapping the mas with a screwdriver and see if it changes....my car was the same way and tapping on the mas told me my mas was bad...my idle was fine while i hit the mas

 

[BWeston]

Sounds like my old GS-T when i first bought it, it had a bad MAF. It idled like shit and died until it was warm but it ran like a champ down the streets. Have you checked for codes or anything? seems like a bad sensor to me.

 

[one_time]

do a boost leak test and check the mas...try tapping the mas with a screwdriver and see if it changes....my car was the same way and tapping on the mas told me my mas was bad...my idle was fine while i hit the mas

Took the mas out cleaned it out it seems to be working fine....

Tomorrow we're going to do a boost leak test and I will post results....

 

[low_n_slow95]

I went throughout it again today and still no luck. I'm starting to think I'm a tooth off and just too dumb to see it.

 

[miguelmcv]

It sounds like a timing problem, Dirty Throttle Body, Boost Leak Or ECU Related.

 

[BWeston]

Keep us posted, good luck

 

[one_time]

So we did it....fixed the idle issue. We're unsure of what the problem was but today we took ALL the vacuum hoses off and replaced and ran them correctly....

This thread was a godsend

http://www.dsmtuners.com/forums/art...-speed-shop-vacuum-diagram-removal-1g-2g.html

I'd like to thank everyone of you for your input without it we'd probably be stuck at square 1....Thanks again!

 

[low_n_slow95]

That is a good thread. I used the same one on my car, unfortunately mine still don't run