# After Installing exhaust...



## Rephlex (Mar 7, 2005)

What needs to be done with the ECU after installing a cat back? I'm running rich as hell and when the a/c is off, it likes to idle around 300-600rpm. Just did a tune-up consisting of plugs, wires, dist. cap, rotor, air filter. Just wondering if maybe the exhaust has something to do with the idle speed.

Going out on a limb here, anybody dealt with Kuruma Motoring?


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## spec240sx (Aug 22, 2004)

Rephlex said:


> What needs to be done with the ECU after installing a cat back? I'm running rich as hell and when the a/c is off, it likes to idle around 300-600rpm. Just did a tune-up consisting of plugs, wires, dist. cap, rotor, air filter. Just wondering if maybe the exhaust has something to do with the idle speed.
> 
> Going out on a limb here, anybody dealt with Kuruma Motoring?


It should run 600-750rpm. The Exhaust you had was bad news and plug city.
The new 1 is OPEN and the 02 is seeing more air than fuel.
So You need to reset the timing and idle. Run it for awhile(1 - 2 tanks of fuel) to have the ECU and exhaust work together. Then revisite the situation.


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## Rephlex (Mar 7, 2005)

Probably a stupid question, but is timing something I should be messing with? I was thinking of just taking it to a shop to get it tuned, but if it's something I can handle, I don't mind doing it.


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## cwrr226 (Feb 24, 2005)

Rephlex said:


> What needs to be done with the ECU after installing a cat back? I'm running rich as hell and when the a/c is off, it likes to idle around 300-600rpm. Just did a tune-up consisting of plugs, wires, dist. cap, rotor, air filter. Just wondering if maybe the exhaust has something to do with the idle speed.


wow damn i bought my catback off of ebay and im not runnin rich....

post the link of the catback u bought...


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## spec240sx (Aug 22, 2004)

Rephlex said:


> Probably a stupid question, but is timing something I should be messing with? I was thinking of just taking it to a shop to get it tuned, but if it's something I can handle, I don't mind doing it.


If you have played under the hood besides just adding oil/water and litle stuff. You should be able to handle it. Yet, if not really mechanical then no worries, find someone.
YET., before you do, find http://240sx.org/faq/
Frequently Asked Questions
And review the timing and anything else you are interested in.


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## StreetTech180 (Mar 30, 2005)

I've heard adjusting the timing on a KA24DE is really hard... I can't speak for any of you, but that's something I would have a shop perform...


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## bridrive55 (Aug 26, 2004)

Rephlex said:


> What needs to be done with the ECU after installing a cat back? I'm running rich as hell and when the a/c is off, it likes to idle around 300-600rpm. Just did a tune-up consisting of plugs, wires, dist. cap, rotor, air filter. Just wondering if maybe the exhaust has something to do with the idle speed.


I'd say you have a vaccuum leak or sensor problem. I'd inspect the vaccuum lines, and if it looks okay, maybe take it to a dealer. Dealers often give free diagnostics, because they expect that you will get the work done by them. I would take the car in and ask for a free diagnostic, maybe hinting that you'll have it fixed by them. Then I'd sneak off and do whatever they suggest myself. It might just be a bad 02 sensor, clogged fuel filter, or poorly adjusted auxiliary air valve.


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## Rephlex (Mar 7, 2005)

bridrive55 said:


> I'd say you have a vaccuum leak or sensor problem. I'd inspect the vaccuum lines, and if it looks okay, maybe take it to a dealer. Dealers often give free diagnostics, because they expect that you will get the work done by them. I would take the car in and ask for a free diagnostic, maybe hinting that you'll have it fixed by them. Then I'd sneak off and do whatever they suggest myself. It might just be a bad 02 sensor, clogged fuel filter, or poorly adjusted auxiliary air valve.


Wouldn't most of this trigger an engine light? This is a very intermittent problem, it's only done it twice a couple days apart, and only when the engine is cold, so I'm hoping it's running rich. It spits uncombusted gas (?) out the exhaust when you rev it, and burns through a tank a little quicker than I'd like it to. I got the exhaust put on at Meineke (yeah I know...) and it's got the 3 way adjustable tip on the muffler. Can't remember the name exactly, probably something with extreme (without the e) in the name.


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## bridrive55 (Aug 26, 2004)

Rephlex said:


> Wouldn't most of this trigger an engine light? This is a very intermittent problem, it's only done it twice a couple days apart, and only when the engine is cold, so I'm hoping it's running rich. It spits uncombusted gas (?) out the exhaust when you rev it, and burns through a tank a little quicker than I'd like it to. I got the exhaust put on at Meineke (yeah I know...) and it's got the 3 way adjustable tip on the muffler. Can't remember the name exactly, probably something with extreme (without the e) in the name.


My engine light was burned out. 
It could be a sticky CSV (cold start valve). That would make it run rich for a while after a cold start.


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## Rephlex (Mar 7, 2005)

bridrive55 said:


> My engine light was burned out.
> It could be a sticky CSV (cold start valve). That would make it run rich for a while after a cold start.


Interesting... Seems to be running rich at all times though. It's almost always sluggish, and it's burning through a lot of gas. I just wish I had time to get in there and figure out the problem, but between work and school and girl, damn I'm getting stretched thin.


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## bridrive55 (Aug 26, 2004)

There are several vacuum vavles that could cause richness. A vacuum leak could make one of these valves stick closed or open. I would just take it to a dealer if you don't have time to deal with it.


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## rogoman (Dec 16, 2004)

Rephlex said:


> What needs to be done with the ECU after installing a cat back? I'm running rich as hell and when the a/c is off, it likes to idle around 300-600rpm. Just did a tune-up consisting of plugs, wires, dist. cap, rotor, air filter. Just wondering if maybe the exhaust has something to do with the idle speed.


Nothing needs to be done to the ECU or the motor when installing a custom CAT-back exhaust system. When you did your tune-up, you may have messed something up to cause your problem. Make sure the O2 sensor and the temperature sensor is properly connected.


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## Rephlex (Mar 7, 2005)

Now I just need to find a good dealer to take it to. Anybody in metro Houston area recommend any place? Seems to be running nice, aside from the slight sluggishness, did my second drift tonight on the way home from work :thumbup: too much fun.


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## Rephlex (Mar 7, 2005)

So I just took it to a shop for advice, and they recommended changing the fuel filter, adjusting the timing to solve my problems. I told them, a-ok and they did it. It runs great now, seems to be right where it should, only now I think my PCV valve is shot, I checked another thread and it seems that could be the reason I'm coming really close to stalling every time I come to a stop. As soon as I put in the clutch, it drops all the way, then comes back up after a second. Murphy's law in action, I gues....


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## S14240SR (Aug 20, 2004)

rogoman said:


> Nothing needs to be done to the ECU or the motor when installing a custom CAT-back exhaust system. When you did your tune-up, you may have messed something up to cause your problem. Make sure the O2 sensor and the temperature sensor is properly connected.


Thats true that he could have messed with something like the O2 sensor and not noticed.

Shouldent you reset the ECU after installing an exhaust?


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## bridrive55 (Aug 26, 2004)

The PCV valve isn't in a conspicious place. It's under the intake runners. I would have that diagnosed and repaired by a shop as well.


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## Rephlex (Mar 7, 2005)

S14240SR said:


> Thats true that he could have messed with something like the O2 sensor and not noticed.
> 
> Shouldent you reset the ECU after installing an exhaust?


Dude said: "Running nice! Sound good, idle just right!" 
Works for me. I drove it a few more times since bringing it back from the shop and it's running fine... That idle thing is gone (for now). Weird...


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## rogoman (Dec 16, 2004)

S14240SR said:


> Shouldent you reset the ECU after installing an exhaust?


No need to reset the ECU.


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## bridrive55 (Aug 26, 2004)

Rephlex said:


> Dude said: "Running nice! Sound good, idle just right!"
> Works for me. I drove it a few more times since bringing it back from the shop and it's running fine... That idle thing is gone (for now). Weird...


Intermittent problems can be worse than constant problems, because they are harder to diagnose. Valve behavior is often the cause of intermittent mixture issues.


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## Rephlex (Mar 7, 2005)

It's weird, I drove it about 20miles total today, the problem is all gone. Had the a/c cranked up and driving all over town. I'm starting to think my gas guage needle is stuck, I filled it up after getting the timing adjusted (20 miles ago) and the damn thing hasn't moved. God it's nice having a car that runs (mostly) right.


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