LS1 Running Rich

[TA 91 WA]

Hi everyone.

I've searched the forums and the internet, but mostly it comes back to the car running rough, which mine isn't, just plain rich.

I understand this is a extremely broad topic and I've done some homework into this and am hoping some others might be able to help me out here. Long story short, the LS1 is running far too rich. The car is off the road for 3 months, so now I can begin the process of elimination and fixing up loose ends with it.

The question is, what can cause the car to run rich? The fuel economy in the car isn't good, due to a s**t K&N air intake, and because it's been neglected to some degree.

So far I have changed:
- Spark plugs
- Ignotion leads
- Oxygen sensors

I know it isn't much so far, but I'm looking to get all bases covered. Can things such as the items listed below, adversely effect the fuel/air ratio?:
- ECU Coolant Temperatue
- Air Flow meter
- Throttle body
- Idle Air Controller
- Injectors

I'm not too sure where to honestly start, but I like to do my homework before I go to a mechanic for example, so I don't look dumbfounded.

Sorry for the rambling, I'm just looking for some direction to an awfully large question.

Many thanks, Tom.

[Darcon666]

Hey Tom,

Sorry to ask a question with a question... but... How do you know it's running rich?

[DLFHUB666]

^^^thats what i was gonna ask.

[accentstencil]

I was going to suggest oxygen sensors but I see you have changed them. Did you replace them with a good well known brand or cheapies.

[TA 91 WA]

Hey Tom,

Sorry to ask a question with a question... but... How do you know it's running rich?

Hi there Darcon.

Well, I can't be certain that it's running rich, but from what the old man and a few others have told me, the exhaust fumes smell pretty bad, like the fuel isn't being completely combusted (If that's the right wording)

I could be way off the mark, but the fuel usage is pretty high, and I don't know if you have to have the "nose" to know it's running rich.

It's what people have told me who are in the automotive industry have said. So I am going off what they have said, to some degree.

[TA 91 WA]

I was going to suggest oxygen sensors but I see you have changed them. Did you replace them with a good well known brand or cheapies.

I replaced them with Bosch 4-wire Oxygen sensors. The ones that were in the car, we're from factory (195,000 ago..)

[accentstencil]

You can tell if it's running rich by looking a the spark plugs or the exhaust pipe. If it's black then it is running rich.

[Darcon666]

High fuel consumption can be attributed to a number of thiings.

Provided there has not been any "TUNE" done to the ECU it will react according to it's inputs from a number of sources.

1. Spark Plugs(You have changed these, so good)
2. Leads(Done...)
3. Coilpacks
4. Blocked Air Filter
5. Dirty or blocked MAF
6. O2 Sensors(Done...)
7. PCV / Vacum leak
8. Fuel Leak
9. Fuel Filter blooked
10. TPS off
11. Injectors, as you have said.
12. Increased oil use???

...And the list could go on and on and on.

Suggest you take the car to a reputable LS1/Holden mechanic you trust in your area that can hook up the beast to a tech2 and check for any codes being thrown up.

[DLFHUB666]

beat me again.

[Darcon666]

You can tell if it's running rich by looking a the spark plugs or the exhaust pipe. If it's black then it is running rich.

Sort of agree.... My exhaust tips are black as black can be.

However I am getting between 15-18/100km arround the city on a head/cammed & tuned LS1 with 303.6rwkw.

beat me again.

^^^^^^^^^^^ got to be quick

[TA 91 WA]

Sort of agree.... My exhaust tips are black as black can be.

However I am getting between 15-18/100km arround the city on a head/cammed & tuned LS1 with 303.6rwkw.

^^^^^^^^^^^ got to be quick

I'm getting that just with an exhaust, no manifolds or engine work done.

As for exhaust tips, mine are pretty black, weren't black when I got the car 6 months ago, but pretty darn black now.

On a side note, how do you reset the ECU? Some say hold it at 2500 rpm for 10 seconds, some say just leave the battery disconnected for a duration of time.

[Darcon666]

On a side note, how do you reset the ECU? Some say hold it at 2500 rpm for 10 seconds, some say just leave the battery disconnected for a duration of time.

Both...starting with disconnect the battery for ~30min.

Holding the rpm @ 2500 is not the best... but up/down between 2500-3000rpm for about 30sec, this is to reset the idle back to normal.

[TA 91 WA]

Another thing.

Say for example I put the car into reverse, the revs surge. It gets the feeling like it's going to stall, but then the revs shoot back up.

It also does it in first before snapping into second. It doesn't usually stop till I give it some decent acceleration.

Fuel delivery problem maybe?

Also, do the throttle body and MAP look okay?:

[Darcon666]

Sounds like you could have a pcv/vacum leak somewhere or the IAT/MAF could be at fault.

TB looks ok, a little oily so got and buy a NON-Vented catch can and put it between the pcv hose and the TB.

MAP/MAF looks ok even though it's a little dirty(There are special cleaners to use on them as they are sensitive, so don't touch/scrub them...) Also I would go and get an LS2 MAP/MAF. Cheap as chips and no restriction(The mesh) and larger(95mm) compared to 80/85mm.

[accentstencil]

Sounds like you could have a pcv/vacum leak somewhere or the IAT/MAF could be at fault.

The rubber parts of the PCV hoses are prone to perishing, especially the "Y" piece at the rear of the engine. Worth having a look at the condition they are in.

[DLFHUB666]

if it is the pcv hose your car will idle like shit , i just replaced mine an put in a catch can aswell just for looks really.

[TA 91 WA]

Sounds like you could have a pcv/vacum leak somewhere or the IAT/MAF could be at fault.

TB looks ok, a little oily so got and buy a NON-Vented catch can and put it between the pcv hose and the TB.

MAP/MAF looks ok even though it's a little dirty(There are special cleaners to use on them as they are sensitive, so don't touch/scrub them...) Also I would go and get an LS2 MAP/MAF. Cheap as chips and no restriction(The mesh) and larger(95mm) compared to 80/85mm.

I really don't want to sound stupid here, but I think I am. What does IAT stand for. Having a pre new years dumb moment

[Darcon666]

I really don't want to sound stupid here, but I think I am. What does IAT stand for. Having a pre new years dumb moment

IAT = Intake Air Temp sensor on the Air Intake pipe.

If the sensor is rooted it will give false readings to the BCM/ECU increasing/decreasing the idle and I believe it will change the amount of air that passes through the TB by changing the throttle opening.

[TA 91 WA]

IAT = Intake Air Temp sensor on the Air Intake pipe.

If the sensor is rooted it will give false readings to the BCM/ECU increasing/decreasing the idle and I believe it will change the amount of air that passes through the TB by changing the throttle opening.

I'll try and get a video for you. It will probably explain the problem better than I could typing it into words.

[TA 91 WA]

Thought I might update everyone here and let everyone know that the problem has been found. Turns out it was the coil packs. Apparently there is a misfire through the rev range and really bad on low to medium revs. Shame I couldn't pick it :/

Thanks to everyone who has contributed their time to helping me solve the problem. Rep will be given accordingly