BoostBuggy

So are you suggesting I put the stock ships back in and adjust the FQS to the -3% mixture change?

Rogue_Ant

If you have the stock chips, then yes, that would be a great start.

BoostBuggy

Does the retard/ignition timing need to change also? i.e. setting the FQS to the #6 position with -3% fuel mix change and -3 degree timing retard?

odb812

I'd try to figure out why you are running that rich first. I understand that passing the test is your number one priority right now, but it looks like both of your problems derive from the same cause.

If you are running that rich, you have to be seeing smoke out the exhaust under boost, so you should be able to tell when you lean it out to a normal range without a wideband. You are going extremely rich maybe a little later in the RPMs than you should be seeing full boost. I see that as a big red beacon saying "check your vac lines."

Rogue_Ant

You can, which might help bring NOx down... however, for this next try, I would not.
The APE chips are quite aggressive with ignition timing, and fueling (especially in the mid-range). By simply going to factory chips, you will be reducing the ignition timing advance, and enleaning the car. Most likely that alone will be enough to pass. So, no need to reduce timing further via the FQS (at least not at this point).

BoostBuggy

I'll change the chips, adjust the FQS (for fuel only,) chk vac lines and check for the altitude sensor tonight (or sooner if I can.)

Is there a way to chk the alitude sensor for operation? i.e. Is is good?

Rogue_Ant

The altitude sensor should be a closed-circuit up here... You can simply short the two pins, in-place of the altitude sensor, and that will tell the DME to pull fuel in order to account for the altitude.

quinnfiske

When I failed emissions, I replaced the O2 sensor with the correct 3 wire one. Afterwards, the test numbers were VERY different, but still failed. I ended up adjusting the AFM at the air bypass screw. Since the cap over the screw was missing, I guess the PO had adjusted it to pass at an earlier time with a worn sensor. When I put the new one in, it was out of adjustment. I got it to pass in the end. In the future I am going to treat these O2 sensors as a replacement item and toss another one in after 30K miles or so.

Bri Bro

Looking at your dyno run, I am inclined to agree that something is wrong with the current setup. Your AFR took a nose dive to the bottom of the graph after 4K RPM. I am guessing it when even lower then the last line on the graph which was 10/1 and stayed there. It is interesting that at lower RPMs, it looks like your closed loop is working since it is at around 15/1.

If it was me, I would check the DME temp sensor, do a vacuum test, check door and the air temp sensor(if you have factory air box), and check that the fuel pressure is correct for you chips.

Tom M'Guinn

My APE chips ran very rich, especially under load in the middle of the rpm range -- even though I believe they were CARB-certified -- go figure. I bet just returning to the stock chips and doing nothing else will help significantly. Altitude sensor is tucked way up behind glove box -- super fun to get to.

My post crossed with Brian's above -- his suggestions all seem sound to me...

Bri Bro

That is so true, APE chip did run rich. I remember a friend said he could always tell when I went on boost because a big black poof of smoke would come out of the exhaust and then the car was gone.

I am sure they ran at the high 10 to low 11s, his Dyno run had it pegged at 10 or below so that just doesn't look right to me. Going to factory setup is a good step, I just wonder if something else is going on here.

BoostBuggy

Hey thx to all of you for the suggestions and help. I really do appreciate it.

I wasn't able to get to things last night as I had planned (hoped.) The emission testing is not open again until Tuesday so the plan now is to get at things on Monday.

FWIW it does still have the factory airbox. In fact other than the APE ships and LR downpipe it is all factory and original. All 204k miles of it. I wouldn't be all that surprised if there ended up being several items that need repair/replacing, like the O2 sensor. Who knows if it has ever been replaced.

I'll let all know how it goes after the weekend and if I had to replace anything else.

BTW, what is the best way to check the vac lines other than eyeballing them?

Ky944TurboNewbie

For testing the vacuum lines, I prefer to hook up a 2" OD pvc cap with a valve inserted. Less than $5 to make one with some parts from home depot and the FLAPS. Pressurize to about 10 psi and use soapy water and your ears to check for leaks. I had problems under my J Boot and at the Throttle Body. I will be rebuilding my Throttle Body as soon as the kit arrives from Arnnworx. Here are some tools that are available and a write up.

http://arnnworx.com/boost_testing.htm

Here is a video with a slightly different setup attaching the device at the J Boot.


I can snap a picture of my adapter if you think it will help. I bet you get the idea from the above links.

Droops83

That is a good way to check for vacuum and boost leaks.

Just to be clear, the original poster is having issues with running rich under load. A vacuum leak will cause an engine to run lean, especially at idle and at low RPM. On turbocharged engines like in the 951, a vacuum leak can also become a boost leak, depending on where the leak is. The point is that while being a common cause of many issues with these cars, a vacuum leak would not be a likely cause of his issue.

I agree with the consensus of starting with stock chips. The aftermarket chips are too big of a variable to work around.

blown 944

I can see APE chips going to less than 10:1 afr at this elevation easily. DA is generally over 8000ft