kghaas

My car is ideling verry nicely at 11.5 AFR. However to meet legislation i Norway I have to have it at 14ish(as it should be)

My problem is that I have a lot of upgrades such as Mafterburner, MAF, LR65 turbo, 72# Injectors, chips etc. All LR stuff matched to each other.

I have mapped the car inn realy well, but the problem is the Idle and cruise. No way I can get it close of 14.7. It is in the 11s all the time.

I have checked all wires, I have checked the Temp sensor at the front of the block and pretty much everything. I have also tried to tune the idle with the mafterburner but it does not affect the idle AFR

My question: Is there some way of telling if the DME is in a fault mode? Is there some way of telling what the DME is doing ie Closed loop, open loop.
Any way of sending a cheat signal throug the original O2 wiring(Car is non-cat, without o2 sensor)

Any suggestion welcome.

kghaas

The Map at WOT. Not realy linked to the Idle issue...



The Car:

hp18racer

A failed TPS switch made my car run as you describe, rich all the time. Search for 'blink code tester', you can make one with an LED, the KLR will tell you if your throttle position sensor is failed.

kghaas

Thanks for the reply hp18racer, but it is not the TPS. In the mafterburner software I can read all details from the TPS and it is all fine, both angle and voltages.

Any other suggestions?

I will investigate the blink code tester

rlm328

My 2 cents. The car only idles at an AFR 14.7 at cold idle. It will drop to mid 11s when it is warm. The high AFRs are to rich for the car and will cause cylinder washing if you are not careful.

Stupid question #1, why does Norway require AFRs of 14s when it is an over rich situation and will cause more pollution?

kghaas

Thanks for replying Bob, but I think I might not have explained it properly. It idles when warm at 1:11,5 and the same when cold. It should be at 1:14,7 when warm, which is much leaner than and therfore more eco friendly

Bri Bro

What I would do is bump down fuel using the Mafterburner from 700-1500 rpm until the afr is around 14.7/1. If it is running in closed loop, the DME will ditter the mixture and you should see the AFR go below 14.7, then above 14.7 about twice a second. If it doesn't, I would look at the O2 sensor voltage to see were it is. Above 14.7 say, at 15, it should be below 0.3 volts, below about 12 it should be around 0.8 to 0.9 volts. If the O2 is working correctly and the DME is in closed loop, the O2 voltage will ditter around 0.5 volts.

hp18racer

The O2 sensor test is a good idea. You can make it go lean by intentionally disconnecting something (brake booster hose is easy) to cause a big vacuum leak.

Did it ever idle right with the current chip/injector combo? When I first got my 2.8 running it idled very rich. I found that the idle mixture table in my chip set was unchanged from the stock values. I had to change my chip to fix it. Once the idle mixture table it was close enough to go into closed loop it maintained 14.7 everywhere else too.

Might also ohm out the connection for the 'full load signal' from the KLR to the DME and then monitor the value when it is running. Seems likely your DME is getting a false signal for O2 or 'full load'.

76 911s

Have you checked your FPR?

kghaas

Thanks all for helping out with this problem.

As to some of the suggestions:
Mafterburner has been used to tune the idle. I have taken the Mafterburner to 100% lean. It does not affect the AFR at all. This to me indicates that the chip is running at a pre programed table and does not take account of AFM signals. There is no O2 sensor on the car so not much to chase after there i guess.

I will test a vacume leak to see what happens
It has never Ideled at the right values with this setup, but since Lindsey racing made me a new chip free of charge(good customer service!) I would guess it has all the right values.
I will definitly ohm the full load signal. Just have to check up what it is

The FPR is brand new, and i have also measured it. 2.5bar as standard. I previoslu tried 3.0bar but struggled to get the AFR curve correct. With 2.5 it is all good all the way (excep idle....)

Thanks again guys

Van

Put an air pump on there... That was the solution in the '70s - pump fresh air into the exhaust to make the parts-per-million values go down.

If you pump fresh air into the exhaust, it will likely fool the wide band!

Bri Bro

You adjust it to 100% lean and no change, that is just strange. Does the Maferbuner effect any RPM band outside of idle? I can stall my car with a 20% change at idle. With the Lindsey setup you should be running a 3 bar FPR unless you ordered custom ICs. With a 2.5 you should be lean across the RPM band. Are you sure you have it setup for the correct injector size? Did you check that the TPS contacts close (click) at idle, this is what changes the DME to the idle map. The contacts are a separate circuit from the TPS angle voltage readout.

Here is the procedure for testing the Full load contact:

schip43

Hmm well I had the opposite problem, my had been idling fine at 14.7 but it started to idle lean all of a sudden. I checked for vacuum leans and the only thing I found was a bad seal in the throttle body. It reacted to carb spray. I rebuilt the TB and now it was fine but the lean idle was still there.
So I started looking at stuff and I found that the lock nut on my 3 bar regulator was gone???
I adjusted the fuel pressure up and it's at 14.7 again. Replaced the nut and used blue loctite.
Just a thought.