The car: S5 TII engine, big street port. Recently rebuilt, so still building compression. Idle is currently set at about 1500-1600 RPM until the engine settles down.

The ECU: Microtech LT-8

The problem: Tweaking the idle map has no effect at all. The status of the Microtech clearly shows "IDLE". Vacuum is about 17-19". Idle is 1500 RPM as memtioned before. However, changing the LOAD map in that vacuum range will have the desired result.

Conclusion: Microtech knows the car is at IDLE, yet is reading fuel from the LOAD map? That's just plain weird. Any suggestions?

 

Try adjusting some of the lower vacuum points as well (~10inHg), if you've set the TPS correctly and you're getting IDLE status then you should be running off the Idle map. Also, when I have my %stage really aggressive (~99%) the idle map tends to get all whack due to dumping way too much fuel, just a thought.

-David Guy

 

are you in matrix mode or normal mode??

in matrix mode the idle map is the 500rpm map

Dale

 

Thanks. That's sort of why this is an issue. Yes, it should be reading from the idle map, but it is not. Adjusting any points under the idle map has no effect.

Setting the MIXTrim DOES have an effect as it should.

All other settings should be default.

Should be in normal mode. Unfortuantely I don't have the car with me now so I can't confirm for sure. Everything on the ECU should be at default.

 

are u positive that the tps is calibrated corectly? aka reading zero?

 

Yes. Absolutely. Without a doubt. There is not a question in my mind that everything is wired correctly and the TPS is set. The status CLEARLY shows IDLE, which it would NOT show if the TPS is not set correctly.

 

Thanks for rolling your eyes at my suggestion. I've had my idle set up to ~1600 for break in procedure as well and only had problems when my idle curve wasn't smooth, seems as though this is wrong due to its interpolation between two points, but this is what worked. Seeing as you're saying that you're 100% right on your wiring, then some other default setting has been adjusted that is having an undesired effect or your microtech is borked, being that your 100% right and all. Ciao.

 

If you notice, there's a smiley after the rolleyes graphics. That indicates that it is a joke. I used the rolleyes graphics because all you did was post exactly the information I had already included in my question. This indicates to me that you did not know the answer, didn't read the question, or didn't understand the problem.

Yes, I am very sure it is wired correctly. I have wired a number of these units, and it's very simple. Also, this car was running before just fine. The engine seized up (fault of the engine builder) so it was pulled, rebuilt and reinstalled. No settings were changed between the time the engine was pulled and the time it was reinstalled. Hence, it qualifies in my book as a "weird problem". Unfortunately, I do not have as much actual tuning time as I would like. Generally, I install the unit, get the car running, and then the owner is in charge of tuning.

The Microtech clearly shows that the TPS is properly calibrated (we verified this many times), that the ECU is in IDLE mode. Yet changing the idle map has no effect. Changing the load map does.

 

could it be that since the rpms are so high it is automatically defaulting to the load maps? hav eu tried lowering th rpms below or around 1000 to see if that changes anything?

 

pardon me if i'm flogging a dead horse ,
but it is possible for the idle screen to show 00% TPS but still be out of calibration.
You must see an asterix(*) in the middle of the second line of your idle screen to actually be in idle.
If you dont have the asterix the TPS is not calibrated and no amount of adjusting of the idle screen will work(Ecu thinks your at load)ie. throttle is open.
There is a few percent range in TPS calibration and you may need to run toward one end of this range.
On my car if I set TPS in the TPS calibration screen it wont always be in calibration in the Idle screen.
I hope this is of some help


hop13bt

 

Astrisk is present.

There is also a noticable change in the engine when the TPS is properly set.

Unfortunately I don't have the car in front of me so I must go by memory.

 

its been a long time since i have tuned a LT4, from memory there is a setting in the OPT or settings screen that will say IDLMAP or something, this will be a rpm style thing the idle map will only work if the rpm is below this

Dale

 

I am having the same issue, but my IDLE is at 800. My tps is also calibrated.

 

I will check that setting. Thanks.

 

OK, I have a 3rd gen with an LT8. The TPS is set correctly (it has the *). But the "status" is IDLE and the injector time is set at 4.76ms when ONLY the ignition is on (ie. 0 rpm). I dataloged this and still get 4.76ms.

When I crank the engine the status alternates between CRANK and IDLE, but no fuel is being injected (my wideband is AFR 20+). I did a Test Mode check (ie. set config to 0) and I can feel all the injectors pulsing. What's causing this?

Adrian