LSJ tuning need help...idc doubles in blink of an eye

**djt81185** · 10-22-2007

Here is the log from my car (motor actually threw a rod threw a rod bearing which led to rod thru block 4 miles down the road from the end of this log)

I know the boost is incorrct so just interpret from the map kpa.

Why is it between 5 and 6k rpm that the car goes really lean then the inj duty cycle doubles and the car is fine? Any ideas?

Around 1:26 is best place to look

Thanks,
Dan

**JMHZ2401** · 10-22-2007

Looks like you are not commanding enough fuel around 5700 RPM

**djt81185** · 10-23-2007

But the question is...why wont the afr actual follow the commanded and why is my maf getting that strange hump in it at 9900hz. Ive tried correcting it via pe and it doesnt help. The weird injector spike is what really worries me.

**JMHZ2401** · 10-23-2007

I do not see a spike in MAF. From my understanding the car will try for whatever set AFR you give it, but that does not mean it will keep that. Adjustments still have to be made to get the fuel you need. As for you IDC numbers, yes they are high, but not as high as most SS/SC. What injectors are you running. Seems most SS/SC (even stock) run over 100% close to 130%. From looking at the log, I would say your IDC starts low (where you are needing more fuel), then raises up where you are good.

**BlackSS/SC** · 10-23-2007

He is very far from stock, turbo conversion. He knows his IDC is high but he's talking about how it goes from like 40% to 80 % in a split second. I don't have the answer but hope this clarifies it a bit more.

**JMHZ2401** · 10-23-2007

Originally Posted by BlackSS/SC

He is very far from stock, turbo conversion. He knows his IDC is high but he's talking about how it goes from like 40% to 80 % in a split second. I don't have the answer but hope this clarifies it a bit more.

I know what he is talking about in the IDC, but that is the same time as his lean spot. SO I think it is because he did not have enough fuel (adjustments need to be made), then IDC went up because request fuel was up and the car was running in safe AFR's.

**BlackSS/SC** · 10-23-2007

When I look at his log I see a commanded afr of 12.00 even where the IDC spikes. I dunno, maybe I'm missing something.

**JMHZ2401** · 10-23-2007

Originally Posted by BlackSS/SC

When I look at his log I see a commanded afr of 12.00 even where the IDC spikes. I dunno, maybe I'm missing something.

Yes you do. From my understanding (and I could be very wrong, still learning myself) you have a command AFR, but that does not mean the car will run at that AFR, it might need tweaks in the VE tables to get it there. Maybe Bill or someone from HPT can chime in and verify this info, or set me straight on this.

**BlackSS/SC** · 10-23-2007

Ya you set the commanded afr at what you want it to be, which doesn't mean it will automaticly run at that afr. You need to tweek the Maf table to get it right and also tweek the PE table a little if needed to make it match. DJT is a great tuner though so that's not his issue.

**JMHZ2401** · 10-23-2007

What kind of turbo set-up? Intercooled? Looking at his IAT temps they are very high, and I was wondering on the set-up. How much boost?

**djt81185** · 10-23-2007

21psi, stock water to air intercooler. IAT 1 will be higher then IAT2. If i keep retuning the maf the maf table keeps getting worse looking but the afr situation remains the same or even worsens.

car has 60lb injectors

**JMHZ2401** · 10-23-2007

Originally Posted by djt81185

21psi, stock water to air intercooler. IAT 1 will be higher then IAT2. If i keep retuning the maf the maf table keeps getting worse looking but the afr situation remains the same or even worsens.

car has 60lb injectors

Really needs a front mount intercooler. Alsio shouldn't IAT1 be lower than IAT2, or do you have it set-up differently for some reason?

**zinner** · 10-23-2007

Originally Posted by JMHZ2401

Really needs a front mount intercooler. Alsio shouldn't IAT1 be lower than IAT2, or do you have it set-up differently for some reason?

Blow through MAF is the cause of that sir.

**JMHZ2401** · 10-23-2007

Originally Posted by zinner

Blow through MAF is the cause of that sir.

Still needs a front mount.

**djt81185** · 10-23-2007

It doesnt NEED one but it wouldnt hurt either after seeing some logs of cars running both...under wot im only seeing 140 deg max for air post intercooler

BACK to the original question...anyone have any answers to the injector problem?

**fullthrottle** · 10-24-2007

Originally Posted by JMHZ2401

Still needs a front mount.

Are you saying DJT should eliminate the stock intercooler and Just run a FMIC or are you saying that he should run both? If he ran both wouldn't it create too much of a pressure drop resulting in less boost?

**JMHZ2401** · 10-24-2007

anyone have any answers to the injector problem?

Tuning.

Are you saying DJT should eliminate the stock intercooler and Just run a FMIC or are you saying that he should run both? If he ran both wouldn't it create too much of a pressure drop resulting in less boost?
Yesterday 11:07 PM

A new intake manifold (to get rid of the exchanger) and use a front mount. Just like what Hahn's kit is using.

**djt81185** · 10-24-2007

Ive tried every tuning trick I know of to get rid of that injector spike. Now another cobalt that is turboed is having the same issue and we each designed our own tunes. Lastly a cobalt that is still supercharged is starting to see the same issue. I think its somewhere in the hardware but I have no idea. Wish Bill or one of them would jump in here.

**djt81185** · 10-26-2007

Any of the pros have any ideas?

**djt81185** · 10-29-2007

Any support...from the guy who write the stuff?

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LSJ tuning need help...idc doubles in blink of an eye