Hey guys, Started tuning my LT8S. Well... "started" We busted *** finishing up my car, stayed up late all week, couple all nighters, like yesterday. Finally got the car started and then on the dyno at 7:00 am. At 4:00 pm we gave up. That's a long *** time to sort out all different possibilities.

Changed CAS, some wires were grounding out on my first one. Ran better, but problem still occurred.

I have a fucked up intake air temp sensor. (possible problem?)

I have a (we think) fucked TPS. At 30% throttle, it will start reading 100% voltage. WTF.

Despite those issues, we figured we could muscle past it and at least lay down a couple solid runs with boost.


I am running stock 550 primaries and RC Engineering 1000cc secondaries, T04S, HKS mani, HKS GT 'gate, TiAL BOV, Greddy compression tube, V-mount setup, and that's all the important stuff.


From the moment we cranked it and got it to start (resolved some mixed up wiring issues) it ran awesome. AWESOME. I mean, 12:1 then going to 10.5:1 AFR, and as soon as it really started to get into boost around 4k and we had the secondaries come in, BOOM spike up to 16:1, even more, then we obviously would let off as soon as that would happen.


WTF!!!


Checked a billion times to make sure the secondaries were opening, and operating. Yes. All good.


We put back 550cc secondaries.

Same thing.




Then I said **** it, lets try 1000cc primaries. After massaging a map to allow those suckers an idle, we got them dialed in, boost, nice, then about 4K again BOOM lean as ****! WTF! With 1000cc PRIMARIES!!!!!!!!!!!


Ok, we've been up for a couple days so maybe we're missing something super obvious, but right now my experience with the Microtech is driving me goddamn insane!!! We even had the previous tuning guru help out. Darren (now the landlord) from RnD Dyno. He spent a good 2 hours volunteering to help me out. STILL, even stumped him, and he's tuned LT8S 13BTs all day before!



I will bet its due to lack of sleep, but has this happened to anyone else before? Are we underestimating the importance of a proper good TPS and IAT? Like I said up till decent boost at 4k, the bitch runs PERFECTLY, really amazing, lots of flames (not even from being obscenely rich) and an amazing sound. So sad, I wanna take her to 8k!!!!!


Thanks anyone who can help!!

-Lindsay

 

You wired up the short range TPS, if this is an s5.

My intake air temp sensor is reading wierd, and my car runs fine, so no problems there. I have no idea how to solve your other problems.

 

what have you set the rev_stg and map_stg to.

if you have 550cc injectors and 1000cc injectors


set your map_stg @ 4HG
and your rev stg @ 2250rpm.
see if this solves your problem.

 

We had very close to those numbers during tuning. It did help, but it wasn't a complete fix.

I am going to switch to a Haltech. Kinda mutual decision between me and the shop, cause they are much more comfortable and able with the Haltech.

 

sorry to thread steal but i am having the same issues. and i was wondering what do you mean when you say you wired up the short range tps???

 

dont worry about the tps. as long as it has 0% on idle and 99% on any amount of throttle that will satisfy the microtech when running in map sensor mode.

 

Dont know if this helps but i had the same problem..
My 1680 was opening to much at 3000.. it felt like hitting a wall.. The problem was a map made for alot smaller injectors than 1680cc.. Newb map problems, i know... Just an ide..

 

This sounds very familiar to what i experienced on the dyno a few weeks ago....

Initially the car went fine did a few good pulls, got some good numbers, after a while i started experiencing what ur describing... car started hitting a wall when coming on boost, like when the secondaries are (or not) coming on...it was really weird... did a comp test whilt on the dyno 110psi on all faces on both rotors...

Tuned the car the best we could with it behaving as described, took it off the dyno and took it for a road test...Well the car went like a bullet, no problems pulling like a train, even when the motor was loaded up heaps boosting up a hill in 4th...was very weird....

After some discussion, we put it down to two things
1. badly sealing motor, possilbly due to worn out side seals and springs(Unlikely with those comp numbers and the age of the motor, 10,000kms) or

2. Dyno loading issues, dyno loading up the motor too much?... could be ur problem aswell.. just a thought...

Motor is a 13BT Full-Bridgeport, Microtech LT10S, 1000/1600cc injector combo Masterpower T70, Bosch 044 fuel Pump and all the requried extras.